Study of the Relation between Entropy Flux Density Production and Thermal Efficiency of a Thermoacoustic Engine
* Presenting author
When the traveling wave propagates in a bundle of narrow tubes (the regenerator) whose channel radius is smaller than thermal penetration depth and experience a positive temperature gradient, the thermodynamic cycle of working gas in the regenerator undergoes the isothermal reversible thermodynamic cycle similar to that of Stirling cycle. The thermoacoustic engine is classified as a type of heat engine which has high thermal efficiency theoretically. However, in actual, it is difficult to execute the isothermal reversible process because of the irreversibilities such as dissipation and heat transport from hot to cold by oscillating flow in the regenerator. These irreversibilities causes decrease of thermal efficiency. These irreversibilities depends on two parameters: (1) the ratio of channel radius to the thermal penetration depth, and (2) the specific acoustic impedance at the regenerator. By setting these two parameters appropriately, irreversibilities can be reduced. In this study, the entropy flux density production is focused as an indicator of the reversible and irreversible characteristics. The relation between the entropy flux density production and thermal efficiency of the regenerator is investigated by changing two parameters both of (1) and (2).