Mixed laminar convection in a horizontal tube with natural convection around its boundaries

1986 ◽  
Vol 29 (3) ◽  
pp. 391-402 ◽  
Author(s):  
J.Pascal Coutier ◽  
Ralph Grief
Keyword(s):  
Natural Convection ◽  
Horizontal Tube ◽  
Laminar Convection

A note on natural convection effects in fully developed horizontal tube flow

AIChE Journal ◽  
1962 ◽  
Vol 8 (4) ◽  
pp. 570-574 ◽  
Author(s):  
Eduardo Del Casal ◽  
William N. Gill
Keyword(s):  
Natural Convection ◽  
Horizontal Tube ◽  
Tube Flow

Improved Correlations for Counting the Effect of Natural Convection on Laminar Flow of Nanofluids

2013 ◽  
Author(s):  
Si-pu Guo ◽  
Zhao-zan Feng ◽  
Ze-cong Fang ◽  
Wei Li ◽  
Jin-liang Xu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Natural Convection ◽  
Laminar Flow ◽  
Prandtl Number ◽  
Single Phase ◽  
Colloidal Suspensions ◽  
Horizontal Tube ◽  
Laminar Mixed Convection ◽  
Wide Range ◽  
Phase Fluid

Nanofluids are colloidal suspensions of nano-scale particles in water, or other base fluids. In this paper, the effect of natural convection on laminar flow of nanofluids in a horizontal tube has been addressed. The obtained experimental data could not be reconciled with existing correlations over a wide range of Prandtl number under laminar mixed convection. Three improved correlations have been derived by using single-phase fluid approach. These correlations fit our data to within ± 10 % and also agree with the data in literature quite well. Such results verify that nanofluids can be treated as a homogeneous mixture with effective thermophysical properties. Utimately, the new correlations have grasped the essence of natural convection and can reduce to both normal forced convection and pure natural convection equations at limiting cases.

Natural Convection From a Horizontal Tube Heat Exchanger Immersed in a Tilted Enclosure

Solar Energy ◽  
2002 ◽  
Author(s):  
Wei Liu ◽  
Jane H. Davidson ◽  
F. A. Kulacki ◽  
Susan C. Mantell
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Horizontal Tube ◽  
Heating System ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Tube Heat Exchanger ◽  
Flux Boundary Conditions ◽  
Solar Water Heating System

Heat transfer rates of a single horizontal tube immersed in a water-filled enclosure tilted at 30 degrees are measured. The results serve as a baseline case for a solar water heating system with a heat exchanger immersed in an integral collector storage. Experiments are conducted for isothermal and stratified enclosures with both adiabatic and uniform heat flux boundary conditions. Natural convection flow in the enclosure is interpreted from measured water temperature distributions. Formation of an appropriate temperature difference that drives natural convection is determined. Correlations for the overall heat transfer coefficient in terms of the Nusselt and Rayleigh numbers are reduced to the form NuD = 0.675RaD0.25 for 106 ≤ RaD ≤ 108.

Natural Convection from a Horizontal Tube Heat Exchanger Immersed in a Tilted Enclosure

2003 ◽  
Vol 125 (1) ◽  
pp. 67-75 ◽  
Author(s):  
Wei Liu ◽  
Jane H. Davidson ◽  
F. A. Kulacki ◽  
Susan C. Mantell
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Horizontal Tube ◽  
Heating System ◽  
Convection Flow ◽  
Uniform Heat Flux ◽  
Tube Heat Exchanger ◽  
Flux Boundary Conditions ◽  
Solar Water Heating System

Heat transfer rates of a single horizontal tube immersed in a water-filled enclosure tilted at 30 deg are measured. The results serve as a baseline case for a solar water heating system with a heat exchanger immersed in an integral collector storage. Experiments are conducted for isothermal and stratified enclosures with both adiabatic and uniform heat flux boundary conditions. Natural convection flow in the enclosure is interpreted from measured water temperature distributions. Formation of an appropriate temperature difference that drives natural convection is determined. Correlations for the overall heat transfer coefficient in terms of the Nusselt and Rayleigh numbers are reduced to the form NuD=0.675RaD0.25 for 9×105⩽RaD⩽4×107.

Numerical Simulations on Natural Convection From a Circular Cylinder in Oscillating Flows

2013 ◽  
Author(s):  
Yan Su
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Circular Cylinder ◽  
Heat Transfer Enhancement ◽  
Numerical Results ◽  
Transfer Enhancement ◽  
Oscillating Flows ◽  
Enhancement Of Heat Transfer ◽  
Buoyancy Forces ◽  
Laminar Convection

Natural convection from a circular cylinder in oscillating flows has been simulated by projection method with two dimensional exponential stretched staggered cylindrical meshes. Present numerical results are validated by comparing the heat transfer results of free convection over a circular cylinder to published experimental and numerical results. The effects of wave directions, amplitudes, frequencies and buoyancy forces on the enhancement of heat transfer have also been presented. Based on turning points of the curves of the overall Nusselt numbers versus Reynolds numbers, the heat transfer can be divided into three linear regimes (conduction, laminar convection and turbulent convection dominated regimes) and two non-linear transient regimes. The valid ranges of the governing parameters for heat transfer enhancement have been identified. The effects of wave directions, amplitudes, frequencies, and buoyancy forces on the enhancement of heat transfer are also investigated. The effective ranges of the governing parameters for heat transfer enhancement are identified.

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