Two-objective optimization of a transcritical carbon dioxide based Rankine cycle integrated with evacuated tube solar collector for power and heat generation

Abstract

In this study, two-objective optimization of a solar-driven carbon dioxide (CO2) based transcritical Rankine cycle for power and heat generation is carried out. With Engineering Equation Solver (EES), the monthly thermodynamic performance of the integrated system is determined. Results show that the exergy rate of recovered heat in the winter is 0.029 kW, which is relatively low due to low solar intensity for the winter season (512 W/m2). The results revealed that the highest overall energy efficiency of the system takes place in July, and the highest overall exergy efficiency is calculated for August. The results of the parametric study indicate that changing the considered decision parameters has different effects on the recovered heat and net output power of the integrated system. Hence, a two-objective optimization with net output power and recovered heat as optimization targets is performed. In order to achieve the optimization solutions, the objective functions are defined seasonally. The results of optimum states regarding the concept of ideal point show that the best performance of the system is in summer with 0.262 kW for net power output and 0.921 kW for recovered heat.