heat heat engine gas efficiency working fluid engines piston cycle cylinder heat energy isometric steam entropy isobaric isothermal power work done thermodynamics Carnot cycle adiabatic process temperatures Stirling heat sink liquid regenerator cycles diagrams energy pressure mechanical engineering heat cycle closed cycle exploit vapour steam cycle processes adiabatic Eq second law of thermodynamics steam engines reservoir external device entropy change ammonia first reservoir Stirling engine displacer piston Stirling cycle Nave Organ heat exchanger first law heat source Thermodynamics exhausts low temperature heat reservoir expansion high temperature engine cycle PV diagram ideal gas conservation of energy energy flow reservoir model energy reservoir relationships constrain application STIRLING ENGINE stirling generator FFF FFF STIRLING CYCLE cord smoke spark moisture content Mitsubishi MODELS Tlow boiler Steam Engine Thigh khirata refrigerator piston moves coefficient of performance thermal energy steam engine compressor valve fuel one cylinder Energy Reservoir air conditioner Q1 LTER Brayton cycle Q2 Heat Engine Low Temperature heat pump High Temperature work input Rankine HTER body converts total heat mechanical energy boundaries work output displacer Stirling engines cooler gas temperature the cooling crankshaft equation BDC Heat transfer thermodynamic cycle bekkoame