Computational and Experimental Analysis of a Meso-Scale Heat Exchanger

The main objective of this study is to develop an efficient meso-scale thermo-catalytic air purification system for battlefield applications. In this system, heated air is passed through a catalytic reactor to destroy toxic materials. The main constraints in designing this system are size, weight and fuel/power consumption. A successful design of this type of purification system depends to a large extent on the efficiency and performance of the heat exchanger. As a first step, a heat exchanger system that consists of several units of planar counter flow heat exchangers stacked on top of each other has been designed and fabricated. A CFD (Computational Fluid Dynamics) model has been used to understand the flow and heat transfer characteristics as well as to predict the effectiveness of the heat exchanger. A series of experiments have been performed to collect data to validate the CFD results. It will be shown that the data for temperature and effectiveness are in agreement with CFD predictions. Parametric simulations have also been performed to evaluate the heat exchanger performance as functions of geometric and operating conditions. The results indicate that axial conduction in the exchanger plate and the thermal boundary layer film resistance are the limiting factors in the heat exchanger performance.