Prediction of the frost formation on a cold flat surface

Frost density increases rapidly in the early stage of frost growth (less than about 30 min), and the rate of increase is small for times in excess of about 120 min.

“The frost density increases rapidly in the early stage of frost growth (less than about 30 min), and the rate of increase of frost density is small for times in excess of about 120 min.”

There is considerable agreement between theory and data in the initial growth period (t < 30 min).

“It is however noticed that there is considerable agreement between the theory and the data in the initial growth period (t &lt; 30 min).”

The data suggest that sensible heat flux is considerably larger than latent heat flux (by a factor of about two), and decreases continuously during frost formation as the surface temperature of the frost layer increases with its growth.

“The data suggest that the sensible heat flux is considerably larger than the latent heat flux (by a factor of about two), and decreases continuously during frost formation as the surface temperature of the frost layer increases with its growth (Lee et al. [7]).”

As pointed out in Lee et al. [7], there are very few experimental data for frost surface temperature reported in the literature due to difficulty of measurement with reasonable accuracy.

“As pointed out in Lee et al. [7], there are very few experimental data for frost surface temperature reported in the literature on account of the difficulty of measurement with a reasonable accuracy.”

The latent heat flux remains fairly constant with time, following a small drop at the commencement of frost formation.

“On the other hand, the latent heat flux remains fairly constant with time, following a small drop at the commencement of frost formation.”

From Fig. 7a, there is considerable deviation between prediction and data for frost thickness for times in excess of about 90 min, with a maximum deviation of 1 mm at t = 120 min (25% error), even though the predicted growth rate is reasonably satisfactory.

“From Fig. 7a, it is evident that there is considerable deviation between the prediction and the data for frost thickness for times in excess of about 90 min, with a maximum deviation 1 mm at t = 120 min (25% error), even though the predicted growth rate is seen to be reasonably satisfactory.”

At t = 180 min, the model prediction is within about 1.0 °C of the test data.

“At t = 180 min, the model prediction is within about 1.0 ⁰C of the test data.”

The total heat flux reduces from about 500 W/m2 at t = 15 min to about 400 W/m2 at t = 180 min (a 25% drop).

“The results also suggest that the total heat flux reduces from about 500 W/m² at t = 15 min to about 400 W/m² at t = 180 min (a 25% drop).”

Excellent agreement is noted between predicted and measured frost density during the entire test period.

“Excellent agreement is noted between the theory and experiments during the entire test period.”

The trend of frost growth and densification for cell no. 30 is consistent with existing experimental data (Chen et al. 1999, Lee et al. 2003).

“The trend of change shown is consistent with existing experimental data (Chen et al. 1999, Lee et al. 2003).”

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.”

The convection coefficients hconv and hmass change along the airflow direction, so frost growth is not homogeneous on the plate and the problem is actually 2D.

“Although a 1D problem through frost thickness is considered, the convection coefficients hconv and hmass actually change along the airflow direction. Hence, the frost growth is not homogeneous on the plate and the problem is actually 2D (Lee et al., 2003; Mao et al., 1992; Robinson and Jacobi, 2001).”

Lee et al. (2003) reported Lewis number values of 0.905.

“For information, Lee et al. (2003) reported values of 0.905.”

Le = 0.905 is the Lewis number [22].

“where Le = 0.905 is the Lewis number [22].”

Frost formation on flat plate and cylindrical surfaces is relatively well known and can be predicted reliably with existing models and correlations.

“Therefore, frost formation on flat plate and cylindrical surface is relatively well known and can be predicted reliably with existing models and correlations.”

The frosting process involves a complex, nonlinear, transient phase change coupled with heat and mass transfer, which makes accurate determination of frost-layer properties by experimental means challenging and costly.

“The frosting process involves a complex, nonlinear, transient phase change coupled with heat and mass transfer, which makes accurate determination of frost-layer properties by experimental means chal­ lenging and costly [28,57 -60].”

The calculation method proposed by O'Neal and Tree [6] was improved by Webb and coworker [7], Lee et al. [8], and Yao et al. [9].

“The calculation method proposed by O'Neal and Tree [6] was improved by Webb and coworker [7], Lee et al. [8], and Yao et al. [9].”

Lee et al. observed an initial rapid increase followed by a continuous decrease over time in frost thickness, frost density, and frost surface temperature.

“The authors observed a trend of an initial rapid increase followed by a continuous decrease over time in frost thickness, frost density and frost surface temperature”

Latent heat transfer remained constant, perhaps due to constant mass transfer caused by saturated absolute humidity.

“Indeed, the latent heat transfer remained constant, perhaps due to constant mass transfer caused by the saturated absolute humidity.”

Frost layer growth is accelerated by higher inlet velocity and absolute humidity.

“acknowledged that frost layer growth was accelerated by higher inlet velocity and absolute humidity.”

The drastic decrease of 25% in heat flux after 180 min was due to a decrease in sensible heat transfer as the frost-layer surface temperature increased.

“The authors also claimed that the drastic decrease of 25% in heat flux after 180 min was due to a decrease in sensible heat transfer as the frost-layer surface temperature increased.”