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research article

Experimental study on condensation heat transfer in vertical minichannels for new refrigerant R1234ze(E) versus R134a and R236fa

Park, Jung Eung  
•
Vakili Farahani, Farzad  
•
Consolini, Lorenzo  
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2011
Experimental Thermal And Fluid Science

Experimental condensation heat transfer data for the new refrigerant R1234ze(E), trans-1,3,3,3-tetrafluoropropene, are presented and compared with refrigerants R134a and R236fa for a vertically aligned, aluminum multi-port tube. Local condensation heat transfer measurements with such a multi-microchannel test section are very challenging due to the large uncertainties related to the heat flux estimation. Presently, a new experimental test facility was designed with a test section to directly measure the wall temperature along a vertically aligned aluminum multi-port tube with rectangular channels of 1.45 mm hydraulic diameter. Then, a new data reduction process was developed to compute the local condensation heat transfer coefficients accounting for the non-uniform distribution of the local heat flux along the channels. The condensation heat transfer coefficients showed the expected decrease as the vapor quality decreased (1.0-0.0) during the condensation process, as the mass velocity decreased (260-50 kg m(-2) s(-1)) and as the saturation temperature increased (25-70 degrees C). However, the heat transfer coefficients were not affected by the condensing heat flux (1-62 kW m(-2)) or by the entrance conditions within the tested range. It was found that the heat transfer performance of R1234ze(E) was about 15-25% lower than for R134a but relatively similar to R236fa. The experimental data were then compared with leading prediction methods from the literature for horizontal channels. In general, the agreement was poor, over-predicting the high Nusselt number data and under-predicting the low Nusselt number data, but capturing the mid-range quite well. A modified correlation was developed and yielded a good agreement with the current database for all three fluids over a wide range of operating conditions. (C) 2010 Elsevier Inc. All rights reserved.

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Type
research article
DOI
10.1016/j.expthermflusci.2010.11.006
Web of Science ID

WOS:000287618400003

Author(s)
Park, Jung Eung  
•
Vakili Farahani, Farzad  
•
Consolini, Lorenzo  
•
Thome, John Richard  
Date Issued

2011

Publisher

Elsevier

Published in
Experimental Thermal And Fluid Science
Volume

35

Issue

3

Start page

442

End page

454

Subjects

Two-phase flow

•

Condensation heat transfer

•

multiport tube

•

Vertical minichannel

•

R1234ze(E)

•

R236fa

•

R134a

•

Aluminum Multichannel Tubes

•

Pressure-Drop

•

Micro-Fins

•

Circular Microchannels

•

Diameter Tubes

•

Flow Regimes

•

Model

•

Channels

•

Friction

•

R-22

Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LTCM  
Available on Infoscience
December 16, 2011
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/74457
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