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

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.

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1328 ◽  
Author(s):  
Hyung Ju Lee ◽  
Seong Hyuk Lee

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.


2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Sirine Chtourou ◽  
Hassene Djemel ◽  
Mohamed Kaffel ◽  
Mounir Baccar

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.


2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 355-365
Author(s):  
Koray Karabulut

Plate heat exchangers have a widespread usage and the simplest parallel plate channel structures. Cross-corrugated ducts are basic channel geometries used in the plate heat exchangers. In this study, the increasing of heat transfer from the cross-corrugated triangular ducts by inserting triangular baffles with different placement angles into the channel upper side and pressure drop have been numerically investigated. Numerical calculations have been carried out to solve Navier-Stokes and energy equations by employing k-? turbulence model as 3-D and steady with ANSYS-FLUENT program. While inlet temperature of the air used as working fluid is 293 K, constant surface temperature values of the the lower corrugated channel walls are 373 K. The height of the baffle and apex angle of the corrugated duct have been taken constant as 0.5 H and 60?, respectively. Investigated Reynolds number range is 1000-6000 while the baffle placement angles are 30?, 45?, 60?, and 90?. Numerical results of this study are within 3.53% deviation with experimental study existed in literature. The obtained results have been presented as mean Nusselt number temperature and pressure variations of the fluid for each baffle angle. The temperature and velocity vector contour distributions have been also assessed for different Reynolds numbers and baffle angles. The value of the Num for the corrugated channel with 60? baffle angle is 8.2% higher than that of the 90? for the Re = 4000. Besides, for Re = 1000 the value of the pressure drop is 39% lower in the channel with 60? baffle angle than that of 90?.


Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 556 ◽  
Author(s):  
Hyung Lee ◽  
Jaiyoung Ryu ◽  
Seong Lee

The present study conducts the numerical investigation of flow characteristics and thermal performance of spiral finned-tube heat exchangers. The effects of location of perforations (90°, 120°, and 150°) on heat transfer and pressure drop are analyzed for the air-side. The commercial computational fluid dynamics code ANSYS Fluent (V.17.0) is used for simulations with the RNG k-ε model based on the Reynolds-averaged Navier–Stokes equations. The velocity field, Colburn j-factor, and friction factor are analyzed to evaluate the heat transfer and pressure drop characteristics. Because of the flow through the perforations, the boundary layers on the fin surfaces are interrupted. This results in increased flow disturbances close to the fin, and the heat transfer performance increases compared to the reference case. The pressure drop, which is one of the disadvantages of spiral finned tubes comparing to plate or circular fins, decreases with perforations on the fin. Overall, the cases with perforated fin exhibit greater performance of area goodness factor considering the relationship between the heat transfer and the pressure drop.


2017 ◽  
Vol 48 (4) ◽  
pp. 357-362
Author(s):  
Denis Vyacheslavovich Anokhin ◽  
Evgenia Sergeevna Dyagileva ◽  
Oleg Petrovich Minin ◽  
Dmitrii Aleksandrovich Olishevskii ◽  
Sergei Grigorievich Shevel'kov

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.


Author(s):  
Л. А. Кущев ◽  
В. Н. Мелькумов ◽  
Н. Ю. Саввин

Постановка задачи. Рассматривается теплообменный процесс, протекающий в модифицированном гофрированном межпластинном канале интенсифицированного пластинчатого теплообменного аппарата с повышенной турбулизацией теплоносителя. Необходимо разработать компьютерную модель движения теплоносителя в диапазоне скоростей 0,1-1,5 м/с и определить коэффициент турбулизации пластинчатого теплообменника. Результаты. Приведены результаты компьютерного моделирования движения теплоносителя в межпластинном гофрированном канале оригинального пластинчатого теплообменного аппарата с помощью программного комплекса Аnsys . Определены критерии устойчивости системы. Выполнено 3 D -моделирование канала, образуемого гофрированными пластинами. При исследовании процесса турбулизации были рассмотрены несколько скоростных режимов движения теплоносителя. Определен коэффициент турбулизации Tu, %. Выводы. В результате компьютерного моделирования установлено увеличение коэффициента теплопередачи К, Вт/(м ℃ ) за счет повышенной турбулизации потока, что приводит к снижению металлоемкости и уменьшению стоимости теплообменного оборудования. Statement of the problem. The heat exchange process occurring in a modified corrugated interplate channel of an intensified plate heat exchanger with an increased turbulence of the heat carrier is discussed. A computer model of the coolant movement in the speed range of 0.1-1.5 m/s is developed and the turbulence coefficient of the plate heat exchanger is determined. Results. The article presents the results of computer modeling of the coolant movement in the interplate corrugated channel of the original plate heat exchanger using the Ansys software package. The criteria of system stability are defined. 3D modeling of the channel formed by corrugated plates is performed. In the study of the process of turbulence several high-speed modes of movement of the coolant were considered. The turbulence coefficient Tu, % is determined. Conclusions. As a result of computer simulation, an increase in the heat transfer coefficient K, W/(m ℃) was found due to an increased turbulization of the flow, which leads to a decrease in metal consumption and a decrease in the cost of heat exchange equipment.


2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Satyender Singh ◽  
Prashant Dhiman

Thermal performance of a single-pass single-glass cover solar air heater consisting of semicircular absorber plate finned with rectangular longitudinal fins is investigated. The analysis is carried out for different hydraulic diameters, which were obtained by varying the diameter of the duct from 0.3–0.5 m. One to five numbers of fins are considered. Reynolds number ranges from 1600–4300. Analytical solutions for energy balance equations of different elements and duct flow of the solar air heater are presented; results are compared with finite-volume methodology based numerical solutions obtained from ansys fluent commercial software, and a fairly good agreement is achieved. Moreover, analysis is extended to check the effect of double-glass cover and the recycle of the exiting air. Results revealed that the use of double-glass cover and recycle operation improves the thermal performance of solar air heater.


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