A team of researchers led by Prof. Luo Ercang from the Technical Institute of Physics and Chemistry (TIPC) of the Chinese Academy of Sciences has developed a groundbreaking heat-driven thermoacoustic refrigerator (HDTR) with a unique bypass configuration that significantly enhances the efficiency of this cooling technology. The findings of their study were published in Cell Reports Physical Science.
HDTR is a promising cooling technology that offers several advantages, including the absence of moving parts, the use of eco-friendly substances such as helium and nitrogen, and high reliability. However, its commercial application has been hindered by its relatively low efficiency.
The efficiency of HDTRs is measured by the coefficient of performance (COP), which represents the ratio of output cooling power to input heating power. The researchers discovered that existing advanced direct-coupled HDTRs experience a surprising decrease in COP as the heating temperature increases, and they identified the reason behind this phenomenon: a temperature matching constraint present in these systems that prevents the improvement of COP at high heating temperatures.
To overcome this obstacle, the researchers proposed a novel bypass configuration that eliminates the temperature matching constraint. This innovative configuration allows for a portion of the acoustic power to be bypassed, enabling efficient acoustic power matching between the engine unit and the cooler unit at high heating temperatures.
As a result, energy flow field synergy is achieved, leading to a significant improvement in efficiency. The researchers constructed a kilowatt-scale HDTR prototype and obtained a record high experimental COP of 1.12 with a cooling capacity of 2.53 kW using helium as the working gas. These results were achieved at heating, ambient, and cooling temperatures of 450°C, 35°C, and 7°C, respectively. The COP achieved is 2.7 times higher than the best result ever reported for existing HDTRs.
The researchers claim that their new HDTR technology outperforms adsorption refrigerators and single-effect absorption refrigerators in the field of room-temperature, heat-driven refrigeration, and is comparable to double-effect absorption refrigerators. These remarkable results demonstrate the potential of this novel HDTR technology in commercial air conditioning applications.
Additionally, the researchers tested the performance of the system using nitrogen, which is a more abundant and cost-effective refrigerant with environmental friendliness. The COP results surpassed the previously reported findings from TIPC. The study was published in Applied Physics Letters on January 8th and was specifically reported by Scilight.
The research team asserts that the novel HDTR system inherently possesses a higher COP than absorption refrigerators due to its efficient utilization of high-temperature thermal energy. Their numerical analysis suggests that the proposed HDTR system has an outstanding potential COP value of 2 at a heating temperature of over 800°C.
The researchers plan to make modifications to the current HDTR system and increase the heating temperature to further enhance the cooling performance. They anticipate surpassing the efficiency of double-effect absorption refrigerators in the foreseeable future.
1. Source: Coherent Market Insights, Public sources, Desk research
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