Investigation Of A Mechanical Resonant Thermoacoustic Refrigerator

Compared with the conventional heat engines, thermoacoustic heat engines (including refrigerators) have some advantage, such as simple structure,no or least moving parts,high reliability, potential possibility of operating on low energy level heat source, using environmentally friendly working substance, and etc. For these, thermoacoustic heat engines are becoming significantly promising in applications. However, the practical applications of thermoacoustic heat engines have been restricted by some issues on power density and frequency matching. In order to find the solutions for these issues, in this thesis, a mechanical resonant thermoacoustic refrigerator with mass-spring system is mainly investigated for the application aim as freezer. The key points investigated are placed on mode frequencies and operating behavior of resonant system studied.Several thermoacoustic refrigerators with different configurations of resonators are firstly discussed in this thesis. Operating behaviors of refrigerators are analyzed using equivalent network method, and then merits and drawbacks in these aspects of sizes, energy dispersion, and characteristic of frequency modulation are compared and discussed among various configurations of thermoacoustic refrigerators. The optimal configuration scheme is finally determined and adopted in this thesis.A lumped two-dimensional spring-mass equivalent model is established for the resonant system of the thermoacoustic refrigerator studied. The frequency relations of modes for the mechanical resonant system are obtained analytically. The effects of the resonant parameters for the system on mode frequencies and amplitude-frequency characteristic are also investigated numerically. Simultaneously, the effective methods are discussed for the resonance modulating and frequency modulating.The design parameters of a thermoacoustic refrigerator as a freezer are determined through the analyzed and simulated results for the resonant system of refrigerator. A design optimization of the themoacoustic refrigerator has been made using the network method, and the main structural parameters are defined for the experimental refrigerator prototype. Performance predicts have also been made for the experimental investigation.In the end of this thesis has provided some referential suggestions for further research in these aspects of distributed parameter model, the calculation of acoustic field distribution using DeltaE analysis tool, and the analysis on energy losses, etc.