Experimental and numerical investigation of temperature distributions in a compact thermoacoustic cooler

This paper presents a measured temperature distribution inside a compact and axisymmetric thermoacoustic refrigerator's core and compares it with numerical calculations. The design of the device benefited from insightful discussions with Steven Garrett and David Gardner, particularly during the design phase. To achieve compactness, the system utilizes two electroacoustic sources around its thermoacoustic core, of which the diameter is 164 mm and the length is 39 mm, capable of supporting a temperature difference of about 70 °C at a working frequency of 47 Hz. Fifteen thermocouples were used to probe the core, revealing significant transverse temperature gradients not predicted by the design tool DeltaEC. To account for these discrepancies, a 2-D numerical model incorporating gravity effects was developed under the low Mach number approximation, and simulations were conducted for a configuration slightly different from the experimental prototype. Calculations were performed for various relative orientations between the device axis and the gravity force to explore the impact of natural convection on the temperature distribution. A hanging system was employed to perform measurements under similar relative orientations, enabling a comparison between experimental data and simulations.