A Gamma type Stirling refrigerator optimization: An experimental and analytical investigation

Abstract

Abstract In this study, multi-objective optimization of a Gamma type Stirling refrigerator is carried out based on the experimental and analytical results. The cooling capacity and the coefficient of performance (COP) are experimentally investigated for helium and air. Beside to helium and air, carbon dioxide is also considered as the working fluid in the simulation. A non-ideal adiabatic analysis is developed for the simulation. The experimental and simulation results showed that the cooling capacity increases continuously with the rotational speed where the COP has a maximum value. The optimum COP value for helium occurs at higher rotational speed than that of the air. The Design of Experiment (DOE) method is used for multi-objective optimization. Three parameters namely COP, cooling capacity and pressure drop are investigated in this optimization study. Only helium and carbon dioxide are considered for optimization because of their higher specific heat capacity and enthalpy with respect to air. The optimum working pressure for the carbon dioxide takes place at lower pressure than that of helium. When the importance and weight factors equal one, the optimum point for helium is obtained at working pressure and rotational speed of 9 bar and 451.1 rpm, respectively. Where, the optimum point for carbon dioxide is found at working pressure and rotational speed of 3.3 bar and 798.5 rpm, respectively.