• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.135-139
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• 2002

In this study, the experimental open-tube and close-tube thermoacoustic apparatuses were built. In order to determine the optimum length of resonant tube and the optimum length of stack, the resonant characteristics of thermoacoustic apparatuses were investigated, The length of resonant tube varies from 400mm to 850mm. The experimental frequency varies from 100Hz to 1000Hz. In case of the second and third harmonics, the maximum temperature difference of open-tube thermoacoustic apparatus is 53$^{\circ}C$ (resonator length: 400mm) and the maximum temperature difference of closed-tube thermoacoustic apparatus is 51$^{\circ}C$ (resonator length: 500mm). In the open-tube thermoacoustic apparatus, the peak efficiency point is about 2%, 55%, 69% in the resonant tube and in the closed-tube thermoacoustic apparatus, the peak efficiency point is about 2%, 41%, 50% in the resonant tube.

• Journal of electromagnetic engineering and science
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• 제16권1호
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• pp.1-6
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• 2016

Computer simulations were conducted to demonstrate the generation of microwave-induced thermoacoustic signal. The simulations began with modelling an object with a biological tissue characteristic and irradiating it with a microwave pulse. The time-varying heating function data at every particular point on the illuminated object were obtained from absorbed electric field data from the simulation result. The thermoacoustic signal received at a point transducer at a particular distance from the object was generated by applying heating function data to the thermoacoustic equation. These simulations can be used as a foundation for understanding how thermoacoustic signal is generated and can be applied as a basis for thermoacoustic imaging simulations and experiments in future research.

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.129-134
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• 2002

In this study, the experimental open-tube and close-tube thermoacoustic apparatuses were constructed. In order to determine the optimum length of resonant tube, frequency and the optimum length of stack, the resonant characteristics of thermoacoustic apparatuses were investigated, The length of resonant tube varies from 400mm to 850 mm. The experimental frequency varies from 100 Hz to 1000 Hz. In case of first harmonic, the maximum temperature difference of the open-tube thermoacoustic apparatus is 41$^{\circ}C$)resonator length: 500 mm), and the maximum temperature difference of the close-tube thermoacoustic apparatus is 42$^{\circ}C$ (resonator length : 850 mm).

• 한국초전도ㆍ저온공학회논문지
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• 제4권2호
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• pp.52-57
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• 2002

In this study, a thermoacoustic refrigerator, using a resonant standing acoustic wave. has been built. The refrigerant is helium gas. The description of thermoacoustic refrigerator was Presented. The temperature ratio (cold part temperature over hot part temperature) and the COP (Coefficient of Performance) that normalized by carnot's COP are plotted versus the thermal load applied to the cold end, for- various speaker power.

• 설비공학논문집
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• 제8권1호
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• pp.110-119
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• 1996

A numerical of thermoacoustic refrigerators has been developed. Effects of heat transfer and viscosity on pressure and velocity distributions in resonators and heat exchangers were considered. Predictions of cooling capacity and COP agreed well with previous experimental results. Effects of important design parameters, such as pressure ratio, spacing between the plates in the stack and stack length, on the performance of thermoacoustic refrigerators were shown.

• 설비공학논문집
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• 제7권2호
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• pp.329-340
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• 1995

Basic refrigeration effect and efficiency of a thermoacoustic refrigerator is studied. The refrigerator model for numerical simulation is composed of half wavelength resonator and appropriate stack of plate. Theoretical model for thermoacoustic refrigeration suggested by Swift et. al is adapted for numerical calculation. The model contains arbitrary viscosity effect of the gas filled in the resonator. The wave equation is integrated by using 4-th order Runge-Kutta algorithm to give pressure distribution along the stack of plate. Heat flux and COP are also calculated based on the energy flux equation. By analyzing the numerical simulation results, optimum values of design parameters for thermoacoustic refrigerator are obtained.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.229-234
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• 2001

The thermoacoustic refrigerator bas not only considerable possibility but also commercial usability, because it bas high reliability, lower vibration, no moving part, and can easily be constructed. In this study, the resonance characteristics of the thermoacoustic refrigerator were investigated for better performance, varying length of the resonance tube to 400mm, 500mm, 600mm, 700mm. In order to determine the optimum resonance tube length and the frequency, the $\lambda/4$ thermoacoustic engine and the similar apparatus of Wheatly type refrigerator were constructed. It was used air as a coolant. in the fifth harmonic, it was taken the highest ${\Delta}t$ that was $56.3^{\circ}C$ at 626Hz in 400mm tube with 40mm stack.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.217-222
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• 2001

The thermoacoustic refrigerator has not only considerable possibility but also commercial usability, because it has high reliability, lower vibration, no moving part, and can easily be constructed. In this study, the resonance characteristics of the thermoacoustic refrigerator were investigated for better performance, varying the length of Resonant Tube to 400mm $\sim850mm$. In order to determine the optimum position of stack in the resonance tube and the frequency, the simple $\lambda/2$ thermoacoustic refrigerator was constructed. It was used air as a coolant. in the fifth harmonic, it was taken the highest ${\Delta}t$ that was $52.6^{\circ}C$ at 827Hz in 400mm tube with 40mm stack.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.223-228
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• 2001

The thermoacoustic refrigerator has not only considerable possibility but also commercial usability, because it has high reliability, lower vibration, no moving part, and can easily be constructed. In this study, The thermoacoustic refrigerator were constructed. The apparatus is capable of driving closed systems containing He or air at mean pressures ranging from 1-9.3 bar, at frequencies ranging from 100-1000Hz. The resonance characteristics of the thermoacoustic refrigerator were investigated for better performance, The resonance tube is 340.5mm in length. In case of using air as a coolant. Freezing frequency is 174Hz, In case of using He as a coolant Freezing frequency is 625Hz. Using He, The cold-part temperature of the heat exchanger fell to $-23.7^{\circ}C$ after 120 minutes in 70W.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.730-733
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• 2017

액체 로켓 엔진을 작동하기 위해서는 추진제 점화를 위한 점화기가 필수적이다. 이 점화기의 중요한 현상은 열 음향 공진이다. 본 논문에서는 주로 열 음향 공진 현상에 대한 노즐과 공진관 사이의 거리에 따른 실험 결과를 다루었다. 이 연구의 최종적인 목적은 이 현상을 이용하여 다중 점화가 가능한 점화기 개발에 있다.