Interactions Between Parallel Minichannels During Flow Boiling of R134A

Abstract

This work focuses on the study of flow boiling of R134a in 0.54 mm square parallel minichannels, with a particular focus on the transient pressure drop of individual channels and their interaction. The individual pressure drop in each passage was analyzed to establish the inter-channel relationship; additionally, the effect of heat and mass flux and the inlet vapor qualities on the flow patterns of each channel was studied based on flow visualization and pressure drop measurements. The mass flux and heat flux in the experiments were varied up to 800 kg/m2s and 10 kW/m2 respectively. The heat flux was controlled and varied independently in each channel. Results illustrate that interaction between channels exists, and the correlation degree depends on the flow boiling dynamics in each passage. The pressure drop oscillation in each channel affects the flow redistribution between channels. A channel subjected to the least heat flux tends to correlate the most with greater heated channels because of the mass flux fluctuations caused by boiling phenomena in other channels.