Study On Structure And Phase Modulation Mechanism Of Regenerator For Two Stage Traveling Wave Loop Thermoacoustic Engine

The traveling-wave thermoacoustic engine is a energy conversion device with the advantages of simple structure,no moving parts,high reliability,and inert gas as its working medium.In recent decades,researchers have paid more and more attention to thermoacoustic engine technology.Thermoacoustic theory’s continuous improvement has made constructive progress and has broad prospects in refrigeration,electric power generation,and other aspects.However,compared with the conventional internal combustion engine,the thermoacoustic engine is still in infant states.Recently,the multi-stage traveling-wave thermoacoustic engine has become a hot topic owing to its characteristics of high intrinsic efficiency,low starting temperature,and high energy-flux density.This dissertation explores the method of optimizing the performance of a two-stage traveling-wave thermoacoustic engine using simulation and experimental.It was used to study the influence of regenerator and resonance tube on the thermoacoustic conversion.The main research contents are as follows:(1)According to the working medium’s temperature gradient,the effective heat loss can be reduced in the low-temperature section and the viscous section.Without changing the other conditions,The energy produced in the single-layer regenerator is about 501.7W,dividing the regenerator into multi-layer and selecting the mesh gradient reasonably,the energy produced by the regenerator is about 530.32 W,the thermoacoustic engine’s performance increases by about 5.7% compared with that of the single layer.(2)According to the different thermal conductivity of different materials,the suitable combination of stainless steel and copper filler can enhance the heat transfer capacity of the fluid working medium between the regenerators.The simulation results show that the regenerator’s energy can be improved by filling the appropriate copper wire mesh.When adding copper wire mesh,the maximum energy generated in the regenerator is 609.86 W.Compared to the single material mesh structure,the maximum energy increased by 15%,which can effectively improve the two-stage traveling-wave thermoacoustic engine’s thermoacoustic conversion ability.(3)The acoustic field structure of the two-stage traveling-wave thermoacoustic engine can be adjusted by changing the resonance tube’s cross-sectional area based on the linear thermoacoustic theory.The simulation results show that the phase change of pressure amplitude and volume flow rate can be adjusted by reasonably adjusting the resonant tube’s cross-sectional area.When the inner diameter length of the 10 cm resonant tube is increased to 8 cm in position 1,the phase at the regenerator changes from-41.7 degree to-36.2 degree.In position 2,the resonant tube is decreased to 3cm,and the phase at the regenerator changes from-41.6 degree to-33.9 degree.The regenerator of the two-stage thermoacoustic engine can work in the phase of traveling-wave.(4)A two-stage traveling-wave thermoacoustic engine test rig was built.The experimental data on the frequency characteristics and load characteristics of the system under the condition of different hot end temperatures shows that the influence of different hot end temperatures on the frequency of the system does not change much.As the temperature difference of the heat exchanger rises,the sound power extracted by the load is more.Compared with the numerical simulation results,the latter two are more consistent,which shows that the numerical model can effectively reflect the two-stage traveling wave thermoacoustic experimental platform’s operation characteristics.