Optimization Design And Experimental Investigation Of A Type Stirling Engine With Rhombic Drive Mechanism

The Stirling engine is a simple type of external combustion engine which operates over a closed, regenerative thermodynamic cycle with the ability to use a wide variety of energy sources. Faced with international crisis of energy resources consumption, the Stirling engine has drew attention of researchers for the last30years. The kinematic and thermodynamic properties directly affects the output performance of the Stirling engine, however, the heat and mass transfer, as well as the trajectory inside the engine are difficult to be measured with scientific instruments, so the research on dynamics and thermodynamics of the Stirling engine is of strong engineering significance and important academic value. Meanwhile, the experimental data of Stirling engine performance obtained from the test can be used in designing process and helpful for the improvement of the theoretical model.Thus, the experimental platform is also very important.A brief introduction is made on history of the Stirling engine, then the key technologies in the field of Stirling engine is also described. The relevant development on the Stirling engine at home and abroad is analyzed. After that the development and application prospect in China is well described.The main work of this dissertation is to design a β type Stirling engine with rhombic drive mechanism, and analyze the output performance of the prototype engine through experimental research. Firstly, this article analyzed the existing Stirling cycles from the view of thermodynamic, found out their strengths and weaknesses, and then proposed the irreversible factor concept, which is cited into the Stirling isothermal model to build an improved Stirling thermodynamic model. This improved model could be used to guide the design of the Stirling engine.A comprehensive analysis was conducted to this engine from the perspective of kinematic, also the kinematic model and mechanical model of the rhombic drive mechanism were established. This kinematic model describes the kinematic characteristics of the driving assemblies through the speed and acceleration formulas, while the mechanical model gives the force relationships of the driving assemblies through the force and torque formulas. A set of preliminary parameters of the rhombic driving system is obtained through the application of these two models. Then, the classic Similarity Design was introduced, and was cited to the design of Stirling engine initiatively. On the basis of the GPU-3Stirling engine, several similarity parameters, such as temperature ratio, volume ratio, dead volume ratio and phase angle are defined and the parameters of the prototype engine are obtained.When conducting the optimized design of Stirling engine, it is impossible to solve multi objectives at the same time as the application the methods above, the solution usually contradicts to the multi objectives, and the globally optimization is impossible to be obtained. Considering this, the Multi-objective Particle Swarm Optimization algorithm is cited to the design of Stirling engine. Firstly, the principles of the multi-objective optimization and particles swarm optimization are introduced. Secondly, the key performance parameters are defined as objectives of this optimization, and ten parameters (temperatures of working fluid in both hot and cold space, total dead volume, expansion volume, compression volume, dead volume ratios of the hot space and the cold space, dead volume ratio of the regenerator, effectiveness of the regenerator, and the system charge pressure) as the systematical constraint conditions, then these conditions are loaded in MOPSO program based on Matlab code to obtain a set of Pareto optimal solution. Then, the comparison of different decision-making methods is made, and the final result from the Pareto optimized solution is selected through the LINMAP decision-making method. From the comparison of relevant experimental data, it can be found that the output power and thermal efficiency obtained through the MOPSO method is15%and20%better than those obtained through the traditional approach.A prototype Stirling engine is successfully developed using the optimized design data obtained above. In order to reduce the mass flow losses of the working chamber, the two laps of the pipeline inside and outside of the heater is connected with top girth. The sealing arrangement of the piston is dual piston rings, which is used to prevent the working fluid from leaking into the crankcase. Based on the objective of studying the output performance of the Stirling engine, a test system is well established. In this platform, an electrical heating equipment is used as the external heating source, multiple sets of experimental data were recorded and compared under different heating temperatures and pressures. Finally, the maximum torque (12.96Nm) and the maximum output power (288W) are obtained under the heating temperature-600℃and working pressure-15bar respectively.