Performance improvement of two-stage serial organic Rankine cycle (TSORC) integrated with absorption refrigeration (AR) for geothermal power generation

Abstract Compared with ORC, the two-stage serial organic Rankine cycle (TSORC) can improve the temperature matching between the heat source and the working fluid. However, the power output of the low-pressure stage is relatively low. In this paper, the TSORC is integrated with the absorption refrigeration (AR), with the residual heat of the discharge water from AR used as a supplementary heat source for the low-pressure stage. The TSORC-AR is proposed, and the objective of this paper is to enhance the comprehensive performance. Furthermore, a comprehensive formula, which includes several variables such as the net power output, the thermal conductance, the volumetric flow ratio and the size parameter of the turbine, is chosen as the objective function. The results show that the supplementary heat source largely increases the evaporating load, especially in the low-pressure stage, of the TSORC-AR but makes the evaporating temperatures lower than those of the TSORC. Compared with the TSORC, the TSORC-AR can output more net power, but with a lower thermal efficiency. Overall, the TSORC-AR can make better use of the heat source and it can be popularized in engineering applications.