scholarly journals Closure to “Discussion of ‘Application of a Simplified Velocity Profile to the Prediction of Pipe-Flow Heat Transfer’” (1968, ASME J. Heat Transfer, 90, p. 199)

1968 ◽  
Vol 90 (2) ◽  
pp. 199-200
Author(s):  
R. D. Haberstroh ◽  
L. V. Baldwin
Keyword(s):  
Heat Transfer ◽  
Velocity Profile ◽  
Pipe Flow ◽  
Flow Heat

Simultaneous Wall and Fluid Axial Conduction in Laminar Pipe-Flow Heat Transfer

1980 ◽  
Vol 102 (1) ◽  
pp. 58-63 ◽  
Author(s):  
M. Faghri ◽  
E. M. Sparrow
Keyword(s):  
Heat Transfer ◽  
Pipe Flow ◽  
Numerical Solutions ◽  
Transfer Problem ◽  
Upstream Region ◽  
Heated Region ◽  
Axial Conduction ◽  
Conductance Parameter ◽  
Flow Heat ◽  
Laminar Pipe Flow

Consideration is given to a laminar pipe flow in which the upstream portion of the wall is externally insulated while the downstream portion of the wall is uniformly heated. An analysis of the problem is performed whose special feature is the accounting of axial conduction in both the tube wall and in the fluid. This conjugate heat transfer problem is governed by two dimensionless groups—a wall conductance parameter and the Peclet number, the latter being assigned values from 5 to 50. From numerical solutions, it was found that axial conduction in the wall can carry substantial amounts of heat upstream into the non directly heated portion of the tube. This results in a preheating of both the wall and the fluid in the upstream region, with the zone of preheating extending back as far as twenty radii. The preheating effect is carried downstream with the fluid, raising temperatures all along the tube. The local Nusselt number exhibits fully developed values in the upstream (non directly heated) region as well as in the downstream (directly heated) region. Of the two effects, wall axial conduction can readily overwhelm fluid axial conduction.

Application of a Simplified Velocity Profile to the Prediction of Pipe-Flow Heat Transfer

1968 ◽  
Vol 90 (2) ◽  
pp. 191-198 ◽  
Author(s):  
R. D. Haberstroh ◽  
L. V. Baldwin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Velocity Profile ◽  
Pipe Flow ◽  
Energy Equation ◽  
Momentum Equation ◽  
Turbulent Pipe Flow ◽  
Transfer Coefficients ◽  
Constant Property ◽  
Wide Range

The temperature profiles and heat-transfer coefficients are predicted for fully developed turbulent pipe flow with constant wall heat flux for a wide range of Prandtl and Reynolds numbers. The basis for integrating the energy equation comes from a continuously differentiable velocity profile which fits the physical boundary conditions and is a rigorous (though not necessarily unique) solution of the Reynolds equations. This velocity profile is the semiempirical relation proposed by S. I. Pai, reference [12]. The assumptions are those of steady, incompressible, constant-property, fully developed, turbulent flow of Newtonian fluids in smooth, circular pipes with constant heat flux at the wall. The ratio of the turbulent thermal diffusivity to the turbulent momentum diffusivity is taken to be unity. The thermal quantities are obtained by numerical integration of the energy equation, and they are presented as curves and tables. A compact formula for the Nusselt number is given for a wide range of Reynolds and Prandtl numbers. The results degenerate identically to the case of laminar flow. The heat-transfer calculation requires neither adjustable factors nor data-fitting beyond the empirical constants in the momentum equation; thus this analysis constitutes a heat-transfer prediction to be tested against heat-transfer data.

scholarly journals Development of Pulsating Twin Jets Mechanism for Mixing Flow Heat Transfer Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Ali Ahmed Gitan ◽  
Rozli Zulkifli ◽  
Shahrir Abdullah ◽  
Kamaruzzaman Sopian
Keyword(s):  
Heat Transfer ◽  
Velocity Profile ◽  
Heat Transfer Analysis ◽  
Pulsation Frequency ◽  
Pulse Profile ◽  
Pulsed Jet ◽  
Impingement Heat Transfer ◽  
Twin Jets ◽  
Flow Heat ◽  
Transfer Problems

Pulsating twin jets mechanism (PTJM) was developed in the present work to study the effect of pulsating twin jets mixing region on the enhancement of heat transfer. Controllable characteristics twin pulsed jets were the main objective of our design. The variable nozzle-nozzle distance was considered to study the effect of two jets interaction at the mixing region. Also, the phase change between the frequencies of twin jets was taken into account to develop PTJM. All of these factors in addition to the ability of producing high velocity pulsed jet led to more appropriate design for a comprehensive study of multijet impingement heat transfer problems. The performance of PTJM was verified by measuring the pulse profile at frequency of 20 Hz, where equal velocity peak of around 64 m/s for both jets was obtained. Moreover, the jet velocity profile at different pulsation frequencies was tested to verify system performance, so the results revealed reasonable velocity profile configuration. Furthermore, the effect of pulsation frequency on surface temperature of flat hot plate in the midpoint between twin jets was studied experimentally. Noticeable enhancement in heat transfer was obtained with the increasing of pulsation frequency.

Theoretical non-Newtonian pipe-flow heat transfer

AIChE Journal ◽  
1973 ◽  
Vol 19 (1) ◽  
pp. 197-199 ◽  
Author(s):  
Arthur M. Hecht
Keyword(s):  
Heat Transfer ◽  
Pipe Flow ◽  
Flow Heat
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