Two-phase flow oscillation and distribution in parallel channels during R1233zd(E) subcooled flow boiling: A numerical study

Abstract

The uniformity of two-phase flow distribution in a multi-channel heat sink is important for heat transfer performance. During flow boiling, flow oscillations such as transient reverse flow could cause severe flow mal-distribution, thus degrading heat transfer performance and thermal uniformity. Due to the shortcomings of experimental instruments, a 3D numerical simulation was conducted on a heat sink with 21 parallel micro-channels to study the transient flow oscillations and distributions during the subcooled flow boiling of R1233zd(E). The numerical model was validated by the flow pattern visualization experiments. The flow instability was studied on its cause and phenomenon like reversed flow and asymmetric flow. The two-phase flow pattern, heat transfer performance and pressure drop oscillation was also researched and a relationship between them was built. Based on the results, an optimized structure is conducted. The comparison between the optimized and original structure showed that the optimized structure could mitigate the reversed flow, meanwhile the uniformity of mass and temperature distribution were improved by 11.2 % and 8.89 %, respectively. The heat transfer performance of side channels was also enhanced, which in turn improved the overall heat transfer performance.