ABSTRACT

In this study, thermodynamic analysis of a gamma-type Stirling engine driven by Scotch Yoke mechanism was conducted. The advantages of Scotch Yoke mechanism over classical crank mechanism were discussed in detail. In the analysis hydrogen was used as working gas. Working space was divided into 16 nodal volumes. Solution of conservation of mass and energy equation were obtained for each nodal volume. Wall temperatures of nodal volumes were assumed to be constant and temperature variations in nodal volumes were calculated by means of the first law of the thermodynamics. Maximum engine power was obtained as 1105 W at 800 rpm engine speed and gas mass of 0.3 g for 1200 W/m²K heat transfer coefficient. The optimum phase angle, which was not affected significantly by hot end temperature, gas mass, and heat transfer coefficient variations, was determined as 90° degrees at engine speed of 600 rpm. However, it was determined that engine speed has a great impact on optimum phase angle and a variable phase angle mechanism may be useful to obtain maximum specific power from the engine at different engine speeds. At engine speed of 600 rpm, the maximum specific power of the engine was 695 W/l for 1.65 compression ratio and 90° degrees phase angle.

摘要

在这项研究中，对由苏格兰轭机构驱动的伽马式斯特林发动机进行了热力学分析。详细讨论了苏格兰轭机构相对于经典曲柄机构的优势。在分析中，将氢气用作工作气体。工作空间分为16个节点。对于每个节点体积，获得了质量守恒和能量方程的解。假定节点体积的壁温是恒定的，并且借助于热力学第一定律计算节点体积中的温度变化。发动机转速为800 rpm时最大发动机功率为1105 W，1200 W / m ^2的气体质量为0.3 gK的传热系数。不受热端温度，气体质量和传热系数变化影响不大的最佳相位角在发动机转速为600 rpm时确定为90度。然而，已经确定发动机转速对最佳相位角有很大影响，并且可变相位角机构对于在不同发动机转速下从发动机获得最大比功率可能是有用的。在600 rpm的发动机转速下，对于1.65压缩比和90°相角，发动机的最大比功率为695 W / l。