Evaluation of solid-solid and solid-liquid phase change materials in pin-finned heat sinks for cooling of avionics electronics

This paper discusses a comparative performance evaluation study of pin-finned heat sinks packed with solid-solid phase change material (SS-PCM) and solid-liquid phase change material (SL-PCM) for cooling of Field Gate Programmable Array (FGPA) devices used in avionics applications. A polyethylene glycol-based form-stable SS-PCM and a commercial organic-based SL-PCM named A24 with comparable thermophysical properties are considered in this numerical study. A numerical model coupled with the enthalpy method is developed to study the transient heat transfer characteristics of the two PCMs under the same heat input rates and chargingdischarging time. It is found that at lower heat input, an SS-PCM performs better than an SL-PCM after the heating cycle, whereas the considered SL-PCM shows a better performance, larger safe operational time (SOT) period, high energy storage potential, and efficiency compared to the chosen SS-PCM. The safe operation time (SOT) for SS-PCM and SL-PCM is increased by an average time interval of 668 s and 788 s, respectively. The heat storage efficiency of SS-PCM and SL-PCM is found to be 32 % and 60 %, respectively. This numerical study provides a quantitative comparison of both the PCMs and helps in the selection of the best PCM among SS-PCM and SL-PCM for a specific thermal storage-based application.