scholarly journals Investigation of а stress-strained state of a screw-shape tubes of heat exchangers

2020 ◽  
pp. 13-23
Author(s):  
Serhii Pyskunov ◽  
Serhii Trubachev ◽  
Oleksandr Baranyuk
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Strain State ◽  
Air Flow ◽  
Strained State ◽  
Test Task ◽  
Geometric Characteristics ◽  
Simulation Results ◽  
Brass Screw

Based on the results of the study of the parameters of the air flow inside of the brass screw-shape tube of the heat exchanger, the determination of their optimal geometric characteristics and further modeling of the stress-strain state was performed. Verification of simulation results is carried out on the basis of comparison with the test task.

Design and Analysis of Thermoacoustic Refrigerators Using Air as Working Substance

2019 ◽  
Vol 27 (01) ◽  
pp. 1950008 ◽  
Author(s):  
B. G. Prashantha ◽  
S. Seetharamu ◽  
G. S. V. L. Narasimham ◽  
M. R. Praveen Kumar
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Low Cost ◽  
Design Strategies ◽  
Software Simulation ◽  
Design And Optimization ◽  
Theoretical Design ◽  
Resonator Design ◽  
Simulation Results ◽  
Thermoacoustic Refrigerators

In this paper, the design of 50 W thermoacoustic refrigerators operating with air as working substance at 10 bar pressure and 3% drive ratio for a temperature difference of 28 K is described. The design strategies discussed in this paper help in design and development of low cost thermoacoustic coolers compared to helium as the working substance. The design and optimization of spiral stack and heat exchangers, and the promising 0.2[Formula: see text] and 0.15[Formula: see text] resonator design with taper and divergent section with hemispherical end are discussed. The surface area, volume, length and power density of the hemispherical end design with air as working substance is found better compared to the published 10 and 50 W coolers using helium as the working substance. The theoretical design results are validated using DeltaEC software simulation results. The DeltaEC predicts 51.4% improvement in COP (1.273) at the cold heat exchanger temperature of [Formula: see text]C with air as working substance for the 50[Formula: see text]W 0.15[Formula: see text]TDH resonator design compared to the published 50[Formula: see text]W 0.25[Formula: see text]TDH resonator design with helium as working substance.

Geometrical optimization of bare tube heat exchangers for process industries

2005 ◽  
Vol 219 (2) ◽  
pp. 139-147
Author(s):  
T. Q. Ma ◽  
K. T. Ooi ◽  
T. N. Wong
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Optimization Design ◽  
Design Method ◽  
Outer Diameter ◽  
Process Industries ◽  
Performance Improvements ◽  
Geometrical Optimization ◽  
Simulation Results ◽  
Bare Tube

This paper presents simulation results on the geometrical optimization design of bare tube heat exchangers. By linking a mathematical model with an optimization alogorithm, it is possible to predict which combination of five geometrical variables would produce a given coil capacity of a heat exchanger, the minimum core volume size operating at the minimum pressure drop. A constrained multivariable direct search technique is used in which the five geometrical variables and a mixture of five explicit and implicit constraints are accommodated. Using this design method, three typical sizes of bare tube optimization cases have been studied. The simulation results predict significant performance improvements for heat exchanger design. The range of tube outer diameter in this optimization study is from 4.9 to 9.0 mm.

Deflections of A Multipass Shell-and-Tube Heat Exchanger Bolted Joint Subjected to Nonaxisymmetric Thermal Loading

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Natalia Petrova ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermal Loading ◽  
Cocurrent Flow ◽  
Finite Element Models ◽  
Bolted Joint ◽  
Tube Heat Exchanger ◽  
Specific Geometry ◽  
Shell And Tube

Despite the fact that multipass shell-and-tube heat exchangers operating at high temperature are subject to frequent problems related to flange sealing, there is neither detailed explanations for the reasons of the failures nor an adequate solution to this problem. Specific geometry of multipass heat exchangers and the temperature difference between the inlet and the outlet fluids is responsible for the existence of a thermal circumferential gradient at the shell-to-channel bolted joint. However, existing flange design methods do not address nonaxisymmetrical temperature loading of the flanged joint assembly. The circumferential thermal gradient, as the cause of frequent failures to seal the flanged joints, is ignored. This paper outlines the analytical modeling of a flanged joint with a tube sheet of a multipass heat exchanger subjected to a nonaxisymmetrical thermal loading. A shell-and-tube heat exchanger of 51 in. diameter with cocurrent flow was used for analysis. The main steps of the theoretical analysis used for the determination of the circumferential temperature profiles and the thermal expansion displacements and distortions of the bolted joint components are given. The results from the proposed analytical model are compared with those obtained from finite element models.

A General Expression for the Determination of the Log Mean Temperature Correction Factor for Shell and Tube Heat Exchangers

2003 ◽  
Vol 125 (3) ◽  
pp. 527-530 ◽  
Author(s):  
Ahmad Fakheri
Keyword(s):  
Heat Exchanger ◽  
Correction Factor ◽  
Heat Exchangers ◽  
Direct Determination ◽  
Temperature Correction ◽  
Tube Heat Exchanger ◽  
Mean Temperature ◽  
Shell And Tube ◽  
Graphical Presentation

This paper presents a single closed form algebraic equation for the determination of the Log Mean Temperature Difference correction factor F for shell and tube heat exchangers having N shell passes and 2M tube passes per shell. The equation and its graphical presentation generalize the traditional equations and charts used for the determination of F. The equation presented is also useful in design, analysis and optimization of multi shell and tube heat exchanger, particularly for direct determination of the number of shells.

Determination of Temperature Limits for Heat Exchanger Joint Assembled of Solid Stainless Tubesheet With Girth Flanges

2017 ◽  
Author(s):  
Bassel Y. Mohamed ◽  
Mohamed A. Hamdy ◽  
Tamer I. Eid
Keyword(s):  
Heat Exchanger ◽  
Temperature Distribution ◽  
Heat Exchangers ◽  
Transient Analysis ◽  
Transient Temperature ◽  
Heating Rates ◽  
Element Analysis ◽  
Transient Temperature Distribution ◽  
Steel Heat

Although heat exchangers are built according to international codes and proved to be leak tight by hydrotesting at ambient temperature, leak of stainless steel heat exchangers girth flanges at the tubesheet gaskets likely occurs during startup and operation at high temperatures. Accordingly, evaluation of the design to assure leak free operation considering anticipated thermal events is required. WRC 510 bulletin [4] introduces a simplified analytical method to address this issue and provides safe guarding against leakage. This study is performed on solid 300 series stainless stationary tubesheet flanged with girth flanges having the same or different material of construction. A thermal finite element analysis is performed to obtain the transient temperature distribution through a girth flanges and stationary tubesheet assembly of a heat exchanger using SOLIDWORKS® SIMULATION [7]. The model of the flanged joint consists of two girth flanges with a tubesheet and gaskets in between. Thermal time dependent transient analysis of the above model is conducted to compute the temperature distribution in the flanged joint assembly for different time steps. Further, these temperature distributions are used to compute the expansion, deflection and rotation for the flanged joint parts using WRC 510 bulletin [4] equations. The study determines both the permissible heating rates during startup and the temperature limits, for the example studied, which are suitable for using solid 300 series stainless tubesheet for both material types of the girth flanges to have the most leak tight & economical assembly when the minimum design metal temperature allows these materials.

scholarly journals Research of variable characteristics of heat exchange equipment

2019 ◽  
Vol 114 ◽  
pp. 07001
Author(s):  
Tatyana Rafalskaya ◽  
Valery Rudyak
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Variable Parameter ◽  
Simulation Method ◽  
Operating Modes ◽  
Mode Of Operation ◽  
Heat Exchange Equipment ◽  
Large Systems ◽  
Simulation Results

Heat exchangers used in various industries, most often work in conditions of variable flows and temperatures. At the same time, the existing theories of calculation of heat exchanger modes are based on the use of constant dimensionless parameters in any mode of operation. The purpose of this work is to obtain dependencies to determine the effect of coolant temperatures on the variable parameter of the heat exchanger. Using the simulation method, dependencies were found that describe the change in the heat exchanger parameter which made it possible to obtain a general formula for the change in the heat exchanger parameter at varying coolant temperatures. To test the applicability of the existing relations describing the change in the heat exchanger parameter and the formula obtained, a large number of heat exchangers were calculated in variable operating modes. Comparison with the simulation results showed that the ratios of the known theories of heat exchangers do not work in all modes and their application can lead to significant errors. A formula has been obtained allows one to find the effect of coolant temperatures on the variable parameter of the heat exchanger. The formula can be used to predict the modes of large systems.

scholarly journals Numerical Study of Compact Plate-Fin Heat Exchanger for Rotary-Vane Gas Refrigeration Machine

2017 ◽  
Vol 53 (2) ◽  
Author(s):  
V. V. Trandafilov ◽  
M. G. Khmelniuk
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Development Research ◽  
Aspen Hysys ◽  
Simulation Results ◽  
Refrigeration Machine

Plate-fin heat exchangers are widely used in refrigeration technique. They are popular because of their compactness and excellent heat transfer performance. Here we present a numerical model for the development, research and optimization of a plate-fin heat exchanger for a rotary-vane gas refrigeration machine. The method of analysis by graphic method of plate - fin heat exchanger is proposed. The model describes the effects of secondary parameters such as axial thermal conductivity through a metal matrix of the heat exchanger. The influence of geometric parameters and heat transfer coefficient is studied. Graphs of dependences of length, efficiency of a fin and pressure drop in a heat exchanger on the thickness of the fin and the number of fins per meter are obtained. To analyze the results of numerical simulation, the heat exchanger was designed in the Aspen HYSYS program. The simulation results show that the total deviation from the proposed numerical model is not more than 15%. 

Flanged Joints of Multi-Pass Shell-and-Tube Heat Exchangers Subjected to Non-Axisymmetric Thermal Loading

2010 ◽  
Author(s):  
Natalia Petrova ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermal Loading ◽  
Current Flow ◽  
Finite Element Models ◽  
Bolted Joint ◽  
Tube Heat Exchanger ◽  
Specific Geometry ◽  
Shell And Tube

Despite the fact that multipass shell-and-tube heat exchangers operating at high temperature are subject to frequent problems related to flange sealing, there is neither detailed explanations for the reasons of the failures nor adequate solution to this problem. Specific geometry of multipass heat exchangers and the temperature difference between the inlet and the outlet fluids are responsible for the existence of a thermal circumferential gradient at the shell-to-channel bolted joint. However, existing flange design methods do not address non-axisymmetrical temperature loading of the flanged joint assembly. The circumferential thermal gradient, as the cause of frequent failures to seal the flanged joints, is ignored. This paper outlines the analytical modeling of a flanged joint with a tube sheet of a multipass heat exchanger subjected to a non-axisymmetrical thermal loading. A shell-and-tube heat exchanger of 51 in diameter with co-current flow was used for analysis. The main steps of the theoretical analysis used for the determination of the circumferential temperature profiles and the thermal expansion displacements and distortions of the bolted joint components are given. The results from the proposed analytical model are compared to those obtained from finite element models.

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