Finite time thermodynamic analysis of a solar duplex Stirling refrigerator

Highlights: • A solar duplex Stirling refrigerator system is proposed. • A thermodynamic model considering finite time is developed. • Polytropic process in expansion/compression is adopted. • Two constraints including power and time are considered. -- Abstract: Stirling engine is a machine that has the same theoretical efficiency as that of a Carnot cycle under ideal conditions and has an aptitude for utilizing sustainable energy such as solar and biomass energy. In this study, a solar duplex Stirling refrigerator system was proposed to capture solar energy for refrigeration. The system is composed of a solar collector for collecting solar thermal energy, a Stirling heat engine for converting thermal energy into power, and a Stirling refrigerator to utilize power for cooling. The system is modeled based on finite time thermodynamics. Moreover, two constraints i.e., power and cycle time equality of the engine and refrigerator are considered in this model. In addition, the linearized heat loss of the solar collector, finite rates of heat transfer, regenerative heat loss, and conductive thermal bridging loss of the Stirling engine and refrigerator are considered in this model. Finally, the effects of design parameters on the performance of the system are investigated. This may serve as clean technology for solar refrigeration.