Reduction of the heat capacity in low-temperature adsorption chillers using thermally conductive polymers as heat exchangers material

Abstract

Aside from the low adsorption capacity of silica gel, often used in commercially available low-temperature adsorption chillers today, the cooling performance of such chillers is limited due to the high heat capacity of the mostly metal-based heat exchangers. As a completely new approach, thermally conductive polymers have been studied and examined as heat exchanger materials for low temperature adsorption chillers in order to decrease the energy consumption during the adsorption cycle. The modification of polyamide 6, which was chosen as a model polymer in this study, with expanded graphite leads to enhanced thermal part properties for adsorption heat exchangers. Compared to aluminum as the commonly used heat exchanger material, the heat capacity of a chiller can be reduced by 30%, if such a thermally conductive polymer is applied. Moreover, the increased thermal conductivity of the polymer based part leads to no significant limitation in the adsorption kinetic of water used as a refrigerant in adsorption chillers.