Cited by 0Refrigeration and Air Conditioning TechnologiesPhase Equilibria and ThermodynamicsHeat Transfer and Boiling Studies

How equation-of-state choice and property uncertainty influence numerical heat exchanger design: A case study of an n-butane/CO₂ mixture

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Welp, Alexandra, Buchenfeld, Jessica, Saric, Denis, Sabozin, Fabian, Thol, Monika, Vrabec, Jadran, Span, Roland, Atakan, Burak·2027·International Journal of Heat and Mass Transfer

Abstract

Numerical design of heat transfer and pressure loss in heat exchangers depends strongly on the thermophysical property models used for the working fluid. This is particularly relevant for zeotropic mixtures, where saturation behavior, temperature glide, and transport properties determine local driving temperature differences during phase change. This work analyzes the interplay between heat exchanger modeling and thermophysical property models from user and developer perspectives, examining how model choice affects engineering predictions and analyzing how uncertainties in individual fluid properties propagate into application-level results. A one-dimensional spatially resolved double-pipe condenser model is applied to a zeotropic n -butane/CO₂ mixture with water as secondary fluid. The equations of state GERG-2008, Peng–Robinson, and a molecular-simulation-based Helmholtz model are combined with transport-property models based on the extended corresponding states principle and residual entropy scaling. Local heat-transfer coefficients and pressure gradients are evaluated using correlations suitable for zeotropic mixtures. Results show that fluid-model choice substantially affects temperature profiles and heat-exchanger sizing, mainly through differences in saturation states. Predicted heat exchanger lengths vary from −7.3% to + 11.8% relative to the mean; in a limiting case with small temperature difference full condensation is not always reached. Sensitivity analyses show that uncertainties in thermal conductivity, dynamic viscosity, and isobaric heat capacity dominate fluid-property uncertainty propagation into heat-transfer predictions, whereas pressure-drop-related properties have only minor influence on exchanger length under present conditions with relatively large tube diameters. Including empirical correlation uncertainties for heat-transfer coefficients and pressure loss makes them dominate the total output uncertainty; nevertheless, fluid-property uncertainties remain a relevant secondary contribution.

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Crossref · 10.1016/j.ijheatmasstransfer.2026.129557

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Authors
Welp, A., Buchenfeld, J., Saric, D., Sabozin, F., Thol, M., Vrabec, J., Span, R., & Atakan, B.
Affiliations
  • University of Duisburg-Essen (DE)
  • Ruhr University Bochum (DE)
  • Technische Universität Berlin (DE)
Corresponding author
Welp, Alexandra
Venue
International Journal of Heat and Mass Transfer
Publisher
Elsevier BV
Published
2027-01
Volume
272
Pages
129557
ISSN
0017-9310 (ISSN-L)
OpenAlex
W7213953988
Cited by
0
References
52
FWCI
0.00
Type
journal article
Language
en
Open access
Locations
  • International Journal of Heat and Mass Transfer (publishedVersion, cc-by)
  • Universitätsbibliographie, Universität Duisburg-Essen (submittedVersion)
Funders
German Research Foundation (526086126, 525876331, 525971077)
Topics
  • Physical Sciences › Engineering › Mechanical Engineering › Refrigeration and Air Conditioning Technologies
  • Physical Sciences › Engineering › Biomedical Engineering › Phase Equilibria and Thermodynamics
  • Physical Sciences › Engineering › Mechanical Engineering › Heat Transfer and Boiling Studies
Keywords
heat exchanger design, equation of state, zeotropic mixtures, GERG-2008, Peng-Robinson equation of state, Helmholtz equation of state, heat transfer coefficient, pressure drop, saturation behavior, temperature glide, error propagation, heat exchanger length

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