Agung Bambang Setio Utomo

Design, construction and evaluation of a standing wave thermoacoustic prime mover

A standing wave thermoacoustic prime mover (TAPM) has been succesfully designed, constructed, and evaluated. It consists of a resonator with length of 128 cm, a stainless-steel wire-mesh stack with 14 mesh number, two heat exchangers, and air at atmospheric pressure as the working gas inside the resonator. The stack is placed inside the resonator near one of its closed-ends and has 4 cm length. The hot and ambient heat-exchangers are attached at each end of the stack to provide a large temperature gradient along the stack which is required for generating acoustic energy. An electric heater with maximum power of 400 W is used to supply thermal energy to the TAPM. The temperatures and dynamic pressures are measured by using type-K thermocouples and pressure transducers, respectively. We evaluated the prime mover by experimentally investigating the influence of heat input power on the onset temperature difference, time to reach the onset condition, sound frequency, and sound pressure amplitude. It was found ...

Experimental Demonstration of the Dependence of Temperature Decrease on the Hydraulic Radius of Regenerator in a Traveling-Wave Thermoacoustic Refrigerator

Thermoacoustic refrigerators are cooling devices that employ sound wave in heat removal process. They mostly use air or other inert gas as working fluid and hence they are environmentally benign. The cooling process takes place in a porous medium (regenerator or stack). This paper presents an experiment on a loudspeaker-driven traveling-wave thermoacoustic refrigerator to demonstrate the dependence of temperature decrease on the hydraulic radius (rh ) of regenerator. The refrigerator has a looped tube and a resonator tube, with the length of 260 cm and 150 cm, respectively. Six different regenerators are used, each of which is made of a tight stack of stainless-steel wire-mesh screens with different mesh sizes, providing rh from 0.07 mm until 0.28 mm. The regenerator length is 60 mm. Atmospheric air is used as the working gas, driven at operating frequency of 30 Hz, giving thermal penetration depth (δκ ) of 0.49 mm. The experimental results show that there is an optimum rh which gives the largest temperature decrease at the cooling point. It is found, in this case, that the optimum rh is 0.10 mm (that is, rh /δκ = 0.20) and the corresponding temperature decrease is 18.7°C (i.e. from 28.0 °C down to 9.3 °C).

The effect of organic stack and heat exchanger on the temperature change of the thermoacoustics cooling system

The influence of organic stack and heat exchanger on the temperature changes of a standing wave thermoacoustic cooling system has been observed. This study used an organic material stack, which has a non-parallel pore (random), namely a dry sponge gourd (luffa acutangula). In this research, the resonator tube is made of a PVC pipe with the length of 83 cm and the diameter of 5.25 cm. As a result, the decreasing temperature on both hot and cold reservoirs has been developed. Using the 15 watt of loudspeaker power, the temperature decrease is at 5.3 °C and with increasing loudspeaker power, the decrease in temperature changes accordingly at 6.1 °C for 60 watt of loudspeaker power.

Influence of parameter on the performance of a standing-wave thermoacoustic prime mover

The standing-wave thermoacoustic prime mover is a device to convert heat into work in the form of sound. It is one of the most potential applications for a thermoacoustic prime mover to utilize low-grade heat source to drive a refrigerator or electrodynamic linear alternator. Low efficiency of the device becomes interesting to be studied; it is because of no optimum heat exchange between the channel wall and the working gas that occur in the stack. The stack is the main part of the thermoacoustic prime mover in where the thermoacoustic energy conversion process takes place. The ωτ parameter is regarded as a nondimensional parameter determining the efficiency of the heat exchange in the stack and it depends on the hydraulic radius of the stack. This experiment was carried out by changing the hydraulic radius of the stack to control the value of ωτ. The stack was made of a pile stainless steel wire mesh because it is easier to vary the hydraulic radius than another kind of stack. The length of the resonator...

Influence of resonator length on the performance of standing wave thermoacoustic prime mover

A research on the influence of resonator length on the performance of a standing wave thermoacoustic prime mover has been conducted. The thermoacoustic prime mover consists of an electric heater, a resonator tube filled with atmospheric air, and a stack. The stack was made of stainless steel wire mesh screens with mesh number of #14. The stack had a length of 5 cm and placed 13 cm from resonator hot-end. The resonator tube was made of stainless steel pipe with 6.8 cm inner diameter. The electric heater which has a maximum power capability of 299 W was attached to the hot side of the stack. We varied the resonator length from 105 cm until 205 cm. It was found that the thermoacoustic prime mover with a resonator length of 155 cm generated the sound with the smallest onset temperature difference and shortest time to reach the onset condition, those are 252 °C and 401 s, respectively. Also, the prime mover with a resonator length of 105 cm produced the highest frequency that is 174 Hz. On the other hand, by using resonator length of 180 cm, the prime mover generated the highest pressure amplitude of 0.0041 MPa, and the thermoacoustic device delivered the highest acoustic power of 2.8 W and efficiency of 0.9%.