On Thermodynamic Peculiarities of the Absorption Heat Transformers

Abstract

In this paper we describe the peculiarities of the thermodynamics of the absorption heat transformers (AHTs) pointing to the possibility of examining the AHT models from the standpoint not only of the equilibrium thermodynamics, as it usually is, but also of the non-equilibrium one. In the well-known models of absorption refrigerators commonly represented by a combination of the reversible Carnot cycles, the absorption effects are not taken into account. At that, the mechanical energy required for operation of the refrigerator in such a model is superior to its real value, such as in cycles with solutions of H2O / LiBr and NH3 / H2O in several times. The examination of another AHT model represented by new cycles for a concurrent generation of electric power and cold shows that it also does not quite correlate with the earlier known models of the equilibrium (classical) thermodynamics. The evaluation of the performance of such cycles with the CH3OH/LiBr and NH3/LiNO3 solutions shows that under certain circumstances it can exceed the performance of the corresponding Carnot cycles. The application in this event of the non-equilibrium thermodynamics to a greater extent conforms to the physical model of the absorption cycles and creates prerequisites for further improvement of the performance of the combined cycles for generation of energy and cold.