Numerical analysis on the heat and fluid flow in the stacks of a thermoacoustic refrigerator

Based on compressible pressure correction method, computational codes for oscillating flows are developed in body-fitted coordinates. AUSM+ scheme is adopted to discretize the momentum and energy conservation equations. The codes are used to simulate the heat and fluid flow process in the stacks of a thermoacoustic refrigerator. The temperature variation near the stacks and time-averaged energy flow in one cycle are obtained and analyzed. Through the simulation results, it's clear that at the cold end energy flows from the gas to the stacks and the time-averaged energy is positive, while at the hot end the condition is reversed. The energy flow at the hot end is larger than that of the cold end, which means a transmission of cooling capacity. In comparison with the input power, the cooling capacity is still very small, which leads to an increase of the total energy in the system and the average temperature increases gradually. With the increase of stacks thickness, temperature difference at the two ends of stacks increases first and then decreases, which indicates an optimal thickness for the stacks.