کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
670162 | 1458779 | 2011 | 13 صفحه PDF | دانلود رایگان |

Flow pattern in the tubes of an innovative scraped surface heat exchanger with reciprocating scrapers has been experimentally investigated. The scraper consists of a concentric rod inserted in each tube of the heat exchanger, mounting an array of semicircular plugs that fit the inner tube wall. A hydraulic piston provides the scraper with constant-velocity reciprocating motion. Phase-averaged velocity fields have been obtained with PIV technique for both scraping semi-cycles, with special emphasis on the effect of the scraping velocity (velocity ratio) and Reynolds number. Visualization results have been contrasted with experimental data on Fanning friction factor, obtaining a clear relation between flow patterns, pressure drop augmentation and turbulence promotion. CFD simulations for quasi-steady laminar flow provide a further insight into the relation of the flow structures with wall shear stress, and the contribution of pressure forces to global head losses, for each scraping semi-cycle.
Journal: International Journal of Thermal Sciences - Volume 50, Issue 5, May 2011, Pages 803–815