Performance optimization of a solar air-conditioning with a three-phase accumulator based on the energy-economic analysis

Abstract

The intermittent and instability problem of solar energy is solved by using "three-phase accumulator" with the medium of LiBr–H2O instead of the auxiliary heater in a solar air conditioning (SAC) system based on independent-developed solar parabolic trough collectors (PTC), in which, "three-phase" refers to LiBr solution, LiBr crystal and vapor. The multi-objective optimization is conducted based on the energy and economy analysis. Pareto frontier for the multi-objective optimization has been obtained with NSGA II. The optimal points have been selected by LINMAP and TOPSIS decision-making methods. The multi-objective optimization results show that the solar fraction, the energy storage density and the system efficiency of the SAC system with TOPSIS are 89.67%, 624.67 kWh/m³, 0.833, respectively, compared with LINMAP, which are 88.31%, 604.22 kWh/m³, 0.848. Based on the TOPSIS decision-making results, the annual average investment of the SAC system is 161,100RMBY, the economic indexes of the system, i.e., AFC (annual cash flow), PBP (payback period), NPV(net present value) and IRR (internal rate of return) are 38,100RMBY, 5.53 years, 140,500RMBY and 7.82%, respectively. In addition, the economic sensitivity analysis results show that the prices of PTCs and refrigeration equipment have a greater impact on the economic index.