带阻性管的环路行波热声发动机性能研究

Study on the Performance of a Looped Thermoacoustic Prime Mover With Resistance Tube

高效的行波热声发动机要求回热器处在接近行波和高声阻抗的声场。为此,本文拟采用阻性管进行调相,设计了一台单级环路行波热声发动机,分别以He,N2和CO2为工质,对该热声发动机的起振特性和稳态运行工况进行了系统的实验研究。结果表明,安装阻性管后,单级环路行波热声发动机的起振温度可以被降低300℃以上,最低起振温度仅为55C(工质为CO2,平均压力为2.35 MPa)。此外,系统可以在200℃以下的加热温度达到比较可观的压比。可见,阻性管可以作为环路行波热声发动机的一种有效调相方式,本文所提出的热声发动机系统具有利用低品位热源驱动的潜力。

One key issue for a highly efficient travelling-wave thermoacoustic engine is the acoustic field characterized by near-travelling wave field and high acoustic impedance in the regenerator. A single-stage travelling-wave thermoacoustic prime mover has been designed, including a resistance tube to adjust the acoustic field. Systematic experiments on the onset characteristics and the steady state of the prime mover have been conducted with helium, N2 and CO2 as working fluids, respectively. The results show that the onset temperature of the prime mover can be lowered by more than 300 ℃when the resistance tube was introduced into the loop. The lowest heating temperature to initiate the onset is only 55 ℃, when the working fluid is CO2 and the mean pressure is 2.35 MPa. Besides, the prime mover can be operated with a considerable pressure ratio when the heating temperature is below 200 ℃. Consequently, the resistance tube can be used as an effective phase adjustor for a looped thermoacoustic prime mover and the system proposed in this work shows a promising potential to utilize low-grade thermal energy.