Basic Limitations on the Performance of Stirling Engines

The performance of Stirling engines is subject to limitations resulting from power dissipation in the regenerator. The dissipation is caused by pressure gradients in the regenerator to generate flow. Without this flow the power output would by zero. Hence the dissipation is an essential element of the operation of the engine. Using linearized theory, the equation for pressure in the regenerator is solved for the case of a linear temperature distribution. The regenerator is taken to be thermally perfect. All various are taken to be sinusoidal in time. Expressions are derived for the net power output and the thermal efficiency. The net power output is optimized under various constraints. The constraint yielding the best results is fixed piston amplitude in the compression chamber. Upper bounds on the dimensionless power output are found as function of regenerator void volume and regenerator temperature. These bounds are derived in the limit of zero frequency, and ae independent of the conductance of the regenerator. Both power output and thermal efficiency decrease decreases as frequency and regenerator void volume increase.