LOCAL HEAT MASS-TRANSFER DISTRIBUTIONS AROUND SHARP 180 DEG TURNS IN 2-PASS SMOOTH AND RIB-ROUGHENED CHANNELS

The detailed heat/mass transfer distributions in and around the sharp 180 degree turn of a three-pass square channel were determined by using the naphthalene sublimation technique. The top, bottom, inner (divider) and outer walls of the test channel were naphthalene plates. For the case of rib-roughened tests, the ribs of square cross section were glued periodically in-line on the top and bottom walls of the naphthalene channel in a required distribution. The rib height-to-hydraulic diameter ratios (e/D) were 0. 063 and 0. 094, whereas the rib pitch-to-height ratios (P/e) were 10 and 20, respectively. The channel Reynolds numbers varied from 30,000 to 60,000. The results showed that, for both the smooth and the ribbed channels, the Sherwood numbers after the sharp 180 degree turn were higher than that before the sharp 180 degree turn; after the turn the Sherwood numbers of the inner wall were higher than that of the outer wall.

LOCAL HEAT MASS-TRANSFER DISTRIBUTIONS AROUND SHARP 180 DEG TURNS IN 2-PASS SMOOTH AND RIB-ROUGHENED CHANNELS Conference Paper