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이상재(S.J.Lee),김대훈(D.H.Kim),이민규(M.K.Lee),권영철(Y.C.Kweon),장근선(K.S.Chang),윤준원(J.W.Yun),정지환(J.H.Jeong) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The purpose of this study is to investigate me characteristics of the air-side heat transfer and pressure drop on the fin pattern of six types of φ 9.52 nun finned-tube heat exchangers. An air-enthalpy Calorimeter is used in this experiment. Experiments are carried out by changing velocity (from 0.7 m/s to 1.5 m/s). From results, we can see that the air-side heat transfer coefficients and the pressure drop depend upon the geometry of the heat exchanger. With increasing the inlet air velocity, the heat transfer and the pressure drop increase linearly and exponentially, respectively. At the same heat transfer area, the heat transfers in the low velocities are nearly the same and those in 1.5 m/s have the maximum 3% difference. The pressure drops have the different trend for the fin patterns.
[論文] 온도보상을 고려한 열선형 공기유량 측정시스템에 관한 실험적 연구
이민형(M.H.Lee),유정열(J.Y.Yoo),고상근(S.K.Kauh),윤준원(J.W.Yun),김사량(S.R.Kim),김동성(D.S.Kim) 한국자동차공학회 1991 오토저널 Vol.13 No.4
The purpose of this study is to perform modelings and experiments to measure air flow rate using hot-wires and a CTA(Constant Temperature Anemometer). The flow rate can be obtained by measuring the heat loss of the hot-wire due to the variations of flow velocity when the hot-wire is maintained at uniform temperature. But the defect of this method is that the output signal changes not only by the flow rate but also by the ambient temperature. Thus, in the present study, a method which compensates the variations of the ambient temperature has been introduced to measure exact flow rate. To be more specific, the bridge circuit of the usual hot-wire anemometer system has been modified in such a way that a temperature resistance sensor and a variable resistance are placed in one of the legs to compensate the different temperature coefficients of both the hot-wire and the temperature compensating resistance for flow velocity or for flow mass up to the flow temperature of 50℃. Comparing the modeling and experimental results, it has been shown that the compensating point differs as the flow rate varies. Therefore, optimum compensation points are sought to construct the circuit. The present modeling and experimental results may be applied to the design of actual air flow meters for automobiles.