Cogeneration by combining gas turbine engine with organic rankine cycle

The gas turbine engine is known by its relatively low efficiency especially at part load. Therefore, to conserve energy and reduce the operating cost, waste heat is recovered by combining a heat-exchange gas turbine cycle with closed organic Rankine cycle. A computer programme was made to calculate parametrically the individual and combined cycle performances, namely the work and efficiency of each. The parameters considered were: gas turbine pressure ratio; maximum cycle temperature; fluid-air mass ratio; and type of working fluid.This analytical study shows that R113 is the optimum choice because it gives the smallest, hence the most economical, size of turbo-expander. Maximum cycle temperature and pressure ratio are relatively the most important parameters. Economic analysis indicates very good rate of return on investment, related with heat recovery by cogeneration.