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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.
삽입물에 의한 관내 층류열전달 증진에 관한 실험적 연구
권영철,장근선,정지환 대한설비공학회 2000 설비공학 논문집 Vol.12 No.7
In order to understand the laminar flow heat transfer enhancement by the swirl flow, the effects of heat transfer in a circular pipe with a twisted tape insert were investigated experimentally. In the present study, the uniform heat flux condition was considered. The laminar heat transfer correlations were developed using the least-square-fit from the surface temperature distribution of an electrically-heated pipe and flow property data. Average Nusselt number correlations with the twisted tape insert were expressed as a function of swirl parameter, Reynolds number and Prandtl number. In the case of the twisted ratio y = 6.05, the mean Nusselt number increased approximately 500% and the friction factor increased approximately 300%, compared to the case of the empty pipe, respectively.