95/05079 Performance of a heat-pipe based waste-heat recovery and utilisation system for a gas-turbine engine

Abstract

The results of a modelling and simulation study on the combined performance of a power system are presented. The combined system comprises an industrial, simple-type gas-turbine engine and a heat-pipe-based waste-heat recovery and utilisation system, and the engine itself comprises an axial-flow compressor, tubular combustion chambers and an axial-flow turbine. A water-in-steel type two-phase thermosyphon loop extracts waste energy from the stack of the gas turbine and delivers it to the generator of an aqua-ammonia absorption chiller, to produce chilled water which cools ambient air via a cooling tunnel; the cooled air is fed to the intake of the gas turbine compressor. Net power output of the overall system, when utilising the water-in-steel heat-recovery system, is improved by 12% even when the inlet air to the turbine is cooled to a modest 20 °C; this is true for both the base load and 75% part-load operation. Considerably higher boosting of output power is possible if the inlet air is cooled to lower temperatures. One of the most striking findings of the modelling and simulation study is that the water-in-steel heat-recovery system is capable of producing considerably more cold air than is required by the gas-turbine engine. It is further concluded that the thermal efficiency of the engine does not deteriorate with rising ambient temperatures, as is the case in a system without the heat-recovery and utilisation system.