Exergetic evaluation of methods for improving power generation efficiency of a gas turbine cogeneration system

A cogeneration system generating both heat and power for district heating and cooling is required to be more efficient to improve its economy. In this paper, three typical methods for improving the power generation efficiency of a gas turbine cogeneration system are evaluated by examining exergy flow at various points of the system. The three methods investigated are: (a) to raise turbine inlet temperatrue, (b) to incorporate a regenerative cycle, and (c) to introduce a dual-fluid cycle. Exergy flows at various points of each cogeneration system have been evaluated. It has been shown through quantitative analyses of exergy flows (1) what kind of exergy loss of the system can be reduced by introducing each efficiency-improving method, (2) that the method of incorporating a regenerative cycle is highly useful in improving exergy efficiency of the cogeneration system. (C) 1997 by John Wiley & Sons, Ltd.