The solar energy collection used to power a thermoacoustic prime mover has been calculated. The solar energy is concentrated by a Fresnel lens into a water-filled thermal storage container to produce pressurized hot steam which is then supplied to sealed-off hot exchangers of a thermoacoustic prime mover. We consider collecting the solar energy in Yogyakarta, Indonesia in where the average energy of solar global radiation of 4.8. kWh/m^2/day (17.3 MJ/m^2/day) is available around the year. The calculations include the amount of the remaining heat stored, steam pressure, and water/steam temperature, and were done for various lens area and water volume as a function of time for several days. We found that appropriate combinations of lens area and water volume enable us to operate the prime mover continuously all day and night.

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In this research, our interests focused on the thermoacoustic prime mover to recover the waste heat and to utilize it effectively. The advantages of this prime mover are the flexibility for various heat sources such as external engine and a possibility as the cost effective system due to simple structure. For the practical application, various efforts have been made experimentally to grasp the optimization of stack structure which plays an importante role to energy conversion. In this paper, we install the linear alternator into the thermoacoustic engine as an energy conversion device from acoustic to electric energy.

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The thermoacoustic effect is energy conversion between heat and sound. When thermal energy is converted to the oscillation of sound, the heat pump cycle is driven by using that oscillation. In this work, the heat exchanger for a prime mover of loop type thermoacoustic refrigerator was designed with the concept of Stirling engine. It was found that the efficiency of the heat exchanger depends on the surface area. To analyze the efficiency of the thermoacoustic refrigerator, the energy flow was calculated by measuring temperature distribution and energy flow. About 75% of the input heat was transferred by the sound flow and radiation. When the orifice was inserted in the tube to reduce the heat transfer by sound, the efficiency was improved.

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In order to build a thermo acoustic engine of high efficiency, the structure of the device needs to be decided so that it enables efficient energy exchange, by accurate calculation of the distribution of acoustic impedance, while the engine is in an excited state, and by feeding back the information. In this report we aim to derive critical point and distibution of acoustic impedance theoretically by applying thermo acoustic theory, and we also aim to achieve the realization of low-temperature excite by controlling distribution of acoustic impedance using a expended pipe. The theoretically calculated result shows approximately consistency with the actual experimental result, therefore confirming the validity of our method. Also, it is learned that exciting temperature can be largely reduced by installing the expended pipe right before the stack.

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Numerical simulation of heat and fluid flow has been performed to estimate the value of heat transfer coefficient between the working gas and the wall in oscillatory flows. Transient two-dimensional equations of continuity, momentum and energy were solved utilizing a TVD scheme. A physical model of a simple circular tube in which the wall temperature is constant was used for the numerical simulation. In this study, the value of local heat transfer coefficient in oscillatory flows was clarified by analyzing the numerical result of the two dimensional simulation and the heat exchanged between the working gas and the wall were analyzed.

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Tow types of thermoacoustic sound-wave generator are employed. One is a conventional thermoacoustic sound-wave generator, 32 mm in inner diameter and 860 mm long, including high- and low- temperature exchangers inside the resonance tube. The other is a simplified thermoacoustic sound-wave generator, 72 mm in inner diameter and 860 mm long, and has no heat exchangers inside the resonance tube. The calculation software, Mathematica, was employed for simulating the oscillatory flow and the fluid work both in the resonance tube and in the stack. Maximum energy conversion efficiency of 6.5% from heat to fluid work inside the resonance tube is performed at medium position of the resonance tube, on condition that the oscillatory frequency f is 100Hz, and thermal input Q is 400W. In addition, optimum shape and size of stack are discussed with hydraulic diameter.

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