Entransy transfer analysis methodology for energy conversion systems operating with thermodynamic cycles

ABSTRACT The entransy transfer analysis methodology proposed in this article offers an alternative novel approach of thermodynamic analysis for assessment and optimization of various energy conversion systems. It is proved that TdU entransy and TdH enthalpy-entransy are not state functions for thermodynamic systems with non-ideal gas substances, so the entransy transfer analysis methodology is constructed based on entransy process functions for generic systems operating with thermodynamic cycles. Accordingly, the thermodynamic evaluation indices of entransy (transfer) dissipation, cyclic net entransy transfer, and entransy (transfer) efficiency are defined. From the case studies of an organic Rankine cycle and a vapor-compression heat pump cycle, lower entransy (transfer) dissipation and higher entransy (transfer) efficiency can be adopted as the optimization objectives for heat engine and compression heat pump systems. Besides, lower cyclic net entransy transfer is preferred for thermal energy storage systems given the charging/discharging heat. The core difference between entransy transfer analysis and exergy (entropy) analysis is that entransy transfer highlights the heat transfer phenomenon, while exergy and entropy focus on the heat–work conversion phenomenon. Moreover, thermodynamic cycles can be classified into forward and reverse cycles in the sense of entransy transfer according to positive and negative cyclic net entransy transfer.