Inverted brayton cycle heat engine

An apparatus comprising:

• a plurality of heat engine means for converting heat to work each operating using a respective heat engine cycle, at least one of said plurality of heat engine means combusting a fuel and generating exhaust gas comprising water as a combustion product, said plurality of heat engine means including an inverted Brayton cycle heat engine means having an inverted-Brayton-cycle turbine means driven by said exhaust for driving an inverted-Brayton-cycle compressor means for receiving and compressing said exhaust gas from said Inverted-Brayton-cycle turbine,
• condenser means located in a fluid path of said exhaust gas between said inverted-Brayton-cycle turbine and said inverted-Brayton-cycle compressor for condensing at least some of said water from said exhaust gas to form condensed water,
• wherein the condenser is supplied with a circulating flow of coolant, wherein the circulating flow of coolant is separate from the fluid path of said exhaust gas and forms a closed loop path, and
• wherein said plurality of heat engines comprise a steam driven heat engine and a recirculation path supplying at least some of said condensed water to a steam-generating heat exchanger to transfer heat to said condensed water to generate steam to drive said steam driven heat engine, wherein exhaust steam exiting said steam driven heat engine is supplied as at least part of a working fluid of at least one of said one or more heat engines, wherein said exhaust steam is supplied into said exhaust gas flowing between said inverted-Brayton-cycle turbine and said inverted-Brayton-cycle compressor upstream of the inverted-Brayton-cycle compressor and downstream of the steam-generating heat exchanger.

A method operating heat engines comprising:

• combusting a fuel and generating exhaust gas comprising water as a combustion product within at least one heat engine;
• driving an inverted-Brayton-cycle turbine with said exhaust gas and driving an inverted-Brayton-cycle compressor with said inverted-Brayton-cycle turbine to receive and to compress said exhaust gas from said Inverted-Brayton-cycle turbine,
• at a location in a fluid path of said exhaust gas between said inverted-Brayton-cycle turbine and said inverted-Brayton-cycle compressor, condensing at least some of said water from said exhaust gas to form condensed water,
• wherein the condenser is supplied with a circulating flow of coolant, wherein the circulating flow of coolant is separate from the fluid path of said exhaust gas and forms a closed loop path, and
• wherein said plurality of heat engines comprise a steam driven heat engine and a recirculation path supplying at least some of said condensed water to a steam-generating heat exchanger to transfer heat to said condensed water to generate steam to drive said steam driven heat engine, wherein exhaust steam exiting said steam driven heat engine is supplied as at least part of a working fluid of at least one of said one or more heat engines, wherein said exhaust steam is supplied into said exhaust gas flowing between said inverted-Brayton-cycle turbine and said inverted-Brayton-cycle compressor upstream of the inverted-Brayton-cycle compressor and downstream of the steam-generating heat exchanger.