13. Air-Condition and Refrigeration

A free-piston Stirling combined cooling, heating, and power cogenerator (FPS-CCHP) is developed and studied in this study. The proposed FPS-CCHP comprises a free-piston Stirling engine, a free-piston Stirling cooler, and a linear generator. The generator connects the engine and the cooler. The engine part of the system can be driven using any type of external heat source. Then the cooler part and the generator can be driven, producing heating capacity, cooling capacity, and electric power simultaneously. In this study, a prototype FPS-CCHP was manufactured and tested. A general theoretical model was established which model combined with the thermodynamic model, dynamic model, electric model, and magnetic model. The variation in the thermal properties of the working fluid in the engine part and cooler part, the dynamic behavior of the moving components, the current and voltage in the circuit, and the magnetic flux in the generator are simulated. To validate the proposed model, a testing platform for the linear generator is built. The cooling temperature of the cooler part under different heat loading was measured and compared with the simulation results. The no-loading cooling temperature of the system under different stiffness of spring, damping coefficient, mass of moving component, and bore size were simulated. The results indicate that the above parameters have optimum design values for the lowest cooling temperature. The maximum efficiency of the generator can reach 4.1 % as the electrical loading is 400 Ω. The no-loading cooling temperature of the system can reach 262.3 K. The cooling temperature and the coefficient of performance increase to 298 K and 0.07 as the heat loading increases to 45 W. The proposed model can be used to design and optimize the design of FPS-CCHPs.