5. Thermodynamic Cycles of Solar Gas Turbines

Thermodynamic cycles play a vital role in the development of solar gas turbines. Currently, the Rankine cycle is the most-widely exploited engine cycle in concentrating solar power (CSP) technology. However, this cycle exhibits high loss of low grade heat at the condenser. In view of this limitation, researchers are paying attention to gas cycles. The Brayton cycle (gas turbine) is a good candidate for solarisation because it has a higher thermodynamic efficiency than the Rankine cycle. Based on flow path, gas turbines are classified into three basic types: (a) closed cycle gas turbine (CLCGT), (b) open cycle gas turbine (OCGT) and (c) semi-closed cycle gas turbine (SCLCGT). It is also possible to combine the Brayton cycle with a bottoming cycle such as the Rankine cycle to yield a combined cycle which is advanced with high thermodynamic efficiency (>50%). Many studies have examined the solarisation of the CLCGT and OCGT systems. In spite of the environmental and other potential benefits of the SCLCGT, integration of this cycle with the CSP technology is scarce. So, a conceptual semi-closed cycle solar gas turbine (SCLCSGT) has been proposed in this book.