scholarly journals Dynamic Characteristics of Heat Exchanger Tubes Vibrating in a Tube Support Plate Inactive Mode

1986 ◽  
Vol 108 (3) ◽  
pp. 256-266 ◽  
Author(s):  
J. A. Jendrzejczyk
Keyword(s):  
Experimental Study ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Damping Ratio ◽  
Steam Generators ◽  
Support Plate ◽  
Interaction Dynamics ◽  
Fabrication Tolerances ◽  
Shell And Tube ◽  
Inactive Mode

Tubes in shell-and-tube heat exchangers, including nuclear plant steam generators, derive their support from longitudinally positioned tube support plates (TSPs). Typically, there is a clearance between the tube and TSP hole. Depending on design and fabrication tolerances, the tube may or may not contact all of the TSPs. Non-contact results in an inactive TSP which can lead to detrimental flow-induced tube vibrations under certain conditions dependent on the resulting tube-TSP interaction dynamics and the fluid excitation forces. The purpose of this study is to investigate the tube-TSP interaction dynamics. Results of an experimental study of damping and natural frequency as functions of tube-TSP diametral clearance and TSP thickness are reported. Calculated values of damping ratio and frequency of a tube vibrating within an inactive TSP are also presented together with a comparison of calculated and experimental quantities.

scholarly journals A Theory for Fluidelastic Instability of Tube-Support-Plate-Inactive Modes

1992 ◽  
Vol 114 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Y. Cai ◽  
S. S. Chen ◽  
S. Chandra
Keyword(s):  
Heat Exchangers ◽  
Linear Models ◽  
Cross Flow ◽  
Bilinear Model ◽  
Steam Generators ◽  
Unstable Region ◽  
Fluid Forces ◽  
Support Plate ◽  
Fluidelastic Instability ◽  
Inactive Mode

Fluidelastic instability of loosely supported tubes, vibrating in a tube support plate (TSP)-inactive mode, is suspected to be one of the main causes of tube failure in some operating steam generators and heat exchangers. This paper presents a mathematical model for fluidelastic instability of loosely supported tubes exposed to nonuniform cross flow. The model incorporates all motion-dependent fluid forces based on the unsteady-flow theory. In the unstable region associated with a TSP-inactive mode, tube motion can be described by two linear models: TSP-inactive mode when tubes do not strike the TSP, and TSP-active mode when tubes do strike the TSP. The bilinear model (consisting of these linear models) presented here simulates the characteristics of fluidelastic instability of loosely supported tubes in stable and unstable regions associated with TSP-inactive modes. Analytical results obtained with the model are compared with published experimental data; they agree reasonably well. The prediction procedure presented for the fluidelastic instability response of loosely supported tubes is applicable to the stable and unstable regions of the TSP-inactive mode.

scholarly journals Performance Analysis and Design Optimization of Shell and Tube Heat Exchangers

2021 ◽  
Author(s):  
praveen math
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Pressure Loss ◽  
Fluid Flows ◽  
Hot Water ◽  
Flow Conditions ◽  
Shell Side ◽  
Shell And Tube ◽  
Side Flow

Abstract Shell and Tube heat exchangers are having special importance in boilers, oil coolers, condensers, pre-heaters. They are also widely used in process applications as well as the refrigeration and air conditioning industry. The robustness and medium weighted shape of Shell and Tube heat exchangers make them well suited for high pressure operations. The aim of this study is to experiment, validate and to provide design suggestion to optimize the shell and tube heat exchanger (STHE). The heat exchanger is made of acrylic material with 2 baffles and 7 tubes made of stainless steel. Hot fluid flows inside the tube and cold fluid flows over the tube in the shell. 4 K-type thermocouples were used to read the hot and cold fluids inlet and outlet temperatures. Experiments were carried out for various combinations of hot and cold water flow rates with different hot water inlet temperatures. The flow conditions are limited to the lab size model of the experimental setup. A commercial CFD code was used to study the thermal and hydraulic flow field inside the shell and tubes. CFD methodology is developed to appropriately represent the flow physics and the procedure is validated with the experimental results. Turbulent flow in tube side is observed for all flow conditions, while the shell side has laminar flow except for extreme hot water temperatures. Hence transition k-kl-omega model was used to predict the flow better for transition cases. Realizable k- epsilon model with non-equilibrium wall function was used for turbulent cases. Temperature and velocity profiles are examined in detail and observed that the flow remains almost uniform to the tubes thus limiting heat transfer. Approximately 2/3 rd of the shell side flow does not surround the tubes due to biased flow contributing to reduced overall heat transfer and increased pressure loss. On the basis of these findings an attempt has been made to enhance the heat transfer by inducing turbulence in the shel l side flow. The two baffles were rotated in opposite direction to each other to achieve more circulation in the shell side flow and provide more contact with tube surface. Various positions of the baffles were simulated and studied using CFD analysis and th e results are summarized with respect to heat transfer and pressure loss.

scholarly journals Experimental Study of Hydraulically Expanded Tube-to-Tubesheet Joints for Shell-and-Tube Heat Exchangers

2015 ◽  
Vol 130 ◽  
pp. 263-274 ◽  
Author(s):  
H. Ma ◽  
H.J. Yu ◽  
C.F. Qian ◽  
Z.S. Liu ◽  
J.X. Zhou
Keyword(s):  
Experimental Study ◽  
Heat Exchangers ◽  
Shell And Tube

The Stress Analysis of Heat Exchanger Expansion Joints in the Elastic Range

1973 ◽  
Vol 95 (1) ◽  
pp. 145-150 ◽  
Author(s):  
L. J. Wolf ◽  
R. M. Mains
Keyword(s):  
Heat Exchanger ◽  
Stress Analysis ◽  
Strain Gage ◽  
Analytical Method ◽  
Heat Exchangers ◽  
Expansion Joints ◽  
Elastic Range ◽  
Shell And Tube ◽  
Strain Gage Tests

Expansion joints of the style most commonly used in shell and tube heat exchangers were studied analytically and experimentally in the elastic range. A method of computing stresses and deformations for pressure and expansion loadings is demonstrated. Strain-gage tests show the analytical method to be accurate.

Modelling the Transient Behaviour of Heat Recovery Steam Generators

1995 ◽  
Vol 209 (4) ◽  
pp. 265-273 ◽  
Author(s):  
P J Dechamps
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Computation Time ◽  
Assisted Circulation ◽  
Steam Generators ◽  
Two Phase ◽  
Linear Heat ◽  
Numerical Predictions ◽  
Equivalent Linear

This paper describes a method used to compute the transient performances of assisted circulation heat recovery steam generators. These heat recovery steam generators are composed of several heat exchangers, each of which is a bundle of tubes. The method presented here treats each heat exchanger in a similar way, replacing the bundle of tubes with an ‘equivalent’ linear heat exchanger. This equivalent linear heat exchanger is then discretized in as many slices as required by the accuracy. The mass and enthalpy equations on each of these control volumes are solved by a fully explicit numerical method, adapted for the special conditions encountered in this kind of problem, allowing a considerable reduction of the computation time compared to other methods. Some emphasis is put on the modifications required to solve the equations for the evaporators because they are two-phase heat exchangers. A model for the steam drums is also presented together with simple models for the main control loops used in such systems. An example is presented in which an existing dual pressure level heat recovery steam generator is started from a cold state. The numerical predictions are in good agreement with measurements.

Comparative Experimental Study on Performance of Corrugated Tube and Straight Tube Heat Exchanger

2012 ◽  
Vol 560-561 ◽  
pp. 156-160
Author(s):  
Lin Ping Lu ◽  
Liang Ying
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Straight Tube ◽  
Lower Stress ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Corrugated Tube

The experiments on heat transfer coefficient, pressure drop and thermal stress were done to heat exchangers with corrugated tubes and staight tubes. By analyising and comparing the heat transfer coeffient, pressure drop in tube side and shell side and axial force and stress, some conclusions can be conducted that the corrugated tube heat exchanger has better heat transfer coeffient, higher pressure drop and much lower stress caused by temperatur difference, also, it has obvious advantages under the circumstance of low Reynolds number and high temperature difference.

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