Equivalent Carnot cycles for sorption refrigeration: Cycles de Carnot équivalents pour la production de froid par sorption

Abstract

Temperature–entropy diagrams are usually used to describe heat-driven engines as well as vapour compressor refrigerators, but they have not yet been used for sorption refrigeration. Such Carnot cycles are introduced here to describe three sorption refrigeration technologies (liquid absorption, solid adsorption, chemical reaction). This is performed for basic cycles (without heat recovery) and for simple advanced cycles. Equivalent four-temperature Carnot cycles are obtained for basic cycles, whereas equivalent six-temperature Carnot cycles are obtained for advanced cycles. This approach shows that the quantity Δ H- TΔ S (where Δ H and Δ S are the enthalpy and entropy variations associated with mass transfer during a cycle in/out of the sorbers) plays the same role as the mechanical energy in vapour compression cycles.