Second-law-based analysis of vapor-compression refrigeration cycles: Analytical equations for COP and new insights into features of refrigerants

This article reports a second-law-based analysis of the vapor-compression refrigeration cycle, which leads to a set of explicit theoretical formulas for the coefficient of performance (COP). These analytical expressions provide a fast and accurate approach to computer simulations of the vapor-compression cycle without recourse to thermodynamic diagrams or equations of state. The second-law-based analysis yields specific expressions for the entropy generations of irreversible processes, enabling us to evaluate the thermodynamic features of the refrigerant and to elucidate the thermodynamic mechanisms behind the effects of the cycle processes, including superheat, subcooling, and throttling processes. In particular, these processes can interact, therefore this paper presents a global entropy generation analysis for evaluating the impact of the interacted processes on COP.