Insight Into Recompression Brayton Cycle

Abstract

Recompression cycles have the potential to offer high performance when design parameters such as feasibility, performance, and compactness are considered. These cycles have recently gained attention especially in nuclear and concentrating solar power plants because of their high efficiency and environmentally friendly. A study has been done to investigate and learn more about recompression cycles. In this paper, a recompression Brayton cycle has been analyzed by performing parametric studies on the effectiveness of recuperators, pressure ratio, and split ratio as well as other input variables. To understand the relations between these factors and the performances of the cycle, argon was used as a working fluid because of its constant specific heat. The solution to temperatures at each state has been derived analytically, which is presented as a function of independent input variables. Thermal efficiency and exergy efficiency of this cycle have been determined in these analyses. The model indicates following results: entropy generation of recuperators is lower at a minimum split and decreases with increasing effectiveness. When the cycle is optimized for maximum efficiency it does not operate on maximum specific net work. The energy and exergy efficiencies of the cycle increase with increasing pressure ratio reaching a maximum value at the optimum pressure ratio. The effect of split ratio on temperature difference around recuperators shows that energy recovered at low temperature is higher at a minimum split which yields a higher efficiency in the cycle. The performance of the cycle is strongly affected by turbine inlet temperature.