Heat/mass transfer characteristics in two-pass smooth channels with a sharp 180-deg turn

Abstract

Heat/mass transfer characteristics for turbulent flow in rectangular cross-sectioned two-pass channels with a sharp 180-degree turn have been examined experimentally using the naphthalene sublimation method. The channel cross-section is 50×25 mm, and three turn clearances of 30, 50, and 70 mm have been tested under Reynolds numbers of (2.0–6.0)×10 4. Local mass transfer rates on all walls of the channel have been measured to clarify the three-dimensional heat and fluid flow characteristics in the channel. Detailed maps of the local Sherwood number are presented, which make clear the complex and steep changes in the local heat/mass transfer rates in and after the sharp turn section and their dependency on the turn clearance and Reynolds number.