The Simulation Of Thermodynamic Performance Of A Hybrid Ejector-Absorption Heat Pump With LiBr-H₂O

Absorption heat pump (AHP) can recover and utilize waste heat with lower temperature, As driven by heat source it consume electric energy a little. AHP is more available in using energy source and decreasing the global warming and stratospheric ozone depletion than other method of heating. The emphasis study in this work is a hybrid ejector-absorption heat pump (EAHP) using lithium bromide-water. An ejector is introduced between condenser and generator in this novel cycle. Using high-pressure steam from the generator as the primary fluid, the ejector entrains part of low-pressure vapour from the evaporator, and discharges to the condenser after the temperature and pressure of the vapour enhanced. Thus, more units are condensed and evaporated in condenser and evaporator respectively for one unit of refrigerant vapor generated from the generator.To get more exact and credible thermodynamic parameter in every point of the cycle, the results for various state equations of LiBr-H₂O solution in present are calculated in this research. A modified Patterson equation for enthalpy values is established based on the differences among the outputs from the Patterson equation and the domestic diagram of concentration-enthalpy relation, and other heat physical equations are founded on the same benchmark. The quality of COP is mostly rested with ejector entrainment ratio in this novel cycle. The relation of entrainment ratio and various operation temperatures is studied using the aerodynamics technique with configuration of big expansion ratio, big compression ratio or moderate compression ratio. Subsequently, the influence of entrainment ratio to system's performance is explained in theory.The thermodynamic circuit process performance of the hybrid heat pump system is calculated in detail. A computer program and its subroutines by FORTRAN language are compiled, which introducing a set of mass and heat conservation equations based on the first law, the second law of thermodynamic and the aerodynamics technique. The weakness of energy transformation process in the hybrid system and the reasons, improvement methods for this system has been proposed by analyzing theoretical exergy of each furnishment. The influences of variation of parameters to the system's COP and ECOP are researched, while the system's operation characteristics are analyzed and the practical range for system is pointed out. The comparisons between the combined heat pump and conventional absorption heat pump show that the novel system can utilize high temperature heat source effectively,and crystallization matter does not easily occur. This is also shown to significantly increase the COP of the novel heat pump above that of a conventional absorption unit with little increase in system complexity. Therefore, the novel pump has superior application worthiness.In all, the simulation and analysis results obtained can be helpful to improve the system performance and make the design of the system optimum for the LiBr ejection-absorption heat pump.