Energy and exergy analyses of an externally fired gas turbine (EFGT) cycle integrated with biomass gasifier for distributed power generation

Biomass based decentralized power generation using externally fired gas turbine (EFGT) can be a technically feasible option. In this work, thermal performance and sizing of such plants have been analyzed at different cycle pressure ratio (r(p) = 2-8), turbine inlet temperature (TIT = 1050-1350 K) and the heat exchanger cold end temperature difference (CETD = 200-300 K). It is found that the thermal efficiency of the EFGT plant reaches a maximum at an optimum pressure ratio depending upon the TIT and heat exchanger CETD. For a particular pressure ratio, thermal efficiency increases either with the increase in TIT or with the decrease in heat exchanger CETD. The specific air flow, associated with the size of the plant equipment, decreases with the increase in pressure ratio. This decrease is rapid at the lower end of the pressure ratio (r(p) < 4) but levels-off at higher r(p) values. An increase in the TIT reduces the specific air flow, while a change in the heat exchanger CETD has no influence on it. Based on this comparison, the performance of a 100 kW EFGT plant has been analyzed for three sets of operating parameters and a trade-off in the operating condition is reached. (C) 2009 Elsevier Ltd. All rights reserved.