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Cited by 0Refrigeration and Air Conditioning TechnologiesHeat Transfer and OptimizationAdsorption and Cooling Systems

Studies of an air cooler under frost condition

Open access
Cheng, Yeong Chang·2019
DOI 10.32657/10356/6557
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Abstract

Frost accumulation on an air cooler, a direct result of combined heat and mass transfer between the moist air flowing across a cold surface, causes heat transfer performance degradation due to the insulating effect of frost layer and the coil blockage as the frost grows. The complex geometry of finned tube air cooler leads to uneven wall and air temperature distribution inside the coil, and causes variations of frost growth rate and densification along the coil. In this study, a general distributed model with frost formation was developed to predict the dynamic behavior of an air cooler both under non-frost and frost condition. Results include frost accumulation and its effect on energy transfer, air off-coil temperature, refrigerant liquid dry-out position and propagation of frost formation along the coil.

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Written from the paper’s full text.

TL;DR

This thesis develops a distributed transient model of a finned-tube air cooler that couples two-phase or single-phase refrigerant flow with a quasi-steady frost layer, then checks it against published single-row data and field measurements from an R-12 refrigerated container. The model reproduces major frosting trends but under-predicts multi-row pressure drop and frost mass, with the latter attributed mainly to condensate drip.

Key findings

  • For a single-row flat finned-tube test, the model predicted 0.46 kg frost mass versus 0.43 kg measured, about a 7% discrepancy, and matched air-side pressure drop within 8%; in the full-scale container, energy transfer agreed within ±3% although experimental uncertainty was ±6%.
  • In the container field tests, the model under-predicted air-side pressure drop by about 20%, air outlet temperature deviation grew to roughly 1–2 °C under frosting, and predicted frost mass was 6.13, 6.62, and 6.73 kg versus collected condensate of 8.28, 8.49, and 8.82 kg, about 25% low.
  • Frost degraded performance: energy transfer decreased as frost accumulated, air pressure drop rose from about 20 Pa to about 330 Pa, frost first appeared at the ends of the first row near the refrigerant inlet, and it propagated toward the coil exit with the first row accumulating the most frost.
  • Parametric simulations showed greater frost accumulation at lower air mass flow (3.07 kg at 0.75 kg/s versus 2.41 kg at 1.5 kg/s), higher relative humidity (70% RH gave 13.7 Pa pressure drop versus 3.8 Pa at 50% RH), higher inlet air temperature (3.15 kg at 7 °C versus 2.36 kg at 3 °C), and larger fin pitch (2.93 kg at 6 fpi versus 2.57 kg at 10 fpi); fin-base frost height was 0.315 mm versus 0.239 mm at the tip after 50 min.

Methods

  • A distributed finite-difference model was built for refrigerant mass, momentum, and energy in one-dimensional transient form, using a two-phase drift flux approach with the Chisholm correlation selected, plus a single-phase refrigerant version; tube-wall and fin energy equations, air-side heat and mass balances, and a quasi-steady frost growth/densification model with permeation were included.
  • Sensitivity studies selected 10 fin nodes, a convergence criterion of 10⁻⁴, and 40 cells per row; frosting simulations ran for 3600 s with a 30 s time step, while a validation case used 40 cells per coil and a 10 s time step.
  • Validation used published single-row flat finned-tube data with 50% ethylene glycol/water, inlet air at 0 °C and 80% RH, face velocity 0.762 m/s, and refrigerant inlet at −15 °C, plus field tests on a 40-ft refrigerated container with R-12, a 6-row/9-circuit evaporator, 514 aluminum fins, 12.7 mm copper tubes, three observations over more than 3 hours, outdoor temperatures of 33–35 °C, and steam injection at 5.9 kg/h.

Limitations

  • The paper states that the model under-predicts pressure drop for multi-row coils by about 20%, that the air-side heat transfer coefficient deviates once frost forms, that frost mass is under-predicted by about 25% mainly because condensate drip and post-shutdown vapor transfer are not modeled, that the permeation model needs experimental validation, and that the model is limited to flat fins and smooth tubes and is not linked to a system model.
  • Evident from the text: field validation rests on only three observations; the frosting simulations hold inlet conditions constant to isolate frost effects, unlike real transient operation; the simulation assumes uniform air distribution while the field showed uneven flow; and predicted frost propagation reached later rows earlier than observed.

Model-written summary. Check it against the paper before relying on it.

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Registry

Crossref · 10.32657/10356/6557

Cites

61 of 61 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

3 of 96 cited sources checked · 1 supported · 0 flagged · accuracy not yet measured

  • Premisecitation
    § 3.4.3 Pressure drop across coil

    The friction factor correlation from Wang et al. (2000) is only valid for the condition without frost.

    “The above friction factor is only valid for the condition without frost.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Wang et al. (2000) source

      The Results and discussion (p. 7) present a friction-factor correlation, and the Conclusions (p. 8) specify its applicable fin geometry and dimensions. Neither passage addresses frost or says the correlation is valid only without it; searches for frost and dry-surface conditions found no such statement in our copy. (LLM, conf=0.72)

      Experimental — accuracy not yet measured
  • Premisecitation
    § 3.4.3 Pressure drop across coil

    Wang et al. (2000) friction factor correlation can predict 85.1% of the test cores within ±15%, with a mean deviation of 8.31%.

    “Wang et al. (2000) correlated the friction factor, f, from a total of 74 test cores.The proposed friction factor correlation can predict 85.1% of the test cores within ± 15%, with a mean deviation of 8.31%.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Wang et al. (2000) source
  • Findingown data
    § 2.1 Frost Property

    There is a wide spread in predicted thermal conductivity for a particular frost density among earlier frost thermal conductivity models.

    “Figure 2.1 shows comparison of some earlier frost thermal conductivity models.It shows that there is a wide spread in the predicted thermal conductivity for a particular frost density.”
    Quote in the paperNot a substantial claim
  • Findingown data
    § Abstract

    The presented model is able to predict the dynamic behavior of an air cooler under both non-frost and frost conditions.

    “The presented model is able to predict the dynamic behavior of an air cooler both under non-frost and frost condition.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    Model predictions agree well with reported experimental results based on frost mass accumulation, pressure drop across coil and energy transfer coefficient.

    “Comparisons were made based on the frost mass accumulation, pressure drop across coil and energy transfer coefficient, and results were found to agree well with reported experimental results.”
    Quote in the paperSubstantial claim
  • May combine two claims. 139
  • The quote only partly states this claim. 3
  • Classified as probably not a substantial claim. 69

  • May combine two claims.

    Premisecitation
    § 3.3 Governing Equation for Tube Wall Side

    Wang and Chi (2000) air-side heat transfer correlation can predict 88.6% of the test points within ±15%, with a mean deviation of 7.51%.

    “Wang and Chi (2000) correlated the air side heat transfer coefficients, U o , from a total of 74 test cores.The proposed heat transfer correlation can predict 88.6% of the test points within ± 15%, with a mean deviation of 7.51%.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Wang and Chi (2000) source

      The Results and discussion (p. 7) report that the heat-transfer correlation describes 88.6% of j factors within 15%, supporting that part of the claim. They give a mean deviation of 7.53%, as do the Conclusions (p. 8), rather than the claimed 7.51%. (LLM, conf=0.85)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data
    § Abstract

    The air outlet and energy transferred compare well between experiment and model.

    “The air outlet and energy transferred compare well between experiment”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    Air pressure drop is highest for the 7°C condition at 9 Pa, followed by 5°C at 6.8 Pa and 3°C at 5.8 Pa.

    “From Fig 4.25, it can be seen that the air pressure drop is highest for 7 o C condition with pressure drop of 9 Pa, followed by 5 o C of 6.8 Pa and 3 o C of 5.8 Pa.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 4.1.4 Selection of time step

    The three drift flux models give almost the same predictions, while the homogeneous flow model predicts a larger two-phase flow region than the drift flux models.

    “From the graph, it can be shown that the three drift flux models give almost the same predictions while homogeneous flow model predicts a larger two-phase flow region than the drift flux models.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 4.2.2 Effect of refrigerant liquid dry-out position and air temperature distribution inside the evaporator

    The more rows flooded by two-phase flow, the lower the air temperature difference; that is, lower superheat gives more uniform air temperature off the coil.

    “It is also observed that the more rows flooded by the two-phase flow, the lower the air temperature difference would be resulted, i.e., the lower the superheat, the more uniform air temperature off the coil may be obtained.”
    Quote in the paperSubstantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    The frost height at 3600 s is highest for the first row at the refrigerant inlet, followed by the second and third rows.

    “The frost for the first row at the refrigerant inlet is the highest, followed by the second and third row.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 4.1.4 Selection of time step

    The drift flux models predict results close to experimental data, but the experimental data show a continuous decrease trend.

    “The drift flux models predict the result close to the experimental data but the experimental data shows continuous decrease trend.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    The total energy transfer rate for inlet temperature 3°C decreases from 10.59 kW to 10.40 kW, for 5°C from 10.75 kW to 10.65 kW, and for 7°C from 10.87 kW to 10.81 kW.

    “From Fig. 4.21, the total energy transfer rate for inlet temperature of 3 o C decreases more from 10.59 kW to 10.40 kW as compared to 5 o C, from 10.75 kW to 10.65 kW, and 7 o C, from 10.87 kW to 10.81 kW.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    Cells 180 and 221 are not represented because their wall temperatures are above the freezing point and no frost is formed.

    “Note that cells 180 and 221 are not represented, because the wall temperatures of these cells are above the freezing point and hence no frost is formed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    The wall temperature at the first row where the refrigerant enters is the lowest and it increases in the following rows.

    “The wall temperature at the first row where the refrigerant enters is the lowest and it increases in the following rows.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    All three air inlet temperature conditions show an increase trend with an average temperature of 0.2°C by the end of the simulation.

    “All the three conditions show an increase trend with an average temperature of 0.2 o C by the end of the simulation.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Findingnone given
    § 3.8 Numerical Solution

    The liquid dry-out position is unknown beforehand and varies with time.

    “However, the liquid dry-out position is unknown beforehand and varies with time.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 4.1.4 Selection of time step

    The drift flux models Chisholm, CISE and Smith give results close to each other and to experimental data compared with the homogeneous model.

    “From this figure, it can be seen that the results of drift flux models, namely Chisholm, CISE and Smith model, are close to each other and experimental data as compared with the homogeneous model.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 4.2.2 Effect of refrigerant liquid dry-out position and air temperature distribution inside the evaporator

    Cells 161 to 175 on the fifth row are in two-phase flow, while the rest of the cells on the fifth row are in single-phase flow.

    “This implies that the cell no 161 to 175 on the fifth row are in two-phase Air inlet T a ( o C) while the rest of the cells on fifth row are in single-phase.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    Higher air inlet temperature implies less frosted area and higher total energy transfer rate.

    “This also implies that higher air inlet temperature has less frosted area (Fig. 4.20) and higher total energy transfer rate (Fig. 4.21).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    Frost accumulation is highest for inlet air condition of 7°C with 3.15 kg, followed by 5°C with 2.83 kg and 3°C with 2.36 kg.

    “From Fig. 4.23, the frost accumulation is highest for inlet air condition of 7 o C with 3.15 kg of frost accumulated, followed by 5 o C with 2.83 kg and 3 o C with 2.36 kg of frost accumulated.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 4.6 Conclusion

    The temperature along the fin varies and causes uneven frost growth.

    “The temperature along fin varies and this causes uneven frost growth.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § 5.3.1 Field observation on air side

    The air inlet temperature continues to decrease while the air inlet humidity increases.

    “The air inlet temperature continues to decrease while the air inlet humidity increases.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 4.4.2 Effect of air relative humidity on frosted evaporator

    The total energy transfer rate for 70% RH decreases from 10.76 kW to 10.59 kW, for 60% RH from 10.75 kW to 10.65 kW, and for 50% RH from 10.73 kW to 10.65 kW.

    “The total energy transfer rate for 70 % RH decreases more from 10.76 kW to 10.59 kW as compare to 60 % RH, from 10.75 kW to 10.65 kW, and 50 % RH, from 10.73 kW to 10.65 kW.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given
    § 4.4.4 Effect of fin pitch on evaporator

    Although frost height for larger fin pitch is higher, the air flow area is still larger for larger fin pitch.

    “Although the frost height for larger fin pitch is higher, the air flow area is still larger for larger fin pitch.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given
    § 4.4.4 Effect of fin pitch on evaporator

    For fin pitch 4.23 mm/fin, air outlet temperature increases from -2.58°C to -2.35°C; for 2.54 mm/fin, it increases from -2.87°C to -2.69°C.

    “The fin pitch of 4.23 mm/fin increases from -2.58 o C to -2.35 o C while for 2.54 mm/fin, the air outlet temperature increases from -2.87 o C to -2.69 o C.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.3.1 Field observation on air side

    The mass flow rate of refrigerant was rather constant at around 0.075 kg/s for all three observations and started fluctuating at approximately 10700 s for observation 1, 10830 s for observation 2, and 10350 s for observation 3.

    “The mass flow rate of refrigerant was rather constant at around 0.075 kg/s for all three observations, and starts fluctuating at approximately 10700 s for observation 1, 10830 s for observation 2 and 10350 s for observation 3.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given
    § 5.3.1 Field observation on air side

    The air outlet temperature continues to decrease until it reaches around -3.9°C for observation 1, -4.0°C for observation 2, and -3.5°C for observation 3 at the end of the test.

    “The air outlet temperature continues to decrease until it reaches around -3.9 o C for observation 1, around -4.0 o C for observation 2 and around -3.5 o C for observation 3 at the end of the test.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 5.3.1 Field observation on air side

    The air outlet temperature increases at around 2950 s for observation 1, 2730 s for observation 2, and 1830 s for observation 3, when the artificial load generator was initiated.

    “The air outlet temperature increases at around 2950 s for observation 1 (Fig. 5.6 (a)), around 2730 s for observation 2 (Fig. 5.6 (b)) and around 1830 s for observation 3 (Fig. 5.6 (c)), when the artificial load generator was initiated.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 5.3.1 Field observation on air side

    After 8500 s, a minimum air inlet temperature around 2.5°C existed for all three observations, probably due to frost blockage reducing air flow and heat transfer.

    “It can be observed on the air inlet temperature for all three observations that, after 8500 s, there was a minimum temperature existing around 2.5 o C, probably due to the frost blockage that reduces air flow and heat transfer.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 4.4.4 Effect of fin pitch on evaporator

    The average frost height for the first row is slightly higher and more rows are covered with frost for the larger fin pitch condition.

    “the average frost height for the first row is slightly higher and more rows are covered with frost for condition with larger fin pitch.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 4.5.1 Frost growth

    The frost height at the fin base is 0.315 mm and at the fin tip is 0.239 mm.

    “The frost height at fin base is 0.315 mm and frost height is 0.239 mm at fin tip.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 5.3.1 Field observation on air side

    There was a hike in air relative humidity and the rate of decrease of air inlet temperature reduced at around 2950 s for observation 1, 2730 s for observation 2, and 1830 s for observation 3.

    “There was a hike in the air relative humidity and the rate of decrease for air inlet temperature reduced at around 2950 s for observation 1 (Fig. 5.4 (a)), around 2730 s for observation 2 (Fig. 5.4 (b)) and around 1830 s for observation 3 (Fig. 5.4 (c)).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 4.5.1 Frost growth

    The fin surface temperature is colder at the base at -8.38°C and -7.27°C at the fin tip.

    “The fin surface temperature is colder at base with temperature of -8.38 o C and -7.27 o C at fin tip.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 4.4.4 Effect of fin pitch on evaporator

    Total frost mass accumulated is 2.93 kg for 4.23 mm/fin, 2.57 kg for 2.54 mm/fin, and 2.83 kg for the base 3.18 mm/fin.

    “The total frost mass accumulated for condition of 4.23 mm/fin (6 fpi) is 2.93 kg while for lower fin pitch of 2.54 mm/fin (10 fpi), the total frost accumulated is 2.57 kg.The base condition of 3.18 mm/fin (8 fpi) has a total frost accumulated of 2.83 kg.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.4.1 Air side comparisons

    There is close agreement between experiment and model prediction with frost formation, with the model under-predicting air outlet temperature by approximately 1 to 2 °C for all three observations.

    “There is also close agreement between the experiment and model prediction with frost formation, with the model under-predicting the air outlet temperature by approximately 1 to 2 o C for all three observations.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given
    § 6.2 Recommendations

    The model for air pressure drop across the air cooler matched closely with experiment for single row but not for air cooler greater than one row.

    “The model for air pressure drop across the air cooler matched closely with experiment for single row but not for air cooler greater than one row.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    Energy transfer begins to fluctuate at 10700 s for observation 1, around 10800 s for observation 2, and around 10300 s for observation 3 with hunting of the TXV.

    “The energy transfer begins to fluctuate at 10700 s for observation 1, around 10800 s for observation 2 and around 10300 s for observation 3 with hunting of the TXV, as described earlier in section 5.3.2.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    At 9840 s, simulated result shows frost covers the fifth row with an average height of 0.4 mm for observation 1, but in the field only four rows are covered with frost.

    “At 9840 s, the simulated result shows frost covers the fifth row with an average height of 0.4 mm for observation 1, but in the field, only four rows are covered with frost.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given
    § 6.2 Recommendations

    The heat transfer coefficient employed in the model predicts well for non frost condition but starts to deviate when frost starts to form.

    “The heat transfer coefficient employed in the model predicts well for non frost condition but starts to deviate when frost starts to form.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.3.3 Field observation of frost formation

    Clear vision of frost was observed on the entrance of the third row around 6000 s and frost propagated toward the end of the third row by 7700 s for first observation.

    “Clear vision of frost was observed on the entrance of the third row around 6000 s and the frost propagates toward the end of third row by 7700 s for first observation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    From field observation, frost covers the first three rows at around 7700 s for first observation, but simulated result shows frost appearing at the fourth row with an average frost height of around 0.25 mm.

    “From the field observation, the frost covers the first three rows at around 7700 s for the first observation but the simulated result shows frost appearing at the fourth row with an average frost height of around 0.25 mm.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.3.3 Field observation of frost formation

    In second and third observations, frost was seen around 4200 s and 4500 s, and first and second rows were covered with frost around 5600 s and 6000 s.

    “In second and third observation, frost was seen around 4200 s and 4500 s and first and second rows were covered with frost around 5600 s and 6000 s.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    The total amount of condensate collected after the experiment is 8.28 kg, 8.49 kg, and 8.82 kg for observations 1, 2, and 3.

    “The total amount of condensate collected after the experiment is 8.28 kg, 8.49 kg and 8.82 kg for observation 1, 2 and 3.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.3.3 Field observation of frost formation

    Frost was seen on fins at the refrigerant inlet side at around 4300 s for observation 1, and by 5900 s the first and second rows were covered with frost.

    “Frost was seen on fins at the refrigerant inlet side at around 4300 s for observation 1, and by 5900 s, the first and second rows were covered with frost.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 5.3.3 Field observation of frost formation

    At the same time, frost on the first and second rows continued to grow, with growth on the first row faster than on the second row.

    “At the same time, frost on the first and second rows continued to grow with growth on the first row faster than that of the second row.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.1 Air side comparisons

    The trend of pressure drop increasing with frost growth is true for both simulation and experiment and is consistent with other researchers.

    “The trend of pressure drop increasing with frost growth is found to be true for both cases and consistent with other researchers as mentioned in section 5.3.1.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.1 Air side comparisons

    When frost height starts to grow and cause air pressure drop to increase, predicted values deviate to a maximum of around 22% and then closer again to approximately 7% at the end.

    “When frost height starts to grow and cause the air pressure drop to increase, the predicted values deviates to a maximum value of around 22 % and then closer again to approximately 7 % at the end.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    The difference between predicted and actual frost mass is 2.15 kg, 1.87 kg, and 2.09 kg, or approximately 25% less than the actual amount.

    “The difference is 2.15 kg, 1.87 kg and 2.09 kg or approximately 25 % less than the actual amount.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data
    § 5.3.3 Field observation of frost formation

    At the time of the first frost observation, the refrigerant pressure was 264.6 kPa and the refrigerant temperature was -4.6 °C.

    “The refrigerant pressure was 264.6 kPa with refrigerant temperature of -4.6 o C.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.5 Conclusions

    For this counter flow arrangement, model and experimental results are agreeable on the propagation of frost from the first row at the refrigerant inlet to subsequent rows, as well as that the first row has the highest frost accumulation.

    “For this counter flow arrangement, model and experimental results are agreeable on the propagation of frost from the first row at the refrigerant inlet to subsequent rows, as well as that the first row having the highest frost accumulation.”
    • Also stated in: § 6.1 Conclusions · plain
      “For this counter flow arrangement, model and the data collected are agreeable on the propagation of frost from the first row at the refrigerant inlet to subsequent rows, as well as that the first row having the highest frost accumulation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.4.1 Air side comparisons

    For second observation, air pressure drop starts to deviate around 7200 s to a maximum of around 20% and approximately 10% at the end.

    “For second observation, the air pressure drop starts to deviate around 7200 s to a maximum of around 20 % and approximately 10 % at the end.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given
    § 6.1 Conclusions

    Temperature along the fin varies and causes uneven frost growth.

    “The temperature along fin varies and this causes uneven frost growth.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.4.1 Air side comparisons

    Air outlet temperatures begin to deviate at around 5400 s for first observation, 5300 s for second observation, and 5800 s for third observation, where the first row and most of the second row are covered with frost.

    “the temperatures begin to deviate at around 5400 s for first observation, 5300 s for second observation and 5800 s for third observation, where the first row and most of the second row are covered with frost.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.1 Air side comparisons

    For third observation, air pressure drop starts to deviate around 7200 s to a maximum of around 20% and approximately 10% at the end.

    “As for third observation, it starts to deviate around 7200 s to a maximum of around 20 % and approximately 10% at the end.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    The energy transferred to refrigerant has good agreement between field observation and model with differences within ±3%, although the uncertainty in the experiment is within ±6%.

    “The energy transferred to refrigerant has good agreement between the field observation and model with differences within ± 3 %, although the uncertainty in the experiment is within ± 6 %.”
    • Also stated in: § 6.1 Conclusions · plain
      “The energy transferred to refrigerant has good agreement between the collected data and model with differences within ± 3 %, although the uncertainty in the experiment is within ± 6 %.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    For second and third observations, at around 7600 s and 7800 s, frost covers the first three rows, but simulated results show frost on the fourth row with average frost heights of 0.3 mm and 0.27 mm.

    “Similarly for the second and third observation where at around 7600 s and 7800 s, frost covers the first three rows but the simulated results shows frost on forth row with average frost height of 0.3 mm and 0.27 mm.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.3.3 Field observation of frost formation

    Fins for the fourth row were covered with frost by 9840 s for observation 1, 9700 s for observation 2, and 9900 s for observation 3.

    “The fins for the fourth row were covered with frost by 9840 s for observation 1, 9700 s for observation 2 and 9900 for observation 3.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.3.3 Field observation of frost formation

    Second and third observations showed signs of frost at the entrance of the third row around 5900 s and 6300 s and covered the third row at around 7600 s and 7800 s.

    “Second and third observation also showed sign of frost at the entrance of third row around 5900 s and 6300 s and covered the third row at around 7600 s and 7800 s.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.3.3 Field observation of frost formation

    Frost progressively builds up at the end of the first row/beginning of the second row and eventually blocks the fin gaps at around 5900 s for observation 1, 5600 s for observation 2, and 6000 s for observation 3.

    “The frost progressively builds up at this area and eventually blocks the fin gaps at around 5900 s for observation 1, 5600 s for observation 2 and 6000 s.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    Simulated results based on second and third observations show similar condition with average frost heights of 0.54 mm and 0.55 mm, but only four rows are observed covered with frost.

    “The simulated results based on second and third observation shows similar condition with average frost height of 0.54 mm and 0.55 mm but only four rows are observed covering with frost.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 5.4.2 Energy transfer rate comparison

    The first row has the highest frost growth rate, as found in both experimental and model results and consistent with experimental data of Aoki et al (1991).

    “where the first row has the highest frost growth rate is found to be true for both experimental and model and is consistent with experimental data of Aoki et al (1991).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Aoki et al (1991)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    The air outlet temperature compares well with model results for non-frosting condition, but for the frosting condition the deviation increases slowly to 2°C at the end of field investigation.

    “d) The air outlet temperature compares well with model results for non-frosting condition, but for the frosting condition, the deviation increases slowly to 2 o C at the end of field investigation.”
    • Also stated in: § 6.2 Recommendations · hedged
      “d) The air outlet temperature compares well with model results for non-frosting condition, but for the frosting condition, the deviation increases slowly to around 1 -2 o C toward the end of the field observation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Additional information

    The wall temperature is colder at the refrigerant inlet and increases as it moves toward the outlet point.

    “The wall temperature is colder at the refrigerant inlet and increases as it moves toward the outlet point.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    Frost height varies within a row and also within a coil.

    “Fig.4.19, which shows that the frost height varies within a row and also within a”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    Frost accumulation is highest for 0.75 kg/s with 3.07 kg, followed by 1.14 kg/s with 2.83 kg and 1.5 kg/s with 2.41 kg.

    “From Fig.4.35, the frost accumulation is highest for condition 0.75 kg/s with 3.07 kg of frost, followed by 1.14 kg/s with 2.83 kg and 1.5 kg/s with 2.41 kg of frost accumulated.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    For higher fin pitch of 4.23 mm/fin (6 fpi), frost covers 169 cells and propagates to cell 205; lower fin pitch of 2.54 mm/fin (10 fpi) has lowest frost coverage among the three, covering only 132 cells and progressing to cell 163.

    “For higher fin pitch of 4.23 mm/fin (6 fpi), the frost covers 169 cells and propagate to cell 205.The lower fin pitch of 2.54 mm/fin (10 fpi) has lowest frost coverage among the three where the frost covers only 132 cells and progress to cell 163.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    For lower air mass flow rate of 0.75 kg/s, frost formation covers 190 cells initially and propagates to 231 cells by the end of 3600 s; for 1.14 kg/s, frost increases from 147 to 180 cells; for 1.5 kg/s, frost increases from 129 to 155 cells.

    “Fig. 4 . 32, the frost formation covers 190 cells initially and propagates to 231 cells by the end of 3600 s for lower air mass flow rate of 0.75 kg/s.For the condition where the air mass flow rate is 1.14 kg/s, the frost increases from 147 cells to 180 cells and for higher air mass flow rate of 1.5 kg/s, the frost covers least cell where it increases from 129 to 155 cells by the end of 3600 s.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § Additional information

    From field observation, frost begins to form at both ends of the first row before 4500 s, but the simulated result shows frost formation at around 5000 s.

    “From field observation, the frost begins to form at both ends of first row before 4500 s but the simulated result shows frost formation at around 5000 s.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    Air pressure drop for 70% RH is 13.7 Pa, for 60% RH is 6.8 Pa and for 50% RH is 3.8 Pa.

    “From Fig4.31, it can be seen that the air pressure drop for 70 % RH is 13.7 Pa, for 60 % RH is 6.8 Pa and for 50 % RH, the air pressure drop is 3.8 Pa.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    Total frost mass predicted is 0.46 kg as compared to 0.43 kg from experiment, with a discrepancy of 7%.

    “(i) Total frost mass predicted is 0.46 kg as compared to 0.43 kg from experiment with discrepancy of 7 %.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given
    § 6.2 Recommendations

    The TXV responds to its set-point by increasing the refrigerant mass flow.

    “TXV set-point and therefore, the TXV responds by increasing the refrigerant mass flow.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    For 50% RH, frost covers 157 cells and increases to 179 cells; for 60% RH, it increases from 147 to 180 cells; for 70% RH, it covers from 138 cells and increases to 191 cells by the end of 3600 s.

    “For condition of 50 % RH, the frost covers 157 cells and increases to 179 cells, for 60 % RH, increases from 147 cells to 180 cells and for 70 % RH, the frost covers from 138 cells and increases to 191 cells by the end of the 3600 s.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Findingnone given
    § Additional information

    The frost continues to grow in height and increase in density with time.

    “The frost continues to grow in height and increase in density with time.”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data
    § 6.2 Recommendations

    At 3600 s, the liquid dry-out position occurs at cell 180.

    “from Fig. 4.10, the liquid dry out position occurs at cell 180.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § 6.2 Recommendations

    The number of cells covered with frost increased from 175 to 207 cells for 3 °C, from 147 to 180 cells for 5 °C and from 122 to 156 cells for 7 °C.

    “The number of cells covered with frost increased from 175 to 207 cells for 3 o C, from 147 to 180 cells for 5 o C and from 122 to 156 cells for 7 o C as shown in Fig.4.20.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § Additional information

    The calculated frost height at cell 1 is 0.315 mm and at cell 40 it is 0.29 mm, with a difference of about 7.9%.

    “The calculated frost height at cell 1 is 0.315 mm and at cell 40, it is 0.29 mm.It is found that the difference is about 7.9 %.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § Additional information

    The calculated wall temperature at cell 1 is -8.38°C and at exit cell 40 is -8°C.

    “The calculated wall temperature at cell 1 is -8.38 o C and at exit cell 40 is -8 o C.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given
    § Additional information

    The evaporating refrigerant pressure reduces as the air temperature reduces.

    “The evaporating refrigerant pressure reduces as the air temperature reduces.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given
    § 6.2 Recommendations

    For inlet air temperatures of 3 °C and 5 °C, although more rows are covered with frost compared with 7 °C, the frost height is lower than that of 7 °C.

    “The inlet air condition of 3 o C and 5 o C, although have more rows covered with frost as compared with 7 o C condition, the frost height is lower than that of 7 o C condition.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation
    § Additional information

    The linear trend of frost mass accumulation is consistent with results in Kondepudi and O'Neal (1993) and other researchers.

    “This linear trend is consistent with results in Kondepudi and O'Neal (1993) and other researchers.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kondepudi and O'Neal (1993)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given
    § 6.2 Recommendations

    The fluctuation caused by this increase and decrease of refrigerant mass flow was aggravated when frost growth continues.

    “The fluctuation caused by this increase and decrease of refrigerant mass flow was aggravated when frost growth continues.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Chapter 2

    Pressure drop across the heat exchanger increases with frost and is the most important factor affecting heat exchanger performance.

    “The pressure drop across the heat exchanger increases with frost and is the most important factor affecting the heat exchanger performance.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Stoecker (1957,1960)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Gatchilov and Ivanova (1979)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § 2.2 Frost Growth

    Abdel-Wahed et al. and Lee and Ro found no sign of a critical Reynolds number.

    “Abdel-Wahed et al. (1984) took their data for the range of Reynolds number from 3000 to 140000 while Lee and Ro (2001) range from 10430 to 18200, but both results showed no sign of critical Reynolds number.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Abdel-Wahed et al. (1984) source
    • cites Lee and Ro (2001) source

  • May combine two claims.

    Premisenone given
    § 2.2 Frost Growth

    Frost growth increases with a decrease in temperature of the heat transfer surface and with an increase in humidity of the air flowing across the surface.

    “Frost growth increases with a decrease in temperature of the heat transfer surface and with an increase in humidity of the air flowing across the surface.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given
    § 2.1 Frost Property

    Frost density depends on the structure of the frost layer and is affected by environmental parameters such as temperature, diffusion and deposition of water vapor within the frost layer.

    “The frost density is dependent on the structure of the frost layer; therefore, it is affected by the environmental parameters such as temperature, diffusion and deposition of the water vapor within the frost layer.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § List of Figures

    When the evaporator heat transfer rate is reduced, the evaporator temperature and suction pressure drop.

    “When the evaporator heat transfer rate is reduced, the evaporator temperature drops and suction pressure drops.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § 2.2 Frost Growth

    At higher Reynolds numbers, the frost layer is almost homogeneous, with the leading edge thickness remaining near constant and the downstream height increasing.

    “Luer and Beer (2000) also observed that at higher Reynolds numbers, the frost layer is almost homogeneous, with the leading edge thickness remaining near constant and the downstream height increasing.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Luer and Beer (2000) source

  • May combine two claims.

    Interpretationreasoning
    § 2.1 Frost Property

    Two frost layers with identical density may have different thermal conductivity due to different frost layer structure, and the shape and orientation of ice crystals could affect thermal conductivity.

    “It may also imply that two frost layers with identical density may have different thermal conductivity due to different frost layer.The shape and orientation of the ice crystals within the frost layer structure could affect the thermal conductivity as well.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § Chapter 2

    Frost growth restricts air flow in the heat exchanger and insulates the heat exchanger surface; the overall heat transfer coefficient decreases as frost continues to grow.

    “The growth of frost restricts air flow in the heat exchanger and also insulates the heat exchanger surface.The overall heat transfer coefficient decreases as the frost continues to grow.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Stoecker (1957,1960)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Gatchilov and Ivanova (1979)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 2.1 Frost Property

    The observed frost crystal structure depends on temperature.

    “Table 2.2 summarizes the observed frost crystal structure as a function of temperature (Mason and Hallet, 1971)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Mason and Hallet, 1971

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisereasoning
    § List of Figures

    As frost grows, it blocks the air flow passage, decreasing the air flow area and increasing pressure drop across the coil.

    “As the frost grows, it acts to block the air flow passage.This blockage causes decrease in the air flow area and result in higher pressure drop across the coil and hence affects the fan system characteristics.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning
    § List of Figures

    During defrosting, power consumption still occurs, melting frost without cooling capacity, and frequent or long defrosting cycles increase energy consumption and decrease system efficiency.

    “During the defrosting cycle, it is noted that power consumption still occurs, melting the frost on the evaporator without cooling capacity.Frequent or long defrosting cycles cause the energy consumption to increase and the system efficiency to decrease.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § List of Figures

    Defrost using hot gas or electric heater supplies heat to raise the air cooler temperature above freezing, and only 15% to 20% of the supplied heat is actually used for defrosting while the rest is lost.

    “Niederer (1976) indicated that only 15% to 20% of the heat supplied was actually carried out for defrosting while the rest of the heat input increased the temperature of the air cooler and it was lost to the surrounding enclosure.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Niederer (1976)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisereasoning
    § 2.3 Finned-Tube Heat Exchanger

    The humidity of air flow through the evaporator decreases along the flow direction due to mass transfer to the fin surface, causing non-uniform frost thickness on the fins.

    “The humidity of the air flow through the evaporator decreases along the flow direction due to the mass transfer to the fin surface.This phenomenon causes non-uniform frost thickness on the fins.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § List of Figures

    Designs of refrigeration systems currently used in industry often oversize the coil by about 50% compared to the no-frost case, while average energy input is 25% greater than the same system with no frost accumulation.

    “To cater for the capacity lost due to frost accumulation, designs of refrigeration systems currently used in the industry often oversize the coil by about 50% as compare to the case of no frost, while the average energy input is 25% greater than the same system with no frost accumulation (Chen et al. 2002).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Chen et al. 2002

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning
    § List of Figures

    The reduction in airflow and increased thermal resistance reduce the heat energy extracted by the evaporator and decrease system capacity and efficiency.

    “The reduction in airflow and increased thermal resistance reduce the heat energy extracted by the evaporator and decrease the system capacity and efficiency.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisenone given
    § 2.1 Frost Property

    If the frost surface reaches 0°C, condensation occurs at the surface, and the condensate soaks into the frost layer and freezes, affecting porosity, density, thermal conductivity and water vapor migration.

    “If the temperature of the frost surface reaches 0 o C, condensation occurs at the surface.This condensate soaks into the frost layer and freeze.It will affect the porosity, density, thermal conductivity and the water vapor migration in the frost layer.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisenone given
    § 2.2 Frost Growth

    In frost formation and densification, water vapor from the air flow is transferred to the frost layer; some deposits on the frost surface to make it thicker while the rest moves into the frost layer making it denser.

    “In the process of frost formation and densification, water vapor from the air flow is transferred to the frost layer.Some of the water vapor deposits on the frost surface to make the frost layer thicker while the rest of the water vapor moves into the frost layer which result in the frost layer become denser.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 2.2 Frost Growth

    Data from Yamakawa et al. suggested a critical Reynolds number above which velocity has no effect, appearing to lie between 12000 and 18000.

    “Data from other investigators such as Yamakawa et al. (1972) suggested that there is a critical Reynolds number above which the velocity has no effect.This critical number appears to lie between 12000 and 18000.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Yamakawa et al. (1972)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation
    § 2.2.1 Modeling of Frost growth

    The total mass of water vapor diffusing into the frost layer approximately half goes to increase frost density and half goes to increase thickness of the frost layer.

    “White and Creamers (1981) suggested that the total mass of water vapor which diffuses into the frost layer approximately half of it goes to increase frost density and the other half goes to increase thickness of the frost layer.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites White and Creamers (1981)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisenone given
    § 2.1 Frost Property

    Frost thermal conductivity and density are two properties that have major effects on heat transfer and frost growth calculations.

    “Frost thermal conductivity, k fst , and density, ρ fst , are two properties that have major effects on the heat transfer and frost growth calculations.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § 2.2 Frost Growth

    O'Neal and Tree found a critical Reynolds number of about 15900, above which Reynolds number had no effect on frost growth but below which there was a strong dependence on Reynolds number.

    “O'Neal and Tree (1984) found that there was a critical Reynolds number of about 15900, above which the Reynolds number had no effect on frost growth but below which there was a strong dependence on Reynolds number.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites O'Neal and Tree (1984)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning
    § List of Figures

    Correlating frost data with seven or more independent variables is very difficult, and for humidity and temperature the uncertainty is large, causing poor reliability of correlations.

    “Correlating such frost data with seven or more independent variables would be very difficult and for some variables such as humidity and temperature, the uncertainty is large.This could cause poor reliability of correlations.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisenone given
    § 2.1 Frost Property

    If the wall initial temperature is very low such as -40°C, frost with hollow prism crystals initially forms; as frost growth progresses, the surface temperature approaches 0°C, causing new frost with a different structure on top of the existing frost.

    “If the wall initial temperature is at a very low temperature such as -40 o C, the frost with hollow prisms crystals will initially form at that temperature.As frost growth progresses, the surface temperature would eventually approach 0 o C.This will cause new frost with a difference structure than the initial frost forming on the top of the existing frost.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § List of Figures

    There are seven or more independent operating and design variables for heat exchangers with frost growth: time, coil depth, coil surface temperature, air supply temperature, humidity, air velocity and coil geometry.

    “There are seven or more independent operating and design variables for heat exchangers with frost growth, namely, time, coil depth, coil surface temperature, air supply temperature, humidity, air velocity and coil geometry.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisereasoning
    § 2.3 Finned-Tube Heat Exchanger

    The complex surface geometry of the heat exchanger, thermodynamic properties of refrigerant flow in the tubes and thermodynamic properties of humid air make the problem very complex and a complete general model difficult to formulate.

    “The complex surface geometry of the heat exchanger, thermodynamic properties of refrigerant flow in the tubes and the thermodynamic properties of humid air complicate the matter further.In view of this, the problem becomes very complex and a complete general model is difficult to be formulated.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning
    § List of Figures

    The frost layer results in significant heat transfer resistance from the air to the air cooler surface and reduces the heat transfer rate between the air and the refrigerant.

    “This layer results in a significant heat transfer resistance from the air to the air cooler surface.It acts as insulation to the cold evaporator surface from the warmer air which results in reduction in heat transfer rate between the air and the refrigerant.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § Waters et al. (2001a, 2001b

    Coils with louvered fins have more frost accumulation and the greatest pressure drop than flat, wavy and corrugated fin types.

    “Coils with louvered fins have more frost accumulation than other fin types.This can be attributed to the increased surface area of contact for the mass transfer to occur and frost to settle down.The other three fin types were very close together, ostensibly because of similar geometries.b.Coils with louvered fins have the greatest pressure drop.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kondepudi and O'Neal (1989a, 1989b, 1990, 1991)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § CHAPTER 3 3 Mathematical Models

    On the refrigerant side, it is a two-phase flow in which vapor and liquid phase changes along the coil.

    “On the refrigerant side, it is a two-phase flow which vapor and liquid phase changes along the coil.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given
    § Waters et al. (2001a, 2001b

    The simulated results for frost distribution for the counter flow configuration were different as reported by Aoki et al. (1991); their results showed that frost at the refrigerant outlet was thicker than the refrigerant inlet row.

    “The simulated results for the frost distribution for their counter flow configuration was different as reported by Aoki et al. (1991).Their results showed that the frost at the refrigerant outlet was thicker than the refrigerant inlet row.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Aoki et al. (1991)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § CHAPTER 3 3 Mathematical Models

    The growth of frost depends on the cold surface temperature and the absolute humidity difference between the air and the cold surface.

    “The growth of frost depends on the cold surface temperature and absolute humidity difference between the air and the cold surface.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § 2.4 Conclusions

    The pressure drop across the coils has an effect on the heat transfer performance of the coils.

    “The pressure drop across the coils has an effect on the heat transfer performance of the coils.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Chapter 2

    Increasing air temperature increases the frosting rate, but Sanders showed that frost thickness was less at higher air temperature.

    “In the category of air temperature, Tantakitti and Howell (1986) and Rite and Crawford (1991b) found that increasing the air temperature increases the frosting rate but Sanders (1974) showed that the frost thickness was less at higher air temperature.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Tantakitti and Howell (1986)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Rite and Crawford (1991b)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Sanders (1974)

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Chapter 2

    Senshu et al. and Yan et al. observed that mean fin temperature increased as air velocity increased, leading to lower frosting rate, and that surface temperature became colder as air velocity decreased, increasing frosting rate.

    “Senshu et al. (1990) explicated that the mean temperature of fin increased as the air velocity increased which leaded to lower frosting rate.Yan et al. (2003) further explained that the surface temperature become colder as the air velocity decreased.Lower temperature tends to increase the frosting rate.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Senshu et al. (1990)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Yan et al. (2003) source

  • Classified as probably not a substantial claim.

    Premisecitation
    § 3.6.2 Frost layer side

    Jones and Parker (1975) concluded that as long as the initial value of the frost density is significantly smaller than the expected frost, it will not affect the solution for the frost growth and densification.

    “They concluded that as long as the initial value of the frost density is significantly smaller than the expected frost, it will not affect the solution for the frost growth and densification.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jones and Parker (1975) source

  • May combine two claims.

    Premisecitation
    § Chapter 2

    Staging and partial cutting of fins to allow air bypass is effective in decreasing air pressure drop and increasing the heat transfer rate.

    “They found that staging and partial cutting of fins to allow air bypass is effective in decreasing air pressure drop and increasing the heat transfer rate.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Ogawa et al. (1993)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation
    § Waters et al. (2001a, 2001b

    As frosting commences, heat extracted from the air by the evaporator is reduced, resulting in a decrease in refrigerant temperature, a decrease in refrigerant density at the compressor inlet, and reduction in both refrigerant flow rate and compressor power.

    “As frosting commences, the heat extracted from the air by evaporator is reduced, resulting in a decrease in refrigerant temperature, yielding a decrease in refrigerant density at the compressor inlet and leading to reduction in both refrigerant flow rate and compressor power.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Tassou and Marquand (1987) source
    • cites Ameen (1993)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § Waters et al. (2001a, 2001b

    The heating capacity and COP of the heat pump increased initially but later showed a gradual drop due to the insulating effect and drop in air flow.

    “The heating capacity and COP of the heat pump increased initially but later showed a gradual drop due to the insulating effect and drop in air flow.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Tassou and Marquand (1987) source
    • cites Ameen (1993)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § 2.4 Conclusions

    The overall heat transfer increases with the relative humidity of the air flowing across the coils.

    “The overall heat transfer increases with the relative humidity of the air flowing across the coils.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § Waters et al. (2001a, 2001b

    Widening of the first row increases cycle time and cyclic COP, but narrowing of the back row reduces the COP benefit compared to the base case while increasing the frost/defrost time benefit.

    “Their results showed that widening of first row increases cycle time and cyclic COP but narrowing of back row reduces the benefit in COP compared to the base case, while increasing the benefit in frost/defrost time.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Waters et al. (2001a, 2001b)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation
    § Chapter 2

    Higher air velocity leads to a higher heat and mass transfer coefficient, thereby increasing the amount of moisture converted to frost in the same time period.

    “They explained that higher air velocity leads to a higher heat and mass transfer coefficient, thereby increasing the amount of moisture being converted to frost in the same time period.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kondepudi and O'Neal (1989) source

  • May combine two claims.

    Premisenone given
    § 2.4 Conclusions

    Heat exchangers with wider fin spacing perform better than narrow fin spacing under frosting condition; variable fin spacing or fin staging seems to perform better.

    “Heat exchangers with wider fin spacing perform better as comparing with narrow fin spacing under frosting condition.Variable fin spacing or fin staging seems to perform better.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Premisereasoning
    § CHAPTER 3 3 Mathematical Models

    Modeling frost growth using fundamental heat and mass transfer relationships is a complicated process.

    “Modeling frost growth using the fundamental heat and mass transfer relationships is a complicated process.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 3.7 Permeation phenomena

    When the frost surface temperature reaches the melting point, the frost surface may melt and some liquid water soaks towards the surface.

    “When the frost surface temperature reaches the melting point, the frost surface may melt and some liquid water soaks towards the surface.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 3.7 Permeation phenomena

    Sherif et al. (1993) proposed an equation to calculate the new frost density after one cycle of melting and refreezing.

    “Sherif et al. (1993) proposed a way to account for this changes by introducing the following equation to calculate the new frost density after one cycle of melting and refreezing has occurred:”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Sherif et al. (1993) source

  • May combine two claims. The quote only partly states this claim.

    Interpretationreasoning
    § 4.3.1 Effect of frost on air outlet, refrigerant liquid dry-out position and total energy transfer rate

    The air outlet temperature on the right hand side is colder than that on the left hand side because more rows on the right were in two-phase flow.

    “This causes the air outlet temperature on the right hand side is colder than that on the left hand as shown in Fig. 4.11.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductreasoning
    § 4.1.4 Selection of time step

    The Chisholm model was selected for two-phase refrigerant flow simulations because it is simple.

    “Among the three drift flux models presented, the Chisholm model is preferred due to its simplicity of the correlation.Therefore, the simulation will base on the Chisholm model for two-phase refrigerant flow.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    Higher frost height reduces air flow area and leads to an increase in air pressure drop.

    “The higher the frost height, the less air flow area allows for the air to pass through the evaporator coil.This will also lead to the increase in air pressure drop.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.4.2 Effect of air relative humidity on frosted evaporator

    Higher humidity leads to more frost formation and growth and consequently a higher frost height and density.

    “Higher humidity leads to more frost formation and growth and consequently a higher frost height and density is formed.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    Aoki et al. (1991) reported that frost layer formation depends on cold surface temperature and air absolute humidity.

    “They reported that the formation of frost layer depends on the cold surface temperature and the air absolute humidity.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Aoki et al. (1991)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning
    § 4.3.1 Effect of frost on air outlet, refrigerant liquid dry-out position and total energy transfer rate

    As surface area coverage increases with frost accumulation, less heat exchange occurs between air and cold surface, and hence air outlet temperature increases.

    “As the surface area coverage increases with frost accumulation, less heat exchange occurs between air and cold surface and hence the air outlet temperature increases.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    Lower wall temperature increases frost growth, so the first row has the highest frost height and the coil closer to exit has the lowest.

    “Lower wall temperature increases frost growth and therefore, the first row has the highest frost height, and the lowest at the coil closer to exit.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.1.4 Selection of time step

    The homogeneous model's equal-velocity assumption oversimplifies liquid-vapor interaction in the two-phase flow region, resulting in lower pressure loss and faster transient response.

    “This assumption oversimplifies the interaction between liquid and vapor in the twophase flow region, which results in a lower pressure loss and a faster transient response.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The homogeneous model assumes equal velocity for both liquid and vapor.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given
    § 3.7 Permeation phenomena

    Continuous deposition of frost will result in a continuous increase in the frost thickness, surface temperature, density and thermal conductivity.

    “Continuous deposition of frost will result in a continuous increase in the frost thickness, surface temperature, density and thermal conductivity.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § 4.4.2 Effect of air relative humidity on frosted evaporator

    The higher the air humidity, the more moisture content the air has.

    “The higher the air humidity, the more moisture content the air has.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    The frost accumulation phenomenon is consistent with Tantakitti and Howell (1986) and Rite and Crawford (1991b).

    “This phenomenon is consistent with Tantakitti and Howell (1986) and Rite and Crawford (1991b).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Tantakitti and Howell (1986)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Rite and Crawford (1991b)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Study design and conductreasoning
    § 4.3 Simulation Results on Frosted Evaporator

    To understand changes due to frost growth alone, the simulation kept air and refrigerant input parameters constant through the simulation period.

    “In order to understand the changes of evaporator performance due to frost growth alone, the simulation will keep the input parameter for air and refrigerant constant through the simulation period.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data
    § 4.1.2 Selection of convergence criterion

    A convergence criterion of 10^-4 was used for simulations based on the last row refrigerant temperature and velocity.

    “Therefore, based on the results of the last row refrigerant temperature and velocity, convergence criterion of 10 -4 was used for simulations.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.3.3 Variation of frost, air and wall temperature inside coil

    The early-stage lower wall temperature at the right side cells is due to friction pressure drop of refrigerant in the tube and colder air temperature caused by phase change.

    “This is due to the friction pressure drop of refrigerant in the tube and the colder air temperature caused by the phase change effect at the early stage.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data
    § 4.1.3 Selection of number of cells

    40 cells per row was selected for all subsequent simulations.

    “Therefore, 40 cells per row was selected for all subsequence simulations.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.4.3 Effect of air mass flow rate on evaporator

    A higher air mass flow rate leads to a higher Reynolds Number and hence an increase in the rate of energy transfer.

    “A higher air mass flow rate leads to a higher Reynolds Number and hence an increases in the rate of energy transfer.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.4.4 Effect of fin pitch on evaporator

    The higher frost height and coverage for larger fin pitch is caused by less heat transferred from air to refrigerant and is worsened by the insulation effect of frost.

    “This is caused by less heat being transferred from the air to the refrigerant and further worsens by the insulation effect of frost.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 4.4.3 Effect of air mass flow rate on evaporator

    Such trends have been reported by Senshu et al. (1990) and Yan et al. (2003).

    “Such trends have also been reported by Senshu et al. (1990) and Yan et al. (2003).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Senshu et al. (1990)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Yan et al. (2003) source

  • May combine two claims.

    Interpretationreasoning
    § 4.4.4 Effect of fin pitch on evaporator

    The higher frost accumulation for larger fin pitch is due to lower energy transfer rate, which causes the surface temperature to be lower than the other two conditions.

    “This is due to lower energy transfer rate which causes the surface temperature to be lower than the other two conditions.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.4.3 Effect of air mass flow rate on evaporator

    Higher air mass flow rate increases the heat transfer coefficient, which increases wall surface temperature.

    “Higher air mass flow rate increase the heat transfer coefficient which will also increase the wall surface temperature.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.3.1 Field observation on air side

    Growth and propagation of frost reduce the air flow passage, resulting in increased air pressure difference between inlet and outlet.

    “The growth and propagation of frost reduce the air flow passage resulting in increased air pressure difference between the inlet and outlet.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given
    § 4.5.2 Airside pressure drop across heat exchanger coil

    Deposition and growth of frost on the heat exchanger surface leads to a narrower fin pitch and a smaller air flow passage area.

    “The deposition and growth of frost on the surface of heat exchanger leads to a narrower fin pitch and a smaller air flow passage area.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.3.1 Field observation on air side

    Less heat transferred implies less refrigerant evaporation, and to maintain refrigerant superheat leaving the coil, the TXV limits refrigerant flow into the coil.

    “Less heat transferred implies less refrigerant evaporation and in order to maintain the refrigerant superheat leaving the coil, the TXV limits the refrigerant flow into the coil.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 4.4.3 Effect of air mass flow rate on evaporator

    A larger frost accumulation insulates the evaporator quicker and causes the energy transfer rate to degrade faster.

    “Because of a larger frost accumulation, the frost layer insulates the evaporator quicker and causes the energy transfer rate degraded faster.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § 4.4.4 Effect of fin pitch on evaporator

    The test coil was a single row flat finned-tube heat exchanger.

    “The test coil was a single row flat finned-tube heat exchanger as shown in Fig. 4.44.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Kondepudi and O'Neal (1990)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 4.4.4 Effect of fin pitch on evaporator

    The working refrigerant was a 50% ethylene glycol/water mixture.

    “The working refrigerant was 50% ethylene glycol/water mixture.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kondepudi and O'Neal (1990)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisenone given
    § 4.5.1 Frost growth

    Higher air humidity, higher air temperature and lower refrigerant temperature boost frost growth.

    “Higher value of air humidity, air temperature and lower refrigerant temperature boost the frost growth.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 4.4.4 Effect of fin pitch on evaporator

    The result is agreeable with Gatchilov and Ivanova (1979) and Yan et al. (2003).

    “This is also agreeable with Gatchilov and Ivanova (1979) and Yan et al. (2003).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Gatchilov and Ivanova (1979)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Yan et al. (2003) source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 4.5.3 Energy transfer coefficient

    Kondepudi and O'Neal (1989) proposed that the energy transfer coefficient E_o can be expressed by equation (4.4).

    “Kondepudi and O'Neal (1989) in their paper proposed that the energy transfer coefficient, E o , can be expressed as follow: p,a o Q.C E LMED.A = (4.4)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kondepudi and O'Neal (1989) source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § 5.3.1 Field observation on air side

    The increase in air outlet temperature could be due to more of the cooling load being used for latent rather than sensible cooling.

    “The increase in temperature could be due to the fact that more of the cooling load was used for latent rather than sensible cooling.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning
    § 5.3.1 Field observation on air side

    The relative humidity of air increases as the air temperature decreases, because lower air temperature has less moisture-holding capacity.

    “The relative humidity of air increases as the air temperature decreases, since lower air temperature has less moisture-holding capacity.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.4.1 Air side comparisons

    The differences in air outlet temperature could be due to under-prediction of pressure drop across the coil and accuracy of the heat transfer coefficient.

    “The differences could be due to the under-prediction of the pressure drop across the coil and also the accuracy of the heat transfer coefficient.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given
    § 5.4.2 Energy transfer rate comparison

    Less evaporated refrigerant reduces the enthalpy of the refrigerant leaving the coil.

    “Less evaporated refrigerant reduces the enthalpy of the refrigerant leaving the coil.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.3.3 Field observation of frost formation

    As less refrigerant evaporates, wall temperature decreases and therefore frost growth increases.

    “As less refrigerant evaporates, the wall temperature decreased and therefore the frost growth increases.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisereasoning
    § 6.2 Recommendations

    The studies on frost formation and growth on finned tube coils are limited.

    “The studies on frost formation and growth on finned tube coils are limited.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.4.2 Energy transfer rate comparison

    Formation and propagation of frost seems to be slower than simulated results because during coil frosting at the first few rows, wall temperatures for last few rows are still above freezing point but could be below dew point.

    “The formation and propagation of frost seems to be slower than the simulated results because during the coil frosting at the first few rows, the wall temperatures for last few rows of the coil are still above freezing point but could be below the dew point.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationnone given
    § 5.5 Conclusions

    The main reason for the model under-predicting frost mass accumulation could be due to the condensate drip effect.

    “The main reason for this could be due to the condensate drip effect.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The condensate drip effect is more dominant than the additional mass transfer after system shutdown.

  • May combine two claims.

    Interpretationnone given
    § 5.4.2 Energy transfer rate comparison

    When the system is shut-down and allowed to melt at room temperature, the coil and frost surfaces are still below freezing or dew point, and mass transfer of water vapor from air continues to occur after shutdown.

    “Secondly, when the system is shut-down and allowed to melt at room temperature, the coil and frost surfaces are still below freezing or dew point.Mass transfer of water vapor from air continues to occur even after the system has shut-down.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.4.1 Air side comparisons

    Pressure drop influences air flow, which is one of the variables that affects frost growth.

    “The pressure drop influences the air flow which is also one of the variables that affects the frost growth.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.3.3 Field observation of frost formation

    The tube bend causes refrigerant pressure to decrease, resulting in lower wall temperature, which promotes frost formation.

    “The tube bend causes the refrigerant pressure to decrease and results in a lower wall temperature which also promotes frost formation.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § 6.2 Recommendations

    For a constant air flow rate through heat exchanger fins, frost growth blockage increases pressure drop across the fin by up to a factor of 8 while heat transfer rate decreases by as much as 20%.

    “They found that for a constant air flow rate through the heat exchanger fins, the blockage of air flow resulting from the frost growth increases the pressure drop across the fin by up to a factor of 8 times while the heat transfer rate decreases by as much as 20 %.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Chen et al. (2000a, 2000b)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § 6.2 Recommendations

    Chen et al.'s results are limited to heat exchanger fins only and not the practical finned tube heat exchanger.

    “Their results, however, only limited to the studies on heat exchanger fin only and not the practical finned tube heat exchanger.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Chen et al. (2000a, 2000b)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisereasoning
    § 5.4.1 Air side comparisons

    Reynolds and Prandtl numbers, Colburn j factor, and spacing between fins change with time.

    “The Reynolds and Prandtl numbers, Colburn j factor and the spacing between fins changes with time too.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.3.3 Field observation of frost formation

    Less air flow leads to lower heat transfer rate, lower wall temperature, and encourages frost growth.

    “Less air flow leads to lower heat transfer rate and therefore, the wall temperature was lower, and this encourages frost growth.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § 5.4.1 Air side comparisons

    Pressure drop changes the air side heat transfer coefficient as a consequence of the velocity associated with blockage at the fins.

    “It changes the air side heat transfer coefficient as a consequence of the velocity associated with the blockage at the fins.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given
    § 6.2 Recommendations

    A number of investigators have made both experimental and theoretical studies to determine the rate of heat transfer and thermal conductivity but the results are inconclusive.

    “A number of investigators have made both experimental and theoretical studies to determine the rate of heat transfer and thermal conductivity but the results are inconclusive.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationown data
    § 6.2 Recommendations

    The condensate drip effect will affect the frost.

    “This condensate drip effect will affect the frost and should be accounted in the modeling.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 5.4.2 Energy transfer rate comparison

    Condensation of water on the fin and wall surface could occur, and the condensate drip effect causes water to soak into the frost layer at the subsequent row below.

    “This could lead to the condensation of water on the fin and wall surface, and the condensate drip effect causes water to soak into the frost layer at the subsequent row below.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § Additional information

    The sensors deliver a voltage signal that has been calibrated against pressure.

    “The sensors deliver a voltage signal that has been calibrated against pressure.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § Additional information

    Pressure transducers of accuracy ±0.25% were installed to record the dynamic responses of the evaporating and condensing pressures.

    “Pressure transducers of accuracy ± 0.25 % were installed to record the dynamic responses of the evaporating and condensing pressures.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given
    § 6.2 Recommendations

    The presented model includes the permeation process where the frost surface melts and some liquid soaks into the frost layer when frost surface temperature reaches the melting point.

    “The presented model includes the permeation process where the frost surface melt and some liquid soak into the frost layer when frost surface temperature reaches the melting point.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 6.2 Recommendations

    For frost conditions, Lee et al. (2003) correlated their experimental results and postulated the Lewis number as 0.905 ± 0.005.

    “For the condition of frost, Lee et al. (2003) correlated their experimental results postulated the Lewis number as 0.905 ± 0.005.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Lee et al. (2003) source

  • May combine two claims.

    Interpretationown data
    § 6.2 Recommendations

    The frost formation is greater at lower air mass flow rate, higher relative humidity, higher air inlet temperature and higher fin pitch.

    “The frost formation is greater at lower air mass flow rate, higher relative humidity, higher air inlet temperature and higher fin pitch.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Additional information

    Temperature sensitive products require precise temperature control in the chilled cargo range.

    “Temperature sensitive products require precise temperature control in the chilled cargo range (Chia et al. 1997)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Chia et al. 1997

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § Additional information

    Calibrated K-type thermocouples with an accuracy of ±0.5°C were used for measurement of air and refrigerant circuit temperatures.

    “Calibrated K-type thermocouples with an accuracy of ± 0.5 o C were used for measurement of air and refrigerant circuit temperatures.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § 6.2 Recommendations

    Dietenberger's (1983) semi-empirical correlation is chosen because it applies to a wide range of frost density and temperature, i.e., ρ_air < ρ_fst < ρ_ice and 80 K < T_w < 273 K.

    “Dietenberger's (1983) semi-empirical correlation is chosen because the correlation can apply to a wide range of frost density and temperature, i.e., ρ air < ρ fst < ρ ice and 80 K < T w < 273 K.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Dietenberger (1983) source

  • May combine two claims.

    Interpretationreasoning
    § Additional information

    More frost grows and propagates faster on higher fin pitch, which affects the total energy transfer rate to decrease faster than other.

    “As such, more frost grow and propagate faster on higher fin pitch which affect the total energy transfer rate to decrease faster than other.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationnone given
    § 6.2 Recommendations

    A general distributed model with two-phase flow for refrigerant coupled with a frost model for non-steady performance of finned-tube evaporator under frosting and non-frosting conditions has been presented.

    “A general distributed model with two-phase flow for refrigerant coupled with a frost model for non-steady performance of finned-tube evaporator under frosting and non-frosting conditions has been presented.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisereasoning
    § 6.2 Recommendations

    Modeling a finned tube evaporator using volatile refrigerant is more complicated than using a single-phase fluid such as brine or glycol/water.

    “Modeling of finned tube evaporator in the refrigeration system uses volatile refrigerant as a cooling medium to cool the air is complicated as compared to singlephase fluid such as brine or glycol/water concentration.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisereasoning
    § 6.2 Recommendations

    The agreement between wet-bulb temperature and adiabatic saturation temperature is a direct consequence of the nearness of the Lewis number to unity for air and water vapor.

    “The agreement between wetbulb temperature and adiabatic saturation temperature is a direct consequence of the nearness of the Lewis number to unity for air and water vapor.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data
    § Additional information

    The refrigerant mass flow rate was measured by a rotameter, and the error on the flow rate was corrected based on a factor provided by the manufacturer, with accuracy estimated to be within ±2%.

    “The refrigerant mass flow rate was measured by a rotameter.The error on the flow rate was corrected based on a factor provided by the manufacturer and the accuracy estimated to be within ± 2 %.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § Additional information

    Differential pressure across the evaporator coil was measured with a pressure differential transducer of accuracy ±1%.

    “Differential pressure across the evaporator coil was measured with a pressure differential transducer of accuracy ± 1 %.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation
    § Additional information

    The uncertainty calculation method used is the one described by Kine and McClintock (1953).

    “The method used for the uncertainty calculation is the one described by Kine and McClintock (1953).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kine and McClintock (1953)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisereasoning
    § 6.2 Recommendations

    Because of two-phase evaporating flow inside coils, the local heat transfer coefficient varies over a great range at different locations.

    “Because of the two-phase evaporating flow inside coils, the local heat transfer coefficient varies in a great range at different locations.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § 6.2 Recommendations

    The diffusion coefficient of water vapor in air is a function of temperature, pressure and composition.

    “The diffusion coefficient, D v , is a function of temperature, pressure and composition.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Sherwood and Pigford (ASHRAE Fundamentals, 2001)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Study design and conductnone given
    § 6.2 Recommendations

    The results have been qualitatively compared with what has been reported in literature.

    “The results have been qualitatively compared with what have been reported in literature.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § Additional information

    As less heat is transferred to the refrigerant, the cold refrigerant that passes through the next cell propagates frost formation along the coil, resulting in an increase of frost mass accumulation with time.

    “As less heat is being transferred to the refrigerant, the cold refrigerant that passes through the next cell propagating the frost formation along the coil, resulting in the increase of frost mass accumulation with time.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given
    § 6.2 Recommendations

    One of the key problems in distributed parameter models is the description of void fraction and two-phase flow.

    “However, one of the key problems in these models is the description of void fraction and two-phase flow.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given
    § 6.2 Recommendations

    With the increase of frost growth, the total airside heat transfer decreases and the air pressure drop across evaporator increases.

    “With the increase of frost growth, the total airside heat transfer decreases and the air pressure drop across evaporator increases.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § Additional information

    Two humidity sensors with an accuracy of ±3% were used for measurement on the air on and off the coil.

    “Two humidity sensors with an accuracy of ± 3 % were used for measurement on the air on and off the coil and the current signals are outputs to the data logger.”
    Quote in the paperNot a substantial claim
191 of 191

  • The paper relies on this without support.

    The existence of frost on the surface of an air cooler is undesirable and is a common problem in refrigeration systems.

    “The existence of frost on the surface of air cooler is undesirable and it is a common problem in refrigeration system.”

  • The paper relies on this without support.

    Water evaporated during the defrost cycle often ends up back on the air cooler in the next cycle of operation.

    “The water evaporated during defrost cycle often ends up back on the air cooler in the next cycle of operation.”

  • The authors state this as an assumption.

    The refrigerant mass flow rate in each circuit is uniform, and there is no heat conduction between circuits, so the evaporator is simplified as one circuit.

    “1.The refrigerant mass flow rate in each circuit is considered uniform, and there is no heat conduction between circuits so that the evaporator is simplified as one circuit.”

  • The authors state this as an assumption.

    The two-phase evaporating flow inside the tube is simplified as a one-dimensional drift flux flow.

    “2. The two-phase evaporating flow inside the tube is simplified as a onedimensional drift flux flow.”

  • The authors state this as an assumption.

    The vapor and liquid flow are incompressible and in thermal equilibrium conditions.

    “The vapor and liquid flow are incompressible and in thermal equilibrium conditions.”

  • The authors state this as an assumption.

    The axial heat conduction within the tube wall is ignored, as transverse conduction along the fins will be dominant.

    “3. The axial heat conduction within the tube wall is ignored, as transverse conduction along the fins will be dominant.”

  • The authors state this as an assumption.

    Frost formation process is quasi-steady state.

    “4. Frost formation process is assumed to be quasi-steady state.”

  • The authors state this as an assumption.

    The frost density at any instant is the average value of a layer.

    “5. The frost density at any instant is average value of a layer.”

  • The authors state this as an assumption.

    The amount of water vapor absorbed into the frost layer is proportional to water vapor density in the frost.

    “6.The amount of water vapor absorbed into the frost layer is proportional to water vapor density in the frost.”

  • The authors state this as an assumption.

    The initial conditions for air and refrigerant are in the steady state initially.

    “The initial conditions for air and refrigerant are assumed to be in the steady”

  • The authors state this as an assumption.

    For a given instant of time, the properties of the air stream across the heat exchanger and of the frost layer are constants.

    “For a given instant of time, t, the properties of the air stream across the heat exchanger and that of the frost layer are assumed to be constants.”

  • The authors state this as an assumption.

    The evaporator is in the steady state initially.

    “The evaporator is assumed to be in the steady state initially, thus the steadystate initial conditions are applied.”

  • The authors state this as an assumption.

    When solving for unknowns at the refrigerant and tube wall side, the air conditions (T_a, ω_a) of each cell are known.

    “When solving for unknowns at the refrigerant and tube wall side, the air conditions (T a , ω a ) of each cell are assumed to be known”

  • The authors state this as an assumption.

    The initial temperature can be taken as the cold surface temperature if the initial frost thickness is so thin that its heat transfer resistance is negligible compared to the air side heat transfer resistance.

    “The initial temperature can be taken as the cold surface temperature if the initial frost thickness is so thin that the heat transfer resistance of the initial frost thickness is negligible compared to the air side heat transfer resistance.”

  • The authors state this as an assumption.

    The initial frost height and density ideally should be as close to zero as possible since there is no frost initially.

    “The initial frost height and density ideally should be as close to zero as possible since there is no frost initially.”

  • The authors state this as an assumption.

    The constant value for C_melt is between zero and 1 and should be determined using experimental data.

    “According to their assumption, the constant value for C melt is between zero to 1 and this value should be determined using experimental data.”

  • The authors state this as an assumption.

    The excess saturated vapor density is redistributed inside the frost layer.

    “This permeation process can be adopted in this mathematical modeling by assuming that the excess saturated vapor density is redistributed inside frost layer as shown in Fig. 3.11.”

  • The paper relies on this without support.

    The frost layer is a porous structure of air and ice, so the diffusion path is longer than in free space.

    “The frost layer is a porous structure of air and ice and therefore, the diffusion path is longer than that in free space.”

  • The authors state this as an assumption.

    The homogeneous model assumes equal velocity for both liquid and vapor.

    “because it assumes equal velocity for both liquid and vapor.”

  • The paper relies on this without support.

    Frost formation and growth is an unsteady process that affects system performance.

    “The frost formation and growth is an unsteady process and will affect the system performance.”

  • The paper relies on this without support.

    Frost presence has an impact on evaporator performance.

    “The present of frost has impact on the evaporator performance.”

  • The paper relies on this without support.

    In practical conditions, the evaporator operates in a transient manner.

    “In practical condition, the evaporator operates in transient manner.”

  • The paper relies on this without support.

    Refrigerant and air inlet conditions change based on space cooling load and expansion valve regulation.

    “The refrigerant and air inlet condition change based on space cooling load and the regulating of expansion valve.”

  • The paper relies on this without support.

    The humidity ratio is higher for a higher air temperature with the same relative humidity.

    “The humidity ratio is higher for a higher air temperature with the same relative humidity.”

  • The paper relies on this without support.

    The condensate drip effect is more dominant than the additional mass transfer after system shutdown.

    “Between the two reasons, the condensate drip effect is more dominant.”

  • The paper relies on this without support.

    Less air was channeled to the side of the coil, causing uneven air distribution.

    “The frost starts to form here because of the uneven air distribution, where less air was channeled to the side”

  • The paper relies on this without support.

    The densification rate is strongly related to the water vapor diffusion within the frost layer.

    “The densification rate is strongly related to the water vapor diffusion within the frost layer.”

  • The paper relies on this without support.

    Distributed parameter models have gained popularity for fully simulating heat transfer processes, air temperature and other parameter distributions inside the coil.

    “To fully simulate the heat transfer processes, air temperature and other parameter distributions inside the coil, the distributed parameter models have gained popularity.”

  • The authors state this as an assumption.

    In the simulation, the air flow is assumed to be evenly distributed.

    “in simulation, the air flow is assumed to be evenly distributed whereas the flow is uneven in practice.”

  • The paper relies on this without support.

    There is scarcity in the literature about research on containers, especially in modeling and validation of container refrigeration systems under frosting condition.

    “However, there is scarcity in the literature about research on containers, especially in modeling and validation of container refrigeration systems under frosting condition.”

  • The paper relies on this without support.

    Frost formation on an air cooler degrades the performance of the air cooler and the whole cooling/refrigeration system.

    “Frost formation on air cooler degrades the performance of the air cooler as well as the whole cooling / refrigeration system.”

  • The paper relies on this without support.

    Operating carriage temperature below freezing is subjected to frost deposition and progressive build-up on the evaporator coil.

    “Operating carriage temperature at below freezing temperature is subjected to frost deposition and progressive build-up on the evaporator coil.”

  • The paper relies on this without support.

    The presence of frost affects the system performance and hence the cargo being cooled.

    “The presence of the frost affects the system performance and hence the cargo being cooled.”

  • The paper relies on this without support.

    Higher fin pitch has lower overall heat exchange surface area.

    “Higher fin pitch has lower overall heat exchange surface area.”

  • The paper relies on this without support.

    Frost growth is more rapid with a decrease in the temperature of the heat transfer surface.

    “frost growth is more rapid with a decrease in the temperature of the heat transfer surface.”

  • The paper relies on this without support.

    Temperature variation caused by frost deposition and build-up is a parameter to be concerned.

    “temperature variation caused by frost deposition and build-up is a parameter to be concerned.”

  • The authors state this as an assumption.

    The frost layer is treated as a porous media with transient and one-dimensional heat and mass transfer.

    “The frost layer is treated as a porous media with transient and one-dimensional heat and mass transfer.”
37 of 37

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Tube inner diameter conflicts with the stated wall thickness

    Minor

    Table 4.2 gives a 12.70 mm outer diameter and a 12.27 mm inner diameter. The later description of the same commercial-container evaporator gives a 12.7 mm outer diameter and a 0.432 mm wall thickness, which implies an inner diameter of 11.836 mm.

  • Air-side heat-transfer coefficient has conflicting units

    Minor

    Table 4.1 assigns the heat-transfer coefficient units of W/m K, while the nomenclature assigns the air-side heat-transfer coefficient units of W/m2 K.

2 of 2

Cites

Flagged first, then by citations

7 of the 68 references couldn’t be matched to a known paper.

Research works printed but not linked: 32

  1. [2]2. Ameen, F.R., 1993, "Study of frosting of heat pump evaporator", ASHRAE Transaction, 99 (1), pp. 61-71.
  2. [3]3. Aoki, K., Hattori, M. and Hayashi, Y., 1991, "A study of frost formation", Freezing and Melting Heat Transfer In Engineering, Hemisphere Publishing Corporation, pp. 451-487.
  3. [7]7. Brian, P.L.T., Reid, R.C. and Brazinsky, I., 1969, "Cryogenic frost properties", Cryogenic Technology, 5, pp. 205-212.
  4. [9]9. Chen, H., Thomas, L. and Besant, R.W., 2000a, "Modeling frost characteristics on heat exchanger fins: Part I, Numerical model", ASHRAE Transactions, 106(2), pp. 357-367.
  5. [10]10. Chen, H., Thomas, L. and Besant, R.W., 2000b, "Modeling frost characteristics on heat exchanger fins: Part II, Model validation and limitations", ASHRAE Transactions, 106(2), pp 368-376.
  6. [16]16. Chuang, M.C., 1976, "The frost formation parallel plates at very low temperature in a humid stream", ASME Paper 76-WA/HT-60, pp.1-5.
  7. [17]17. Chung, P.M. and Algren, A.B., 1958a, "Frost formation and heat transfer on a cylinder surface in humid air cross flow, part I: experimental study", Heating, piping and air conditioning, 30(9), pp. 171-177.
  8. [18]18. Chung, P.M. and Algren, A.B., 1958b, "Frost formation and heat transfer on a cylinder surface in humid air cross flow, part II: theoretical study and conclusion", Heating, piping and air conditioning, 30(10), pp. 115-122.
  9. [19]19. Dabiri, A. E., 1982. "A Steady-State Computer Simulation Model for Air-To- Air Heat Pumps", ASHRAE Transactions, 88, Pt. 2, pp. 973-987.
  10. [23]23. Gatchilov, T.S. and Ivanova, V.S., 1979, "Characteristics of the frost formed on the surface of finned air coolers", 15th International Congress of Refrigeration, Venice, B2/71, pp. 997-1003.
  11. [33]33. Kline, S.J. and McClintock, F.A., 1953, "Describing uncertainties in single- sample experiments", Mechanical Engineering, 75, pp. 3-8.
  12. [34]34. Kondepudi, S.N. and O'Neal, D.L., 1989a, "The performance of finned tube heat exchangers under frosting conditions", ASME collected paper in Heat Transfer,HTD-123, pp. 193-200.
  13. [48]48. Mao, Y., Besant, R.W. and Rezkallah, K.S., 1992, "Measurement and correlations of frost properties with air flow over a flat plate", ASHRAE Transactions, 98 (1), pp. 65-78.
  14. [52]52. Na, B. and Webb, R.L., 2004, Int. J. Heat Mass Transfer, 47, pp. 899-911.
  15. [53]53. Niederer, D.H., 1976, "Frosting and defrosting effects on coil heat transfer", ASHRAE Transactions, 81(1), pp. 467-473.
  16. [55]55. O'Neal, D.L. and Tree, D.R., 1984, "Measurement of frost growth and density in a parallel plate geometry", ASHRAE Transactions, 90(2A), pp. 278-290.
  17. [56]56. O'Neal, D.L. and Tree, D.R., 1985, "A review of frost formation in simple geometries", ASHRAE Transactions, 91 (2A), pp. 267-281.
  18. [57]57. Ogawa, K., Tanaka, N. and Tekeshita, M., 1993, "Performance improvement of plate fin-and -tube heat exchangers under frosting conditions", ASHRAE Transactions, 99 (1), pp. 762-771.
  19. [58]58. Oskarsson, S.P., Krakow, K.I. and Lin, S., 1990a, "Evaporator models for operation with dry, wet and frosted finned surfaces, Part I: Heat transfer and fluid flow theory", ASHRAE Transactions, 96 (1), pp. 373-380.
  20. [59]59. Oskarsson, S.P., Krakow, K.I. and Lin, S., 1990b, "Evaporator models for operation with dry, wet and frosted finned surfaces, Part II: Evaporator models verification", ASHRAE Transactions, 96 (1), pp. 381-392.
  21. [63]63. Premoli, A., Francesco, D., and Prina, A. A., 1971, "Dimensionless correlation for determining the density of two-phase mixtures", Lo Termotecnica, 25, pp. 17-26.
  22. [64]64. Rite, R.W. and Crawford, R.R., 1991a, "The effect of frost accumulation on the performance of domestic refrigerator-freezer finned-tube evaporator coils, ASHRAE Transactions, 97(2), pp. 428-437.
  23. [65]65. Rite, R.W. and Crawford, R.R., 1991b, "A parametric study of the factors governing the rate of frost accumulation on domestic refrigerator-freezer finned-tube evaporator coils", ASHRAE Transaction, 97 (2), pp. 438-446.
  24. [72]72. Senshu, T., Yasuda, H., Oguni, K. and Ishibane, K., 1990, "Heat pump performance under frosting conditions: Part I-heat and mass transfer on cross- finned tube heat exchangers under frosting conditions", ASHRAE Transaction, 96 (1), pp. 324-329.
  25. [75]75. Stoecker, W.F and Jones, J.W., 1982, "Refrigeration & air conditioning", McGraw-Hill, pp.239-242.
  26. [76]76. Stoecker, W.F, 1957, "How frost formation on coils affects refrigeration system", Refrigeration Engrg., pp. 42.
  27. [77]77. Stoecker, W.F., 1960, "Frost formation on refrigeration coils", ASHRAE Transactions, 96(1), pp. 91-103.
  28. [78]78. Tantakitti, C. and Howell, R.H., 1986, "Air-to-air heat pumps operating under frosting conditions on the outdoor coil", ASHRAE Transactions, 92(1B), pp. 827-842.
  29. [83]83. Waters, R.J., O'Neal, D.L. and Yang, J., 2001a, "Effect of fin staging on frost/defrost performance of a two-row heat pump evaporator at standard test conditions", ASHRAE Transaction, 107(2), pp. 240-249.
  30. [84]84. Waters, R.J., O'Neal, D.L. and Yang, J., 2001b, "Effect of fin staging on frost/defrost performance of a two-row heat pump evaporator under heavy frosting conditions", ASHRAE Transaction, 107(2), pp. 250-258.
  31. [88]88. Yamakawa, N., Takahashi, N. and Ohtani, S., 1972, "Forced convection heat and mass transfer under frost conditions", Heat Transfer-Japanese Research, Vol(1), No. 2, pp. 1-9.
  32. [91]91. Yasuda H., Senshu, T., Kuroda, S., Atsumi, A. and Oguni, K., 1990, "Heat pump performance under frosting conditions: Part II-simulation of Heat Pump cycle characteristics under frosting conditions", ASHRAE Transaction, 96 (1), pp. 330-336.

Related

Authors
Cheng, Y. C.
Corresponding author
Cheng, Yeong Chang
Publisher
Nanyang Technological University
Published
2006-01-01
DOI
10.32657/10356/6557
OpenAlex
W2272417089
Semantic Scholar
ea5cf25e19201ba85e8b463567e1d05d7f4e370b
Cited by
0
References
68
Type
dissertation
Language
en
Open access
Locations
  • DR-NTU (Nanyang Technological University) (submittedVersion)
  • UPT. Syiah Kuala University Library (Syiah Kuala University) (submittedVersion)
Topics
  • Physical Sciences › Engineering › Mechanical Engineering › Refrigeration and Air Conditioning Technologies
  • Physical Sciences › Engineering › Mechanical Engineering › Heat Transfer and Optimization
  • Physical Sciences › Engineering › Mechanical Engineering › Adsorption and Cooling Systems
Keywords
frost formation, air coolers, finned tube heat exchanger, frost accumulation, refrigerated containers, R12 refrigerant, pressure drop, heat transfer coefficient, non-steady-state heat transfer

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