Apparatus for improving the fuel efficiency of a gas turbine engine

Claim 1

An energy recovery system for a gas turbine of the type including means for supplying a flow of fuel thereto from at least one fuel tank and having at least one support system in which some of the pneumatic energy developed by the engine is made available to the support system, including first means for recovering at least some of the pneumatic thermal energy made available to but not utilized by the support system, second means for utilizing at least some of the energy recovered by the first means to heat the fuel substantially immediately prior to the consumption of the fuel by the engine, third means for utilizing at least some of the energy recovered by the first means to heat the fuel in the fuel tank, and fourth means for selectively utilizing the second and third means, which comprises: a first liquid-to-liquid heat exchanger disposed to receive the flow of fuel substantially immediately prior to its consumption by the engine; second air-to-liquid heat exchanger disposed to receive engine bleed air from the engine and to pass the engine bleed air to the support system; third liquid-to-liquid heat exchanger means coupled to receive fuel from the fuel tank and to pass fuel therethrough and back to the fuel tank; conduit means for coupling said first, second and third heat exchangers, said conduit providing a first continuous loop between said first and second heat exchangers, a second continuous loop between said first, second and third heat exchangers, and a third continuous loop between said second and third heat exchangers; pumping and pressurizing means for circulating a heat transfer medium through said conduit means; and control valve means for controlling the flow of said heat transfer medium to said third heat exchanger.