Theoretical Evaluation of a 10-Watt Cooling Power Thermoacoustic Refrigerator B.G. Prashantha, 1 M.S. Govinde Gowda, 2 S. Seetharamu, 3 and G.S.V.L. Narasimham 4 1 JSS Academy of Technical Education, Uttarahalli-Kengeri Road, Bangalore, India 2 C. Byregowda Institute of Technology, Thoradevandahalli Village and Post, Kolar, India 3 Materials Technology Division, Central Power Research Institute, Bangalore, India 4 Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India This article deals with the design, simulation, and analysis of a 10-watt capacity thermoacoustic refrigerator using short-stack boundary layer approximation assumptions and dimensional normalization technique. The variation of stack diameter with average gas pressure and cooling power is studied. The theoretical evaluation of quarter-wavelength and one-fifth-wavelength resonator using helium gas is discussed for an operating frequency ranging from 300–500 Hz in the steps of 50 Hz. For the optimized stack, a 38.5% improvement in the stack performance for a 10-watt cooling power quarter-wavelength hemispherical-ended resonator operating at 350 Hz frequency resulted in a 13.5% improvement in the coefficient of performance (COP) compared to published results. The resonator design is tested with DeltaEC software with 2% and 3% drive ratios using helium, hydrogen, neon, air, and carbon dioxide as working gases and the results are discussed. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res 2014; Published online 3 October 2013 in Wiley Online Library (wileyonlinelibrary. com/journal/htj). DOI 10.1002/htj.21094 Key words: thermoacoustic, stack, heat exchangers, resonator 1. Introduction The stack-based thermoacoustic refrigerator with a standing wave which uses sound genera- tion for heat pumping from lower to higher temperature region is regarded as a new, promising, and environmentally benign alternative to conventional vapor compression refrigerators. A few advan- tages of this device over conventional devices are simplicity in construction, no exotic material requirement and hence low cost, no moving parts, no heat bridges at room temperature, and capable of producing low temperatures up to 200 K [1]. The performance of these devices is not yet competitive enough to replace conventional cooling systems but efforts are underway to make these devices viable in the near future. A thermoacoustic refrigerator consists of hot and cold heat exchangers placed on either side of a stack contained in a large resonator tube. The loudspeaker is attached to the left side of the large resonator tube and on its right is a small resonator tube terminated with a conical ended design as shown in Fig. 1. In the literature, the effect of the operating frequency on the performance of a quarter-wa velength (λ/4) resonator and one-fifth-wavelength ( λ/5) resonator © 2013 Wiley Periodicals, Inc. 1 Heat Transfer—Asian Research, 43 (7), 2014 577 , 43(7): 577–591,