Performance enhancement of regenerative gas turbine: air bottoming combined cycle using bypass valve and heat exchanger—energy and exergy analysis

The present investigation is the comparative energy and exergy analysis of a proposed gas turbine (PGT) cycle with a simple gas turbine (SGT) cycle while maintaining the same mass flow rate of fuel in both cycles. In the PGT cycle, a bypass valve (BVP) connects the topping regenerative gas turbine cycle with the air bottoming cycle. It is found that with increase in pressure ratio ( r p ), turbine inlet temperature (TIT) of topping cycle of PGT cycle decreases continuously in the absence of the BPV, whereas in the PGT cycle with the BVP, the net output and thermal efficiency increased by 20% at r p = 12 and TIT = 900 K to 81% at r p = 4 and TIT = 1000 K. SFC of PGT cycle is reduced by 43–45% for TIT = 900 K and 1000 K, respectively, at r p = 4 as compared to SGT cycle. Also the total exergy destruction and exergetic efficiency of SGT cycle are 62.1–55% less and 26.5–49.7% more, respectively, in contrast to PGT cycle. In addition to this, the exhaust gas exergy losses decrease by 75.5% at the maximum output as compared to the SGT cycle.