Design and experimental evaluation of a travelling-wave thermoacoustic refrigerator driven by a cascade thermoacoustic engine

Abstract

Summary A travelling‐wave thermoacoustic refrigerator driven by a cascade thermoacoustic engine is evaluated experimentally in this paper. A prototype is developed under the constraint of a low‐cost and less complicated device. In order to reduce the total budget, commercial materials and standard parts are selected, and air at atmospheric pressure is used as working fluid in the system. The thermoacoustic coupled engine‐refrigerator system consists of 1 standing‐wave unit, 1 travelling‐wave unit, and 1 travelling‐wave refrigerator arranged in a linear configuration. A resonator‐tube is connected at each end of the thermoacoustic core. The effects of the length and hydraulic radius of the regenerator in the refrigerator on the cooling performance are investigated at different levels of input power. In the experimental results, the maximum temperature difference of 17.6°C was realised at the no‐load condition. The maximum coefficient of performance relative to Carnot (COPR) of 2.4% was accomplished at the cooling load of 13 W.

Performance of an air‐cooled looped thermoacoustic engine capable of recovering low‐grade thermal energy

“…Under the background of global energy crisis and environmental pollution, there is an urgent need to harvest energy from low‐grade heat . Thermoacoustic engine is considered as a cost‐effective and reliable alternative heat engine for low‐grade heat utilization with the excellent merits of environmental benignity and high reliability …”

An electret‐based thermoacoustic‐electrostatic power generator

“…1 The working principle behind the TAEs is the thermoacoustic effect, which concerns mutual interaction between the acoustic and thermal fields around the solidfluid interfaces. [2][3][4][5][6][7][8] The TAEs can be further transformed into electric power generators by acoustically coupling them with acoustic-to-electric transducers/converters, which provides novel alternative systems for power generation from low-grade thermal energy for niche applications. 9 So far, lots of efforts have been made toward the design and fabrication of robust acoustic-to-electric transducers for thermoacoustic power generators.…”

Performance optimization of the regenerator of a looped thermoacoustic engine powered by low-grade heat

“…8 Hasegawa et al and Hsu et al measured the axial heat flow transported by the oscillatory gas in the regenerator, showing that the thermal diffusion effect was detrimental to the thermoacoustic conversion. 14,15 The engine delivered acoustic power up to 2 kW, with a thermal efficiency up to 20%. Mohd Saat et al investigated the pressure drop in the regenerator and proposed a steady-state correlation to calculate the friction factor.…”

“…9,10 However, the solution to suppressing this effect was not discussed. 12,15,16 A novel looped traveling-wave thermoacoustic engine (LTWTAE) with multiple locally enlarged thermoacoustic cores (each including a regenerator sandwiched by two heat exchangers) was invented by de Blok. 11 Dhuchakallaya et al improved the acoustic field in the regenerator by inserting an appropriate pencil into the down-resonator in a cascade thermoacoustic engine.…”

“…4 Later, Gardner and Swift proposed a straight-line thermoacoustic engine, which includes both standingwave and traveling-wave stages. 14,15 The engine delivered acoustic power up to 2 kW, with a thermal efficiency up to 20%. However, these thermoacoustic engines generally require a heat source at high temperature (typically above 500°C) due to the standing-wave resonator, hindering their utilization of low-grade heat.…”