Investigations on performance improvement of standing wave type thermoacoustic prime mover using acoustic amplifier

Thermoacoustically driven pulse tube cryocooler is gaining significant interest in the recent time due to its key advantage of complete absence of moving components from the entire system. Design and development of a thermoacoustic prime mover is a challenging work which requires thorough understanding of thermoacoustic phenomenon. The system performance, mainly in terms of pressure amplitude is significantly influenced by the operating parameters like heat input, temperature of heat input and charging pressure, geometrical parameters like stack length, stack position, resonator length etc. and the type of working gas. Reduction in length of the device results in higher frequency and lower pressure amplitude of thermoacoustic oscillations. The disadvantage of lower pressure amplitude of thermoacoustic oscillations is offset to some extent by using the acoustic amplifier. In the present work experimental investigations are carried out on a standing wave type thermoacoustic prime mover having parallel plate type stack with around 300 Hz frequency of oscillations. The improvement in pressure amplitude of thermoacoustic oscillations using the acoustic amplifier is studied. The results obtained are compared with the results of theoretical modeling. Effect of charging pressure and stack length is studied for nitrogen and helium gas.