Comparison of Tube-Tube Collision Frequency With and Without the Use of Impingement Plate

2018 ◽  
Author(s):  
Jiří Buzík ◽  
Tomáš Létal ◽  
Pavel Lošák ◽  
Martin Naď ◽  
Marek Pernica
Keyword(s):  
Heat Exchanger ◽  
Tube Bundle ◽  
Cross Flow ◽  
Data Bank ◽  
Shell Side ◽  
Ansys Fluent ◽  
Vibration Data ◽  
Impingement Plate ◽  
Computational Fluid Dynamics Analysis ◽  
Fluent Software

The aim of the present work is to carry out the checking of the tube bundle of heat exchanger for the occurrence of tube-tube collision caused by cross-flow vibration with and without the use of impingement plate. This will be achieved using numerical 2D CFD (computational fluid dynamics) analysis. The 2D analysis is done using ANSYS Fluent software. Tube movement in the shell side is provided by UDF (user-defined function) DEFINE_SDOF_PROPERTIES. By determining the stiffness and weight of the tubes, two-way fluid and tube interaction can be achieved. Due to limitations of 2D CFD analysis, only the occurrence of the tube-tube or tube-shell collisions can be observed. Unfortunately, the first collision causes termination of the simulation due to negative volumes in dynamic mesh. Possible solutions to the issue are also discussed in presented paper. The analyzed geometry of the shell side is taken from the Heat Exchanger Tube Vibration Data Bank [2]. This publication collects heat exchanger data for which vibration phenomena have been reported. The above-mentioned geometry is a domain with tube bundle at the shell side under the inlet. In the same domain, both the tie rod and the seal strips and the 45° turn of the partitions are considered.

scholarly journals Performance Analysis of a Countercurrent Flow Heat Exchanger Placed on the Truck Compartment Roof

2011 ◽  
Author(s):  
Wamei Lin ◽  
Jinliang Yuan ◽  
Bengt Sunde´n
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Cross Flow ◽  
Countercurrent Flow ◽  
Position Change ◽  
Power Requirement ◽  
Ansys Fluent ◽  
Pin Fin ◽  
Fluent Software ◽  
Flow Heat

Due to the increasing power requirement and the limited available space in vehicles, placing the heat exchanger at the roof or the underbody of vehicles might increase the possibility to handle the cooling requirement. A new configuration of the heat exchanger has to be developed to accommodate with the position change. In this paper, a countercurrent heat exchanger is developed for position on the roof of the vehicle compartment. In order to find an appropriate configuration of fins with high thermal performance on the air side, the CFD (computational fluid dynamics) approach is applied for a comparative study among louver fin, wavy fin, and pin fin by using ANSYS FLUENT software. It is found that the louver fin has high thermal performance and low pressure drop. Thus, the louver fin is chosen to be the configuration of the countercurrent heat exchanger, which presents higher heat transfer coefficient than a cross flow heat exchanger. For a specific case, the overall size and the air pumping power of the countercurrent flow heat exchanger is lower than that one for a cross flow heat exchanger. Several suggestions and recommendations are highlighted.

Numerical Analysis of Shell-Side Fluid Flow in Shell-and-Tube Heat Exchanger

2015 ◽  
Vol 797 ◽  
pp. 255-262
Author(s):  
Sławomir Alabrudziński
Keyword(s):  
Heat Exchanger ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Tube Bundle ◽  
Shell Side ◽  
Ansys Fluent ◽  
Tube Heat Exchanger ◽  
Calculation Results ◽  
Shell And Tube ◽  
Volume Method

This work presents velocity field and flow resistance analysis on shell-side of shell-and-tube heat exchanger. Numerical investigations have been carried out using a finite volume method implemented in ANSYS Fluent code. In case of heat exchangers with a great number of tubes in bundle, the finite volume method numerical model representing real geometry of the apparatus becomes very complex and results in a high computing power demand. To overcome the above difficulty, an attempt has been made to represent the tube bundle using the continuum approach. The resulting pressure drop values have been compared with e.g. calculation results using HTRI code and exemplary values obtained from the real apparatus.

Dynamic Characteristics of a Mistuned Heat Exchanger in Cross-Flow

2007 ◽  
Author(s):  
Bo-Wun Huang ◽  
Huang-Kuang Kung ◽  
Jao-Hwa Kuang
Keyword(s):  
Heat Exchanger ◽  
Shock Waves ◽  
Dynamic Characteristics ◽  
Tube Bundle ◽  
Cooling Water ◽  
Cross Flow ◽  
Water Film ◽  
Local Defect ◽  
Mode Localization ◽  
Localization Phenomenon

The dynamic behaviors of tubes of a heat exchanger are frequently affected by the existence of local flaw. These tubes are worn from the hot-cold fluid shock waves. This local defect may alter the tube dynamics and introduce mode localization in the periodically arranged tube array. The variation of the dynamic characteristics of a component cooling water heat exchanger with wear tubes in cross-flow is investigated in this study. Periodically coupled cooling tubes are used to approximate a heat exchanger. Each tube is considered to be coupled to adjacent tubes through the squeezed water film in the gaps. This work addresses the probability of mode localization is occurring in a heat exchanger in cross-flow. A dynamic model of the coupled tube bundle is proposed. The numerical results reveal that the local defect in a tube array may introduce the so-called mode localization phenomenon in a periodically coupled tube bundle.

Modeling and Simulation of Cross-Flow Induced Vibration in a Multi-Span Tube Bundle

2004 ◽  
Author(s):  
Shahab Khushnood ◽  
Zaffar M. Khan ◽  
M. Afzaal Malik ◽  
Zafarullah Koreshi ◽  
Mahmood Anwar Khan
Keyword(s):  
Heat Exchanger ◽  
Tube Bundle ◽  
Cross Flow ◽  
Fatigue Cracking ◽  
Acoustic Resonance ◽  
Computer Code ◽  
Variable Geometry ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Tube Bundles

Flow-induced vibration in steam generator and heat exchanger tube bundles has been a source of major concern in nuclear and process industry. Tubes in a bundle are the most flexible components of the assembly. Flow induced vibration mechanisms, like fluid-elastic instability, vortex shedding, turbulence induced excitation and acoustic resonance results in failure due to mechanical wear, fretting and fatigue cracking. The general trend in heat exchanger design is towards larger exchangers with increased shell side velocities. Costly plant shutdowns have been the motivation for research in the area of cross-flow induced vibration in steam generators and process exchangers. The current paper focuses on the development of a computer code (FIVPAK) for the design (natural frequencies, variable geometry, tube pitch & pattern, mass damping parameter, reduced velocity, strouhal and damage numbers, added mass, wear work rates, void fraction for two-phase, turbulence and acoustic considerations etc.) of tube bundles with respect to cross flow-induced vibration. The code has been validated against Tubular Exchanger Manufacturers (TEMA), Flow-Induced Vibration code (FIV), and results on an actual variable geometry exchanger, specially manufactured to simulate real systems. The proposed code is expected to prove a useful tool in designing a tube bundle and to evaluate the performance of an existing system.

Simulation of Tube Bundle Vibrations: A Numerical 3D-Method

2009 ◽  
Author(s):  
Christoph Reichel ◽  
Klaus Strohmeier
Keyword(s):  
Tube Bundle ◽  
Cross Flow ◽  
Flow Simulation ◽  
Beam Model ◽  
Large Displacements ◽  
Shell Side ◽  
Standard Methods ◽  
Single Cylinder ◽  
Ansys Cfx ◽  
3D Effects

The shell-side cross-flow in tubular heat exchangers may cause vibrations leading to failure within hours or in long term. Design is still based on half-empirical correlation, based on the equation of Connors (1978). Overdesign (Kassera 1996) and singular cases of damage (Fischer and Strohmeier, 2002) are the result. Therefore a structural model for the tube motions has been developed further and coupled to the commercial flow simulation code ANSYS CFX. The predictive capability of such coupled methods is limited by the flow simulation. Still simplifications or modeling are needed, especially for turbulence. The paper starts with an overview of modeling assumptions used so far. In addition to simulations of flow around rigid circular cylinders (Reichel and Strohmeier, 2008) LDA-measurements of flow through rigid glass-bundles have been compared to flow simulations. The sample of results presented below demonstrates that, besides level of fluctuations is predicted far too low, the overall velocity distribution on the shell side is predicted well by the SST turbulence model (Menter 1994), making URANS models like SST worth a try, if mainly flow forces are needed. To capture the tube dynamics an Euler-Bernoulli beam model of Fischer (2001), discretized by central differences in space and Newmark’s method (1959) in time, has been extended and implemented into ANSYS CFX. Calculations will be presented, showing that simulations of initially deflected tubes almost perfectly match analytic predictions. To adapt the numerical grid for the flow calculations to the tube displacements, the code inherent standard methods at large displacements resulted in negative volumes and solver failure. Therefore the standard methods have been replaced by own routines for grid deformation. Even for grids with fine near wall resolution, this method is able to cope with large displacements. Finally, coupled simulations are conducted of a single cylinder and of a cantilevered tube bundle in cross flow. For the single cylinder amplitudes are extremely overpredicted as long as 2D-modeling is used. 3D-modeling shows a phase shift of vortex shedding along the cylinder, which results in noticeably lower tube deflections. But, using the SST-model, amplitudes are still higher than measured. A model extension for laminar to turbulent transition leads to further improvement. The same holds for the tube bundle. Onset velocity of instability is predicted too low, amplitudes are too high. Modeling transition and large scale 3D-effects moves results closer to experimental observations. Further improvements are expected taking small scale 3D-effects into account by introducing more grid layers along the tubes.

Analysis of Flow Mal-Distribution in a Cross-Flow Heat Exchanger

2014 ◽  
Vol 592-594 ◽  
pp. 1428-1432 ◽  
Author(s):  
Krishna P. Mohan ◽  
Shekar M. Santosh ◽  
M. Ramakanth ◽  
M.R. Thansekhar ◽  
M. Venkatesan
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Cross Flow ◽  
Flow Distribution ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Uniform Flow Distribution ◽  
Flow Heat ◽  
Channel Assembly ◽  
Uniform Fluid

Flow mal-distribution is defined as the non-uniform fluid flow distribution among the parallel channels having a common header. Flow mal-distribution is present in every header channel assembly. This mal-distribution has a significant effect on the performance of the heat exchanger by increasing the pressure drop and affecting the heat transfer characteristics. However, in designing a heat exchanger, a uniform flow distribution in each channel is assumed. The present work attempts to reduce the flow mal-distribution in a cross flow heat exchanger. A numerical analysis is done using a commercial code ANSYS FLUENT 3D and the results are validated experimentally. A parametric study is done by changing the size of the channels within the heat exchanger so as to reduce the flow mal-distribution. The effect of varying channel size on flow mal-distribution and pressure drop across the heat exchanger is studied and a geometry with reduced flow mal-distribution is found.

Research on Stress Intensity of Variable Cross-Section H-Type Structure in Heat Exchanger with Longitudinal Flow of Shell Side

2015 ◽  
Vol 750 ◽  
pp. 166-171 ◽  
Author(s):  
Zun Chao Liu ◽  
Ke Wang ◽  
Xin Gu ◽  
Min Shan Liu
Keyword(s):  
Heat Exchanger ◽  
Cross Section ◽  
Maximum Stress ◽  
Tube Bundle ◽  
Plate Thickness ◽  
Variable Cross Section ◽  
Type Structure ◽  
Variable Cross ◽  
Shell Side ◽  
Ring Plate

The variable cross-section H-type structure, which is used in the new type of heat exchanger with longitudinal flow of shell side, could reduce the scour action of imports fluid on the tube bundle and prevent vibration of the tube bundle. It could also improve the state of the shell side fluid flow, reducing the flow dead zone, allowing for a more efficient use of the heat transfer area and improving the energy efficiency. The new structure will make the temperature and stress distribution in the heat distribution more complex, so it is necessary to analyze the stress intensity of the variable cross-section H-type structure. A three-dimensional finite element model of the variable cross-section H-type structure is established in this paper, and the surface temperature of the various parts of the heat exchanger are determined through temperature analysis. Using ANSYS Workbench software, thermal-stress analysis of the H -type structure with different structural parameters is tested, and the temperature and stress field are obtained. The results show that a Ring plate of H-type structure has a larger temperature gradient along the thickness direction. The maximum stress of the heat exchanger is 203.13 MPa, which occurred on the connections of the ring plate and jacket in the lower temperature side. The ring plate thickness of the H-type structure has a significant influence on its maximum stress. Therefore, a reasonable selection of ring plate thickness is important for the safety of the heat exchanger.

scholarly journals DOE/ANL/HTRI heat exchanger tube vibration data bank

1980 ◽  
Author(s):  
H. Halle ◽  
J.M. Chenoweth ◽  
M.W. Wambsganss
Keyword(s):  
Heat Exchanger ◽  
Data Bank ◽  
Heat Exchanger Tube ◽  
Vibration Data ◽  
Exchanger Tube
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