Optimization of binary gas mixture as working fluid for the thermoacoustic prime mover

The thermoacoustic prime mover (TAPM) is an attractive alternative to the conventional drive used in the pulse tube cryocoolers (PTCs), owing to no moving components, less wear and tear, less vibrations, simplicity in construction and use of environmentally friendly working fluids. In our objective to develop such a system, we have designed and developed twin standing wave TAPM. This paper presents the results of an experimental investigation using binary gas mixtures as working fluid. The gas mixtures of different working fluids, namely nitrogen, argon, and helium are used in the experimentation. The measurement shows that the performance of the twin standing wave TAPM improves as the working gas Prandtl number decreases. The operating frequency, pressure amplitude, temperature difference between the stack ends have been studied at different operating pressures and by varying gas mixture composition. However this needs optimization of binary gas mixture composition. The experimental studies show that for the best performance of TAPM, correct binary mixture of working fluids should be used. Among the binary mixtures the pressure amplitude is high when argon is used as the working fluid. However temperature difference across the stack is higher for argon. In view of this an optimal mixture of Helium 60% and Argon 40% can be chosen to obtain best performance of TAPM.