Indicated diagrams of low temperature differential Stirling engines with channel-shaped heat exchangers

The low temperature differential Stirling engine with channel-shaped heat exchangers and regenerators achieved approximately 5 times the indicated power per a stroke volume of displacer of the cases using flat-shaped heat exchangers. The ratio of the maximum fluctuation of ensemble averaged working fluid temperatures, which is the ratio of the internal energy fluctuation to the heat capacity of the working fluid, to the temperature difference between the two heat exchangers in cases using flat-shaped heat exchangers was 0.08-0.09, that in cases using channel-shaped heat exchangers was 0.10-0.17, and that in case using channel-shaped heat exchangers and regenerators was 0.21. The improvement in the experiments is lower than the estimation by the CFD. In terms of the polytropic index, low temperature differential Stirling engines with channel-shaped heat exchangers and regenerators obtained a higher value than low temperature differential Stirling engines with flat-shaped heat exchangers before the displacer reached the dead center.