Development of a thermoacoustically driven thermoacoustic refrigerator

M.Tech. (Mechanical Engineering)Abstract: Thermoacoustic technology is proposed in this study as an alternative sustainable solution to current issues with vapour compression refrigerators because of its environmentally friendlier attributes. However, the main hindrance to the expansion of this technology is its current lack of efficiency. Hence, three experimental investigations were conducted in this study for three standing wave thermoacoustic systems. The influence of the geometrical configuration of the stack, which is described as the heart of the device, formed the main study of this work. The first device experimentally investigated was a simple thermoacoustic refrigerator. The device was equipped with different selected low-cost porous materials (honeycomb ceramic) for performance testing and studies. Porosity, length and position of the stack were parameters changed in the refrigerator. Sixteen ceramic stacks were considered and evaluated separately. Temperature readings across the stack were used to determine the performance and efficiency of a configuration. In addition, clarity on the relationship between stacks and their frequencies of the sound wave are highlighted The second thermoacoustic device experimentally investigated, was an adjustable thermoacoustic engine. The device incorporated a buffer volume, cooling heat exchanger, heating coil and six different honeycomb ceramic stacks. Stack parameters of two porosities, three lengths and three positions were studied. The pressure inside the engine for two types of gases were evaluated. Measurements of temperature difference across the stack and sound pressure levels were used to determine the performance of the device. Results showed that adjusting the resonator length of the engine changed frequency output. Results obtained in the previous studies aided in the design and construction of an adjustable prototype for a thermoacoustic system which couples the engine to the refrigerator. This device is known as a thermoacoustically driven thermoacoustic refrigerator (TADTAR). A final design was selected from three possible conceptual drawings. Details of the procedure used during the design are provided. The development of the adjustable TADTAR was performed by means of a third and final experiment. The device incorporated two heat exchangers, a heating coil and a stack sample of six different honeycomb ceramics. Stack parameters were changed at the refrigerator and engine. The prototype was pressurised and the operation for two different gases were compared. Measurements of temperature difference across the refrigerator stack were used for performance calculations. Adjusting the resonator length for the operation of the TADTAR had significant results on the performance of the device