Power output analyses and optimizations of the Stirling cycle

Abstract

Based on the finite time thermodynamics theory, the entransy theory and the entropy theory, the Stirling cycles under different conditions are analyzed and optimized with the maximum output power as the target in this paper. The applicability of entransy loss (EL), entransy dissipation (ED), entropy generation (EG), entropy generation number (EGN) and modified entropy generation number (MEGN) to the system optimization is investigated. The results show that the maximum EL rate corresponds to the maximum power output of the cycle working under the infinite heat reservoirs whose temperatures are prescribed, while the minimum EG rate and the extremum ED rate do not. For the Stirling cycle working under the finite heat reservoirs provided by the hot and cold streams whose inlet temperatures and the heat capacity flow rates are prescribed, the maximum EL rate, the minimum EG rate, the minimum EGN and the minimum MEGN all correspond to the maximum power output, but the extremum ED rate does not. When the heat capacity flow rate of the hot stream increases, the power output, the EL rate, the EG rate and the ED rate increase monotonously, while the EGN and the MEGN decrease first and then increase. The EL has best consistency in the power output optimizations of the Stirling cycles discussed in this paper.