Abstract
According to Ceperley's calculation, if acoustic impedance z at the position of the regenerator is equal to ρ_mc, the efficiency is limited to 10% of second law efficiency η_2 due to viscous losses in the regenerator. Higher efficiency is possible with higher impedance, e.g., if z=10ρ_mc, η_2 reaches 79%. In order to achieve z=10ρ_mc, he explained the cross-sectional area of the enlarged tube would have to be 10 times larger. than that of the input tube. In this report, we changed the cross sectional area of the regenerator so it is larger than that of resonator, and measured its thermal efficiency and acoustic power gain at regenerator positions of a traveling wave heat engine.
