Multi-Stage Modeling of a Stirling Thermocompressor

Stirling engines are silent, high-efficiency power sources that generate work by shuttling a working fluid between hot and cold volumes while exploiting the working fluid’s change in pressure. Stirling engines are able to use multiple sources of heat to create this needed temperature difference, making them ideally suited for diverse waste heat recovery applications. A novel application of this technology would be to reuse waste heat from one industrial process to generate compressed air to power a second, pneumatic process, thus increasing a manufacturing facility’s overall energy efficiency. In this paper the authors explore the expected performance of using a modified Stirling engine, known as a Stirling thermocompressor, to intake air at standard atmospheric conditions and compress it into a storage container. Simulations were conducted with a multi-stage experimentally validated dynamic model, using input variables that match the author’s physical prototype. Models employing 5 or more thermocompressor stages predicted a 10-fold increase in compressed air pressure compared to ambient conditions. Future work will experimentally verify the paper’s conclusions.