Heat transfer during the flow of an incompressible fluid in a circular tube, allowing for axial heat flow, with boundary conditions of the first and second kind at the tube surface

1966 ◽  
Vol 11 (3) ◽  
pp. 153-155 ◽  
Author(s):  
V. V. Shapovalov
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Boundary Conditions ◽  
Incompressible Fluid ◽  
Circular Tube ◽  
Tube Surface ◽  
Axial Heat

scholarly journals Numerical Investigations on Heat Flow of Nanofluids in Ribs Tube Configurations

2017 ◽  
Vol 13 (3) ◽  
pp. 10-17 ◽  
Author(s):  
Sami D. Salman ◽  
Ramzi Ata Abd Alsaheb
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Flow ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Circular Tube ◽  
Tube Surface ◽  
Numerical Investigations ◽  
Heat Transfer Augmentation ◽  
Two Samples

Abstract In this paper presents two dimensional turbulent flow of different nanofluids and ribs configuration in a circular tube have been numerically investigation using FLUENT 6.3.26. Two samples of CuO and, ZnO nanoparticles with 2% v/v concentration and 40 nm as nanoparticle diameter combined with trapezoidalribs with aspect ratio of p/d=5.72 in a constant tube surface heat flux were conducted for simulation. The results showed that heat flow as Nusselt number for all cases raises with Reynolds number and volume fraction of nanofluid, likewise the results also reveal that ZnO with volume fractions of 2% in trapezoidal ribs offered highest Nusselt number at Reynolds number of Re= 30000. Keyword: Heat transfer augmentation, Friction factor, Thermal performance factor, Ribs configuration, CFD simulation, Fluent.

Numerical study of heat transport in thermally isolated flow-rate microsensors

1992 ◽  
Vol 70 (10-11) ◽  
pp. 904-907
Author(s):  
N. Swart ◽  
A. Nathan
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Boundary Conditions ◽  
Heat Transport ◽  
Flow Rate ◽  
Energy Equation ◽  
Numerical Study ◽  
Control Volume ◽  
Circuit Simulator ◽  
Temperature Distributions

The temperature distributions in thermally isolated cantilever based flow-rate microsensors have been numerically calculated for different gas temperatures and gas velocities. In particular, we investigate the efficiency of heat transfer to the flowing gas and corresponding directions of heat flow in the system. The above analysis is based on a solution to the energy equation under appropriate boundary conditions. The equation was discretized using a control volume procedure, based on which an equivalent circuit was devised and subsequently simulated using a circuit simulator such as SPICE.

Local fluid and heat flow near contact lines

1994 ◽  
Vol 268 ◽  
pp. 231-265 ◽  
Author(s):  
D. M. Anderson ◽  
S. H. Davis
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Flow ◽  
Boundary Conditions ◽  
Polar Coordinates ◽  
Contact Lines ◽  
Rigid Boundary ◽  
Free Surfaces ◽  
Local Boundary ◽  
Local Solutions

We consider steady two-dimensional fluid flow and heat transfer near contact lines in single-phase and two-phase systems. Both single- and double-wedge geometries admit separable solutions in plane polar coordinates for both thermal and flow fields. We consider the class of functions which have bounded temperatures and velocities at the corner. When free surfaces are present, we seek local solutions, those that satisfy all local boundary conditions, and partial local solutions, those that satisfy all but the normal-stress boundary condition. Our aim in this work is to describe local fluid and heat flow in problems where these fields are coupled by determining for which wedge angles solutions exist, identifying singularities in the heat flux and stress which are present at contact lines, and determining the dependence of these singularities on the wedge angles. For thermal fields in two phases we identify two modes of heat transfer that are analogous to the two modes identified by Proudman & Asadullah (1988) for two-fluid flow. For non-isothermal flow, locally, convection does not play a role but coupling through thermocapillary effects on non-isothermal free surfaces can arise. We find that under non-isothermal conditions a planar free surface must leave a planar rigid boundary at an angle of π, the same angle found by Michael (1958) for an isothermal rigid/free wedge, in order to satisfy all local boundary conditions. Finally, we find that situations arise where no coupled solutions of the form sought can be found; we discuss means by which alternative solutions can be obtained.

Heat Transfer to Fully Developed Laminar Flow in a Circular Tube With Arbitrary Circumferential Heat Flux

1960 ◽  
Vol 82 (2) ◽  
pp. 108-112 ◽  
Author(s):  
W. C. Reynolds
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Laminar Flow ◽  
Heat Input ◽  
Circular Tube ◽  
Flux Variation ◽  
Axial Heat ◽  
Insight Into

A solution is presented for fully developed laminar heat transfer in a circular tube with arbitrary circumferential heat flux. Examples included indicate that the influence of circumferential heat-flux variation on wall temperatures can be quite significant and provide some insight into the nature of the effects. The analysis allows calculation of wall temperatures for any arbitrary peripheral heat-flux variation for fully developed laminar flow under the restriction of constant axial heat input.

The influence of some design parameters on the heat transfer in thermal fuel flowmeter

2021 ◽  
Vol 13 (1) ◽  
pp. 54-59
Author(s):  
Andriy Ilchenko ◽  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Flow ◽  
Fuel Consumption ◽  
Design Parameters ◽  
Radial Heat Flow ◽  
Radial Heat ◽  
Axial Heat ◽  
Radial Heat Flux

The article analyzes the influence, relationship and value of design parameters of the heat flow meter on its radial and axial heat fluxes in the tube (tube diameter, heater diameter and their ratio, thermal conductivity of the tube material, etc.). It is shown that at the stage of choosing the design parameters of the flowmeter it is necessary to take into account the influence of its radial heat flux on the axial one. The influence of radial heat flux in the flowmeter tube on the error of fuel loss measurement is substantiated. Analytical dependences which allow to define an axial heat stream are resulted, their analysis concerning influence of flowmeter tube constructive parameters on heat transfer is carried out. Measures are planned and recommendations are developed for the choice of design flowmeter parameters, development or use, provided that the influence of radial heat flow on the axial is reduced, which will reduce the total error of fuel consumption measurement. Regarding the choice of design parameters of heat meters while reducing the error of measuring fuel consumption, it is shown that the maximum possible decrease in the diameter of the heater and increase the diameter of the flow tube reduce the impact of radial heat flow on the axial and thus reduce the total fuel consumption error. Numerical ratios of tube diameter to flowmeter heater diameter for different thermal conductivities of tube materials are given under the condition of minimal influence on fuel consumption measurement error. For tube materials with a thermal conductivity 0.16… 0.25 W / (m ∙ K) (ebonite, fluoroplastic F-5, etc.) the tube diameters ratio and the heater should be within 1.51… 1.62, and for materials with more high thermal conductivity (thermal conductivity greater than 14.9 W / (m ∙ K)), this ratio should be equal to 1.99.

scholarly journals Mantle convection interacting with magma oceans

2019 ◽  
Vol 220 (3) ◽  
pp. 1878-1892 ◽  
Author(s):  
R Agrusta ◽  
A Morison ◽  
S Labrosse ◽  
R Deguen ◽  
T Alboussiére ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Heat Flow ◽  
Boundary Conditions ◽  
Phase Change ◽  
Critical Rayleigh Number ◽  
Lower Boundary ◽  
Magma Ocean ◽  
Non Linear ◽  
Flow Through

SUMMARY The presence of a magma ocean may have characterized the beginning of terrestrial planets and, depending on how the solidification has proceeded, the solid mantle may have been in contact with a magma ocean at its upper boundary, its lower boundary, or both, for some period of time. At the interface where the solid is in contact with the liquid the matter can flow through by changing phase, and this affects convection in the solid during magma ocean crystallization. Linear and weakly non-linear analyses have shown that Rayleigh–Bénard flow subject to two liquid–solid phase change boundary conditions is characterized by a non-deforming translation or weakly deforming long wavelength mode at relatively low Rayleigh number. Both modes are expected to transfer heat very efficiently, at least in the range of applicability of weakly non-linear results for the deforming mode. When only one boundary is a phase change, the critical Rayleigh number is also reduced, by a factor of about 4, and the heat transfer is also greatly increased. In this study we use direct numerical simulations in 2-D Cartesian geometry to explore how the solid convection may be affected by these boundary conditions for values of the Rayleigh number extending beyond the range of validity of the weakly non-linear results, up to 103 times the critical value. Our results suggest that solid-state convection during magma ocean crystallization may have been characterized by a very efficient mass and heat transfer, with a heat flow and velocity at the least twice the value previously thought when only one magma ocean is present, above or below. In the situation with a magma ocean above and below, we show that the convective heat flow through the solid layer could reach values of the same order as that of the black-body radiation at the surface of the magma ocean.

scholarly journals Transient Heat Transfer Through a Thin Circular Pipe Due to Unsteady Flow in the Pipe

1965 ◽  
Vol 87 (4) ◽  
pp. 513-520 ◽  
Author(s):  
N. Hayasi ◽  
K. Inouye
Keyword(s):  
Heat Transfer ◽  
Incompressible Fluid ◽  
Outer Surface ◽  
Circular Tube ◽  
Initial Period ◽  
Transient Heat Transfer ◽  
Insulating Material ◽  
Metallic Tube ◽  
Inner Surface ◽  
The Difference

An analysis of the transient heat transfer between a thin circular tube and the incompressible fluid moving through the tube is made for the case where the temperature of the inlet fluid is kept constant. Both radial conduction of heat in the wall and the heat loss at the outer surface of the cylinder are taken into consideration. It is shown to be especially easy to calculate temperature of both fluid and tube in the initial period by means of the figures. So far, it is common to use the temperature of the wall calculated by the assumption that it is constant radially. It is shown that for the insulated tube in the initial period such temperature is equal to the temperature of the outer surface of the tube. The temperature of the inner surface of the tube may be appreciably different from such temperature even for the metallic tube. The difference is extremely large for the tube made from insulating material.

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