Flow distribution and heat transfer performance of two-phase flow in parallel flow heat exchange system

Two-phase flow parallel heat exchange systems are widely used in solar energy collectors, nuclear reactors, air-conditioners and electronic thermal management. However, flow maldistribution in multiple channels may lead to heat transfer deterioration. In this study, a numerical model is developed to quickly predict the flow distribution and heat transfer of two-phase flow in the parallel flow system, and the maximum average relative deviation with experimental data is 4.4%. The effects of geometric parameters and non-uniform thermal load on flow and heat transfer are discussed. Decreasing the channel to header area ratio AR can significantly improve the flow maldistribution when AR is greater than 0.3. Moreover, dimensionless parameters Y_m and H are introduced to predict the worst operating condition when the heating is non-uniform. The results indicate that the mass flow rate of the channel near the low thermal load channel reduced significantly, especially the downstream channel. The 2nd channel from the inlet should be avoided being the low thermal load channel, and the maximum outlet vapor quality (x_out)_max is a linear function of H. If it's assumed that (x_out)_max = 1 is the worst condition, the thermal non-uniformity dimensionless parameter H must be less than about 198 in this study.