An efficient and eco-friendly heat-driven thermoacoustic refrigerator with bypass configuration

Developing high-efficiency and environmentally friendly cooling technology is crucial for sustainable life. Heat-driven thermoacoustic refrigerator (HDTR) is an emerging cooling technology characterized by no moving components, eco-friendly working substances, and high reliability. This study reports an innovative efficient HDTR with bypass configuration, which employs eco-friendly and economical working substances, the nitrogen and water. The bypass configuration enables good matching of acoustic power between the engine and cooler units at high heating temperatures, thus enhancing the efficiency. In addition, the employment of liquid resonator significantly reduces the working frequency and reduces the loss. An experimental investigation is performed on the onset characteristics and operating performance of the proposed system. The results show that a highest coefficient of performance (COP) of 0.49 and a cooling power of 726 W are achieved at the heating, ambient, and cooling temperatures of 500, 35, and 7 °C, respectively, exhibiting a high level for the HDTRs employing nitrogen. This work supplies an effective way to the efficiency enhancement of the HDTRs, indicating substantial potential of the proposed HDTR in eco-friendly air-conditioning applications.