ARTICLE:

• LOCAL HEAT/MASS TRANSFER CHARACTERISTICS IN THE BOUNDARY LAYER OF A WAVY SURFACE  download article

S.-Y. Yoo
Chungnam National University, Daejeon, Korea

J.-H. Park
Korea Atomic Energy Research Institute, Daejeon, Korea

H.-K. Kwon
Graduate School, Chungnam National University, Daejeon, Korea

ABSTRACT

Flat surfaces are often replaced by wavy surfaces in the compact heat exchangers to enhance heat and/or mass transfer. In the present study, local mass transfer coefficients on the flat and wavy surfaces are measured using a naphthalene sublimation technique for two flow conditions; plate in parallel flow with and without un-sublimated(unheated) boundary layer. And the effect of wave on heat/mass transfer enhancement is investigated by comparing the local and average mass transfer coefficients obtained from the flat and wavy surfaces. The local Sherwood number along the distance from the leading edge increases rapidly at the front of wavy hills, and decreases steeply at the rear of them. And wavy surface has much higher mass transfer coefficient values than flat surface except at the low velocities. Colburn j-factor for the developing flow decreases gradually without remarkable change of slope with increasing Reynolds number, whereas the result of the developed flow shows the noticeable change at the transition region. Both results of two flow conditions are very much alike at high Reynolds number.

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