Analysis and assessment of cascaded closed loop type organic Rankine cycle

Abstract

This paper presents the thermodynamic analysis of an organic Rankine cycle integrated with the cascaded closed loop cycle that is considered one of the advanced heat recovery technologies that enhance thermal efficiency significantly as compared to the simple cycle and the recuperated cycle. A parametric study is performed to investigate the influences of several important operating parameters on energy and exergy efficiencies of all three cycles while using propane as a working fluid. In order to check the accuracy and applicability of the models and validate them with the literature data, a comparison is drawn between the three cycles in terms of net power output, energy efficiency, exergy efficiency, and total exergy destroyed. The results reveal that the net power output of the cascaded cycle shows a significant increase of 73% as compared to the simple cycle. The cascaded cycle shows a promising increase in energy efficiency by 8%, while the exergy efficiency is enhanced by approximately 21%. Total exergy destroyed is reduced by 27% while applying the cascaded technology. The optimization study on the stream mass flow ratio reveals that the maximum energy and exergy performance obtained at the maximum stream mass flow ratio of unity. The study suggests using the cascaded cycle if the heat source temperature is higher than 200 °C.