Performance modelling of single and double absorption heat transformers

Absorption heat transformers (heat pump Type II) enable the temperature of a low heat source to be raised to a higher level. This process takes place by means of the absorption of a vaporized working fluid into a substance which has strong affinity for the vapor. The temperature lift and the coefficient of performance (a measure of the efficiency of the process), are important design parameters which depend on the thermodynamic properties of the working pair and also on the configuration of the equipment. In order to investigate the performance of readily available, not expensive and environmentally friendly fluids in heat transformers, the systems H2O/CaCl2 and H2O/LiCl were studied, by using a Fortran program. The theoretical performance of both systems in a single stage absorption heat transformer (SSHT), was derived and compared to results obtained previously for the system H2O/CaCl2 on a double absorption unit (DAHT).