Design and temperature matching of an efficient heat-driven thermoacoustic cryocooler for 77 K cooling

The 77 K heat-driven thermoacoustic cryocooler (HDTAC) is an environmentally friendly cooling technology featuring high reliability and long operational lifespan, making it suitable for aerospace detector cooling and low temperature superconductivity. To enhance the performance of 77 K HDTAC and address the mismatch between engine and cooler, the key limiting factors in the looped system were investigated, and a novel hybrid configuration combining direct-coupling and interval connection was proposed. A design strategy for the series-configured HDTAC was developed, emphasizing temperature coupling, stage matching, acoustic power balance, and acoustic field coupling. A comprehensive operating map covering the full temperature range was constructed, accompanied by detailed analyses of the acoustic field and performance. The effects of temperature matching on performance, acoustic parameters and structural parameters were further clarified. Results show that the proposed HDTAC achieves a cooling power of 313.8 W at 77 K with a relative Carnot efficiency of 21.24%, representing a 9.04% improvement over previous studies. It also delivers 605.8 W of cooling power at 110 K with an efficiency of 25.21%. Moreover, the study reveals that the quality of temperature matching governs the upper limit of efficiency optimization, with a well-matched region (efficiency >15%) occurring only when the temperature ratio exceeds 1.85. This study provides practical temperature matching guidelines for HDTAC system and highlights the application potential of HDTAC system for 77 K cooling applications.