Design of a laboratory-scaled stirling engine

Abstract

The Stirling engine is a device that operates on a closed regenerative thermodynamic cycle with cyclic compression and expansion of the compressible working fluid, such as air, hydrogen, helium, nitrogen or vapor at different temperature levels. The Stirling engine operation meets the demand of high efficiency with less exhaust emissions and the effective use of energy with environmental security in comparison with the internal combustion engine. Stirling engine has a wide range of applications including mechanical output and propulsion, electrical power generation, heating and cooling and low temperature difference engines. Most of the conventional Stirling engines have a hot heat exchanger with extremely high temperatures input and a cold heat exchanger with ambient temperatures input. In this study, a laboratory-scaled Stirling engine driven by cold energy and low-temperature heat been designed, manufactured and tested. Instead of using extremely high temperatures at the hot end and ambient temperatures at the cold end, a relatively lower temperature hot heat exchanger with maximum 150 ℃ and a cold heat exchanger cooled by liquid nitrogen with -196 ℃ were applied to the designed Stirling engine to study its thermal properties and mechanical behaviors. Experiments showed a successful operation of the Stirling engine with a working frequency between 0.137 Hz to 0.167 Hz at the temperature differences between 287 ℃ to 333 ℃. Experiments also demonstrated that a larger temperature difference would result in a higher operational frequency and a smaller piston motion amplitude. Future research study can be conducted by changing the relative locations of heat exchangers and replacing new regenerator materials with different mesh properties.