Comparative analysis of thermal exchange calculation for refrigerants boiling in channels

DOI: 10.17586/1606-4313-2020-19-1-34-39
UDC 621.56, 621.57

Comparative analysis of thermal exchange calculation for refrigerants boiling in channels

Malyshev A.A., Malinina O. S., Kalimjanov D.E., Sukhov P.S., Kuadio K.F.

For citation: Malyshev A.A., Malinina O.S., Kalimjanov D.E., Sukhov P.S., Kuadio K.F. Comparative analysis of thermal exchange calculation for refrigerants boiling in channels. Vestnik Mezhdunarodnoi akademii kholoda. 2020. No 1. p. 34-39

Abstract
The article concerns an analysis and comparison of heat conductivity calculation techniques for refrigerants boiling in horizontal channels, including popular techniques of average heat conductivity calculation by  Brayan, Guaint, Baker, and Bogdanov, as well as the papers on local thermal exchange such as those by Lokhart-Marinelli, Chawel and Shrama. The techniques of average heat exchange calculation in question are shown  to fit each other in a satisfactory way at mass velocity of 50 kg/(s∙m2), which can be explained by their having analogous mode of two-phase flow at this velocity. At the velocity of 150 kg/(s∙m2) the calculated data vary significantly. The technique based on the use of true phase parameters and flow mode prediction results in 30% higher values of heat exchange coefficients. This fact can be explained by   the techniques of calculating heat exchange average coefficients given being obtained for stratified and slugging flow in general, but it is annular flow that occurs at high velocities and it did not take into account by popular equations. Good convergence of the data obtained with the experimental data by H. Yushida and S. Yamaguchi for the tubes of 6 mm diameter and minichannels of 0.5 mm equivalent diameter justifies the use of the complex technique based on true parameters.

Keywords: minichannels, local thermal exchange, true phase parameters, mass velocity, heat exchange coefficient, design of thermal exchange apparatus.


Read the full article