Maldistribution of Two-Phase Flow in Parallel Channel Heat Sinks: Effects of Thermal Connection Between Channels

Abstract

Two-phase cold plates, in which heat is transferred to a fluid flow via the process of flow boiling, offer a high performance thermal management solution for a variety of applications. Studies have identified that flow in such cold plates can be accompanied by flow instabilities. This work studies the maldistribution of flow in parallel channel cold plates. A dynamic model is developed to solve the hydrodynamics and the heat transfer in a system of parallel channels, embedded in a common base, connected to common inlet and outlet headers. The model solves the hydrodynamics by combining the pressure drop models for single channels with a model for the driving pump. The conduction in the base and the walls is solved by using a resistance network approach. The stability of the steady-state solutions of the model is used to identify the effects of heat transfer in the cold plate base and walls on the distribution of flow in the parallel channels. It is observed that increasing thermal connection among the channels, via the base and the walls, reduces the degree of maldistribution in the parallel channel cold plate. A threshold in the value of the base and wall thermal conductivity is identified, such that any higher value would necessarily lead to a uniform flow distribution in the channels. It is also identified that this threshold increases with increasing number of channels; the threshold has a quadratic polynomial relation with the number of channels. These results provide insight into the relevance of thermal connection between the parallel channels regarding mitigating the maldistribution of flow in parallel channel cold plates.