High efficient engine or heat pump based on thermal-hydraulic conversion

A new concept of heat engine or heat pump is presented. The cycle followed by the working fluid is nearly close to the Carnot cycle (reverse or engine). Heat exchanges with the environment occur during isothermal steps of the cycle with a liquid/vapor phase change of the working fluid. Work exchange involved during each step is realized by an alternating movement of an inert liquid LT which acts as a liquid piston. The work-transfer liquid LT flows either through a hydraulic motor (for the engine mode) or through a hydraulic pump (for the heat pump mode). This intermediary hydraulic fluid avoids the main irreversibility inherent to conventional engine or heat pump. Work generation, cooling and/or heating with work or heat input are possible with this thermal-hydraulic process. According to the available heat source and sink and to the aimed application, associations of basicthermal-hydraulic elements (engine or heat pump) are required, such as thermal cascade or mechanical coupling. The estimated performances, engine efficiency or heat pump COP, are very high: upper than 70% of the corresponding Carnot efficiencies.