Work and Heat Interconversion By Unicursal Cycle Processes

In general, an energy and material production process is a reciprocal or unicursal cycle process that starts and ends at environmental condition, in which work and heat are exchanged between process fluid and other systems such as heat generation system, waste heat removal system, etc. The first law gives the input-output energy balance. Work and heat are interconverted through internal energy of system in the unicursal cycle process which is composed of four thermodynamic elemental process modules: (1) isobaric heating process module (heat receiver, HR), (2) adiabatic compression process module (work receiver, WR), (3) isobaric cooling process module (heat transmitter, HT) and (4) adiabatic expansion process module (work transmitter, WT). Four different combination of thermodynamic elemental process modules as cycle processes can be considered; heat engine, heat pump, hot and cold heat cogenerator and thermal motor. It is noteworthy that no exergy destruction takes place in any thermodynamic elementary process modules. This means that both of exergy and anergy are conserved in the cycle processes.

In this study the work and heat interconversion mechanism of unicursal cycle processes is clarified in terms of exergy analysis. The conceptual design of thermal motor will be described.