4E analysis and multi-objective optimization of a CCHP cycle based on gas turbine and ejector refrigeration

Abstract

In this research paper, the performance of a new configuration of a Combined Cooling, Heating and Power (CCHP) cycle including a Brayton cycle, a Rankine cycle, an ejector refrigeration cycle, and a domestic water heater is studied by utilization of 4E (energy, exergy, economic and environmental) analysis. Firstly, performance evaluation of the cycle is carried out using exergy and energy as a potential tool. In addition, an environmental assessment is applied to address the environmental impacts of the new multi-generation cycle and compare with the simple Brayton cycle. Results demonstrate that the CCHP cycle has greater exergy and energy efficiencies compared to a simple Brayton cycle. Moreover, the effects of several major design variables on the performance of the cycle are studied and the findings are presented. The major design parameters are gas turbine inlet temperature, compressor pressure ratio, heat recovery steam generator (HRSG) pressures, HRSG pinch point temperatures and regenerator effectiveness. In order to optimize the cycle and find the optimal selection of these design variable, two objective functions namely levelized total annual cost and exergy efficiency are defined and a multi-objective optimization is implemented. Based on the optimization outcomes, optimal points are found and the respective Pareto front is plotted. Comparing CCHP cycle to corresponding Brayton cycle, it is revealed that the CCHP cycle has higher exergy efficiency (7%) and energy efficiency (12%) rather than Brayton cycle.