Heat Transfer to Water in Downward Flow in a Uniform Wall Temperature Vertical Tube at Low Graetz Numbers

1977 ◽  
Vol 99 (4) ◽  
pp. 586-589 ◽  
Author(s):  
T. E. Mullin ◽  
E. R. Gerhard
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Experimental Error ◽  
Vertical Tube ◽  
Tube Flow ◽  
Uniform Wall Temperature ◽  
Nusselt Numbers ◽  
A Value ◽  
Uniform Wall ◽  
Convection Parameter

This paper presents an experimental investigation of heat transfer to water in vertical tube flow. Results from both Heating in Upflow and Heating in Downflow with the Natural Convection Parameter (Gr Pr D/L)w held constant at a value of 5.5 × 105 are compared with the expression developed by Martinelli and Boelter. The Nusselt numbers for Heating in Downflow were slightly higher but, within experimental error, equivalent to those values obtained for Heating in Upflow. A description of the flowfield is presented for one set of conditions for Heating in Downflow.

Laminar Heat Transfer in Tubes Under Slip-Flow Conditions

1962 ◽  
Vol 84 (4) ◽  
pp. 363-369 ◽  
Author(s):  
E. M. Sparrow ◽  
S. H. Lin
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Slip Flow ◽  
Mean Free Path ◽  
Uniform Wall Temperature ◽  
Nusselt Numbers ◽  
Temperature Jumps ◽  
Uniform Wall ◽  
Moving Fluid ◽  
Uniform Wall Heat Flux

The effects of low-density phenomena on the fully developed heat-transfer characteristics for laminar flow in tubes has been studied analytically. Consideration is given to the slip-flow regime wherein the major rarefaction effects are manifested as velocity and temperature jumps at the tube wall. The analysis is carried out for both uniform wall temperature and uniform wall heat flux. In both cases, the slip-flow Nusselt numbers are lower than those for continuum flow and decrease with increasing mean free path. Extension of the results is made to include the effects of shear work at the wall, temperature jump modifications for a moving fluid, and thermal creep.

Experimental Study of Laminar Heat Transfer to In-Tube Flow of Non-Newtonian Fluids

1980 ◽  
Vol 102 (3) ◽  
pp. 397-401 ◽  
Author(s):  
S. D. Joshi ◽  
A. E. Bergles
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Circular Tube ◽  
Tube Flow ◽  
Temperature Dependent ◽  
Nusselt Numbers ◽  
Numerical Predictions ◽  
Uniform Wall ◽  
Uniform Wall Heat Flux ◽  
Newtonian Behavior

An experimental study is reported of heat transfer to laminar flow of two water-methocel pseudoplastic (power law) solutions in a circular tube subjected to a uniform wall heat flux. The object of this study was to evaluate the effects of non-Newtonian behavior and temperature-dependent consistency on heat transfer. The experimental Nusselt numbers are compared with numerical predictions and experimental data. Two correlations are recommended according to the temperature-dependence of the rheological characteristics.

Laminar Flow Heat Transfer and Pressure Drop Characteristics of Power-Law Fluids Inside Tubes With Varying Width Twisted Tape Inserts

1999 ◽  
Vol 122 (1) ◽  
pp. 143-149 ◽  
Author(s):  
A. G. Patil
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Swirl Flow ◽  
Twisted Tape ◽  
Full Width ◽  
Uniform Wall Temperature ◽  
Nusselt Numbers ◽  
Twisted Tapes ◽  
Friction Factors ◽  
Uniform Wall

Results of an experimental investigation of heat transfer and flow friction of a generalized power-law fluid in tape generated swirl flow inside a 25.0 mm i.d. circular tube, are presented. In order to reduce excessive pressure drops associated with full width twisted tapes, with less corresponding reduction in heat transfer coefficients, reduced width twisted tapes of widths ranging from 11.0 to 23.8 mm, which are lower than the tube inside diameter are used. Reduced width twisted tape inserts give 18 percent–56 percent lower isothermal friction factors than the full width tapes. Uniform wall temperature Nusselt numbers decrease only slightly by 5 percent–25 percent, for tape widths of 19.7 and 11.0 mm, respectively. Based on the constant pumping power criterion, the tapes of width 19.7 mm perform more or less like full width tapes. Correlations are presented for isothermal and heating friction factors and Nusselt numbers (under uniform wall temperature condition) for a fully developed laminar swirl flow, which are applicable to full width as well as reduced width twisted tapes, using a modified twist ratio as pitch to width ratio of the tape. The reduced width tapes offer 20 percent–50 percent savings in the tape material as compared to the full width tapes. [S0022-1481(00)01401-8]

Second Order Slip Flow Effects on Heat Transfer Performance of Microchannels

2009 ◽  
Author(s):  
Cem Dolu ◽  
Lu¨tfullah Kuddusi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Flow Model ◽  
Slip Flow ◽  
Second Order ◽  
Flow Models ◽  
Uniform Wall Temperature ◽  
Uniform Wall ◽  
Slip Flow Regime ◽  
Flow Effects

First and second order slip flow models in rectangular microchannels heated at constant and uniform wall temperature are studied. The velocity and temperature profiles for hydrodynamically and thermally developed incompressible slip flow regime available in literature are used. The average nondimensional slip velocity and temperature jump are found by using first and second order slip flow models. The average Nusselt number is also derived by using both first and second order slip flow models. The effects of Knudsen number, aspect ratio and second order slip flow model on the heat transfer characteristics of microchannel are explored.

Sign in / Sign up

Export Citation Format

Share Document