| Without moving parts, a thermoacustic engine (TE) is a new type of engine converting thermal energy into acoustic power by thermoacoustic effect with advantages of simplicity, high reliability, non-pollution and long lifetime, which attract much attention in the field of thermal engine.First a review on research history and the latest advances of TEs are given, followed by a brief introduction of the basic principle of thermoacoustic effect, and then the linear theory and fluid network theory are introduced in details.Although a lot of achievements on the research of TEs have been obtained, there are still some deficiencies such as low pressure ratio and efficiency. Moreover, further study is needed on match between a TE and a pulse tube refrigerator(PTR).To solve such problems, work has been done to study the output characteristics of a TE and optimum match between a TE and a PTR.1. A Helmholtz resonator is proposed to improve the output pressure ratio of the TE. In a Helmholtz resonator with 1 L reservoir, the maximum pressure ratio,acoustic power and thermal efficiency reach 1.324,143.5W,and 4.28% respectively, and in a resonator with 90 mL, the maximum values reach 1.49, 115.8W, and 8.28% respectively.2. Numerical and experimental research has been done on a coupled system connecting a Helmholtz resonator with an acoustic amplifier, which is used to match a TE and PTR. Experiments indicate that the coupled system can greatly increase the output pressure ratio much higher than a Helmholtz resonator. With the coupled system, maximum output acoustic power of 105 W and thermal efficiency of 4.9% are obtained under the certain resistance.3. A TE with CO2 as working gas has been studied numerically and experimentally. A TE with CO2 as working fluid can work with lower oscillating temperature (131℃under the charging pressure of 0.8MPa), lower resonant frequency and higher pressure ratio than that with N2 and He under the same experimental condition.
|
PDF Full Text Request