A Unified Analytical Method of Stress Analysis for Tubesheet—Part III: Applicable Configuration of Heat Exchanger

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Hongsong Zhu ◽  
Jinguo Zhai
Keyword(s):  
Heat Exchanger ◽  
Stress Analysis ◽  
Analytical Method ◽  
Heat Exchangers ◽  
Wide Range ◽  
Edge Conditions

Based on the unified analytical (UA) method and the unified and refined analytical (URA) method of stress analysis for fixed tubesheet (TS) heat exchangers (HEXs), floating head, and U-tube HEXs, the applicable configuration of HEX which depends on the combination of the TS edge conditions is discussed in this paper. Comparison shows that the UA and the URA methods cover a wide range of HEX configurations well beyond established ASME methods.

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.

A Unified Analytical Method of Stress Analysis for Tubesheet—Part II: Case Study

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Hongsong Zhu
Keyword(s):  
Stress Analysis ◽  
Analytical Method ◽  
Heat Exchangers ◽  
Numerical Comparison ◽  
Element Analysis ◽  
Comparison Results ◽  
Different Types ◽  
The Unified Method ◽  
Unified Method

Based on the unified analytical method of stress analysis for fixed tubesheet (TS) heat exchangers (HEX), floating head and U-tube HEX presented in Part I, numerical comparisons with ASME method are performed in this paper as Part II. Numerical comparison results indicate that predictions given by the unified method agree well with finite element analysis (FEA), while ASME results are not accurate or not correct. Therefore, it is concluded that the unified method deals with thin TS of different types of HEX in equal detail with confidence to predict design stresses.

Multiscale Simulations of Fluid Flow for Finned Elliptic Tube Heat Exchangers Using Porous Media Approach

2014 ◽  
Author(s):  
T. Qu ◽  
T. Ma ◽  
M. Zeng ◽  
Y. T. Chen ◽  
Q. W. Wang
Keyword(s):  
Porous Media ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Hydrodynamic Characteristics ◽  
Original Structure ◽  
Tube Heat Exchanger ◽  
Fast Running ◽  
Simple Geometry ◽  
Wide Range ◽  
Experimental Effort

A numerical finned elliptic tube heat exchanger (FETHE) model was proposed to investigate the hydrodynamic characteristics of a full-size FETHE by using the porous media approach. A finned elliptic tube heat exchanger was modeled in such a way that the details of the original structure were replaced by a simple geometry, so that the governing equations can be efficiently solved for a wide range of parameters. The first part of the paper reports there-dimensional numerical optimization results for two fins of elliptic tube arrangements, which are validated by direct comparison with experimental measurements with good agreement. The second part of the paper presents different numbers of fins or tubes arrangements to identify this method. The results are reported for air as the external fluid, in the range 1765≤ReL≤12611, where L is the swept length of the fixed volume. The objective is to show the process of heat exchangers being modeled as a porous media and CFD being used in place of a detailed, experimental effort to obtain closure for the model. Apparently, in order to develop a universal fast running computational tool for complicated heat exchangers with multiple parameter, our current work is a step closer to this goal.

OPTIMIZATION OF HEAT EXCHANGERS FOR GEOTHERMAL DISTRICT HEATING

2009 ◽  
Vol 33 (2) ◽  
pp. 239-256
Author(s):  
P. Bahadorani ◽  
G. F. Naterer ◽  
S. B. Nokleby
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
District Heating ◽  
Heating System ◽  
Power Input ◽  
Design Tool ◽  
Geothermal Systems ◽  
District Heating System ◽  
Wide Range ◽  
Net Profit

This paper analyzes the optimal configuration and operating parameters of a heat exchanger in a geothermal district heating system. An optimization algorithm is presented for the nonlinear constrained problem to maximize the annual net profit for a system of counter-flow heat exchangers. Several parameters that affect the net profit are examined, including the mass flow rates of working fluids and heat transfer area, which both directly affect the outgoing temperatures. The performance of the heat exchanger and fuel savings by reducing fuel consumption to generate heat are modeled within the problem formulation. Also, power input to the pump for fluid circulation is included. By formulating these multiple parameters over a wide range of design conditions, the algorithm presents a useful new design tool for the improvement of heat exchanger networks in geothermal systems.

Flow Modifiers for Preventing Sedimentation in Heat Exchangers

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Timo Kulju ◽  
Markus Riihimäki ◽  
Tiina M. Pääkkönen ◽  
Ossi Vilhunen ◽  
Kyösti Lipiäinen ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Flow Fields ◽  
Particulate Material ◽  
Cfd Modeling ◽  
Shear Stresses ◽  
Tube Heat Exchanger ◽  
Critical Areas ◽  
Wide Range ◽  
Wall Shear

Heat exchangers are commonly used in process industries; however, fouling, such as sedimentation of particulate material is a significant challenge hindering the efficient use of heat exchangers in a wide range of industrial processes. This research studied the prevention of sedimentation in tube heat exchanger header sections, which typically are the critical areas for sediment accumulation. Numerous flow modifiers were explored, of which the most advantageous ones are presented in this paper. The study included construction and analysis of a miniature, validation of the used CFD model, and finally simulating an industrial scale heat exchanger. This research considered both flow fields and wall shear stresses for reducing sedimentation. The study showed that CFD models are capable of describing flow fields and their spatial variations in heat exchangers especially in their header sections. The selected flow modifier setups increased wall shear stresses in critical areas and hence reduced sedimentation. The presented solution consisted of utilizing different flow modifiers, filling elements, and their combinations. Industry should consider utilizing flow modifiers in heat exchangers as a potential solution to prevent sedimentation. Industrial cases are worth analyzing by using miniatures and CFD modeling. Analyses should pay special attention to flow fields and wall shear stresses. Heat exchangers include also other fouling mechanisms beside sedimentation; however, further study is required to clarify how flow modifiers influence these mechanisms.

A Unified Analytical Method of Stress Analysis for Tubesheet—Part I: Theoretical Foundation

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Hongsong Zhu
Keyword(s):  
Stress Analysis ◽  
Analytical Method ◽  
Numerical Comparison ◽  
Design Standards ◽  
Element Analysis ◽  
Technical Literature ◽  
Edge Conditions ◽  
The Unified Method ◽  
Special Case ◽  
Unified Method

Based on a brief review of existing tubesheet (TS) design standards and the pertinent technical literature, a unified analytical method of stress analysis for fixed TS heat exchangers (HEXs), floating head and U-tube HEXs is proposed by removing the midplane symmetry (MPS) assumption, which assumes a geometric and loading plane of symmetry at the midway between the two TSs so that only half of the HEX or one TS needs be considered. The unified method can be successfully extended to the situations for different TS materials, unequal TS thicknesses, different TS edge conditions, different TS temperatures, pressures drop and dead weights on two TSs. The effects of pressure in TS perforations and temperature gradient in TS thickness direction are also considered by the unified method. Theoretical comparison shows that ASME method can be obtained from the special case of the simplified mechanical model of the unified method. Numerical comparison indicates that predictions given by the unified method agree well with finite element analysis (FEA), while ASME results are not accurate or not correct.

Refined General Theory of Stress Analysis for Tubesheet

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Hongsong Zhu
Keyword(s):  
General Theory ◽  
Stress Analysis ◽  
Heat Exchangers ◽  
Numerical Comparison ◽  
Refined Theory ◽  
Element Analysis ◽  
Comparison Results ◽  
Special Cases ◽  
Edge Conditions ◽  
Plate On Elastic Foundation

The stress analysis method for fixed tubesheet (TS) heat exchangers (HEX) in pressure vessel codes such as ASME VIII-1, EN13445, and GB151 is based on the classical theory of thin plate on elastic foundation. In addition, these codes all assume a geometric and loading plane of symmetry at the midway between the two TSs so that only half of the unit or one TS is needed to be considered. In this study, a refined general theory of stress analysis for TS is presented which also considers unequal thickness for two TSs, different edge conditions, pressure drop and deadweight on two TSs, the anisotropic behavior of the TS in thickness direction, and transverse shear deformation in TS. Analysis shows floating and U-tube heat exchangers are the two special cases of the refined theory. Theoretical comparison shows that ASME method can be obtained from the special case of the simplified mechanical model of the refined theory. Numerical comparison results indicate that predictions given by the refined theory agree well with finite element analysis (FEA) for both thin and thick TS heat exchangers, while ASME results are not accurate or not correct. Therefore, it is concluded that the presented refined general theory provides a single unified method, dealing with both thin and thick TSs for different type (U type, floating, and fixed) HEXs in equal detail, with confidence to predict design stresses.

scholarly journals The Increasing Role of Heat Exchangers in Gas Turbine Plants

1989 ◽  
Author(s):  
Colin F. McDonald
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Electrical Power ◽  
Plant Performance ◽  
Simple Cycle ◽  
Inlet Temperature ◽  
Full Spectrum ◽  
Wide Range ◽  
Prime Movers

In the introductory phase of gas turbine deployment for industrial service there was a natural reluctance to incorporate heat exchangers, although some variants included recuperators and intercoolers to enhance performance, since only modest values of compressor and turbine efficiency could be realized. Today, following half a century of intensive development, the situation is quite different, since high turbomachinery efficiencies contribute to attractive levels of performance for contemporary simple cycle plants. Because further aerodynamic advancements are likely to be incremental in nature, significant increase in plant performance can only be realized by either going to higher turbine inlet temperature, or utilizing more complex thermodynamic cycles, or both. It is in the latter two cases that heat exchangers will play an increasing role in the evolutionary advancement of gas turbine plant efficiency. This paper highlights the potential use of heat exchangers for a wide range of gas turbine applications, including industrial prime-movers, electrical power generation, marine service, and perhaps their ultimate use in aircraft propulsion systems. In the last decade, significant heat exchanger technology advancements have been made, to the point where previous impediments (to their widespread acceptance) associated with reliability, have been overcome. It is encouraging that today many proven heat exchanger hardware options are available to gas turbine users, and this will enhance their utilization across the full spectrum of applications, and indeed in the long-term may well make the simple cycle gas turbine obsolete.

Thermal-Hydraulic Characterization of Shell-Side Flow in a Cryogenic Coiled Finned-Tube Heat Exchanger

2021 ◽  
Author(s):  
Jonathon Howard ◽  
Nusair Hasan ◽  
Peter Knudsen
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Flow Region ◽  
Finned Tube ◽  
Shell Side ◽  
Improve Design ◽  
Tube Heat Exchanger ◽  
Finned Tube Heat Exchanger ◽  
Wide Range ◽  
Side Flow

Abstract Coiled finned-tube heat exchangers, also called Collins type heat exchangers, are frequently used in small to medium scale cryogenic systems to improve design packaging (compactness) while maintaining high thermal effectiveness. A typical heat exchanger assembly of this kind consists of an inner cylindrical shell, called the mandrel, with helical finned-tube coils wrapped around it, and then enclosed by an outer shell. One flow paths is through the helically wrapped tube, and the other flow path through annular flow region of the tubes. These are also known as tube and shell streams, respectively. An accurate description of the shell-side thermal-hydraulic flow characteristics is a necessary part of the heat exchanger design. In this paper, these characteristics for cryogenic gaseous nitrogen, between 300 to 100 K, are numerically investigated. A computational fluid dynamics model of the shell-side geometry is developed and validated. Simulations are carried out for a wide range of flow conditions. Data obtained from the numerical simulations are used to form correlations between the shell-side Reynolds number (Re), Fanning friction factor (f), and Chilton-Colburn factor (j). In addition, the effect of geometrical variance on the correlation was investigated. The results from this study show reasonable agreement with experimental data.

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