Numerical calculation of a heat-driven thermoacoustic cooler with multiple pair of the cooler and engine cores (Study on cores where the cold side of the cooler and the ambient side of the engine are adjacent)

Abstract

Heat-driven thermoacoustic coolers (HDTACs) are promising technologies for reusing waste heat. Although numerous studies have been conducted on HDTACs, they have predominantly focused on small units at the laboratory scale, with limited work on larger units for factory installations. This study explored a loop-type HDTAC with multiple thermoacoustic cores connected in series with the cold side of the cooler adjacent to the ambient side of the engine using linear thermoacoustic theory. For a large 1000-core diameter HDTAC designed for factory installations and a small 40-core diameter HDTAC designed for laboratory use, the cold heat exchanger temperature (TC), number of engine and cooler core pairs (n = 3-5), and flow path diameter of the regenerator were varied. The engine hot heat exchanger temperature (TH) relative to the cooler cold heat exchanger temperature and the Carnot-specific efficiency coefficient of performance (COP/COPCarnot) of the entire device are calculated, then design parameters of the device to achieve low temperature operation and high efficiency were indicated. The results show that, for small HDTACs, both low-TH operation and high-COP/COPCarnot were achieved at n = 5 (e.g., the maximum value of COP/COPCarnot for TC = −50°C was 0.31 at TH = 248°C). For large HDTACs, the maximum COP/COPCarnot was achieved with n = 3 (e.g., the maximum value of COP/COPCarnot for TC = −50°C was 0.49 at TH = 178°C).

Keywords

• heat-driven thermoacoustic cooler
• waste heat recovery device
• coefficient of performance
• thermal efficiency
• multiple thermoacoustic cores