A numerical and experimental comparative study on the performance of organic and metallic phase change materials under high power millisecond pulses

Abstract

Phase changes materials (PCMs) have been studied as passive cooling alternative for different conditions. Due to the US Army need for the development of a passive cooling system alternative for pulsed power applications, this research studies the performance of PCMs as passive cooling for pulsed power applications. An unidimensional simple model, easy to implement and use, was developed. This model was used to guide and bring understanding on how different materials would perform under different conditions. This model studied the performance, under typical high power short pulse condition, of two organic PCMs (erythritol and n-octadecane), three metallic PCMs (gallium, Bi/Pb/Sn/In and indium) and a silicone dielectric gel. Finite difference method and heat integration method were used to model the heat transfer and melting process. The model showed that metallic PCMs would outperform another material, compared to organic PCMs and dielectric gel, under high power fast transient pulses. The model also shows that high thermal conductivity is beneficial for fast transient, however, this benefit will decrease if using a same energy pulse at longer time, where latent heat of fusion would dominate over thermal conductivity. Once it was known what expect, these results were verified via experimentation. A device that work as heater and temperature sensor was developed to perform the experimental evaluation of metallic PCMs. During the experimentation, metallic PCM, as the model suggested, outperformed organic PCMs and dielectric gel under high power fast pulse condition. An outstanding temperature suppression 80°C was achieved by a metallic PCM (Fields’metal) compared to dielectric gel under a pulse of 160W (338W/cm2). This study shows the great benefit of using metallic PCMs as passive cooling for pulsed power applications.