Inner Surface Of Tube Research Articles

Glass Coating Deposition Temperature on the Inner Surface of Heat-Exchange Tube

The deposition temperature of a glass coating on the inner surface of a heat-exchanger tube was studied. The choice of coating deposition temperature depends on the physico-mechanical properties, geometric dimensions, and temperature distribution at any point of the coating and the metallic part of the heat-exchange tube. The variation of the deposition temperature field of glass coatings on the inner surface of a tube as a function of the heating time of the electric-heating furnace is determined theoretically. It is found that during deposition of a glass coating on the inner surface of the tube the temperature largely depends on the brand and thickness of the sealed glass rod.

Experimental comparative study on a solar still combined with evacuated tubes and a heat exchanger at different water depths

ABSTRACT The low freshwater output is always a matter of concern regarding a solar still. It is observed from the current literature that evacuated tubes are directly connected to the still basin for productivity enhancement. The main limitation of integrating evacuated tubes directly to solar still is rapid scaling on the inner surfaces of tubes due to the presence of dissolved impurities in water. This increases thermal resistance and decreases the overall performance of the still. In the present experimental study, a copper tube heat exchanger is installed in still basin and waste engine oil is utilised as a working fluid in the evacuated tube collector (ETC) and heat exchanger circuit. This modification increases the evaporation rate of basin water and boosts freshwater output. The modified still is experimentally investigated at distinct water depths of 4 cm, 5 cm and 6 cm, and the performance is simultaneously compared with a conventional still. Experimental results showed maximum daily productivity of 7.38 L/m2 day and daily efficiency of 30.5% achieved for modified still at 4 cm water depth. These values are 138.9% and 2.1% higher than that of conventional still respectively at same water depth.

Carbon films deposition as protective coating of titanium alloy tube using PIII&D system

The purpose of this work is to deposit carbon films inside titanium alloy tube of small diameter, in order to increase the corrosion resistance of its inner surface. The use of carbon films as protective coating can increase the lifetime of the tubes used in propulsion and thermal control systems of satellites. They can also inhibit the permeation of corrosive species, originated from the fuels and the cooling fluids, between the film-metal interface. Titanium alloy tube with 11 mm diameter and 150 mm length, with one side closed configuration was placed inside a vacuum chamber and pulsed to a high energy voltage. Carbon film deposition was performed by using a Plasma Immersion Ion Implantation and Deposition (PIII&D) system. The hollow cathode discharges (HCD) were produced with pulses of 2 kV, 15 A, 20 μs, and 500 Hz of repetition rate, using a RUP-6 pulser. The maximum temperature measured at the surface of tubes was about 1000 °C. The as-deposited carbon films were analyzed in terms of their microstructure, chemical composition, surface morphology and thickness. The surface characterization of the carbon films were carried out by means of Raman Spectroscopy, Field Emission Gun Scanning Electron Microscopy (FEG-SEM), Atomic Force Microscopy (AFM) and Potenciodynamic Polarization tests. The experimental results show an interesting change on the chemical structure of the as-deposited carbon films, when the deposition time varied from 30 min to 240 min, resulting in thicker and quite adhered films on the inner surface of tubes. In addition, the changes on the microstructure, seen by SEM analysis, as well as the ID/IG variation indicate that nanocrystalline graphite (NC-G) films can be deposited on the inner surface of titanium tubes by using this type of PIII&D system.

Destruction mechanisms and methods of laboratory autoclave tests of internal coatings of oil pipes

The main mechanisms of destruction of internal anticorrosive polymer coatings (IACPC) of the inner surface of tubing and fielding pipes are review in the article. They are divide into decompression peeling, substrate destruction under the corrosion of and natural aging of the polymeric basis. A critical analysis of the existing standards for the testing of internal anticorrosive coatings was made. The carrying out test on these documents does not allow obtaining the destructions identical to those found during the exploitation of pipelines. Investigations on the selection of optimal regimes of autoclave tests and the methodology for conduct research are describe. A comparison for the results of laboratory and experimental field tests of the coatings presented.

ANALYSIS OF DENICKELIFICATION PHENOMENON ON HEAT EXCHANGER TUBE

DeNickelification is common phenomenon which occurs for alloy metal containing sufficient amounts of Nickel when it is exposed at high temperature in long time periode. One of component which is made of alloy metal containing Nickel is heat exchangers tube. Heat exchanger is a part of processing unit that use for transfering heat from hot fluid to colder fluid through the combined mechanisms of conduction and convection. When the heat exchanger leaks, all of the processing system could be affected. In this research a leakage heat exchanger tube is investigated by failure analysis methods to find the root cause of failure. Several tests and examinations such as fractography, metallography examinations, SEM and EDS, hardnes as well as chemical compositions test are carried out to this tube to obtain detailed information for further analysis. Result of this reseach shows that some Cu residue, Ni, aggressive/corrosive ion such as Cl - and S 2- at the leak area of heat exchanger tube is found. These evidences indicated that denickelification was occurred on inner surface of heat exchanger tube caused by potential difference between Ni 2+ ion and Cu 2+ ion to form a galvanic cell. Furthermore, since the tube is flown by fluid material which contains aggressive / corrosive ions such as Cl - ion and S 2 - then pitting corrosion on inner surface of tube is formed. This mechanism had been taken place continuously during operation of heat exchanger and pitting corrosion keep growing until the tube leaks.

Novel rotating-vibrating magnetic abrasive polishing method for double-layered internal surface finishing

Components with complex internal surfaces are increasingly important for gas and fluid flow applications in aerospace and automotive industries. Recently, as an emerging manufacturing technology, three-dimensional (3D) additive manufacturing (AM) technology enables one-step fabrication of these complex internal surfaces. Although 3D AM technology eliminates the need for complex assembly process, due to the poor surface and sub-surface integrity, achieving a favourable surface condition is challenging. Therefore, a post-polishing process is essential for these 3D AM complex internal surfaces. This paper presents a novel rotating-vibrating magnetic abrasive polishing method to finish a kind of complex internal surface which has a double-layered tube structure made by selective laser melting (SLM) of Inconel 718. The principle of the method was illustrated and the material removal process was modelled. The feasibility of the method was verified and the surface evolution mechanism under different motions was revealed. The effects of process parameters on material removal and surface quality were evaluated quantitatively. The results showed that material was uniformly removed from both of the external surface of inner tube and internal surface of outer tube. The uneven surface caused by partially melt powders during SLM process was smoothed and the surface roughness was reduced from about 7 μm Ra to less than 1 μm Ra. Relatively higher material removal efficiency and lower surface roughness were obtained through combining rotation and vibration motions. The surface quality was improved representing by the increase of surface nanohardness and release of residual stress after polishing. There was no subsurface deformation and damage observed so that a damage-free surface was obtained.

Fatigue and fracture analysis on EAST divertor monoblock heat sink in H-mode operation

Currently the most advanced and mature plasma facing unit (PFU) technology is the ITER W/Cu PFU, which is monoblock composed of tungsten, copper and CuCrZr as plasma facing material, interlayer and heat sink, respectively. Fatigue failure in heat sink structural including fracture under H-mode (High confinement mode)operating condition greatly influence the lifetime of divertor target. In this study, to simplify calculation for complex heat load input, the heat load time evolution with ELMs(Edge localized modes) was defined as an equivalent heat flux for steady-state analysis. To investigate the fatigue damage behavior of CuCrZr tube in EAST divertor monoblock, the thermal-stress analysis was performed firstly with regards to EAST operating and cooling condition. The stress and strain distribution on heat sink tube indicates that the risky position is on the upper inner surface of tube. Combined with the strain-life relationship, the fatigue life and creep-fatigue damage of CuCrZr tube was assessed. The fatigue analysis shows that the cumulative fatigue and creep damage on tube meet the requirement under operating condition now available and it is great influenced by steady heat load. The tube also risks cracking and fracture under long pulse operation in future fusion device. The stress intensity factor and J-integral were applied to investigate crack fracture in risky position on heat sink tube that the pre-crack shows no risk of fast fracture but potential for creep at higher operating temperature.

New methods of thermographic control using multi-scale analysis of non-stationary thermal fields

A set of new approaches and techniques of non-destructive testing is described and implemented within a unified computer analysis of the patterns of multi-scale dynamic thermography. Depending on the size of the inspected area, nature, location, orientation and size of the defects, various energy sources were used for probe dynamic heating of the controlled article: air flow, focused laser beam, and point contact. The non-stationary thermal picture of the monitored area was recorded with a high resolution thermal imaging device and then analyzed using original model approaches and developed software. A set of discussed approaches allows detecting and quantitative characterizing of the defects of various types, size (from fractions to tens of millimeters) and orientation, including cracks, coating delamination or degradation, welding and glue seams defects, deposits, etc., both at the outer and inner surfaces of tubes, tanks, and reactors, etc. The developed methods provides determination of the thermophysical characteristics of the material, i.e., the thermal diffusivity coefficient with an accuracy better than ±3%.

Development of a technical approach to modify the internal surface of biomedical tubes and other elongated small lumen macrodevices with parylene coating

A multitude of differently composed biomedical polymers has been researched for many years for their distinctive ease of production and wide range of applications. New technologies and new material characteristics have always evolved accordingly. The lumina of biomedical polymer tubes such as catheters, intravenous tubes, and biomedical microfluidic channels do not necessarily show the required biocompatibility and desired functionality. In such cases, the products are provided with additional inner liner or coatings to achieve the desired specific properties. Specific adjustments, for example, low friction coefficient, low gas diffusion resistance, wear resistance, and hydrophobicity, are key properties which are in focus for the improvement of biomedical surfaces. In this pilot study, a technical method was developed to deposit parylene-AF4 on the inner surface of silicone tubes with aspect ratios exceeding 78:1. Uncoated and parylene-AF4-coated silicone tubes were investigated in respect to the aforementioned physical properties. Compared to the uncoated tubes, the parylene-coated tubes showed superior quality with respect to friction coefficient, gas diffusivity as well as wear resistance. It could be demonstrated that the new technical approach is suitable to parylene-coat the inner surfaces of tubes with high aspect ratios thereby achieving conformal coatings.

Heat transfer simulation of unsteady swirling flow in a vortex tube

Effectiveness of not-adiabatic vortex tube application in the cooling systems of gas turbine blades depends on characteristics of swirling flows formed in the energy separation chamber. An analysis of the flow structure in the vortex tube channels has shown a presence of a complex three-dimensional spiral vortex, formed under relatively high turbulence intensity and vortex core precession. This indicates the presence of a significant unsteady flow in the energy separation chamber of the vortex tube that has a great influence on convective heat transfer of the swirling flow to the inner surface of tube. The paper contains the results of investigation of gas dynamics and heat transfer in the vortex tube taking into account the flow unsteadiness.

Relationship between material removal distribution and pressure distribution on micro processing for inner surface of tube Utilizing a magnetic compound fluid

Relationship between material removal distribution and pressure distribution on micro processing for inner surface of tube Utilizing a magnetic compound fluid

Experimental study on circular CFST short columns with intermittently welded stiffeners

This paper deals with the experimental study on strength the strength and deformation characteristics of short circular Concrete Filled Steel Tube (CFST) columns. Effect of vertical stiffeners on the behavior of the column is studied under axial compressive loading. Intermittently welded vertical stiffeners are used to strengthen the tubes. Stiffeners are attached to the inner surface of tube by welding through pre drilled holes on the tube. The variable of the study is the spacing of the weld between stiffeners and circular tube. A total of 5 specimens with different weld spacing (60 mm, 75 mm, 100 mm, 150 mm and 350 mm) were prepared and tested. Short CFST columns of height 350 mm, outer tube diameter of 165 mm and thickness of 4.5 mm were used in the study. Concrete of cube compressive strength 41 N/mm2 and steel tubes with yield strength 310 N/mm2 are adopted. The test results indicate that the strength and deformation of the circular CFST column is found to be significantly influenced by the weld spacing. The ultimate axial load carrying capacity was found to increase by 11% when the spacing of weld is reduced from 350 mm to 60 mm. The vertical stiffeners are found to effective in enhancing the initial stiffness and ductility of CFST columns. The prediction models were developed for strength and deformation of CFST columns. The prediction is found to be in good agreement with the corresponding test data.

Research on Inner Surface of Tubes Hydroformed

Research on Inner Surface of Tubes Hydroformed

Film Thickness Estimation for the Oil Applied to the Inner Surface of Slim Tubes

The article deals with the approximation of the results of experimental measurement of coating of the inner surface of slim pipes with special oil, using a dispersion oil fraction. The reason for such treatment of the inner surface of the tubes is the anti-corrosion protection or various other requirements. The oil manufacturer prescribes the minimum required layer to guarantee the anti-corrosion protection parameters. Therefore, it is advisable to know the most exact coating parameters for different pipe diameters. The measured results give us an assumption of how much oil is sufficient to coat the inside of a pipe. The main idea lies in the correct estimation of coefficients in the three-parameter exponential dependence. For the initial estimates, Nelder–Mead’s minimization method was used. The condition for meeting the lower estimate of the minimum thickness of the oil layer was determined. Following graphic processing of minimization of individual pipe diameters, in some cases, the coefficients were adjusted manually. The result is that the oil thickness depends on the distance of the investigated point from the beginning of the tube, or on the point of entry of the dispersion oil fraction.

Research on Protective Coating on Inner Surface of Alloy Tube

Materials are one of the most important factors which limit reactor development. Molten salt not only used as the coolant but used as application in which fissile materials and fission products are dissolved in Molten Salt Reactors (MSRs). Therefore the corrosion resistance of structure materials is the one of most important aspects for application in MSRs. Compatibility and chemical stability with the molten salt should be considered for some common structural alloys such as Incoloy-800H. In this research, the pure nickel coating was obtained by electroplating on the inner surface of nickel alloy to improve the corrosion resistance. However, there are some problems for plating on the inner surface of tube. For example the current is shielded and the anode is easy to passivate. The inner anode was used for solving these problems in this study. Pure nickel coating was obtain and the microstructure and properties of coating were analysed using this method. The thickness, hardness and microstructure of coating were observed by metallographic microscope, micro hardness tester and field emission scanning electron microscope, and the influence of deposition duration and annealing treatment duration on properties were analysed. Thermal shock performance was investigated as well. The results showed that the coating thickness increased linearly with the increasing of plating durations and the size of grain increased with the durations as well, the surface of coating became inhomogeneous correspondingly. The hardness of coating changed as the change of durations of annealing treatment. The thermal shock test showed that bonding strength of coating with substrate was good.

Process parameters influence on formation of oxides in coatings during pulsed laser deposition of titanium on inner surface of tubes

This study concerns droplet phase influence and process parameters influence (laser radiation power, oblique deposition, residual oxygen pressure, etc.) on morphology and composition of the coating and formation of oxides in the coating during pulsed laser deposition of Titanium on inner surface of tubes. It is shown that droplets in the coating in the presence of residual oxygen significantly affect the composition of Ti-coatings.

Effect of tooling design on the cold pilgering behavior of zircaloy tube

Cold pilgering is an incremental forming process through which the preliminary tube is formed to the final product between a mandrel and ring dies. The tooling (ring dies and mandrel) has a significant effect on the property and forming quality of tubes. In this paper, under ABAQUS/Explicit platform, a 3D elastic–plastic FE model of cold pilgering over the whole productive time was established and experimentally verified. A modified cumulative damage function (Lat&Co) was numerically implemented by user-defined material subroutine (VUMAT) in the ABAQUS. And the influence of top side relief on cold pilgering behavior of zircaloy tube, such as rolling force, strain ratio, and forming quality was explored. And the relationship between the strain ratio and texture revolution during cold pilgering was also revealed. It shows that ring dies with tangential side relief have advantage of preventing surface defects on the outer/inner zircaloy tube surface and lowering rolling force. The damage factor on inner surface of tube is slightly larger than which on outer surface. However, the top side relief of ring die has little influence on texture evolution.

New configuration for efficient and durable copper coating on the outer surface of a tube

A well-adhered copper coating on stainless steel power coupler parts is required in superconducting radio frequency (SRF) accelerators. Radio frequency power coupler parts are complex, tubelike stainless steel structures, which require copper coating on their outer and inner surfaces. Conventional copper electroplating sometimes produces films with inadequate adhesion strength for SRF applications. Electroplating also requires a thin nickel strike layer under the copper coating, whose magnetic properties can be detrimental to SRF applications. Coaxial energetic deposition (CED) and sputtering methods have demonstrated efficient conformal coating on the inner surfaces of tubes but coating the outer surface of a tube is challenging because these coating methods are line of sight. When the substrate is off axis and the plasma source is on axis, only a small section of the substrate's outer surface is exposed to the source cathode. The conventional approach is to rotate the tube to achieve uniformity across the outer surface. This method results in poor film thickness uniformity and wastes most of the source plasma. Alameda Applied Sciences Corporation (AASC) has developed a novel configuration called hollow external cathode CED (HEC-CED) to overcome these issues. HEC-CED produces a film with uniform thickness and efficiently uses all eroded source material. The Cu film deposited on the outside of a stainless steel tube using the new HEC-CED configuration survived a high pressure water rinse adhesion test. HEC-CED can be used to coat the outside of any cylindrical structure.

A novel plugged tube detection and identification approach for final super heater in thermal power plant using principal component analysis

During startup or normal operations, tube monitoring systems for steam boilers can considerably improve efficiency and reliability in thermal power plants (TPPs). Although several attempts have been made to detect and locate boiler tube leaks, what seems to be lacking is the study for tube plugging, one of the fundamental causes of the leaks and other tube failures. Scale and deposit formations on inner surfaces of tubes cause the tubes to be plugged. Although the formations can be suppressed and removed by chemical treatments for boiler water and steam blowing during startup procedures, it is still difficult to monitor and prevent tube plugging during startup or normal operations. In this paper, a novel plugged tube detection and identification approach is proposed for final super heater (FSH) tube banks. Principal component analysis is applied to tube temperature data for plugging detection and identification. The data are collected from thermocouples installed on the FSH outlet header section. To identify plugged tubes, contribution analysis and the characteristics of plugged tube temperatures are employed. To verify the performance of the proposed method, tube temperature data from an 870 MW supercritical coal-fired TPP are used. The experiment results show that the proposed method can successfully detect and identify plugged tubes. The proposed method can help to decide how many times steam blowing should be performed, whether startup procedures should be delayed or stopped, and which tubes should be maintained. Furthermore, severe tube failures can be prevented by avoiding damage from overheating due to tube plugging.

Biomimetic Bubble-Repellent Tubes: Microdimple Arrays Enhance Repellency of Bubbles Inside of Tubes.

The adhesion of bubbles underwater remains the greatest cause of malfunctions in applications such as microfluidics, medical devices, and heat exchangers. Recently, the combination of oxidization and peeling the top layer of self-organized honeycomb films with an adhesive tape resulted in the formation of an ultra-bubble-repellent and pillared polymer surface structure. However, the fabrication of honeycomb films on the inner surface of tubes and the formation of structured hydrophilic textures by peeling the top layer of honeycomb films still remain problematic. In this report, a simple fabrication technique for producing a honeycomb-patterned polymer film on the interior of a tube by dip-coating a polymer solution and blowing humid air in the tube is described. Furthermore, an ultra-bubble-repellent dimple-arrayed structure was fabricated by applying ultrasonication to the honeycomb structure formed on the interior surface of the tubes.