2021 Volume 38 Issue 2 Pages 115-
A novel high performance refrigerant-air heat exchanger and heat pipe which have a refrigerant mini-channel have recently been developed. Since flow oscillation of refrigerant occurs in some conditions of parallel mini-channel heat exchangers and in pulsating heat pipes, it is necessary to understand the transient heat transfer characteristics of refrigerant under the flow oscillation condition to predict the heat transfer performance. In this study, as a basis for clarifying the transient boiling heat transfer characteristics under the flow oscillation condition, experiments on boiling heat transfer during flow rate reduction of a refrigerant HFC134a flowing in a horizontal mini-channel with an inner diameter of 1.0 mm were conducted. And the characteristics were compared with experimental results of steady-state heat transfer and the prediction correlation for steady state heat transfer in mini-channels. The experimental results showed that transient boiling heat transfer during flow rate reduction is similar to steady state boiling heat transfer if the local mass flux and quality are accurately predicted.
