Combined Dynamic and Thermodynamic Investigation of a Crank-Shifted Alpha-Type Stirling Engine

In this study, a structurally simple alpha-type Stirling engine was proposed, and its combined thermodynamic-dynamic analysis was conducted. A simulation program capable of working as nodal analysis, isothermal nodal analysis, and combined dynamic-thermodynamic nodal analysis was developed. Some performance characteristics of the crank-shifted engine were obtained and compared with those of the rhombic-drive and V-type alpha engines. According to the results, the thermodynamic cycle of the novel engine possesses a perfect heating process at a constant volume. As a result, the specific work generation, power, and thermal efficiency of the crank-shifted engine become higher than those of the other engines despite its lower compression ratio and working fluid pressure. An engine with 11 bar charging pressure, 380 K cooler temperature, 800 K heater temperature, 1.143 L effective swept volume, and 3.6 L total working space volume provides more than 8 kW effective power. While the heater temperature varies from 650 to 950 K, the effective power varies from 3540 W to 13,089 W, and the indicated thermal efficiency varies between 39.87% and 49.89%. Corresponding to a flywheel with a 0.25 mkg inertia moment of mass, the dimensionless speed fluctuation is determined as 7%.