Low temperature rotary Stirling engine: Conceptual design and theoretical analysis

The use of low-temperature energy sources for electricity generation demands a dual focus: a substantial enhancement in the efficiency of energy conversion devices and a reduction in system production costs. Particularly in scenarios where low-temperature energy sources are scarce, this factor can be pivotal in facilitating widespread adoption of such technologies. The Stirling engine emerges as a promising solution capable of meeting these articulated expectations, owing to its straightforward design and utilization of non-toxic, non-flammable, and cost-effective working mediums. This paper introduces a novel concept of a rotary Stirling engine, exhibiting significant potential for operation with low-temperature energy sources. Additionally, an analytical model of the engine is presented, enabling simulations of its operation under varying supply temperatures and geometric configurations. To analyse the impact of internal leaks on the net efficiency and net power of the engine, a modified adiabatic model was introduced. It was observed that utilizing identical heat exchangers for heat supply at 250 °C and 100 °C could lead to a decline in net efficiency from 8 % to 3 % for the worst case. Furthermore, an analysis was performed to assess the impact of the heater's overall heat transfer coefficient and engine rotational speed on both net efficiency and net mechanical power for a heat supply temperature of 200 °C.