The Effect of Diameter on Natural Convection Heat Transfer from Horizontal Cylinders ... PDF Download

Author: Stanley W. Ehrlich
Publisher:
ISBN:
Category :
Languages : en
Pages : 77

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Author: Sandra K. S. Boetcher
Publisher: Springer
ISBN: 3319081322
Category : Science
Languages : en
Pages : 57

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Book Description
This book presents a concise, yet thorough, reference for all heat transfer coefficient correlations and data for all types of cylinders: vertical, horizontal, and inclined. This book covers all natural convection heat transfer laws for vertical and inclined cylinders and is an excellent resource for engineers working in the area of heat transfer engineering.

Author: Howard G. Maahs
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 532

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Author: Timothy William Martin
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 118

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Book Description
An experimental study has been made of the local natural convective heat transfer coefficient around the circumference of a heated horizontal cylinder oscillating vertically in water. The heat transfer surface consisted of a 1 3/8-inch diameter cylinder with a small test section imbedded in its surface. This enabled data to be taken so that the local and overall values of the heat; transfer coefficient could be determined. The cylinder was oscillated sinusoidally in a tank of distilled water at a frequency of 0 to 25-cps with an amplitude of 0 to 0.100-inch. The temperature difference between the water bath and the test cylinder was held at approximately twenty degrees. Observations of the flow patterns around the cylinder were made using a shadowgraph technique and a dye stream visualization, The local heat transfer coefficient versus position data were taken at six different conditions of frequency and amplitude. These conditions were: (1) stationary, (2) n = 500 rpm, a = 0.100-inch, (3) n = 750 rpm, a = 0.0667-inch, (4) n = 1000 rpm, a = 0.100-inch, (5) n = 1500 rpm, a = 0.0667-inch, and (6) n = 1500 rpm, a = 0.100-inch. The overall cylinder results were similar to the results found by V.H. Swanson and by Martinelli and Boelter in similar work. The maximum increase in the overall cylinder heat transfer rate was of the order of 200 percent. The data for the local heat transfer coefficient showed that the maximum increase in the heat transfer coefficient occurred at the top of the cylinder and was on the order of 290 percent. At the same condition of oscillation the coefficient at the side increased 230 percent while the coefficient at the bottom increased 72 percent. In comparing the shapes of the distributions of local Nusselts number with the shapes Fand, Roos, Cheng, and Kaye found by imposing a sound field on a air-cylinder system, a difference was noted which can be attributed to the difference in the direction of oscillation between the two investigations. In the present investigation the cylinder was oscillated vertically while Fand, Roos, Cheng, and Kaye used a horizontal oscillation of the fluid particles. The resulting differences in the acoustic streaming pattern account for the differences noted in the shapes of the local heat transfer coefficient versus position curves. The shapes did show that the effect of mechanical oscillation and the effect of a sound field on the convective heat transfer rate were similar. A dye stream visualization of the flow pattern indicated Fand, Roos, Cheng, and Kaye were correct when they concluded that the shape of the distribution of Nusselt number was caused by the interaction of a natural convection flow pattern and acoustic streaming. This study sheds some light on the mechanism causing the increase in the natural convection heat transfer coefficient when oscillation is introduced, and it shows the need for more experimental investigation into the distribution of the local heat transfer coefficient around cylinders.

Author: Seymour C. Hyman
Publisher:
ISBN:
Category : Liquid metals
Languages : en
Pages : 20

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Author: WILLIAM R. MARTINI
Publisher:
ISBN:
Category :
Languages : en
Pages : 200

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Author: Oleg G. Martynenko
Publisher: Springer Science & Business Media
ISBN: 3540284982
Category : Science
Languages : en
Pages : 520

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Book Description
Free Convective Heat Transfer is a thorough survey of various kinds of free-convective flows and heat transfer. Reference data are accompanied by a large number of photographs originating from different optical visualization methods illustrating the different types of flow. The formulas derived from numerical and analytical investigations are valuable tools for engineering calculations. They are written in their most compact and general form in order to allow for an extensive range of different variants of boundary and initial conditions, which, in turn, leads to a wide applicability to different flow types. Some specific engineering problems are solved in the book as exemplary applications of these formulas.

Author: Thomas Howard Kuehn
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 602

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 18

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Book Description
Natural convection heat transfer on two horizontal 7.6 mm diameter test cylinders assembled with the ratio of the distance between each cylinder axis to the cylinder diameter, S/D, of 2 in liquid sodium was studied experimentally and theoretically. The heat transfer coefficients on the cylinder surface due to the same heat inputs ranging from 1.0 X 107 to 1.0 x 109 W/m3 were obtained experimentally for various setting angeles, [gamma], between vertical direction and the plane including both of these cylinder axis over the range of zero to 90°. Theoretical equations for laminar natural convection heat transfer from the two horizontal cylinders were numerically solved for the same conditions as the experimental ones considering the temperature dependence of thermophysical properties concerned. The average Nusselt numbers, Nu, values on the Nu versus modified Rayleigh number, R{sub f}, graph. The experimental values of Nu for the upper cylinder are about 20% lower than those for the lower cylinder at [gamma] = 0° for the range of R{sub f} tested here. The value of Nu for the upper cylinder becomes higher and approaches that for the lower cylinder with the increase in [gamma] over range of 0 to 90°. The values of Nu for the lower cylinder at each [gamma] are almost in agreement with those for a single cylinder. The theoretical values of Nu on two cylinders except those for R{sub f}

Author: L. Kirkup
Publisher: Cambridge University Press
ISBN: 1139454900
Category : Science
Languages : en
Pages : 196

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Book Description
Measurement shapes scientific theories, characterises improvements in manufacturing processes and promotes efficient commerce. In concert with measurement is uncertainty, and students in science and engineering need to identify and quantify uncertainties in the measurements they make. This book introduces measurement and uncertainty to second and third year students of science and engineering. Its approach relies on the internationally recognised and recommended guidelines for calculating and expressing uncertainty (known by the acronym GUM). The statistics underpinning the methods are considered and worked examples and exercises are spread throughout the text. Detailed case studies based on typical undergraduate experiments are included to reinforce the principles described in the book. This guide is also useful to professionals in industry who are expected to know the contemporary methods in this increasingly important area. Additional online resources are available to support the book at www.cambridge.org/9780521605793.