Optimal efficiency of an irreversible heat engine with thermal reservoir of finite heat capacitance using method of Lagrangian multiplier

Abstract

The finite time thermodynamic optimization of an irreversible heat engine having thermal reservoirs of finite heat capacitance has been presented. A general expression for the optimum efficiency of heat engine is derived at maximum work output and given heat input flow rate condition. External irreversibility is due to finite temperature difference between system

working fluid and thermal reservoirs (source/sink) while internal irreversibility is due to non-isentropic expansion and compression within the system which is represented by an irreversibility parameter indicating the deviation from

endoreversible case. It is found that the direct of internal irreversibility is more pronounced than the external irreversibility associated with the heat engine. The effect of various operating parameters on the efficiency of the heat engine is studied and numerical results are presented in the end.