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Heat Transfer Coefficient, Pressure Gradient, and Flow Patterns of R1234yf Evaporating in Microchannel Tube.

Authors :
Houpei Li
Hrnjak, Pega
Source :
Journal of Mechanical Design. Apr2021, Vol. 143 Issue 4, p1-12. 12p.
Publication Year :
2021

Abstract

This paper presents the heat transfer coefficient, pressure gradient, and flow pattern of R1234yf in a microchannel tube. Both heat transfer coefficient and pressure gradient are presented against real saturation pressure, while flow pattern captures at the exit of data points are presented in the same plot. The experiment was conducted on a 24-port microchannel tube with an average hydraulic diameter of 0.643?mm. The experiment covers mass flux from 100 to 200?kg m-2s-1, heat flux from 0 to 6?kW m-2, vapor quality from 0 to 1, and inlet saturation temperature from 10 to 30?°C. Comparing the correlations to the HTC measurements at very low quality (about 0.1), Gorenflo, D., and Kenning, D. (2010, Pool Boiling, in: VDI Heat Atlas, 2nd ed, Springer, pp. 757-788) agree with the results. As vapor quality increases, pressure gradient increases. The adiabatic pressure gradient is a strong function of mass flux and saturation pressure (temperature). Flow patterns of R1234yf are also affected by mass flux and saturation pressure. The heat transfer coefficient is a strong function of mass flux and heat flux. The saturation temperature has a smaller effect on HTC in the condition range (10 - 30?°C). Under the test range, the accelerating pressure drop is insignificant compared to friction. Comparing to the results, Mishima, K., and Hibiki, T. (1996, "Some Characteristics of Air-Water Two-Phase Flow in Small Diameter Vertical Tubes," Int. J. Multiph. Flow, 22(4), pp. 703-712) and Muller-Steinhagen, H., and Heck, K. (1986, "A Simple Friction Pressure Drop Correlation for Two-Phase Flow in Pipes," Accessed March 1, 2018)., 20, pp. 297-308.) have small mean absolute error (MAE) to predict local pressure gradient. For the heat transfer coefficient, Sun, L., and Mishima, K. (2009, "An Evaluation of Prediction Methods for Saturated Flow Boiling Heat Transfer in Mini-Channels," Int. J. Heat Mass Transf, 52(23-24), pp. 5323-5329) and Gungor, K. E., and Winterton, R. H. S. (1986, "A General Correlation for Flow Boiling in Tubes and Annuli," Int. J. Heat Mass Transf, 29(3), pp. 351-358) have an MAE less than 30%. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
10500472
Volume :
143
Issue :
4
Database :
Academic Search Index
Journal :
Journal of Mechanical Design
Publication Type :
Academic Journal
Accession number :
149408252
Full Text :
https://doi.org/10.1115/1.4049635