The performance tests of a beta type rhombic drive Stirling engine with regenerator

In this thesis, a beta type Stirling engine with rhombic drive mechanism was designed, manufactured and tested. By bearing the gears from both side on the crankshaft and using helical gears in the rhombic drive mechanism, the reduction of frictional losses was accomplished. A regenerator was placed between the hot and cold ends to provide heat gain. In the regenerator, pipe connection was not used between the cold and hot end to decrease pressure and dead volume losses. Thermodynamic analysis of the rhombic driven engine was performed using nodal analysis method. The effects of rhombus length on the performance of the engine was realized for different heat transfer coefficients. In the engine, the effects of heater, cooler, regenerator and double-side bearing rhombic drive mechanism on the engine torque and power were experimentally investigated. Two different displacers cylinder were designed. One of them was designed without regenerator. The other was designed as a regenerative displacer cylinder. Engine characteristics were determined for different charge pressures and hot end temperatures. Maximum engine torque was obtained as 18,5 Nm at 565 rpm engine speed and the maximum engine power was obtained as 1214 W at 732 rpm engine speed, at working conditions of 800 ºC hot end temperature, 4 bar charge pressure by using helium as working fluid in the cylinder without regenerator. Two different regenerators were designed to investigate the effects of the regenerator volume on the engine performance. The volumes of the regenerators were determined as 60 cc (regenerator - I) and 120 cc (regenerator - II). Porosity ratio of the regenerators were determined as 15%. Stainless steel wires having a diameter of 0,15 mm was meshed as a woven straw and used as a regenerator material. The experiments were performed using different regenerators (for no regenerator, regenerator – I and regenerator - II) at 800 ºC hot end temperature using helium. The results were compared with the tests of the cylinder without regenerator. Maximum engine torque was obtained as 26,11 Nm at 741 rpm engine speed and the maximum engine power was obtained as 2353 W at 1099 rpm engine speed, at 5 bars helium charge pressure with regenerator – I. The engine power was increased by 28,53 % using the regenerator. Key Words: Rhombic drive mechanism, Stirling engine, Regenerator