• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2482-2487
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• 2007

Numerical simulations are conducted for the analysis of a thermal mass air flow sensor with periodic heating pulses on silicon-nitride ($Si_3N_4$) thin membrane structure. This study aims to find the locations of temperature sensors on the thin membrane and the heating pulse conditions, that the higher sensitivity can be achieved, for the development of a MEMS fabricated mass air flow sensor which is driven in periodic heating pulse. The simulations, thus, focus on the membrane temperature profile according to variation of the flow velocity, heating duration time and imposed power. The flow velocity of the simulations is ranging from 3 m/s to 35 m/s, heating duration time from 1 ms to 3 ms and imposed power from 50 mW to 90 mW. The corresponding Reynolds numbers vary from 1000 to 10000.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.154-161
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• 2000

As a mass flow controller is widely used in many manufacturing processes for controlling a mass flow rate of gas with accuracy of 1%, several investigators have tried to describe the heat transfer phenomena in a sensor tube of an MFC. They suggested a few analytic solutions and numerical models based on simple assumptions, which are physically unrealistic. In the present work, the heat transfer phenomena in the sensor tube of the MFC are studied by using both experimental and numerical methods. The numerical model is introduced to estimate the temperature profile in the sensor tube as well as in the gas stream. In the numerical model, the conjugate heat transfer problem comprising the tube wall and the gas stream is analyzed to fully understand the heat transfer interaction between the sensor tube and the fluid stream using a single domain approach. This numerical model is further verified by experimental investigation. In order to describe the transport of heat energy in both the flow region and the sensor tube, the Nusselt number at the interface between the tube wall and the gas stream as well as heatlines is presented from the numerical solution.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.308-313
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• 2003

Thermal mass flow meters (TMFMs) are most widely used for measuring mass flow rates in the semiconductor industry. A TMFM should have a short response time in order to measure the time-varying flow rate rapidly and accurately. Therefore it is important to study transient heat transfer phenomena in the sensor tube of a TMFM that is the most critical part in the TMFM. In the present work, a simple numerical model for transient heat transfer phenomena of the sensor tube of a TMFM is presented. Numerical solutions for the tube and fluid temperatures in a transient state are obtained using the proposed model and compared with experimental results to validate the proposed model. Based on numerical solutions, heat transfer mechanism in a transient state in the sensor tube is explained. Finally, a correlation for predicting the response time of a sensor tube is presented. The correlation is verified by experimental results.

• 대한기계학회논문집B
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• 제34권2호
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• pp.179-184
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• 2010

스트레이트 휜 히트 싱크가 장착된 공간에 팁 클리어런스(tip clearance)와 바이패스 유동이 열성능에 미치는 영향을 실험적으로 규명하고자 한다. 수평 및 수직 방향으로의 바이패스 유동에 의한 열성능 평가는 열식 질량 유량계(MFC)와 소형 풍동으로 이루어진다. 팁 클리어런스와 바이패스 유동에 의한 히트 싱크의 열성능은 열저항을 통하여 평가한다. 실험 결과, 스트레이트 휜 히트 싱크의 열저항은 팁 클리어런스가 증가함에 따라 점진적으로 증가하며, 유동 가이드 장치는 바이패스 유동을 감소하는 역할을 한다. 본 연구에서는 동일 유량 조건에서 히트 싱크의 입구에서 유동 가이드 장치까지의 거리에 따라 스트레이트 휜 히트 싱크의 최적값이 존재함을 확인하였다. 히트 싱크로 유입되는 유량이 증가함에 따라 유동 가이드 장치에 의한 열성능 개선 정도는 증가한다.