An Approximate Model of Bubble Phase Convective Heat Transfer to a Horizontal Tube in a Large Particle Fluid Bed

1982 ◽  
Vol 104 (3) ◽  
pp. 565-567 ◽  
Author(s):  
R. L. Adams
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Large Particle ◽  
Horizontal Tube ◽  
Approximate Model ◽  
Bubble Phase ◽  
Fluid Bed

Heat Transfer in Large Particle Bubbling Fluidized Beds

1984 ◽  
Vol 106 (1) ◽  
pp. 85-90 ◽  
Author(s):  
R. L. Adams
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Residence Time ◽  
Large Particle ◽  
Fluidized Beds ◽  
Horizontal Tube ◽  
Two Dimensional ◽  
Phase Contact ◽  
Emulsion Phase ◽  
Bubble Phase

The potential use of fluidized bed combustion of coal as a means of meeting air quality standards with high-sulfur fuels has motivated the development of theoretical models of heat transfer in large particle gas fluidized beds. Models of the separate contributions of emulsion and bubble phase heat transfer have been developed by Adams and Welty [1] and Adams [2, 3, 4] and have been substantiated by experimental data for a horizontal tube immersed in a two-dimensional cold bed obtained by Catipovic [5, 6]. The consolidation of these models to predict local and overall time-average heat transfer to immersed surfaces requires information regarding emulsion phase residence time and bubble phase contact fraction for the particular geometry of interest. The analytical procedure to consolidate these models is outlined in the present work, then applied to the case of a horizontal tube immersed in a two-dimensional atmospheric pressure cold bed. Measurements of emulsion phase residence time and bubble phase contact fraction obtained by Catipovic [5] are used in the calculations for particle diameters ranging from 1.3 to 6 mm. The results agree favorably with experimental data and further substantiate the fundamental assumptions of the model.

Three-Dimensional Flow Effects on Convective Heat Transfer From a Window Covered by a Simple Plane Blind With No Top Covering

2006 ◽  
Author(s):  
Patrick H. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Approximate Model ◽  
Conductive Heat ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Flow Effects

Most studies of convective heat transfer in window-blind systems assume that the flow over the window-blind arrangement is two-dimensional. In some cases, however, three-dimensional flow effects can become important. The present study was undertaken to determine how significant such effects can be for the particular case of a window covered by a simple plane blind. Only convective heat transfer has been considered. The situation considered is only an approximate model of the real window-blind situation. The window is represented by a rectangular vertical isothermal wall section embedded in a large vertical adiabatic plane wall surface and exposed to a large surrounding "room" in which the temperature is lower than the window temperature. The plane blind is represented by a thin vertical wall having the same size as the "window" which offers no resistance to heat transfer across it and in which conductive heat transfer is negligible. The gaps between the blind and the window at the sides and at the top of the window-blind system are assumed to be open. The flow has been assumed to be laminar and it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces. The solution has been obtained by numerically solving the three-dimensional governing equations written in dimensionless form. The effects of the dimensionless governing variables on the window Nusselt number have been numerically examined.

Some aspects of free-convective heat transfer in eddy flow through a horizontal tube

1993 ◽  
Vol 36 (18) ◽  
pp. 4487-4491 ◽  
Author(s):  
V.F. Vinokurov ◽  
S.V. Volkov ◽  
O.G. Martynenko ◽  
P.P. Khramtsov ◽  
I.A. Shikh
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Horizontal Tube ◽  
Flow Through ◽  
Eddy Flow ◽  
Free Convective Heat Transfer

scholarly journals A Simplified Technique for Thermal Analysis of a Fenestration system with a Venetian Blind

2021 ◽  
Author(s):  
Hidayat Ullah Shahid
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Approximate Model ◽  
Vertical Surface ◽  
Shading Devices ◽  
The One ◽  
The Impact ◽  
Venetian Blind

A simplified 1-D numerical model of a window and horizontal Venetian blind assembly has been developed. This model provides a realistic estimate of the advantage of using blinds to control the window heat gain or loss. The free convective heat transfer rate from an isothermal vertical surface adjacent to a set of horizontal louvres has been studied numerically. This configuration is an approximate model of an indoor window glazing with a Venetian-type blind. Knowledge of the effect of blinds on the free convection at the indoor window surface is important for understanding and predicting the impact of shading devices on the overall thermal performance of a window. The convective heat transfer results are used in the one-dimensional model of the complete fenestration system to study the effect on key performance parameters. The results show that louvred blinds can have a significant beneficial effect on window thermal performance.

scholarly journals Experimental Study on the Flow and Heat Transfer of Graphene-Based Lubricants in a Horizontal Tube

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1675
Author(s):  
Zhongpan Cai ◽  
Maocheng Tian ◽  
Guanmin Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Horizontal Tube ◽  
Lubricating Oil ◽  
Heat Transfer Characteristics ◽  
Experiment Platform ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

To improve the heat transfer characteristics of lubricant, graphene-based lubricants were prepared by adding graphene particles, due to its advantages of excellent thermal conductivity and two-dimensional sheet structure. In the present study, its physical properties were measured. A flow heat transfer experiment platform was built to study the flow and heat transfer characteristics of the graphene lubricating oil in a horizontal circular tube. The results show that the graphene lubricant prepared using a two-step approach had good stability, and the dispersibility was good without the agglomeration phenomenon, according to measurements undertaken using an electron microscope and centrifuge. The thermal conductivity and viscosity of graphene lubricant increased with the increase of the graphene concentration, and the thermal conductivity of graphene lubricant with the same concentration decreased with the increase of temperature. When the concentration was equal, the convective heat transfer Nusselt number (Nu) of graphene lubricant increased with the increase of Reynolds number (Re). When Re was equal, the convective heat transfer Nu increased with the increase of graphene particle concentration, and the maximum Nu increased by 40%.

Natural Convective Heat Transfer From an Inclined Isothermal Square Cylinder With an Exposed Top Surface Mounted on a Flat Adiabatic Base

2009 ◽  
Author(s):  
Abdulrahim Kalendar ◽  
Patrick H. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Base Plate ◽  
Approximate Model ◽  
Fluid Temperature ◽  
Governing Equations ◽  
Wide Range ◽  
The Mean

Natural convective heat transfer from an isothermal inclined cylinder with a square cross-section and which has an exposed top surface and is, in general, at an angle to the vertical has been numerically studied. The cylinder is mounted on a flat adiabatic base plate, the cylinder being normal to the base plate. The situation considered is an approximate model of that which occurs in some electrical and electronic component cooling problems. The flow has been assumed to be steady and laminar and it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces, this having been treated by using the Boussinesq approach. The solution has been obtained by numerically solving the governing equations, these equations being written in terms of dimensionless variables using the height, h, of the cylinder as the length scale and Tw – TF as the temperature scale, TF being the undisturbed fluid temperature far from the cylinder and Tw being the uniform surface temperature of the cylinder. These dimensionless governing equations subject to the boundary conditions have been solved using the commercial cfd solver, FLUENT. The flow has been assumed to be symmetrical about the vertical center-plane through the cylinder. The solution has been used to derive the values of the mean Nusselt number for the cylinder, Nu. The solution has the following parameters: the Rayleigh number, Ra, the dimensionless cylinder width, i.e., the ratio of the width to the height of the heated cylinder, W = w/h, the Prandtl number, Pr, and the angle of inclination of the cylinder relative to the vertical, φ. Results have only been obtained for Pr = 0.7. Values of φ between 0° and 180° and a wide range of Ra and W have been considered. The effects of W, Ra, and φ on the mean Nusselt number, Nu, for the entire cylinder and for the mean Nusselt numbers for the various surfaces that make up the cylinder have been examined.

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