Thermal Characteristics of a Compact, Passive Thermal Energy Storage Device

Abstract

Abstract A Thermal Energy Storage (TES) system uses a Phase Change Material (PCM) to store heat during peak power operation of variable power dissipating devices via the latent heat effect. The TES composite developed is a plate-like structure that consists of a central core of foamed aluminum that is packed with a PCM. By considering the elements of the composite to be thermal resistors and constructing a flat-plate thermal conductivity apparatus, the plate-to-plate effective thermal conductivity is determined. The composite effective thermal conductivity is primarily composed of the thermal conductivity of the aluminum foam which is reduced by the effect of the aluminum foam-to-plate bond resistance. Heat flow through the PCM slightly augments the effective thermal conductivity. An increase in aluminum foam metal fraction results in an increase in the effective thermal conductivity of the composite because only about 2% of the heat flow is through the PCM, and the interfacial bond resistance decreases due to increased contact area. The trade-off is that as there is an increase in aluminum foam metal fraction, the volumetric latent heat decreases; thus, the storage time is reduced.