Research On Operating Characteristics Of Stirling Engines And Optimization Design Of Hybrid Heating System

By external heating,Stirling engine achieves a closed cycle with gas as working fluid.It can adapt different heat source well,and has high efficiency,low pollution.Stirling engine has gradually been promoted and developed in the home use field with the increasing requirements in energy-saving and environmental protection.The Stirling engine,which has kilowatt level,represents a huge market demand.However,the existing Stirling engines mainly use high-cost helium or dangerous hydrogen,and rely on single heat source,which are harmful for the popularization of Stirling engines in home use field.In order to enhance the applicability of the Stirling engine in home use field,this paper explored the feasibility of using cheap gas such as carbon dioxide as the working fluid,analyzed the operating characteristics of kilowatt level Stirling engine,and optimized the design of hybrid heating systems.Based on a self-designed 100 W ?-type Stirling engine,the sealing performance and operating characteristics of the Stirling engine,using carbon dioxide,nitrogen and helium,were studied by experiment.The results of dynamic test showed that the remaining amount of carbon dioxide was 97.31% after 6 minutes.The sealing performance of carbon dioxide was good.At the same working pressure(2.84MPa)and rotating speed(800rpm),the operating characteristics of helium showed that the output power was 116.3W,which of carbon dioxide was 124.8W,and the cycle efficiency of them were both 12.15%.With the rotating speed reduced,the output power of the two kinds of working fluids were closed to each other.Therefore,carbon dioxide was feasible to be the working fluid at low rotating speeds(<800 rpm).Household Stirling engines have low power requirements.The operating characteristics of a self-designed kilowatt Stirling engine were analyzed by numerical simulation.The temperature of the heating pipe's inner walls were divided into multiple parts,because the heater was heated by one side.The numerical simulation results showed that the average temperature of expansion chamber was 860.9 K,and the cycle power was 1188 W.Increasing temperature could reduce the use of working fluid effectively.Changing pressure had little influence on expansion chamber and heating tubes' temperatures.At low rotating speed,while increasing heating temperature,the expansion chamber temperature increased significantly.This paper optimized the hybrid heating systems of two self-design Stirling engines.Based on light radiation and combustion,a double layer structure combining cavity absorber and combustion chamber were designed to optimize the heating system of the 100 W Stirling engine.It could provide 1682 W heat exchange for the heater.Based on the use of waste heat,the outlets and auxiliary inlets were arranged circumferentially to optimize the heating system of the kilowatt Stirling engine.The waste heat could provide 4.04 k W heat for the heater.