Experimental Study on a Standing Wave Thermoacoustic Engine

The aim of this research is to design and construct a standing wave thermoacoustic engine in orderto drive a thermoacoustic refrigerator. The slab stack is selected in this work. To minimize the capital cost,the compressed air of 10 bar is employed as working fluid to operate at designed frequency of 50 Hz. Thepreliminary test to evaluate the performance of this engine is required. The temperature distribution withinthe stack and the oscillating pressure in the system are measured. As the mean pressure in the system isincreased from 5 bar to 10 bar, the onset temperature to oscillate is reduced, resulting to shorter starting-upperiod. This is possible to utilize low-grade energy sources such as waste heat, solar energy, etc. to operatethe thermoacoustic engines at high pressure. The pressure amplitude caused by the oscillating movementof wave is the crucial parameter that indicates the acoustic power generated. The drive ratios (= p1/pm)obtained from this engine are about 2.25% and 3.10% at operating pressures of 5 bar and 10 bar, respectively.This is sufficient to drive the thermoacoustic refrigerator latter on. In addition, the mathematical model iscarried out in order to validate the experimental results. The measurement results give good agreement withthe simulation results. Keywords : Heat engine / Thermoacoustic / Standing wave / Stack / Oscillating flow