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

Highlights

Channel-shaped heat exchanger improved indicated work of LTDSE.

Channel-shape caused higher fluctuation of specific internal energy than conventional.

LTDSE with channel-shaped heat exchangers and regenerators was tested.

The new LTDSE obtained about 5 times the indicated power per displacer stroke volume.

However, the polytropic index of the new LTDSE became larger than that of conventional.

Abstract

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.

Keywords

  • Low temperature differential Stirling engine;
  • Heat exchanger;
  • Regenerator;
  • Indicated diagram;
  • Polytropic index

Abbreviations

  • CFD, Computational fluid dynamics;
  • LTD, Low temperature differential;
  • SE, Stirling engine;
  • MFEAWFT, the maximum fluctuation of ensemble averaged working fluid temperature

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