Effective utilization and influence analysis of DC Flow in thermoacoustically driven pulse tube cryocooler

The thermoacoustically driven pulse tube cryocooler (TADPTC), known for its reliability, long lifespan, and waste heat utilization, represents a highly promising and environmentally friendly cooling solution. The looped multi-stage configuration, a widely used high-performance design, is significantly impacted by DC flow. However, most existing experimental studies focus on directly suppressing DC flow, with limited research on its utilization. To address this, this study investigates the influence of DC flow within the thermoacoustic engine loop of a TADPTC system, using the performance of the pulse tube cryocooler (PTC) as an indicator of DC flow's effect on the engine loop. Experimental results demonstrate that a moderate level of positive DC flow can enhance system performance. Building on this, further optimization of the system structure with DC flow was conducted. Experimental results show that maintaining an appropriate DC flow level within the engine loop enabled the bypassed cooler to reach a minimum temperature of 43.69 K, which is 5.69 K lower than that achieved in the complete suppression of DC flow. At around 100 Hz, the system achieved a cooling power of 5.69 W at 76.64 K, representing a 70% improvement over the system with suppressed DC flow. The optimization results further indicate that with DC flow rate of 0.0082 g/s, a relative Carnot efficiency of 9.225% at 77 K is achieved, whereas at a flow rate of 0.25 g/s, the cooling power reaches a maximum of 16.59 W. These findings validate the potential of DC flow to enhance thermoacoustic system performance and offer new insights for further optimizing thermoacoustic cryocoolers.