Rotary Stirling Engine for Exhaust Energy Recovery

A new type of rotary Stirling engine for exhaust energy recovery is introduced in this paper. This engine is constructed by two eccentric cylinders with displaced centers. The space between these two circles is divided into four chambers. The outside cylinder is stationary while the inside cylinder rotates at a constant speed. The volume of each chamber would vary during the rotation. Part of the wall of the outside cylinder in the circumferential direction is heated with hot gas and the other part of the wall is otherwise cooled with atmosphere air such that the engine could deliver work as heat transfer occurs during rotation. A thermodynamic model of this engine was developed in this paper, and the effect of some parameters, including rotation speed, mass of air inside chamber, compression ratio and different heating temperatures, on the output power as well as thermal efficiency was investigated. It was found that the highest efficiency can reach 10.8% and the maximum output power can reach 0.3684W. The compression ratio of 4 was found to have the highest efficiency, and the compression ratio of 6 was found to have the maximum power output. Besides, it was found that as heating temperature increases the efficiency and power increase too.