Low enthalpy heat stirling engine based electric power generation: A research design

Power generation from renewable and sustainable sources is an important field of technology development owing to the increasing costs (both economically and environmentally) of fired generation. Most research associated with alternative forms of power generation have concentrated on relatively high efficiency systems, as this makes commercial realisation more readily achievable. A new research programme is taking a slightly different approach, where an inherently low efficiency power generation system based on low temperature differential Stirling engine technology is being considered. Here we describe the design of a low temperature differential Stirling engine for research into determining the commercial viability of utilising low enthalpy (or low grade) heat for electric power generation. While the design does not satisfy low cost economic requirements, through its ability to change important operational parameters such as compression ratio, piston phasing, and working gas movement dynamics, it is capable of identifying important features needed to optimise engine performance. The design utilises the Modified Beale Number and some preliminary software modelling, to satisfy the specifications of having a 500 W output with a temperature differential of only 40 K.