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Horizontal Convective Boiling of R448A, R449A, and R452B within a Micro-Fin Tube with Extensive Measurement and Analysis Details

Published

Author(s)

Mark A. Kedzierski, Donggyu Kang

Abstract

This report presents local convective boiling measurements in a micro-fin tube for three low global warming potential (GWP ) refrigerants: R448A, R449A, and R452B as possible replacements for R404A. Water heating either in counterflow or in parallel flow with the test refrigerant was used to vary the heat flux for a given quality. An existing correlation from the literature was modified to predict multi-component mixtures, which predicted 98 % of the measurements to within ± 20 %. The new correlation was used to compare the heat transfer coefficient of the three test fluids at the same heat flux, saturated refrigerant temperature, and refrigerant mass flux. The resulting comparison showed that refrigerant R452B exhibited the highest heat transfer performance in large part due to its approximate 28 % larger liquid thermal conductivity and smaller temperature glide as compared to the tested low-GWP refrigerants. For the example case, the heat transfer coefficient for R449A was approximately 8 % larger than that for R448A, while the heat transfer coefficient for R452B was more than 59 % larger than either R448A or R449A. As predicted by the modified model, the heat transfer coefficients for R448A and R449A are roughly between 26 % and 48 % less than that of R404A for most qualities between 10 % and 70 %. The smaller heat transfer coefficient of R448A and R449A as compared to that of R404A results even though these refrigerants both have an approximate 20 % larger liquid thermal conductivity than R404A. In contrast, the model predicts that the R452B heat transfer coefficient is approximately 13 % larger than that of R404A for thermodynamic qualities between 10 % and 70 %. The measurements are important as part of the evaluation of low-GWP replacement refrigerants for R410A and R404A for the air-conditioning and refrigeration markets, respectively.
Citation
Technical Note (NIST TN) - 1915
Report Number
1915

Keywords

boiling, enhanced heat transfer, low-GWP, micro-fin, refrigerant mixtures

Citation

Kedzierski, M. and Kang, D. (2016), Horizontal Convective Boiling of R448A, R449A, and R452B within a Micro-Fin Tube with Extensive Measurement and Analysis Details, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.TN.1915 (Accessed June 23, 2024)

Issues

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Created May 12, 2016, Updated November 10, 2018