Design, Manufacturing, and Thermodynamic Analysis of a Gamma-type Stirling Engine Powered by Solar Energy

Abstract

Stirling engines are external combustion engines. This feature eliminates the possible dependency of the engine on a specific energy resource and allows it to work with diverse energy sources, especially solar and other renewable energy sources. Also, Stirling engines could be built in different configurations that have a significant impact on the engine performance. With these aspects, Stirling engines have attracted the attention of researchers. In this study, firstly, a double-cylinder V-type air compressor has been converted to a gamma-type Stirling engine. The block, cylinders, connecting rods, and the crank mechanism of the compressor have been used in the converted engine. For this reason, the air compressor has determined some features of the Stirling engine, such as phase angle, strokes, and cylinder diameter. Other parts of the engine, such as piston, cylinder head, displacer, and displacer cylinder have been manufactured. Secondly, the optimum operating parameters to provide maximum thermal efficiency have been investigated using the nodal thermodynamic analysis considering that the engine is powered by solar energy. In the analysis, helium as the working fluid is used due to its suitable thermodynamic features and safety usage. The optimum working fluid mass and engine speed have been determined as 0.15 g and 100 rad/s for all temperatures (750, 800, and 850 K). Also, the optimum displacer height has been preferred as 190 mm since there is no significant improvement in the thermal efficiency after this dimension. The maximum thermal efficiency has been obtained as 46.5%.