Two Phase Flow Maldistribution in Parallel Channels of Evaporators: Experimental and Analytical Modeling

The performance of thermal devices such as evaporators is greatly affected due to flow mal- distribution in the parallel channels. There is inherent flow mal-distribution in manifolds involving single-phase flow which is a result of non- uniformity of the pressure drop across each lateral channel. This will even be more complicated when the flow involves two phase, which is often the case in refrigerant flow of multi-pass evaporators, since there is gravity induced preferential phase separation at the entrance to lateral channels in manifolds. In this book, the result of experimental and theoretical study of single-phase and two-phase flow mal-distribution performed on a model brazed aluminum evaporator having horizontal headers is presented. The analytical method presented here provides a scheme on how to predict the flow split in a downward dividing header. Possible means of reducing mal-distribution is also discussed based on the result of flow visualization test.