scholarly journals Effect of Secondary Vortex Flow Near Contact Point on Thermal Performance in the Plate Heat Exchanger with Different Corrugation Profiles

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1328 ◽  
Author(s):  
Hyung Ju Lee ◽  
Seong Hyuk Lee
Keyword(s):  
Friction Factor ◽  
Thermal Performance ◽  
Cfd Simulation ◽  
Flow Direction ◽  
Contact Point ◽  
Flow Characteristics ◽  
Ansys Fluent ◽  
Plate Heat ◽  
Flow Mixing ◽  
Commercial Code

The present study numerically investigates thermal performance and turbulent flow characteristics of chevron-type plate heat exchangers with sinusoidal, trapezoidal, triangular, and elliptical corrugation profiles. The commercial code of ANSYS Fluent (v. 17.0) is used for computational fluid dynamics (CFD) simulation with the realizable k-ε model. In particular, we focus on the influence of configuration shape on a substantial change in flow direction near the contact point, yielding local vorticity. As a result, secondary vortical motions are observed in the flow passage with vorticity that is distributed locally and which changes near the contact point. Higher flow mixing generated and distributed by the secondary vortical motions contributes to the increase of the Colburn j-factor as well as the friction factor. The highest Colburn j-factor and friction factor are obtained for an elliptical profile, compared to other shapes, because of the increase in the vortex strength near the contact point.

Thermal Performance of a Corrugated Wall With Artificial Roughness

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Rabia Ferhat ◽  
Ahmed Zineddine Dellil ◽  
Khadidja Boualem ◽  
M-Kamal Hamidou
Keyword(s):  
Thermal Performance ◽  
Flow Characteristics ◽  
Artificial Roughness ◽  
Inlet Channel ◽  
Ansys Fluent ◽  
Plate Heat ◽  
Corrugated Channel ◽  
Improve Heat Transfer ◽  
Different Shapes ◽  
Corrugated Wall

This paper aims to determine the flow characteristics and thermal performance of plate heat exchangers. The study is divided into two parts. In the first part, four different shapes of corrugated boundaries have been recommended, rectangular, trapezoidal, triangular, and sinusoidal shapes. In addition, an artificial roughness has been introduced to improve heat transfer within corrugated channel. In the second part, a corrugated wall was used at the inlet channel. Numerical results are presented as Nusselt number (Nu) and friction factor (Cf) using the commercial software ansys-fluent where the Reynolds number is ranged between 3000 and 12,000. The results of this investigation reveal that the overall thermal performance improves greatly by 50% due to the use of the sinusoidal artificial roughness and added undulations in the inlet channel. It is also observed that the latter case with the ratio A″/λ″ = 0.05 is the optimal design for the plate heat exchanger.

scholarly journals Pitch Variations Study on Helically Coiled Pipe in Turbulent Flow Region Using CFD

2020 ◽  
Vol 38 (4) ◽  
pp. 775-784
Author(s):  
Anwer F. Faraj ◽  
Itimad D.J. Azzawi ◽  
Samir G. Yahya
Keyword(s):  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulent Flows ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Simple Algorithm ◽  
Flow Region ◽  
Dean Number ◽  
Ansys Fluent ◽  
Commercial Code

A computational fluid dynamics (CFD) study was conducted to analyse the flow structure and the effect of varying the coil pitch on the coil friction factor and wall shear stress, through utilising different models’ configurations. Three coils were tested, all of them having the same diameter and coil diameter: 0.005m and 0.04m respectively. Pitch variations began with 0.01, 0.05, 0.25 m for the first, second and third model respectively. Two turbulence models, STD(k-ϵ) and STD(k-w), were utilised in this simulation in order to determine the turbulence model which could capture most of the flow characteristics. A comparison was made between the STD(k-ϵ) and STD(k-w) models in order to analyse the pros and cons of each model. The results were validated with Ito’s equation for turbulent flow and compared with Filonenko’s equation for a straight pipe. The governing equations were discretized using finite volumes method and the SIMPLE algorithm was used to solve the equations iteratively. All the models were simulated using the ANSYS Fluent solver CFD commercial code. The results showed that in turbulent flows, Dean number had a stronger effect on reducing coil friction factor than the increment in pitch dimension.

scholarly journals Predicting the effect of the rib pitch on thermal performance factor of small channels plate heat exchangers fitted with Y and C shapes obstacles

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Sirine Chtourou ◽  
Hassene Djemel ◽  
Mohamed Kaffel ◽  
Mounir Baccar
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Computer Aided Design ◽  
Flow Characteristics ◽  
Plate Heat Exchanger ◽  
Geometrical Parameters ◽  
Computational Domain ◽  
Ansys Fluent ◽  
Plate Heat ◽  
Small Channels

AbstractThis study presents a numerical analysis of a laminar counter flow inside small channels plate heat exchanger fitted with Y and C shape obstacles. Using the Computational Fluid Dynamics CFD, an advanced and modern simulation technique, the influence of the geometrical parameters (such as geometry, rib pitch) on the flow characteristics, the thermal and the hydrodynamics performance of the PHE (plate heat exchanger) is investigated numerically. The main goal of this work is to increase the flow turbulence, enhance the heat transfer and the thermal efficiency by inserting new obstacles forms. The computational domain is a conjugate model which is developed by the Computer Aided Design CAD software Solidworks. The results, obtained with Ansys Fluent, show that the presence of the shaped ribs provides enhancement in heat transfer and fluid turbulence. The CFD analysis is validated with the previous study. The non-dimensional factors such as the Nusselt number Nu, the skin friction factor Cf and the thermo-hydraulic performance parameter THPP are predicted with a Reynolds number Re range of 200–800. The temperature and the velocity distribution are presented and analyzed. The Y ribs and the C ribs offer as maximum THPP values respectively about 1.44 and 2.6 times of a smooth duct.

CFD SIMULATION OF A PLATE HEAT EXCHANGER WITH TRAPEZOIDAL CHEVRON

2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Chin Yung Shin ◽  
Normah Mohd-Ghazali
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Exchanger ◽  
Friction Factor ◽  
Cfd Simulation ◽  
General Pattern ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
Flow Configuration ◽  
Heat Transfer Capacity

In this research, the trapezoidal shaped chevron plate heat exchanger (PHE) is simulated using computational fluid dynamics (CFD) software to determine its heat transfer capacity and friction factor. The PHE is modelled with chevron angles from 30° to 60°, and also the performances are compared with the plain PHE. The validation is done by comparing simulation result with published references using 30° trapezoidal chevron PHE. The Nusselt number and friction factor obtained from simulation model is plotted against different chevron angles. The Nusselt number and friction factor is also compared with available references, which some of the references used sinusoidal chevron PHE. The general pattern of Nusselt number and friction factor with increasing chevron angle agrees with the references. The heat transfer capacity found in current study is higher than the references used, and at the same time, the friction factor also increased. Besides this, it is also found that the counter flow configuration has better heat transfer capacity performance than the parallel flow configuration.

scholarly journals The Numerical Diffusion Effect on the CFD Simulation Accuracy of Velocity and Temperature Field for the Application of Sustainable Architecture Methodology

2020 ◽  
Vol 12 (23) ◽  
pp. 10173
Author(s):  
Vladimíra Michalcová ◽  
Kamila Kotrasová
Keyword(s):  
Temperature Field ◽  
Cfd Simulation ◽  
Flow Direction ◽  
Three Dimensional ◽  
Stationary Flow ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Simulation Accuracy ◽  
Numerical Diffusion ◽  
Diffusion Temperature

Numerical simulation of fluid flow and heat or mass transfer phenomenon requires numerical solution of Navier–Stokes and energy-conservation equations, together with the continuity equation. The basic problem of solving general transport equations by the Finite Volume Method (FVM) is the exact calculation of the transport quantity. Numerical or false diffusion is a phenomenon of inserting errors in calculations that threaten the accuracy of the computational solution. The paper compares the physical accuracy of the calculation in the Computational Fluid Dynamics (CFD) code in Ansys Fluent using the offered discretization calculation schemes, methods of solving the gradients of the transport quantity on the cell walls, and the influence of the mesh type. The paper offers possibilities on how to reduce numerical errors. In the calculation area, the sharp boundary of two areas with different temperatures is created in the flow direction. The three-dimensional (3D) stationary flow of the fictitious gas is simulated using FVM so that only advective transfer, in terms of momentum and heat, arises. The subject of the study is to determine the level of numerical diffusion (temperature field scattering) and to evaluate the values of the transport quantity (temperature), which are outside the range of specified boundary conditions at variously set calculation parameters.

Numerical investigation on turbulent convective heat transfer of nanofluid flow in a square cross-sectioned duct

2019 ◽  
Vol 29 (4) ◽  
pp. 1432-1447 ◽  
Author(s):  
Gülbanu Şenay ◽  
Metin Kaya ◽  
Engin Gedik ◽  
Muhammet Kayfeci
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Friction Factor ◽  
Flow Characteristics ◽  
Constant Heat Flux ◽  
Ansys Fluent ◽  
Square Duct ◽  
Content Type ◽  
Volume Fractions ◽  
Darcy Friction Factor

Purpose The purpose of this study is to numerically investigate the heat transfer enhancement by using two different nanofluids flow throughout the square duct under a constant heat flux (500 × 103 W/m2). Design/methodology/approach In numerical computations, ANSYS Fluent code based on the finite volume method was used to solve governing equations by iteratively. Water, Al2O3-water and TiO2-water nanofluids were used for different flow velocities changing 1 m/s to 8 m/s (i.e. Reynolds number varying from 3,000 to 100,000). Findings The results were compared with results published previously in the literature and close agreement was observed especially considering Dittus and Boelter correlation for water. It was found that from the obtained results, increasing flow velocity and volume fractions of nanoparticles has caused to increase Nu number for all cases. Besides, variations of pressure drop, Darcy friction factor are presented graphically and discussed in detail. The results are consistent with a deviation of 1.3 to 15 per cent with the results of other researchers. Originality/value The effects of the Re numbers and volume fractions of nanoparticles (0.01 ≤ Φ ≤ 0.04) on the heat transfer and fluid flow characteristics such as average Nu number, pressure drop (ΔP) and Darcy friction factor (f) were investigated.

CFD Study of Tidal Current Turbine Shroud for Initial Design Evaluation

2014 ◽  
Vol 679 ◽  
pp. 35-38 ◽  
Author(s):  
Azim Arshad ◽  
Shahrani Anuar ◽  
Ahmmad Shukrie ◽  
Rosdi Hussin
Keyword(s):  
Experimental Data ◽  
Tidal Current ◽  
Cfd Simulation ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Simulation And Experiment ◽  
Tidal Current Turbine ◽  
Coefficient Of Velocity ◽  
Current Turbine ◽  
Good Agreement

CFD simulation of a tidal current turbine shroud was performed using Ansys FLUENT commercial code and comparison was made with experimental data. The simulation result obtained was in good agreement with the experimental data. The coefficient of velocity, Cv was in the range of approximately 1.2 to 1.4 for both simulation and experiment. The present study gave useful information on the viability of CFD simulation for the initial evaluation of shroud design performance.

Enhanced Heat Transfer in Square Duct Fitted Diagonally with Double-Sided V-Ribbed Tapes

2015 ◽  
Vol 751 ◽  
pp. 251-256
Author(s):  
Ying Yong Kaewkohkiat ◽  
Sombat Tamna ◽  
Pongjet Promvonge
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Thermal Performance ◽  
Flow Direction ◽  
Longitudinal Vortex ◽  
Experimental Result ◽  
Test Fluid ◽  
Square Duct ◽  
Main Flow Direction ◽  
The One

An experimental study on heat transfer enhancement in a heat exchanger square-duct fitted diagonally with 45° V-ribbed tapes has been conducted. The tested duct has a square section and uniform heat-fluxed walls and the flow rate of air used as the test fluid is presented in terms of Reynolds number from 4000 to 25,000. The insertion of the V-ribbed tape is performed with a rib-pitch to duct-height ratio, (P/H=PR=0.75 and 2) at the rib attack angle of 45° with respect to the main flow direction. The V-ribbed tape inserted diagonally in the duct is expected to generate a longitudinal vortex flow pair in each tape side through the heated duct. Influences of four rib-to-duct height ratios (e/H=BR=0.1, 0.15, 0.2 and 0.25) on the heat transfer and pressure drop in terms of respective Nusselt number and friction factor are investigated. The experimental result indicates that the BR and PR of the V-ribs provide a significant effect on the thermal performance of the test duct. The results reveal that at smaller PR, the V-rib with BR=0.25 provides the highest heat transfer and friction factor but the one with BR=0.2, PR=0.75 yields the best thermal performance.

scholarly journals Numerical Investigation on Turbulent Flow and Heat Transfer of Rectangular Channels With Elliptic Scale-Roughened Walls

2012 ◽  
Author(s):  
Feng Zhou ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Spanwise Direction ◽  
Pressure Drops ◽  
Nusselt Numbers ◽  
Flow Mixing ◽  
Rectangular Channels ◽  
Smooth Channel ◽  
Fluid Flow Characteristics

In the present paper, six new types of rectangular channels with elliptic scale-roughened walls for heat transfer enhancement, which include elongated scale cases (Pt/Pl = 0.3, 0.5, 0.7) and squeezed scale cases (Pt/Pl = 1.43, 2, 3.33), are proposed. Heat transfer and fluid flow characteristics for sixteen different scale-roughened models (with the scale height varying in the range from 1mm to 2.5mm) are predicted numerically using commercial CFD code, Ansys CFX, with the Reynolds number ranging from 5000 to 15000. The turbulent model employed is the k-ω based Shear-Stress-Transport (SST) model with automatic wall function treatment. It is found that the elliptic scales with their long axis oriented perpendicular to the flow direction enhance the heat transfer performance considerably, while the scales elongated in the flow direction have lower Nusselt numbers and pressure drops compared to the circular scale-roughened channels. It is also found that the scale-shaped roughness strongly spins the flow in the spanwise direction, which breaks the near wall boundary layers continuously and enhances the bulk flow mixing. With the flow marching in a spiral pattern, Nusselt number ratios between the squeezed scale-roughened and smooth channel flows (Nu/Nu∞) could be augmented to be within the range of 6.1 to 8.1, which is a 50% improvement over the circular scale-roughened channels.

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