Heat Transfer and Pressure Drop Characteristics Induced by a Slat Blockage in a Circular Tube

[+] Author and Article Information
E. M. Sparrow, K. K. Koram, M. Charmchi

Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minn. 55455

J. Heat Transfer 102(1), 64-70 (Feb 01, 1980) (7 pages) doi:10.1115/1.3244250 History: Received January 11, 1979; Online October 20, 2009


Complementary heat transfer and fluid flow experiments were performed to determine transfer coefficients and pressure drops associated with the presence of a slat-like blockage in a tube. Water was the working fluid for the heat transfer studies (Pr = 4), while for the fluid flow experiments, which were performed under isothermal conditions, air was employed. The flow was turbulent in all cases, with the Reynolds number ranging from 10,000 to 60,000. Three blockage elements were used which respectively blocked 1/4, 1/2, and 3/4 of the tube cross-sectional area. Downstream of the blockage, heat transfer coefficients were measured around the circumference of the tube as well as along its length. The heat transfer coefficients in the region just downstream of the blockage were found to be several times as large as those for a corresponding conventional turbulent pipe flow. With increasing downstream distance, the coefficients diminish and thermal development is completed (to within five percent) at about 10, 15, and 18 diameters from the respective blockages. The blockage-induced circumferential variations of the heat transfer coefficient are dissipated by about five diameters. The pressure losses induced by the blockage are high, with values for the respective blockages that are 1.2, 5.2, and 33.2 times the velocity head in the pipe flow in which the blockage is situated. These losses are comparable to those for a gate valve.

Copyright © 1980 by ASME
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