Heat Transfer and Pressure Drop in an Artificially Roughened Tube at Various Prandtl Numbers

Author: Hastrup, Rolf Constantin

Year: 1958

Degree: Engineer's thesis

Advisor: Sabersky, Rolf H.

Committee Member: Unknown, Unknown

Option: Mechanical Engineering

DOI: 10.7907/SG10-T622

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

An experimental investigation was carried out to provide additional data for the study of heat transfer and its relation to friction in rough tubes. Tests were conducted on a tube of given roughness with the results expressed in terms of the heat transfer coefficient ([...]) and the friction coefficient ([...]). In order to demonstrate the effect of Prandtl Number ([sigma]), results were obtained over a range (6 <[sigma]< 1). This range was obtained by varying the temperature of the test fluid, distilled water, from 70-300[degrees]F in a pressurized system. The tests were carried out under forced convection using an artifically roughened, 3/8 inch diameter tube which was heated electrically by passing a high alternating current axially through its thin wall. Initial tests conducted with a smooth tube checked very well with known data and theory, with only small discrepancies at low Prandtl Number. Results for the rough tube confirm that both [...]and [...] increase with roughness. For the type roughness used, however, [...] increased only 35-50% while [...] increased 60-65% (lower percentage values appearing near [sigma] = 1) indicating that the ratio [...] decreases for increasing roughness.

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