A displacer coupled thermoacoustic cooler driven by heat and electricity

A small-scale, heat-driven cooling system is required for the on-site liquefaction of unconventional natural gas in a distributed station. The thermoacoustic cooler has been considered a promising candidate for meeting such demands due to its high reliability and environmental friendliness. However, conventional thermoacoustic systems use a resonance tube to couple the thermoacoustic engine and cooler, which degrades cooling performancedue to poor phase-shifting capability and significant power dissipation of the resonance tube. To overcome the limitation, this paper introduces a novel driven by heat and electricity thermoacoustic cooler using displacers to replace the resonance tube, which enables better phase-shifting capability and less power dissipation, thus allowing better cooling performance. Numerical investigation and experimental study are performed on the displacer-coupled thermoacoustic cooler driven by heat and electricity. Firstly, the design method of the displacers is presented based on the acoustic impedance matching principle. Numerical investigations are then conducted to understand the operational characteristics better to explore the axial distribution of critical parameters. The effects of the displacer damping coefficient, operating frequency, and mean pressure are further studied. Experimental investigations are then carried out to understand the impact of operating temperatures on system performance. Experimental results show that the system achieves a record thermal-to-cooling exergy efficiency of 13.4 % and cooling power of 117 W at heating and cooling temperatures of 773 K and 110 K. This represents an over 34 % improvement in efficiency when compared to the previous record-holder thermoacoustic cooler.