Abstract
According to Ceperley's calculation, if acoustic impedance z at the position of the regenerator is equal to p_mc (p_m: mean density in tube, c: adiabatic sound speed), the efficiency is limited to 10% of Carnot efficiency due to viscous losses in the regenerator. Higher efficiency is possible with higher impedance, e.g., if z = 10p_mc, reaches 79% of Carnot efficiency. In this study, we changed z at regenerator and measured thermal efficiency at regenerator positions. From the results, maximum thermal efficiency achieved 61.7 % of Carnot efficiency when z =10p_mc.
