TY - JOUR
T1 - A pressure drop model for condensation accounting for non-equilibrium effects
AU - Xiao, Jiange
AU - Hrnjak, Pega
N1 - Funding Information:
The authors thankfully acknowledge the support provided by the Air Conditioning and Refrigeration Center at the University of Illinois at Urbana-Champaign, and technical support from Creative Thermal Solutions, Inc. (CTS).
Funding Information:
The authors thankfully acknowledge the support provided by the Air Conditioning and Refrigeration Center at the University of Illinois at Urbana-Champaign , and technical support from Creative Thermal Solutions, Inc. (CTS).
Publisher Copyright:
© 2018
PY - 2018/11
Y1 - 2018/11
N2 - A mechanistic pressure drop model is proposed in this paper for condensation in horizontal smooth round tubes in order to account for the non-equilibrium effects. The model makes use of a flow regime map and void fraction correlation as well as a mechanistic heat transfer model that are all developed for condensation of superheated vapor in a vapor-compression system. The model provide seamless transition between single-phase and two-phase regions including the superheated, condensing-superheated, two-phase, condensing-subcooled and subcooled regions. Diabatic flow visualizations are used to analyze the effects on pressure drop from the formation of waves. An enhancement factor to represent the frequency and magnitude of the waves is established using Kelvin-Helmholtz and Rayleigh-Taylor instability. The two-phase pressure drop is modeled based on the single-phase pressure drop correlations, the flow regimes, void fractions as well as the enhancement factor. Data obtained from R134a, R32, R1234ze(E), R1233zd(E) and R245fa with mass fluxes from 100 kg m−2 s−1 to 400 kg m−2 s−1 and heat fluxes from 5 kW m−2 to 15 kW m−2 inside two different tubes of 4 and 6 mm are used to validate the model.
AB - A mechanistic pressure drop model is proposed in this paper for condensation in horizontal smooth round tubes in order to account for the non-equilibrium effects. The model makes use of a flow regime map and void fraction correlation as well as a mechanistic heat transfer model that are all developed for condensation of superheated vapor in a vapor-compression system. The model provide seamless transition between single-phase and two-phase regions including the superheated, condensing-superheated, two-phase, condensing-subcooled and subcooled regions. Diabatic flow visualizations are used to analyze the effects on pressure drop from the formation of waves. An enhancement factor to represent the frequency and magnitude of the waves is established using Kelvin-Helmholtz and Rayleigh-Taylor instability. The two-phase pressure drop is modeled based on the single-phase pressure drop correlations, the flow regimes, void fractions as well as the enhancement factor. Data obtained from R134a, R32, R1234ze(E), R1233zd(E) and R245fa with mass fluxes from 100 kg m−2 s−1 to 400 kg m−2 s−1 and heat fluxes from 5 kW m−2 to 15 kW m−2 inside two different tubes of 4 and 6 mm are used to validate the model.
KW - In-tube condensation
KW - Non-equilibrium
KW - Pressure drop model
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U2 - 10.1016/j.ijheatmasstransfer.2018.04.158
DO - 10.1016/j.ijheatmasstransfer.2018.04.158
M3 - Article
AN - SCOPUS:85047078546
SN - 0017-9310
VL - 126
SP - 421
EP - 430
JO - International Journal of Heat and Mass Transfer
JF - International Journal of Heat and Mass Transfer
ER -