Condensation heat transfer characteristics and energy conversion performance analysis for low GWP refrigerants in plate heat exchangers

초록

In this study, we analyzed the effects of heat flux, mass flux, condensation pressure, and mean vapor quality on the condensation heat transfer and friction pressure drop characteristics of R-1234ze(E) and R-1233zd(E) in plate heat exchangers with different chevron angles. When the mean vapor quality increased, the heat transfer coefficient and frictional pressure drop increased. Both increased with increasing the mass flux and with decreasing the condensation pressure. Unlike the heat transfer coefficient, the frictional pressure drop was hardly affected by the heat flux. R-1233zd(E) showed a larger heat transfer coefficient and frictional pressure drop than R-1234ze(E) owing to the differences in thermodynamic properties. The Nusselt number correlation and friction coefficient correlations were derived for various chevron angles from the experimental results. The ratio of the Nusselt number and pressure drop according to the equivalent Reynolds number was compared. It is concluded that R-1234ze(E) has a higher energy performance parameter than R-1233zd(E), which means that R-1233zd(E) has an advantage in terms of heat transfer, but the loss due to the increased pressure drop is relatively large. It is also confirmed that the result from the simple relative economic evaluation agree well with that from the energy conversion performance evaluation. (C) 2020 Elsevier Ltd. All rights reserved.

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