Thermodynamics of the hydride chemical heat pump: Model (I)

The efficiencies of a solid absorption heat pump are calculated with the help of chemical models. The first one is based on a reversible analysis where only the energy contributions to regenerate and insure continuous operations of the engine are taken into account. In the second one, the complete thermochemical behavior is described following the formalism of classical thermodynamics, in which no constraints on time or rate are allowed. Chemical constraints only have been introduced; they are derived from equilibrium studies. This model has been developed for two operating modes: Isotherm or isobar, and has been tested with the LaNi4.77Al0.22/LaNi5 system. The calculated efficiencies amount to 80% to 90% of the Carnot efficiency.