Multi-objective Optimization Model And Experimental Study Of Stirling Cycle Based On Dynamic Analysis

Stirling engines are applied in various fields,such as solar thermal power generation,underwater power,deep space exploration,waste heat utilization and combined heating and power generation system,while the application suitability of the design method is very limited,which hinders the development of Stirling enegine greatly.The thesis focuses on developing a wide-application-suitability design method for Stirling engine,and tries to make a multi-objective optimization model and a practical testing method for Stirling enegine.A second-order Stirling cycle analysis model suitable for positive and reverse Stirling cycles was developed,which fully considered the various energy and power losses,coupled with the actual piston motion law and the physical properties change law of the working gases.A third-order dynamic analysis model was developed considering compressible fluid.The Stirling cycle space was divided into seven parts:expansion space,heater,clearance area between regenerator and heater,regenerator,clearance area between regenerator and cooler and cooler.The conservation principles of mass,momentum and energy were successively applied to the discrete one-dimensional finite control volume array on the basis of more reasonable node division of Stirling engine internal space,in which various energy and power losses were coupled and the input temperatures of heater and cooling water were specified as the boundary condition.A β-type Stirling enigine had been designed and build,and the maximum cycle power and cycle efficiency were 3033W and 30%,respectively.The p-V map,indicated power and cycle efficiency were obtained to verify the reliability and accuracy of the model.The relative deviations of the analysis results of cycle power and cycle efficiency were 8.2%-14.5%and 4.6-10%respectively.A constraint multi-objective model of Stirling cycle based on genetic algorithm was established and used to optimize geometric design of a 100W β-type Stirling engine with efficiency,power and power losses as the three objective functions.The Pareto optimal frontier was obtained and a final optimal solution was selected by using TOPSIS decision scheme.At the final decision point,the cycle power,efficiency and power loss of the optimized Stirling engine by the model obtained 34.5%increase,24.0%increase and 23.3%decrease respectively.The experimental results had achieved 26.3%and 19.6%improvement in power and efficiency respectively,which had been greatly improved.The power and efficiency errors of the constraint multi-objective optimization model were 6.0%and 3.7%respectively.The positive and reverse Stirling cycle characteristics were studied with simulation and experimental methods.The effects of pressure,rotational speed and working gas on the positive and reverse Stirling cycle characteristics were explored.A method to predict the indicated power of the positive cycles by using that of the reverse Stirling cycles is proposed.The mathematical relationship between the indicated powers of posive and reverse Stirling cycles of the 100W β-type Stirling engine was:(W_hea2)/(-W_coo1)=A·((T_e2-T_c2)/(T_c1-T_e1))^0.8321.The error between the predicted results and the experimental ones is within 7.4%.The thesis proposed a practical designing and testing method of Stirling engine,which has been verified by theoretical analysis and experimental data.It is expected to provide useful reference for Striling engine design,manufacture and application in various fields.