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.

scholarly journals Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach

2016 ◽  
Vol 37 (2) ◽  
pp. 3-22 ◽  
Author(s):  
Pavan Kumar Konchada ◽  
Vinay Pv ◽  
Varaprasad Bhemuni
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Entropy Generation ◽  
Single Phase ◽  
Pure Water ◽  
Finned Tube ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Phase Approach ◽  
Finned Tube Heat Exchanger

AbstractThe presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.

Numerical Simulation of a Shell-and-Tube Heat Exchanger with Special Form Helical Baffles

2013 ◽  
Vol 860-863 ◽  
pp. 754-757
Author(s):  
Can Zheng ◽  
Fei Wang ◽  
Yong Gang Lei
Keyword(s):  
Numerical Simulation ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Shell Side ◽  
Fluid Medium ◽  
Tube Heat Exchanger ◽  
New Type ◽  
Shell And Tube ◽  
Side Flow

A new type of helical baffles heat exchanger is presented in this paper. Comparative study, through numerical simulation, was undertook between the new helical baffles heat exchanger and segmental baffle board heat exchanger in shell side flow and heat exchange characteristics. Fluid medium in the shell side is air. At the same velocity in the same flow conditions, pressure drop of helical baffles heat exchangers fell by an average of 26.8% compared with segmental baffle board heat exchangers, and the unit pressure drop of the heat transfer ratio of helical baffles heat exchanger increased by an average of 40.6%.

scholarly journals Optimization and CFD analysis of a shell-and-tube heat exchanger with a multi segmental baffle

2020 ◽  
pp. 293-293
Author(s):  
Ahmet Aydin ◽  
Halit Yaşar ◽  
Tahsin Engin ◽  
Ekrem Büyükkaya
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Exchanger ◽  
Flow Field ◽  
Heat Exchangers ◽  
Operating Cost ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Side Flow

The Shell-and-tube type heat exchangers have long been widely used in many fields of industry. These types of heat exchangers are generally easy to design, manufacturing and maintenance, but require relatively large spaces to install. Therefore the optimization of such heat exchangers from thermal and economical points of view is of particular interest. In this article, an optimization procedure based on the minimum total cost (initial investment plus operational costs) has been applied. Then the flow analysis of the optimized heat exchanger has been carried out to reveal possible flow field and temperature distribution inside the equipment using computational fluid dynamics. The experimental results were compared with computational fluid dynamics analyses results. It has been concluded that the baffles play an important role in the development of the shell side flow field. This prompted us to investigate new baffle geometries without compromising from the overall thermal performance. It has been found that the heat exchanger with the new baffle design gives rise to considerably lower pressure drops in the shell side, which in turn reducing operating cost. The new baffle design is particularly well suited for shell-and-tube heat exchangers, where a viscous fluid flows through shell side with/out phase change.

Temperature Field Prediction of Rectangular Shell-and-Tube Heat Exchanger

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
J. F. Zhou ◽  
Y. Li ◽  
B. Q. Gu ◽  
C. L. Shao
Keyword(s):  
Thermal Expansion ◽  
Temperature Field ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Side Flow ◽  
Rectangular Shell

Shell-and-tube heat exchangers are the most common type of heat exchangers in oil refineries and other large chemical processes. In this manuscript, we demonstrate that the shell-side flow in a cylindrical shell was not as homogeneous as that in a rectangular shell. According to the periodic flow field and the arrangement of tubes in the rectangular shell, the solid-fluid coupling heat transfer model consisting of a single tube section and the outer and inner fluids was developed to represent the whole heat exchanger. Using this model, the relationship among four temperatures, namely the inlet and outlet temperatures of tube-side fluid and the upstream and downstream temperatures of shell-side fluid, was established. By dividing each tube into several tube sections at the sites of baffles, a method for predicting the temperature field of the rectangular shell-and-tube heat exchanger was proposed. Based on the node temperature correlation, all the node temperatures were obtained by iterative computation using the established relationship between the four temperatures and the operating conditions. It was found that the temperature distribution of the fluid in tube was approximately linear along axial direction, but the temperature of tube showed nonlinear regularity. The axial deformation compatibility condition for the tube bundle and shell was considered when resolving the stresses in tubes. For the model established in this paper, the mean temperature of the tube at lower position was found to be larger than that at higher position; hence the thermal expansion of the tube at the lower end is larger. In the case the tube-side fluid was heated, all tubes were pulled because of the larger axial thermal expansion of shell, and the stress in the tube with higher temperature is smaller because of the smaller strain.

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 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 Research on the Thermal Hydraulic Performance and Entropy Generation Characteristics of Finned Tube Heat Exchanger with Streamline Tube

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5408
Author(s):  
Zuoqin Qian ◽  
Qiang Wang ◽  
Song Lv
Keyword(s):  
Heat Exchanger ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Flow Characteristics ◽  
Hydraulic Performance ◽  
Finned Tube ◽  
Tube Heat Exchanger ◽  
Finned Tube Heat Exchanger ◽  
Overall Performance ◽  
Present Simulation

Thermal hydraulic performance of the fin-and-tube heat exchanger is presented in this paper. The purpose of this investigation was to investigate the heat transfer mechanism and flow characteristics in the finned tube heat exchanger with streamline tube. The streamline tube in this paper had the streamline cross section which was composed of a semicircle and a half diamond. Three-dimensional numerical simulation was presented and validated by the experiment and the other numerical simulation from public articles. The present simulation had good agreement with the experimental results. The difference of the j factor and f factor between the experimental results and present simulation results by k-ε-enhance model was less than 7.6%. The geometrical parameters were considered as every single variable to investigate the thermal hydraulic performance. The results showed that smaller transversal and larger tube pitch provided greater compactness and better thermal performance. Moreover, a larger angle was not only beneficial to enhance the thermal performance, but also helpful to improve the overall performance. Secondly, the effects of angle on the heat transfer performance and fluid flow characteristics were investigated as the perimeter kept constant. It was shown that the overall performance of the streamline tube was better than the circular tube. Lastly, the entropy generation including frictional entropy generation and the thermal entropy generation were analyzed. It can be concluded that by using the streamline tube, the wake region can be obviously reduced, and thermal performance can be improved.

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