Numerical Study of Flow Deflection and Horseshoe Vortices in a Louvered Fin Round Tube Heat Exchanger

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
H. Huisseune ◽  
C. T’Joen ◽  
P. De Jaeger ◽  
B. Ameel ◽  
J. Demuynck ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Two Dimensional ◽  
Round Tube ◽  
Tube Heat Exchanger ◽  
Louvered Fin ◽  
Flow Deflection

In louvered fin heat exchangers, the flow deflection influences the heat transfer rate and pressure drop and thus the heat exchanger’s performance. To date, studies of the flow deflection are two-dimensional, which is an acceptable approximation for flat tube heat exchangers (typical for automotive applications). However, in louvered fin heat exchangers with round tubes, which are commonly used in air-conditioning devices and heat pumps, the flow is three-dimensional throughout the whole heat exchanger. In this study, three-dimensional numerical simulations were performed to investigate the flow deflection and horseshoe vortex development in a louvered fin round tube heat exchanger with three tube rows in a staggered layout. The numerical simulations were validated against the experimental data. It was found that the flow deflection is affected by the tubes in the same tube row (intratube row effect) and by the tubes in the upstream tube rows (intertube row effect). Flow efficiency values obtained with two-dimensional studies are representative only for the flow behavior in the first tube row of a staggered louvered fin heat exchanger with round tubes. The flow behavior in the louvered elements of the subsequent tube rows differs strongly due to its three-dimensional nature. Furthermore, it was found that the flow deflection affects the local pressure distributions upstream of the tubes of the downstream tube rows and thus the horseshoe vortex development at these locations. The results of this study are important because the flow behavior is related to the thermal hydraulic performance of the heat exchanger.

Three-Dimensional Simulations of the Flow Deflection in a Louvered Fin Heat Exchanger With Round Tubes in a Staggered Arrangement

2011 ◽  
Author(s):  
Henk Huisseune ◽  
Christophe T’Joen ◽  
Peter De Jaeger ◽  
Bernd Ameel ◽  
Michel De Paepe
Keyword(s):  
Heat Exchanger ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Flow Behaviour ◽  
Local Pressure ◽  
Tube Heat Exchanger ◽  
Pressure Distributions ◽  
Louvered Fin ◽  
Staggered Arrangement ◽  
Flow Deflection

In this study three-dimensional numerical simulations were performed to investigate the flow deflection and its influence on the horseshoe vortex development in a louvered fin round tube heat exchanger with three tube rows in a staggered layout. The numerical results are validated against experimental data. It was found that the flow deflection is affected by the tubes in the same tube row and by the tubes in the upstream tube rows. The flow efficiency values obtained with two-dimensional studies are only representative for the flow behaviour in the first tube row of a staggered louvered fin heat exchanger with round tubes. The flow behaviour in the louvered elements of the subsequent tube rows differs strongly due to its three dimensional nature. Furthermore it was found that the flow deflection affects the local pressure distributions upstream the tubes of the downstream tube rows which explains the stronger horseshoe vortex system at these locations.

CFD Modeling of Plate Louvered Fin Heat Exchangers

2011 ◽  
Author(s):  
Julio Medina ◽  
Antonio J. Bula ◽  
Guillermo Valencia
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermal Field ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Hydraulic Behavior ◽  
F Factor ◽  
Louvered Fin ◽  
Three Dimensional Simulations

The flow and thermal field for Brazed Plate Fin Heat Exchanger (BPFHE) at the air side is presented in this study. Three-dimensional simulations of computational fluid dynamics were developed on a triangular section channel for the heat exchanger considered. The simulation of the fin is done for a given geometry and compared with experimental data presented by other authors, then a plane is raised keeping the original geometry and louver walls are included. The air-side performance of the heat exchanger and the hydraulic behavior is evaluated by calculating the Colburn (j) and frictional (f) factor. The result for the fin showed a deviation close to 3% when compared to experimental data for similar geometries from Keys & London. The results show how the turbulence highly increases the heat transfer phenomena.

Turbulent Flow in a No-Tube-in-Window Shell-and-Tube Heat Exchanger: CFD vs PIV

2014 ◽  
Author(s):  
Salem Bouhairie ◽  
Siddharth Talapatra ◽  
Kevin Farrell
Keyword(s):  
Heat Exchanger ◽  
Mechanical Design ◽  
Tube Bundle ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Adiabatic Flow ◽  
Tube Heat Exchanger ◽  
Shell And Tube

A research-scale shell-and-tube heat exchanger housing a no-tube-in-window (NTIW) arrangement of tubes is analyzed using ANSYS® FLUENT. Three-dimensional, computational fluid dynamic (CFD) simulations of adiabatic flow in a periodic section of the exchanger were conducted. The numerical results were compared to particle image velocimetry (PIV) measurements in the window region where tubes are not present. As part of the study, the k-epsilon with scalable wall function, k-omega with shear stress transport (SST), Reynolds Stress (RSM), and Scale Adaptive Simulation (SAS) turbulence models were assessed. Each turbulence model showed some similarities with the recorded phenomena, but none fully captured the complexity of flow field outside of the tube bundle. Additional simulations of an entire NTIW exchanger model were performed to examine the flow behavior between the window and crossflow regions, as window momentum flux, ρu2, limits are a concern for safe mechanical design.

scholarly journals Thermo-Hydraulic Performance Evaluation of Shell & Tube Heat Exchanger with Different Tube Geometries

2019 ◽  
Vol 9 (1) ◽  
pp. 2125-2132
Keyword(s):  
Heat Exchanger ◽  
Cross Sections ◽  
Heat Exchangers ◽  
Power Plants ◽  
Waste Heat ◽  
Flow Behavior ◽  
Hydraulic Performance ◽  
Fluid Stream ◽  
Ansys Fluent ◽  
Tube Heat Exchanger

A heat exchanger is equipment that transfers heat energy from one fluid stream to another fluid stream across a solid surface by conduction and convection. Heat exchangers are used in air conditioning & refrigeration systems, power plants, automotive industries, chemical processing, waste heat recovery systems, and food industries. Shell & tube heat exchangers are the most widely used heat exchanger. Earlier many types of studies were carried out on baffle of heat exchanger, as the hydraulic performance of shell side of exchanger relies on baffle elements such as changing baffle types, baffle segments, baffle angles, baffle cuts, etc. are introduced. But only a few researches are concentrated on the tube side. In this paper, efforts have been made to design a shell & tube heat exchanger by using the kern method & referring TEMA standards. Also, the fluid flow behavior & heat transfer mechanism of shell & tube heat exchanger with four different cross-sections of the tubes i.e. Circular, Rectangular, Square & Triangular is numerically investigated using ANSYS-fluent. Numerical simulation was carried out for a single tube pass shell & tube heat exchanger with 25% baffle cut. Finally, from the simulation results, suggestions are made for the best geometry which gives the best thermo-hydraulic performance

Experimental and Numerical Investigations on Louvered Fin-and-Tube Heat Exchanger With Variable Geometrical Parameters

2017 ◽  
Vol 9 (2) ◽  
Author(s):  
Kourosh Javaherdeh ◽  
Ahmad Vaisi ◽  
Rouhollah Moosavi ◽  
Mehdi Esmaeilpour
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Geometrical Parameters ◽  
Flow Conditions ◽  
Tube Heat Exchanger ◽  
Numerical Investigations ◽  
Louvered Fin ◽  
Fin Length

The effects of geometrical arrangement on the heat transfer and pressure drop characteristics in compact louvered fin-and-tube heat exchangers were studied experimentally and numerically along with ε−NTU method. Different geometrical parameters including louver angle, louver pitch, louver number, the nonlouvered inlet and exit fin length, and redirection of fluid flow are considered to determine their effects on the flow field. The study is performed for different louver angles varying from θL=12 to 60 deg, and optimal heat transfer rate is obtained at louver angle of θL=28deg. Also, it is found that increasing the louver number, NL, on the fin surface enhances the heat transfer performance. It is shown that the average Nusselt number is increased as the louver pitch is decreased and its optimum value is obtained at Lp=0.9 mm. However, comparing to the effect of louver number, the louver pitch has a small effect on the performance of the heat exchanger. Additionally, the optimum values of nonlouvered inlet and exit fin length and redirection length of fin are obtained with different flow conditions.

scholarly journals Effect of buried depth on thermal performance of a vertical U-tube underground heat exchanger

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 327-330
Author(s):  
Li Yang ◽  
Bo Zhang ◽  
Jiří Jaromír Klemeš ◽  
Jie Liu ◽  
Meiyu Song ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Simplified Model ◽  
Two Dimensional ◽  
Construction Sites ◽  
Full Size ◽  
Unit Depth ◽  
Research Show

Abstract Many researchers numerically investigated U-tube underground heat exchanger using a two-dimensional simplified pipe. However, a simplified model results in large errors compared to the data from construction sites. This research is carried out using a three-dimensional full-size model. A model validation is conducted by comparing with experimental data in summer. This article investigates the effects of fluid velocity and buried depth on the heat exchange rate in a vertical U-tube underground heat exchanger based on fluid–structure coupled simulations. Compared with the results at a flow rate of 0.4 m/s, the results of this research show that the heat transfer per buried depth at 1.0 m/s increases by 123.34%. With the increase of the buried depth from 80 to 140 m, the heat transfer per unit depth decreases by 9.72%.

Analysis of the Thermal Stress at the Tubesheet in Floating-Head or U-Tube Heat Exchangers

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Jiuyi Liu ◽  
Caifu Qian ◽  
Huifang Li
Keyword(s):  
Thermal Stress ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Influence Factors ◽  
Area Ratio ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Numerical Tests ◽  
Hole Area

Thermal stress is an important factor influencing the strength of a heat exchanger tubesheet. Some studies have indicated that, even in floating-head or U-tube heat exchangers, the thermal stress at the tubesheet is significant in magnitude. For exploring the value, distribution, and the influence factors of the thermal stress at the tubesheet of these kind heat exchangers, a tubesheet and triangle arranged tubes with the tube diameter of 25 mm were numerically analyzed. Specifically, the thermal stress at the tubesheet center is concentrated and analyzed with changing different parameters of the tubesheet, such as the temperature difference between tube-side and shell-side fluids, tubesheet diameter, thickness, and the tube-hole area ratio. It is found that the thermal stress of the tubesheet of floating-head or U-tube heat exchanger was comparable in magnitude with that produced by pressures, and the distribution of the thermal stress depends on the tube-hole area and the temperature inside the tubes. The thermal stress at the center of the tubesheet surface is high when tube-hole area ratio is very low. And with increasing the tube-hole area ratio, the stress first decreases rapidly and then increases linearly. A formula was numerically fitted for calculating the thermal stress at the tubesheet surface center which may be useful for the strength design of the tubesheet of floating-head or U-tube heat exchangers when considering the thermal stress. Numerical tests show that the fitted formula can meet the accuracy requirements for engineering applications.

scholarly journals Numerical Simulation of Plain Fin-and-Round Tube Heat Exchanger under Frost Condition

2010 ◽  
Author(s):  
Amar Ali Hussein ◽  
A. R Abu Talib ◽  
N. M Adam ◽  
M. A. Wahid ◽  
S. Samion ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Heat Exchanger ◽  
Round Tube ◽  
Tube Heat Exchanger

scholarly journals Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness

2016 ◽  
Vol 37 (4) ◽  
pp. 137-159 ◽  
Author(s):  
Rafał Andrzejczyk ◽  
Tomasz Muszyński
Keyword(s):  
Heat Transfer ◽  
Surface Modification ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Helical Structure ◽  
Nuclear Industry ◽  
Helical Coil ◽  
Tube Heat Exchanger ◽  
High Heat Transfer ◽  
Coil Heat

Abstract The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow inside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.

Sign in / Sign up

Export Citation Format

Share Document