The Influence of Stack Position and Acoustic Frequency on the Performance of Thermoacoustic Refrigerator with the Standing Wave

Abstract

Thermoacoustic refrigerator uses acoustic power to transport heat from a low-temperature source to a high-temperature source. The increasing interest in thermoacoustic technology is caused due to its simplicity, reliability as well as application of environmentally friendly working fluids. A typical thermoacoustic refrigerator consists of a resonator, a stack of parallel plates, two heat exchangers and a source of acoustic wave. The article presents the influence of the stack position in the resonance tube and the acoustic frequency on the performance of thermoacoustic refrigerator with a standing wave driven by a loudspeaker, which is measured in terms of the temperature difference between the stack edges. The results from experiments, conducted for the stack with the plate spacing 0.3 mm and the length 50 mm, acoustic frequencies varying between 100 and 400 Hz and air as a working fluid are consistent with the theory presented in this paper. The experiments confirmed that the temperature difference for the stack with determined plate spacing depends on the acoustic frequency and the stack position. The maximum values were achieved for resonance frequencies and the stack position between the pressure and velocity node.

Kierunki Rozwoju I Badań Termoakustycznych Urządzeń Chłodniczych Z Falą Stojącą

“…W pozostałych pracach optimum znajduje się gdzieś pomiędzy tymi wartościami. Na przykład w pracy [35] optymalne położenie stosu w rezonatorze wypełnionym powietrzem pod ciśnieniem atmosferycznym dla wszystkich czterech badanych częstotliwości odpowiadało 1/16 długości fali akustycznej. Zbliżoną wartość równą 1/15 długości fali akustycznej uzyskano w [36], gdzie czynnikiem roboczym również było powietrze pod ciśnieniem atmosferycznym, zaś w [37] maksymalne różnice temperatur dla częstotliwości od 150 do 300 Hz wystąpiły dla położenia środka stosu odpowiadającego od 1/10 do 3/10 długości fali akustycznej.…”

Influence of the temperature difference between the heat source and the evaporation temperature in ORC systems working with natural refrigerants

“…The ORC is an unconventional and very promising technology for electricity generation that has been gaining increasing popularity [3,4,13,15]. ORC-based systems employ the steam Rankine Cycle except that instead of water, organic or inorganic fluids characterized by a low boiling point are used as the working fluid [14,15]. Despite numerous advantages, including high latent and specific heat, chemical stability in a wide range of temperatures, low viscosity, non-toxicity, non-flammability and availability, water has a peculiar disadvantage, namely a high normal boiling point of 100 o C, which renders water unusable in practice in low-temperature systems [22,25,28,31] .…”

Experimental Investigation on the Thermoacoustic Effect in Easily Accessible Porous Materials

“…. Most of the current investigations for thermoacoustic devices with standing w have been done on the stack, which especially concern stack geometry [8][9][10][11], pos [12][13][14], and length [15][16][17]. The stack can be made of spiral plate, parallel plate, cir pores, pin arrays, or triangular pores.…”