Designing an environmentally sound sound-powered refrigerator
Designing an environmentally sound sound-powered refrigerator lead image
Heat-driven thermoacoustic refrigerators (HDTRs) can convert thermal energy into acoustic power to pump heat. Devoid of moving parts, this emerging cooling technology is reliable and sustainable. Most HDTR prototypes, however, employ helium as the working gas for efficient thermoacoustic conversion. The rarity and high price of this element will limit the future application of HDTRs.
Xiao et al. developed an HDTR that uses the more plentiful and economical nitrogen as its working gas. They proposed an innovative bypass configuration consisting of a tube that connects the engine and cooler units to achieve good matching between the engine’s acoustic power generation and the cooler’s acoustic power consumption. This reduces loss and enhances efficiency.
The authors further improved their design with a water-filled liquid resonator. Commonly, prototypes use resonance tubes to adjust the acoustic field in a system, but the loss in these tubes can be considerable. The higher density of the water in the liquid resonator lowers the working frequency to reduce loss.
Overall, this design improves the performance of nitrogen-based HDTRs. The refrigerator reached a coefficient of performance of 0.49 in a standard air-conditioning case, suggesting it could be suited for practical applications.
“This work provides an innovative and effective method for the efficiency enhancement of the heat-driven thermoacoustic refrigerator,” said author Lei Xiao. “The proposed system has potential in the field of heat-driven refrigeration, especially in eco-friendly air conditioning applications.”
The researchers plan to try other working gases in this HDTR design to improve its performance.
“We will use helium and other eco-friendly working substances, as well as elevate the heating temperature, to further enhance the coefficient of performance,” Xiao said.
Source: “An efficient and eco-friendly heat-driven thermoacoustic refrigerator with bypass configuration,” by Lei Xiao, Kaiqi Luo, Zhanghua Wu, and Ercang Luo, Applied Physics Letters (2023). The article can be accessed at https://doi.org/10.1063/5.0181579 .
