Theoretical Evaluation of a 10-Watt Cooling Power Thermoacoustic Refrigerator

2013 ◽  
Vol 43 (7) ◽  
pp. 577-591 ◽  
Author(s):  
B.G. Prashantha ◽  
M.S. Govinde Gowda ◽  
S. Seetharamu ◽  
G.S.V.L. Narasimham
2013 ◽  
Vol 21 (04) ◽  
pp. 1350027 ◽  
Author(s):  
B. G. PRASHANTHA ◽  
M. S. GOVINDE GOWDA ◽  
S. SEETHARAMU ◽  
G. S. V. L. NARASIMHAM

This paper presents a design of moving coil loudspeaker for a 10 W cooling power thermoacoustic refrigerator. An electrical model is presented which simulates the behavior of the loudspeaker. The gas spring system for matching the frequency of the commercially available loudspeaker with the frequency of the acoustic resonator tube for maximizing electro-acoustical efficiency of the loudspeaker is discussed. The optimum back volume for the gas spring system is found to be 59.7 cc, which is about 1.9% of the total resonator volume when the loudspeaker frequency and the acoustic resonator frequency is made equal at 400 Hz with a moving mass of 20 g. The effect of force factor Bl on loudspeaker performance is discussed. Analysis results shows that for better performance of a refrigerator, the loudspeaker should be chosen to have a large force factor and small values for electrical and mechanical resistances. The refrigerator system is tested with DeltaEC software and its results are in good agreement with an electrical model results.


2015 ◽  
Vol 23 (03) ◽  
pp. 1550020 ◽  
Author(s):  
B. G. Prashantha ◽  
M. S. Govinde Gowda ◽  
S. Seetharamu ◽  
G. S. V. L. Narasimham

This paper deals with the basic insight of thermoacoustic refrigeration concepts, and the working principle, history and the role of linear thermoacoustic theory in designing a thermoacoustic refrigerator system are discussed. Resonator design optimization procedure for a 10W cooling power thermoacoustic refrigerators is discussed. The optimized resonator designs proposed in this paper are found to be efficient compared to published resonator designs. The effects of drive ratio on the theoretical performance by varying dynamic pressure amplitude from 0.2 bar to 0.4 bar in the steps of 0.05 bar on the optimized resonator designs are discussed. Performance simulation results for the optimized resonator designs using DeltaEC software are discussed. Simulation results are in agreement with theoretical results.


2013 ◽  
Vol 21 (01) ◽  
pp. 1350001 ◽  
Author(s):  
B. G. PRASHANTHA ◽  
M. S. GOVINDE GOWDA ◽  
S. SEETHARAMU ◽  
G. S. V. L. NARASIMHAM

This paper deals with the design and analysis of a quarter-wavelength, 10 W capacity, thermoacoustic refrigerator using short stack boundary layer approximation assumptions. The effect of operating frequency on the performance of the refrigerator is studied using dimensional normalization technique. The variation of stack diameter with average gas pressure and cooling power is discussed. The resonator optimization is discussed and the calculation results show a 9% improvement in the coefficient of performance and 201% improvement in power density for the optimized quarter-wavelength resonator compared to published optimization studies. The optimized resonator design is tested with DeltaEC software and the results show better performance compared to past established resonator designs.


2020 ◽  
Vol 28 (04) ◽  
pp. 2050035
Author(s):  
Oday S. Mahmood ◽  
Abdul Mun’em A. Karim ◽  
Samir Gh. Yahya ◽  
Itimad D. J. Azzawi

Ordinary refrigeration systems such as vapor-compression refrigerators are the commonly used devices in industry, mostly for their high efficiencies. However, they make a significant contribution to the depletion of Ozone and global warming due to their operational refrigerants. Hence, thermoacoustic refrigeration can be a great alternative candidate which uses inert gases such as air, helium and nitrogen as the primary refrigerant. Thermoacoustic refrigerators convert the acoustic power (sound waves) into a thermal effect (cooling power). Thermoacoustics can be counted as a new technology that has a strong potential toward the development of the thermal applications. This study aims to design and fabricate miniaturized traveling wave thermoacoustic refrigerator which can be driven by an ordinary loudspeaker. The optimized numerical design of the refrigerator shows an overall efficiency (cooling power over input electricity) of nearly 66% at a temperature difference of 25[Formula: see text]K (between cold and ambient heat exchangers). The maximum estimated cooling power is 65[Formula: see text]W at coefficient of performance (COP) of 2.65.


Author(s):  
Gaelle Poignand ◽  
Emmanuel Jondeau ◽  
Philippe Blanc-Benon

Thermoacoustic refrigerators produce a cooling power from an acoustic energy. Over the last decades, these devices have been extensively studied since they are environment-friendly, robust and miniaturizable. Despite all these advantages, their commercialization is limited by their low efficiency. One reason for this limitation comes from the complex thermo-fluid process between the stack and the two heat exchangers which is still not sufficiently understood to allow for optimization. In particular, at high acoustic pressure level, vortex shedding can occur behind the stack as highlight by [Berson & al., Heat Mass Trans, 44, 10151023 (2008)]. The created vortex can affect heat transfer between the stack and the heat exchangers and thus, they can reduce the system performance. In this work, aerodynamic and thermal measurements are both conducted in a standing wave thermoacoustic refrigerator allowing investigation of vortex influence on the system performance. The proposed device consists on a resonator operated at frequency of 200 Hz, with hot and cold heat exchangers placed at the stack extremities. The working fluid is air at ambient temperature and atmospheric pressure. The aerodynamic field behind the stack is described using high-speed Particle Image Velocimetry. This technique allows the acoustic velocity field measurement at a frequency up to 3000 Hz. Thermal measurements consist on the acquisition of both the temperature evolution along the stack and the heat fluxes extracted at the cold heat exchanger. These measurements are performed by specific micro-sensors developed by MEMS technology. The combination of these two measurements should be helpful for the further understanding of the heat transfer between the stack and the heat exchangers.


2014 ◽  
Vol 22 (02) ◽  
pp. 1450011 ◽  
Author(s):  
NOR ATIQAH ZOLPAKAR ◽  
NORMAH MOHD-GHAZALI ◽  
ROBIAH AHMAD

Thermoacoustic refrigerators are environmentally friendly cooling systems that use no refrigerants. Optimization of the performance of any cooling system is crucial for an efficient energy management. Most of the optimization techniques in thermoacoustic systems utilized to date involved experimental and numerical parametric studies which are generally limited to the variations of the parameters to be optimized at discrete values. This study reports on the optimization of a thermoacoustic refrigerator using multi-objective genetic algorithm (MOGA). The study introduces the ability of MOGA to optimize four different variables which are length of stack, center position of stack, blockage ratio and drive ratio simultaneously. The four variables are optimized to achieve the two objectives; a maximum cooling and minimum acoustic power required at the stack and provide the optimum coefficient of performance, COP. The results show that the optimum COP = 1.35 with a cooling power of Qc = 6.57 W, acoustic power of Wn = 4.86 W and with the resonator diameter of D = 3.8 cm.


2020 ◽  
Vol 28 (02) ◽  
pp. 2050012
Author(s):  
It Sing Chan ◽  
Normah Mohd Ghazali ◽  
Nor Atiqah Zolpakar ◽  
Maziah Mohamad

The low performance of the thermoacoustic refrigerator has made it uncompetitive to currently available refrigeration systems and hence its path towards commercialization is being restricted. Recently, evolutionary algorithm such as genetic algorithm has become popular among researchers in optimizing the performance of the thermoacoustic refrigerator due to its capability to provide a solution with a global maximum or minimum through simultaneous optimization of several objectives. The purpose of this study was to maximize the performance of the thermoacoustic refrigerator using the Multi-Objective Particle Swarm Optimization (MOPSO), an evolutionary optimization tool that has not been tried in this field before. By optimizing the two conflicting objectives which are maximizing the cooling power and minimizing the acoustic power required, simultaneous optimization of inter-dependent controlling parameters has been performed for two, three and four parameters. Comparing with the results of past studies, MOPSO has improved the stack COP by 6.92% compared to the parametric optimization approach and 2.96% higher than the maximum COP achieved by multi-objective genetic algorithm (MOGA) with an optimum COP of 1.39. Also, a maximum cooling power of 10.8 W was obtained. This study has highlighted the potential of MOPSO in providing optimized conditions for conflicting objectives desired for a thermoacoustic system.


Author(s):  
Tim Ryan ◽  
Laura A. Schaefer ◽  
Jeffrey S. Vipperman

A demonstration thermoacoustic refrigerator was used to test the effectiveness of three operating frequency control schemes. The goal was to determine which control scheme would be most beneficial in terms of efficiency when a driver and resonator are mismatched as may be the case where manufacturing tolerances are involved. The first control scheme was a phase-locked loop, which is the type of control most often used in the literature; the second and third were a gradient ascent algorithm applied to root-mean-squared acoustic pressure and time-averaged acoustic power supplied to the resonator, respectively. The controllers, each operating on a different parameter associated with a strong thermoacoutic effect, were simulated using an identified model of the plant, and adjustments were made to the controller parameters. Finally, the controllers were applied to the test bed device. The performance comparison of the controllers was based on thermoacoustic efficiency, electroacoustic efficiency, and electrothermal efficiency. The phase-locked loop was found to perform better thermoacoustically, but the acoustic pressure gradient ascent control performed better in terms of electroacoustic and electrothermal performance. The acoustic power gradient ascent controller resulted in the thermoacoustic core producing the most steady-state cooling power.


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