scholarly journals Investigating the hydraulic resistance in the flow part elements of pneumatic systems and heat exchangers

2021 ◽  
Vol 2057 (1) ◽  
pp. 012015
Author(s):  
A S Pugachuk ◽  
N F Fominykh ◽  
E O Kalashnikova ◽  
Yu A Gavrilova
Keyword(s):  
Hydraulic Resistance ◽  
Heat Exchangers ◽  
Power Plants ◽  
Selective Laser Sintering ◽  
Additive Technologies ◽  
Distributed Power Generation ◽  
Coefficient Of Hydraulic Resistance ◽  
Flow Part ◽  
Shell And Tube

Abstract The article deals with the development of shell-and-tube heat exchangers for the needs of power engineering, based on additive technologies, in particular, selective laser sintering technology with new configurations of heat exchange surfaces. The role of heat exchangers in microturbines, the most common units of power plants of small distributed power generation, is considered. To intensify heat transfer and increase the efficiency of microturbines, it is proposed to use various configurations of flow channels of shell-and-tube heat exchangers made on the basis of additive technologies. Mathematical modeling and experimental study of a gas medium flow in the tubes of a heat exchanger are carried out. The dependences of the coefficient of hydraulic resistance between the surface of inlet and outlet of gas from tubes of various configurations on the Reynolds number are obtained. The results of the experiment allow us to conclude that the resistance of spiral-shaped tubes is slightly higher than the resistance of tubes with three ribs.

Dynamic Analysis of End Conditions for Shell Side Pipings of STHE

2019 ◽  
Author(s):  
Nitin D. Pagar ◽  
S. H. Gawande
Keyword(s):  
Heat Exchangers ◽  
Vibration Analysis ◽  
Power Plants ◽  
Vital Role ◽  
Fretting Wear ◽  
Shell Side ◽  
Process Industries ◽  
End Conditions ◽  
Energy Conversion Systems ◽  
Shell And Tube

Abstract Shell and tube heat exchangers [STHE] play a very vital role in energy conversion systems, process industries like chemical, pharmaceutical, refineries etc. and in different power plants. For designing shell and tube heat exchangers, the tubes vibrational response (internally) to any random excitations of fluid flow need to be understandable. Also, circumferential inlet pipe or tube at the entrance region of the shell side, generally subject to the fluid thrust in the bends of typical pipe arrangements. It produces loadings forces and moments, leading to unavoidable vibrations. The goal of vibration analysis is to ensure that fatigue damage or fretting wear does not occur, as well as, predicted frequencies, amplitudes shall be within acceptable limits criteria. This paper reports the vibration analysis of different piping arrangement of different end conditions to understand its effects on frequencies and modes so that a designer must mitigate it, at the initial stage. Axial, lateral and torsional vibrations are analyzed for different end conditions. The boundary conditions used are both ends fixed, one end fixed and other end free, both ends free and one end fixed-other end attached to a weight. Analytical procedure is carried out to determine the frequencies for axial, lateral and torsional cases. FEA analysis and experiment using an FFT analyzer is carried out to check the convergence of the results. Very useful results are established which generates the philosophy to protect the pipings from the resonant frequencies subjected to different end conditions.

Development and Application of a Plugging Margin Evaluation Method Taking Into Account the Fouling of Shell-and-Tube Heat Exchangers

2005 ◽  
Author(s):  
Kyeong Mo Hwang ◽  
Tae Eun Jin
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
Power Plants ◽  
Evaluation Method ◽  
Operating Time ◽  
Flow Characteristics ◽  
Shell And Tube

As the operating time of heat exchangers progresses, fouling caused by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of Korean nuclear power plants have been analyzed in terms of heat transfer rate and overall heat transfer coefficient as a means of heat exchanger management. Except for fouling resulting from the operation of heat exchangers, all the tubes of heat exchangers have been replaced when the number of plugged tubes exceeded the plugging criteria based on design performance sheet. This paper describes a plugging margin evaluation method taking into account the fouling of shell-and-tube heat exchangers. The method can evaluate thermal performance, estimate future fouling variation, and consider current fouling level in the calculation of plugging margin. To identify the effectiveness of the developed method, fouling and plugging margin evaluations were performed at a component cooling heat exchanger in a Korean nuclear power plant.

scholarly journals Modelling of Polymeric Shell and Tube Heat Exchangers for Low-Medium Temperature Geothermal Applications

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2737
Author(s):  
Francesca Ceglia ◽  
Adriano Macaluso ◽  
Elisa Marrasso ◽  
Maurizio Sasso ◽  
Laura Vanoli
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Power Plants ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Heat Transfer Area ◽  
Geothermal Fluid ◽  
Shell And Tube

Improvements in using geothermal sources can be attained through the installation of power plants taking advantage of low and medium enthalpy available in poorly exploited geothermal sites. Geothermal fluids at medium and low temperature could be considered to feed binary cycle power plants using organic fluids for electricity “production” or in cogeneration configuration. The improvement in the use of geothermal aquifers at low-medium enthalpy in small deep sites favours the reduction of drilling well costs, and in addition, it allows the exploitation of local resources in the energy districts. The heat exchanger evaporator enables the thermal heat exchange between the working fluid (which is commonly an organic fluid for an Organic Rankine Cycle) and the geothermal fluid (supplied by the aquifer). Thus, it has to be realised taking into account the thermodynamic proprieties and chemical composition of the geothermal field. The geothermal fluid is typically very aggressive, and it leads to the corrosion of steel traditionally used in the heat exchangers. This paper analyses the possibility of using plastic material in the constructions of the evaporator installed in an Organic Rankine Cycle plant in order to overcome the problems of corrosion and the increase of heat exchanger thermal resistance due to the fouling effect. A comparison among heat exchangers made of commonly used materials, such as carbon, steel, and titanium, with alternative polymeric materials has been carried out. This analysis has been built in a mathematical approach using the correlation referred to in the literature about heat transfer in single-phase and two-phase fluids in a tube and/or in the shell side. The outcomes provide the heat transfer area for the shell and tube heat exchanger with a fixed thermal power size. The results have demonstrated that the plastic evaporator shows an increase of 47.0% of the heat transfer area but an economic installation cost saving of 48.0% over the titanium evaporator.

Performance Evaluation of Multi-Stage Shell and Tube Transport Membrane Condenser Heat Exchangers for Low Grade Waste Heat and Water Recovery

2017 ◽  
Author(s):  
Soheil Soleimanikutanaei ◽  
Cheng-Xian Lin ◽  
Dexin Wang
Keyword(s):  
Water Vapor ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Power Plants ◽  
Ceramic Membrane ◽  
Waste Heat ◽  
Low Grade ◽  
Water Recovery ◽  
Multi Stage ◽  
Shell And Tube

In this work for the first time the performance of multi-stage shell and tube Transport Membrane Condenser (TMC) based heat exchangers are evaluated numerically. The present heat exchanger is design to work under high pressure and temperature condition for both heat and water recovery in Oxy-Combustion processes. TMC heat exchangers use the nano-porous and ceramic membrane technology to extract the water vapor and latent heat of condensation from the flue-gas. The most important application of TMC heat exchangers is in the power plants which the water vapor in the presence of other non-condensable gases (i.e. CO2, O2 and N2) exist. Effect of the different arrangement of the multi-stage shell and tube TMC heat exchangers, number of branches and number of heat exchangers in each branch on the heat transfer and water recovery have been studied numerically. A single phase multi-component model is used to assess the capability of single stage TMC heat exchangers in terms of waste heat and water recovery at various inlet conditions. Numerical simulation has been performed using ANSYS-FLUENT software and the condensation rate model has been implemented applying User Define Function. Finally, an optimum configuration for the TMC heat exchanger unit has been proposed and the results of numerical simulations are depicted in terms of temperature and water vapor mass fraction contours.

STUDY OF THE PROPERTIES A FRAGMENT OF THE HYDRAULIC CIRCUIT OF THE SPACECRAFT, OBTAINED BY MEANS OF ADDITIVE TECHNOLOGIES

2020 ◽  
pp. 11-19
Author(s):  
I. E. Mal’tzev ◽  
A. A. Basov ◽  
M. A. Borisov ◽  
A. V. Bystrov
Keyword(s):  
Selective Laser Melting ◽  
Experimental Work ◽  
Heat Exchangers ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Additive Technologies ◽  
Laser Fusion ◽  
Layer By Layer ◽  
Laser Melting ◽  
Hydraulic Circuits

The article discusses the course and results of experimental work on the initial study of the possibility of using one of the varieties of additive technologies – the method of layer-by-layer selective laser melting (SLM) in the manufacture of elements of heat exchangers and hydraulic circuits of spacecraft. Traditional manufacturing techniques for hydro-control elements and spacecraft heat exchangers are based on machining and high-temperature vacuum soldering, leading to a long cycle and high manufacturing costs. As an alternative, the method of layer-by-layer selective laser melting can be considered as a manufacturing method using a three-dimensional model of the product and not requiring additional equipment. This method is based on sequential layer-by-layer fusion of a metal powder with previous fused product layers under the action of a laser beam forming a local region of liquid melt. The article describes experimental work to assess the possibility of using the selective laser melting method. Assessed weld-ability of a sample made by selective laser fusion technology with tips made by traditional technology. Directions for testing the method of selective laser sintering on real structures of heat exchanging units of spacecraft have been determined. A technique is proposed and the results of a study of a sample synthesized by selective laser sintering are presented. Based on the results obtained, an analysis is made of the prospects for using this method in the production of elements of hydraulic circuits and heat exchange units of spacecraft.

Non-Destructive Examination of Diffusion-Bonded Compact Heat Exchangers

2020 ◽  
Author(s):  
Greg Selby ◽  
Shaun Aakre ◽  
Zhaoyan Fan
Keyword(s):  
Heat Exchangers ◽  
Nuclear Power ◽  
Power Plants ◽  
Bonding Process ◽  
Strain Sensors ◽  
Compact Heat Exchangers ◽  
The Core ◽  
Full Penetration ◽  
Shell And Tube ◽  
Non Destructive

Abstract Compact heat exchangers (CHX) fabricated using the diffusion bonding process will be useful in the design and operation of Generation IV nuclear power plants. The NDE challenges posed by diffusion-bonded compact heat exchangers (DBHE) are quite different from those of their more familiar shell-and-tube cousins. The examination scope encompasses three parts: the welds joining the headers to the CHX body; the body’s solid perimeter, serving as the pressure boundary; and the channeled interior. Current investigations are in support of a Section III Code Case including CHX fabrication rules and post-fabrication nondestructive evaluation (NDE) requirements to ensure adequate initial quality. In-service examination methodologies are also considered to inform code developers, regulators, and vendors exploring use of CHX in advanced reactor designs. The welds joining the headers to the CHX body likely will be full-penetration set-on welds of conventional design. Standard fabrication examinations, namely visual, dye penetrant and hydrostatic examinations will likely suffice. Additional methods should be specified for the purpose of ensuring that the weld stresses have not caused degradation or separation of individual layers within the adjacent diffusion-bonded core. The channeled core of the CHX is geometrically complex and does not allow application of traditional NDE methods from the outside. Radiography permits imaging of small demonstration scale components. Meanwhile, identifying bond failures within larger components may require embedded strain sensors. A theory for employing strain sensors to detect failures within the core is introduced here along with early experimental results. The diffusion-bonded solid perimeter should be examined to ensure that any presence of bonding failures is allowable. Ultrasonic examination results are presented, obtained from test blocks containing simulated bond failures and from high-pressure CHX used during lab studies.

scholarly journals On the Role of Nanofluids in Thermal-hydraulic Performance of Heat Exchangers—A Review

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 734 ◽  
Author(s):  
Salah Almurtaji ◽  
Naser Ali ◽  
Joao A. Teixeira ◽  
Abdulmajid Addali
Keyword(s):  
Heat Exchangers ◽  
Gas Turbines ◽  
Power Plants ◽  
Hydraulic Performance ◽  
Domestic Water ◽  
Operational Conditions ◽  
Oil Refineries ◽  
Land Vehicles ◽  
Different Temperatures

Heat exchangers are key components in many of the devices seen in our everyday life. They are employed in many applications such as land vehicles, power plants, marine gas turbines, oil refineries, air-conditioning, and domestic water heating. Their operating mechanism depends on providing a flow of thermal energy between two or more mediums of different temperatures. The thermo-economics considerations of such devices have set the need for developing this equipment further, which is very challenging when taking into account the complexity of the operational conditions and expansion limitation of the technology. For such reasons, this work provides a systematic review of the state-of-the-art heat exchanger technology and the progress towards using nanofluids for enhancing their thermal-hydraulic performance. Firstly, the general operational theory of heat exchangers is presented. Then, an in-depth focus on different types of heat exchangers, plate-frame and plate-fin heat exchangers, is presented. Moreover, an introduction to nanofluids developments, thermophysical properties, and their influence on the thermal-hydraulic performance of heat exchangers are also discussed. Thus, the primary purpose of this work is not only to describe the previously published literature, but also to emphasize the important role of nanofluids and how this category of advanced fluids can significantly increase the thermal efficiency of heat exchangers for possible future applications.

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