Performance comparison of organic Rankine cycles integrated with solar based combined cycle: A thermodynamic and exergoenvironmental analysis

Abstract

In the present study, the two configurations of the combined intercooled cascade supercritical carbon dioxide (sCO2) cycle/organic Rankine cycle (ORC) (configuration-1) and the combined intercooled cascade sCO2 cycle/parallel double evaporator ORC (PDORC) (configuration-2) were considered for the comparison on the basis of thermodynamic performance. Solar power tower (SPT) was considered as heat source for both the configurations. The effects of SPT design parameters on the systems were investigated. It was concluded that the addition of basic ORC and PDORC to the standalone intercooled cascade sCO2 cycle enhanced the thermal efficiency by 2.26% and 6.66% respectively, at 950 W/m2 of direct normal irradiation (DNI). In the case of basic ORC and PDORC, the waste heat recovery ratios were 0.1197 and 0.1775, respectively. It was also discovered that configuration-2 performed better than configuration-1 in terms of waste heat recovery and its optimized thermal efficiency was found as 52.34%. An exergoenvironmental analysis also performed on the present systems. Exergoenvironmental impact index decreases from 1.6504 to 0.6801 with increase in DNI while the exergetic stability factor increase from 0.3773 to 0.5952 with DNI.