Heat Transfer Study of Staggered Thin Rectangular Blocks in a Channel Flow

1991 ◽  
Vol 113 (3) ◽  
pp. 294-300 ◽  
Author(s):  
Ching Jen Chen ◽  
Ramiro H. Bravo
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Channel Flow ◽  
Vector Fields ◽  
Block Size ◽  
Navier Stokes ◽  
Maximum Heat ◽  
Flow And Heat Transfer ◽  
Maximum Heat Transfer ◽  
Energy Equations

In this study, fluid flow and heat transfer in two-dimensional staggered thin rectangular blocks in a channel flow heat exchanger is analyzed by the Finite Analytic Numerical Method. The heat exchanger consists of four staggered thin rectangular blocks at temperature T1 placed inside a channel which is formed by two plates maintained at constant temperature T0. The fluid is considered to be incompressible and the flow laminar. Flow and heat transfer from the inlet of the heat exchanger to the outlet are simulated by solving Navier-Stokes and energy equations. Results were obtained for different block spacing and different size of the blocks. Computations were made for Reynolds numbers 100, 500, and 1,000, and Prandtl numbers 0.7 and 4.0. The results are presented in the form of velocity vector fields, isotherms, and local and global Nusselt numbers. The characteristics of the heat transfer and pressure drop in different block size and block separation are analyzed. The optimal length of separation between thin blocks and the optimal block length for maximum heat transfer are determined.

scholarly journals Numerical Study on Flow and Heat Transfer Mechanisms in the Heat Exchanger Channel with V-Orifice at Various Blockage Ratios, Gap Spacing Ratios, and Flow Directions

2019 ◽  
Vol 2019 ◽  
pp. 1-21 ◽  
Author(s):  
Amnart Boonloi ◽  
Withada Jedsadaratanachai
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Study ◽  
Numerical Results ◽  
Blockage Ratio ◽  
Maximum Heat ◽  
Flow And Heat Transfer ◽  
Maximum Heat Transfer ◽  
Smooth Channel ◽  
Gap Spacing

Numerical assessments in the square channel heat exchanger installed with various parameters of V-orifices are presented. The V-orifice is installed in the heat exchanger channel with gap spacing between the upper-lower edges of the orifice and the channel wall. The purposes of the design are to reduce the pressure loss, increase the vortex strength, and increase the turbulent mixing of the flow. The influence of the blockage ratio and V-orifice arrangement is investigated. The blockage ratio, b/H, of the V-orifice is varied in the range 0.05–0.30. The V-tip of the V-orifice pointing downstream (V-downstream) is compared with the V-tip pointing upstream (V-upstream) by both flow and heat transfer. The numerical results are reported in terms of flow visualization and heat transfer pattern in the test section. The thermal performance assessments in terms of Nusselt number, friction factor, and thermal enhancement factor are also concluded. The numerical results reveal that the maximum heat transfer enhancement is found to be around 26.13 times higher than the smooth channel, while the optimum TEF is around 3.2. The suggested gap spacing for the present configuration of the V-orifice channel is around 5–10%.

Characteristics of Fully Developed Flow and Heat Transfer in Channels With Varying Wall Geometry

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Abhishek G. Ramgadia ◽  
Arun K. Saha
Keyword(s):  
Heat Transfer ◽  
Time Dependent ◽  
Navier Stokes ◽  
Fully Developed Flow ◽  
Flow And Heat Transfer ◽  
Collocated Grid ◽  
Wall Profile ◽  
Energy Equations ◽  
Volume Method ◽  
Wall Geometry

Present study focuses on numerical investigation of fully developed flow and heat transfer through three channels having sine-shaped, triangle-shaped, and arc-shaped wall profiles. All computations are performed at Reynolds number of 600. Finite volume method on collocated grid is used to solve the time-dependent Navier–Stokes and energy equations in primitive variable form. For all the geometries considered in the study, the ratios Hmin/Hmax and L/a are kept fixed to 0.4 and 8.0, respectively. The thermal performances of all the three wall configurations are assessed using integral parameters as well as instantaneous, time-averaged and fluctuating flow fields. The geometry with the sinusoidal-shaped wall profile is found to produce the best thermal properties as compared to the triangle-shaped and the arc-shaped profiles though the obtained heat transfer is the highest for the arc-shaped geometry.

scholarly journals Enhancing Heat Transfer in Tube Heat Exchanger by Inserting Discrete Twisting Tapes with Different Positions

2019 ◽  
Vol 25 (8) ◽  
pp. 39-51
Author(s):  
Nassr Fadhil Hussein ◽  
Abdulrahman Shakir Mahmood
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Constant Heat Flux ◽  
Vertical Position ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Twisted Tapes ◽  
Maximum Heat Transfer

Enhancement of heat transfer in the tube heat exchanger is studied experimentally by using discrete twisted tapes. Three different positions were selected for inserting turbulators along tube section (horizontal position by α= 00, inclined position by α= 45 0 and vertical position by α= 900). The space between turbulators was fixed by distributing 5 pieces of these turbulators with pitch ratio    PR = (0.44). Also, the factor of constant heat flux was applied as a boundary condition around the tube test section for all experiments of this investigation, while the flow rates were selected as a variable factor (Reynolds number values vary from 5000 to 15000). The results show that using discrete twisted tapes enhances the heat transfer rate by about 60.7-103.7 % compared with plane tube case. Also, inserting turbulators with inclined position offers maximum heat transfer rate by 103.7%.  

Scrutiny the Heat Transfer Effect in an Annulus by Mounting Axial Fins with Different Shapes: Without and with Taylor Number

2021 ◽  
Vol 409 ◽  
pp. 142-157
Author(s):  
Farouk Kebir ◽  
Youcef Attou
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Annular Channel ◽  
Reynolds Stress Model ◽  
Taylor Number ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Rsm Model ◽  
Energy Equations ◽  
The Impact

This study aimed to investigate numerically the heat transfer improvement and pressure drop inside annular channel of a rotor-stator provided with fins mounted on the stator without and with Taylor number. The impact of mounting various types of fins (triangular, rectangular, trapezoidal shapes with small and large base) is studied by varying the fin width b from 0 to 14 mm. In the presence of axial air flow, numerical simulations are carried out by solving the governing continuity, momentum and energy equations of turbulent flow in cylindrical coordinates using the Finite Volume Method. The results obtained by Reynolds Stress Model RSM model have indicated that the heat transfer enhances as the surface area of the fins and the effective Reynolds number increase, while there is an increase in pressure drop. Furthermore, we have shown that the presence of Taylor number has a slight increase in Nusselt number and pressure drop compared to the case without Taylor number. Among the four geometries, it is found that the rectangular cavity is the best geometry which gives maximum heat transfer and minimum pressure loss.

scholarly journals Numerical Computation of Turbulent Flow and Heat Transfer in a Radially Rotating Channel with Wall Conduction

2001 ◽  
Vol 7 (3) ◽  
pp. 209-222
Author(s):  
Frank K. T. Lin ◽  
G. J. Hwang ◽  
S.-C. Wong ◽  
C. Y. Soong
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Numerical Computation ◽  
Experimental Models ◽  
Temperature Fields ◽  
Navier Stokes ◽  
Turbine Blade Cooling ◽  
Flow And Heat Transfer ◽  
Energy Equations ◽  
Rotating Channel

This work is concerned with numerical computation of turbulent flow and heat transfer in experimental models of a radially rotating channel used for turbine blade cooling. Reynolds-averaged Navier-Stokes and energy equations with a two-layer turbulence model are employed as the computational model of the flow and temperature fields. The computations are carried out by the software package of “CFX-TASCflow”. Heat loss from the channel walls through heat conduction is considered. Results at various rotational conditions are obtained and compared with the baseline stationary cases. The influences of the channel rotation, through-flow, wall conduction and the channel extension on flow and heat transfer characteristics are explored. Comparisons of the present predictions and available experimental data are also presented.

scholarly journals Investigation of Two-Dimensional Unsteady Stagnation-Point Flow and Heat Transfer Impinging on an Accelerated Flat Plate

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Ali Shokrgozar Abbassi ◽  
Asghar Baradaran Rahimi
Keyword(s):  
Heat Transfer ◽  
Strain Rate ◽  
Flat Plate ◽  
Stagnation Point ◽  
Stagnation Point Flow ◽  
Navier Stokes ◽  
Variable Velocity ◽  
Two Dimensional ◽  
Flow And Heat Transfer ◽  
Energy Equations

General formulation and solution of Navier–Stokes and energy equations are sought in the study of two-dimensional unsteady stagnation-point flow and heat transfer impinging on a flat plate when the plate is moving with variable velocity and acceleration toward main stream or away from it. As an application, among others, this accelerated plate can be assumed as a solidification front which is being formed with variable velocity. An external fluid, along z-direction, with strain rate a impinges on this flat plate and produces an unsteady two-dimensional flow in which the plate moves along z-direction with variable velocity and acceleration in general. A reduction of Navier–Stokes and energy equations is obtained by use of appropriate similarity transformations. Velocity and pressure profiles, boundary layer thickness, and surface stress-tensors along with temperature profiles are presented for different examples of impinging fluid strain rate, selected values of plate velocity, and Prandtl number parameter.

Simulation and Analysis of Air Performance of Multi-Row Finned-Tube Heat Exchanger

2011 ◽  
Vol 347-353 ◽  
pp. 2519-2523
Author(s):  
Wen Wen Wang ◽  
Rui Li
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Finned Tube ◽  
Mathematics Model ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Heat Transfer Efficiency ◽  
Maximum Heat Transfer ◽  
Finned Tube Heat Exchanger ◽  
Pressure Changes

In this paper, simulates the air performance of multi-row finned-tube heat exchanger by Fluent. The mathematics model is established, using standard k-ε turbulence model. The temperature, velocity and pressure changes of air are analyzed. By research the multi-row finned-tube heat exchanger, analyzed the different structures have different effects on the efficiency of heat transfer, obtained the most appropriate number of tube rows, making the heat exchanger for maximum heat transfer efficiency.

Unsteady Flow and Heat Transfer Characteristics of Fluid Flow Over a Shrinking Permeable Infinite Long Cylinder

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Emad J. Elnajjar ◽  
Qasem M. Al-Mdallal ◽  
Fathi M. Allan
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Navier Stokes ◽  
Suction Parameter ◽  
Similarity Transformations ◽  
Flow And Heat Transfer ◽  
Runge Kutta Method ◽  
Method Of Solution ◽  
Energy Equations ◽  
Long Cylinder

The present work studies the unsteady, viscous, and incompressible laminar flow and heat transfer over a shrinking permeable cylinder. The unsteady nonlinear Navier–Stokes and energy equations are reduced, using similarity transformations, to a system of nonlinear ordinary differential equations. The boundary conditions associated with the governing equations are the time dependent surface temperature and flow conditions. The method of solution is based on a combination of the implicit Runge–Kutta method and the shooting method. The present study predicts two solutions for both the flow and heat transfer fields, and a unique solution at a specific critical unsteadiness parameter. An analysis of the results, for a specific suction parameter, suggests that the corresponding unique unsteadiness parameter does not depend on the Prandtl number. However, the unique rate of heat transfer is increasing as the Prandtl number increases. In addition, our results confirm that the unique value of heat transfer rate increases as the suction parameter increases, regardless the value of the Prandtl number.

scholarly journals Optimization Performance on Plate Fin Tube Heat Exchanger

2019 ◽  
Vol 5 (3) ◽  
pp. 10
Author(s):  
Mahtab Alam ◽  
Dr. Dharmendra Singh Rajput
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Circular Tube ◽  
Fluid Dynamic ◽  
Cfd Analysis ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Tube Arrangement ◽  
Maximum Heat Transfer ◽  
Fin Tube

The main objective of the present work is to investigation of optimum design of plate fin tube heat exchanger using Computational fluid dynamic approach and maximizing thermal performance. There are total five designs of plate fin and tube heat exchanger are used in present work and CFD analysis have been performed in it to get maximum heat transfer. It has been observed from CFD analysis that the maximum heat transfer can be achieved from plate fin and tube heat exchanger with elliptical tube arrangement inclined at 30o with 23.22% more heat transfer capacity as compared to circular tube plate pin heat exchanger. So that it is recommended that if the plate fins and tube heat exchanger with inclined elliptical tube used in place of circular tube arrangement, batter heat transfer can be achieved.

scholarly journals A heat pipe heat recovery heat exchanger for a mini-drier

2006 ◽  
Vol 17 (1) ◽  
pp. 50-57 ◽  
Author(s):  
A Meyer ◽  
R T R T Dobson
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Theoretical Model ◽  
Heat Pipe ◽  
Experimental Testing ◽  
Thermal Design ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Maximum Heat Transfer

This paper considers the thermal design and the experimental testing of a heat pipe (thermosyphon) heat exchanger for a relatively small commercially available mini-drier. The purpose of the heat exchanger is to recover heat from the moist waste air stream to preheat the fresh incoming air. The working fluid used was R134a and the correlations are given for the evaporator and condenser inside heat transfer coefficients as well as for the maximum heat transfer rate. The theoretical model and computer simulation program used for the thermal design calculations are described. The validity of the as-designed and manufactured heat exchanger coupled to the drier is experimentally verified. The theoretical model accurately predicted the thermal performance and a significant energy savings and a reasonable payback period was achieved.

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