Energetic and Exergetic Performance Evaluation of a Solar Dish Based Dual Receiver Combined Cycle

Solar Thermal Power Plants with concentrating technologies are important for providing a major share of the clean and renewable energy needed in the future. Dish based system is a promising option for power generation since it has high concentration ratio and it does not require a large space. This paper presents a proposed solar dish based combined cycle: air based Brayton cycle as the topping cycle with a bottoming steam cycle. This paper also proposes a dual receiver, which can be utilized for heating the air for topping Brayton cycle as well as to produce the superheated steam required for the bottoming cycle. Program coding on C language has been developed and the detailed thermodynamic parametric analysis of the combined cycle has been carried out energetically as well as exergetically for the varying pressure ratio of the compressor. Component wise exergy analysis has been done to identify the component where the exergy loss is maximum. The thermodynamic analysis shows that for the topping gas turbine cycle only, both the work obtained and the thermal efficiency maximizes at very high pressure ratio. But the incorporation of a simple downstream HRSG drags the point to lower pressure ratio range. It has also been found that at pressure ratio 9, where the overall thermal efficiency is maximum, solar receiver shares the maximum exergy destruction among all the other components. Exergetic performance of the solar receiver, dish, HRSG and stack has also been carried out in the present study.