Theoretical And Experimental Research On Energy Conversion Characteristic In Traveling-wave Thermoacoustic Power Generation System

In the new energy utilization technology,thermoacoustic engine and thermo acoustic power generation technology can play an important role in expanding the energy mix and environment-friendly energy production,which is an important method to solve the current environmental problems,energy crisis and achieve sustainable development.It is of great significance to study the energy conversion mechanism in the thermo acoustic system for its efficient and stable operation.Based on the numerical calculation,the traveling-wave thermoacoustic engine and thermoacoustic power generation system are designed and developed,and the energy conversion characteristics of thermo-acoustic and thermo-electric are studied.The main research work is as follows:(1)Based on one-dimensional linear thermoacoustic theory,the performance simulation of traveling wave thermoacoustic engine is carried out by using DeltaECsoftware,the variation of the performance of the thermoacoustic engine with the structural and operational parameters is obtained.The effects of the structural parameters of the engine acoustic pipeline on the oscillation frequency,the phase in the regenerator,the pressure amplitude and the output acoustic work are discussed in detail.The structural parameters such as the length of the thermoacoustic core and the porosity are optimized.Finally,a traveling wave thermoacoustic engine experimental system is developed.(2)The characteristics of thermo-acoustic conversion in regenerator with various hydraulic radius and when the thermoacoustic engine is filled with three different gases as working fluid are studied,the variaton of the conversion characteristic(onset temperature,pressure amplitude,pressure ratio)is obtained.From the research,when the hydraulic radius of the regenerator is different,there is an optimal mean pressure to minimize the onset temperature of this engine.With the decrease of hydraulic radius,the mean pressure corresponding to the lowest onset temperature increases.At the same mean pressure,the reduction of the hydraulic radius of the regenerator is helpful to increase the pressure amplitude.For nitrogen and argon,the onset temperature increases with the increase of mean pressure,and the onset temperature of argon is higher than that of nitrogen.In the range of mean pressure in which the engine can work,helium has obvious advantage.The maximum pressure ratio of nitrogen and helium can only be obtained in low mean pressure area.(3)The matching of traveling wave thermo acoustic engine and linear alternator in thermoacoustic power generation system is studied,and the acoustic matching between them is realized.The results shows that the frequency is the key factor to affect the performance of linear generator.When the generator works at resonance frequency,the output electric power and the conversion efficiency of acoustic electricity are the highest.When a traveling wave thermoacoustic engine drives a pure resistive acoustic load at the resonator,increasing the real part of the acoustic impedance of the acoustic load will improve the acoustic power flowing to the load and the pressure amplitude at the position of the acoustic load.Finally,the performance of the thermoacoustic power generation system composed of traveling wave thermoacoustic engine and linear generator is calculated by acoustic impedance matching.The results show that the oscillation frequency can be adjusted to the resonance frequency of linear alternator when mean pressure in the thermo acoustic engine and the load resistance of the circuit outside the linear alternator will be increased.With proper selection,the maximum electric power output can be obtained on the premise that the piston of linear generator does not exceed the limit stroke.(4)The traveling wave thermo acoustic engine is connected with a linear generator,and the thermoelectric conversion performance of the thermoacoustic power generation system is studied experimentally.The working frequency of the system is modulated to the mechanical resonance frequency of the linear generator by using the mixed working fluid,and the thermo-electric conversion of the thermo acoustic power generation system is finally realized.In the experiment,the mixture is composed of helium and nitrogen with molar ratio of 1.5 MPa of 70%and 30%,respectively.When the heating temperature and power are 500? and 1000W respectively,the maximum electric power output of the traveling-wave thermo acoustic power generation system is 54W.