Theory of a New Electrochemical Heat Pump

Abstract

An idea of a new electrochemical heat pump that uses the combination of an electrolytic reaction at lower temperature to absorb low grade thermal energy and a thermochemical reaction at higher temperature to produce more efficient thermal energy has been proposed. At lower temperature an endothermic reaction proceeds with electrolysis, where the reaction could not occur thermochemically. At higher temperature an exothermic reaction that is the reverse reaction of the electrolysis proceeds thermochemically to produce high grade thermal energy. The thermodynamic consideration showed that the theoretical coefficient of performance of this electrochemical heat pump with continuous transportation of working substances could reach up to the value of the inverse Carnot factor that is defined by the higher and the lower temperatures of the system. The irreversibility of the system such as the mechanical work required to transport of working substances and the thermochemical reaction at higher temperature decreased the coefficient. Introducing the quantity of the entropy production due to irreversibility, the relationship between the coefficient and the irreversibility was derived. The ΔH°‒ΔS° diagram (ΔH°: the standard enthalpy change of the reaction, ΔS°: the standard entropy change of the reaction) was found to be useful for the selection of the reactions.