Abstract
This study includes theoretical analysis and experiment of a small size beta-type Stirling, following with the design and test of a medium size beta-type Stirling. A commercially available small size Stirling was examined for its power performance and the results have been compared with theoretical analysis using Schmidt theory. The small size Stirling with swept volume of 5.65 c.c can generate 0.25 W at 618 rpm rotation speed while TH equals to 410 oC and TC equals to 120 oC. However, the power output estimated by theoretical calculation is around 2.41W under the same operation condition. The cam-drive design of the small size Stirling produces the friction which dramatically decreases power output of the small Stirling engine. The flow fields in the expansion chamber inside the Stirling engine have been examined with PIV (Particle Image Velocimetry) technique. The acquired velocity profiles showing non-symmetrical vortex generation inside the expansion chamber confirm the observation of displacer deflection during its movements. After inspecting the small size Stirling engine, a medium size Stirling was designed for manufacturing, using rhombic-drive mechanism instead of cam-drive mechanism. The medium size Stirling engine has the size of 529 c.c swept volume and it can generate 13.6 W power output at the rotation speed from 162 to 198 rpm while heating to 280 oC. The measured power output of the medium size Stirling engine is about half of the power calculated from the Schmidt theory, which is 23.8 W at the same operation condition. The power performance of the medium Stirling engine is improved by using the rhombic-drive design.