A different view of the tube surface in Minkowski 3-space $E_{1}^{3}$

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Muradiye Çimdiker Aslan ◽  
Yasin Ünlütürk
Keyword(s):  
Tube Surface

scholarly journals Bacteriophage Cocktail-Mediated Inhibition of Pseudomonas aeruginosa Biofilm on Endotracheal Tube Surface

Antibiotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 78
Author(s):  
Viviane C. Oliveira ◽  
Ana P. Macedo ◽  
Luís D. R. Melo ◽  
Sílvio B. Santos ◽  
Paula R. S. Hermann ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Endotracheal Tube ◽  
Metabolic Activity ◽  
Bacterial Colonization ◽  
Multidrug Resistant ◽  
Scientific Data ◽  
Tube Surface ◽  
Screening Assay ◽  
Biofilm Growth ◽  
Phage Cocktail

Although different strategies to control biofilm formation on endotracheal tubes have been proposed, there are scarce scientific data on applying phages for both removing and preventing Pseudomonas aeruginosa biofilms on the device surface. Here, the anti-biofilm capacity of five bacteriophages was evaluated by a high content screening assay. We observed that biofilms were significantly reduced after phage treatment, especially in multidrug-resistant strains. Considering the anti-biofilm screens, two phages were selected as cocktail components, and the cocktail’s ability to prevent colonization of the endotracheal tube surface was tested in a dynamic biofilm model. Phage-coated tubes were challenged with different P. aeruginosa strains. The biofilm growth was monitored from 24 to 168 h by colony forming unit counting, metabolic activity assessment, and biofilm morphology observation. The phage cocktail promoted differences of bacterial colonization; nonetheless, the action was strain dependent. Phage cocktail coating did not promote substantial changes in metabolic activity. Scanning electron microscopy revealed a higher concentration of biofilm cells in control, while tower-like structures could be observed on phage cocktail-coated tubes. These results demonstrate that with the development of new coating strategies, phage therapy has potential in controlling the endotracheal tube-associated biofilm.

Design and testing of energy-efficient heat exchangers for Newtonian and non-Newtonian fluids – A review

2021 ◽  
pp. 095765092110470
Author(s):  
Jayesh P ◽  
Mukkamala Y ◽  
Bibin John
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Exchangers ◽  
Internal Surface ◽  
Surface Modifications ◽  
Newtonian Fluids ◽  
Tube Surface ◽  
Pumping Power ◽  
Transfer Enhancement ◽  
The Impact

Heat transfer enhancement, pumping power and weight minimization in enhanced heat exchangers has long been achieved by deploying tubes with internal surface modifications like microgrooves, ribs, fins, knurls, and dimples with and without tube inserts. This article presents a very extensive review of experimental and computational studies on heat transfer enhancement, which covers convectional and unconventional working fluids under different fluid flow conditions. Compound augmentation with tube surface modifications and inserts has yielded enhancements in the overall heat transfer coefficient of over 116% in the fully developed turbulent flow regime. Exotic fluids like nano-coolants deployed in spiral grooved mircofin tubes yielded 196% enhancement in tube side heat transfer rate for concentrations as low as 0.5% by volume, while the thermal efficiency index measuring the overall enhancement in relation to the pumping power was 75%. However, reviews that address the combined effect of unconventional fluids, surface modifications and tube inserts on the overall thermo-hydraulic performance of annular heat exchangers seem to be limited. Further, nano-coolants aren’t frequently used in the process industry. The goal of this study is to document and evaluate the impact of cost-effective and energy-saving passive enhancement techniques such as tube surface modifications, tube inserts, and annular enhancement techniques on annular heat exchangers used in the process industries with Newtonian and non-Newtonian fluids. This review should be useful to engineers, academics and medical professionals working with non-Newtonian fluids and enhanced heat exchangers.

Enhancing Tribological Conditions in Tube Hydroforming by Using Textured Tubes

2004 ◽  
Author(s):  
Gracious Ngaile ◽  
Mark Gariety ◽  
Taylan Altan
Keyword(s):  
Deformation Behavior ◽  
Hydrodynamic Lubrication ◽  
Tube Hydroforming ◽  
Great Influence ◽  
Tribological Performance ◽  
Tube Surface ◽  
Sliding Velocity ◽  
Textured Surfaces ◽  
Interface Pressure ◽  
Surface Textures

The effects of textured tubes on the tribological performance in Tube Hydroforming (THF) are discussed. Textured surfaces, namely sand blasted, knurled, and as rolled surfaces were tested under various interface pressure and sliding velocity conditions. Sand blasted textured tubes were found to have the best tribological performance. It was also found that the interface pressure has a great influence on the attainment of Micro-Plasto HydroDynamic Lubrication (MPHDL) and Micro-Plasto HydroStatic Lubrication (MPHSL) conditions at the tool-workpiece interface. Preliminary finite element simulations on the deformation behavior of tube surface shows that surface textures can be optimized to enhance tribological performance.

Virtual-sample-based defect-detection algorithm for aluminum-tube surface

2021 ◽  
Author(s):  
Ning Lang ◽  
Decheng Wang ◽  
Peng Cheng ◽  
Shanchao Zuo ◽  
Pengfei Zhang
Keyword(s):  
Defect Detection ◽  
Detection Algorithm ◽  
Tube Surface ◽  
Virtual Sample ◽  
Aluminum Tube

Wettability Effects on Falling Film Flow and Heat Transfer Over Horizontal Tubes in Jet Flow Mode

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Avijit Karmakar ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Nusselt Number ◽  
Film Flow ◽  
Jet Flow ◽  
Equilibrium Contact Angle ◽  
Flow Mode ◽  
Falling Film ◽  
Tube Surface ◽  
Horizontal Tubes

Abstract The performance of a falling-film heat exchanger is strongly linked to the surface characteristics and the heat transfer processes that take place over the tubes. The primary aim of this numerical study is to characterize the influence of surface wettability on the film flow behavior and its associated surface heat transfer in the jet-flow mode. Volume of fluid (VOF) based simulations are carried out for horizontal tubes with different surface wettabilities. The wettability of the tube surfaces is represented using the Kistler's dynamic contact angle model. Surface wettability effects ranging from superhydrophilic to superhydrophobic are studied by varying the equilibrium contact angle from 2 deg to 175 deg. Two different liquid mass flow rates of 0.06 and 0.18 kg/m-s corresponding to the inline and staggered jet flow modes are studied. Results are presented in terms of the liquid film thickness, the contact areas between the different phases (solid–liquid and liquid–air), and the heat transfer coefficient or Nusselt number. The resistance imposed by the increasing contact angles inhibits the extent of the liquid spreading over the tube surface, and this, in turn, influences the liquid film thickness, and the wetted area of the tube surface. A significant decrement in the heat transfer rate from the tube surfaces was observed as the equilibrium contact angle increased from 2 deg to 175 deg. The local distributions of the Nusselt number over the tube surface are strongly influenced by the flow recirculation in the liquid bulk.

INFLUENCE OF DEPOSITION AND FOULING ON WALL TEMPERATURE DISTRIBUTION IN CONVECTIVE PATH

2020 ◽  
pp. 1-21
Author(s):  
Deli Li ◽  
Enlu Wang ◽  
Jinda Mao ◽  
Wei Wu ◽  
Yiyang Wang
Keyword(s):  
Temperature Distribution ◽  
Surface Temperature ◽  
Temperature Control ◽  
Theoretical Calculations ◽  
Influence Factors ◽  
Control Technology ◽  
Tube Surface ◽  
Gas Temperature ◽  
Surface Distribution ◽  
Super Heater

Abstract To develop a method of controlling the deposit tube surface temperature, the rules of deposition and fouling on the fireside, and the influence factors of the surface distribution were determined through experiments and theoretical calculations. The surface temperature distribution of a clean tube was compared with that of a deposit tube. Through theoretical calculations, the influence factors of the deposit tube surface temperature were evaluated. Based on the investigation, surface temperature control technology applicable to a super-heater was proposed and the feasibility of this heater was determined. A bimodal distribution was obtained when the temperature distribution of the deposit tube was plotted as a function of the angle, whereas a unimodal distribution was obtained for the clean tube. The results revealed that the heat exchange tube surface temperature is most effectively controlled by controlling the flue gas temperature. Prior to the development of higher performance materials (compared with conventional materials), surface temperature control technology can be used to ensure that the super-heater surface temperature lies below the allowable temperature of existing super-heater materials.

Experimental Measurements of Eddy Current Signal From SG Tubes of Fast Breeder Reactor Covered by a Thin Sodium Layer Using a SG Mock-Up

2009 ◽  
Author(s):  
Toshihiko Yamaguchi ◽  
Ovidiu Mihalache ◽  
Masashi Ueda ◽  
Shinya Miyahara
Keyword(s):  
Layer Thickness ◽  
Eddy Current ◽  
Eddy Currents ◽  
Material Surface ◽  
Straight Tube ◽  
Tube Surface ◽  
Experimental Conditions ◽  
Water Steam ◽  
Sodium Layer ◽  
Before And After

In Fast Breeder Reactors (FBR) which are sodium cooled, the steam generator (SG) heat exchanger tubes separate the low pressure sodium flowing in the SG vessel with the high pressure water-steam in tubes. During In-Service Inspection (ISI), sodium is first drained and then SG tubes are cooled down to the room temperature. After sodium draining, due to the high temperature (more than 500 °C), sodium adheres to SG tubes and structures around (SG support plates, welds) in a thin layer, filling eventually the gaps between SG support plates and tubes. During ISI, SG tubes are inspected for cracks and corrosions using differential eddy currents (EC) probes. Due to the high electrical conductivity of sodium adhering to the outer SG tube surface, the eddy current testing (ECT) signal modifies, in accord with sodium layer thickness or sodium deposits located on the outer SG tube surface. The sodium wetting properties depends on several factors as: material surface, temperature and sodium wetting time. The effect of sodium adhering to the outer SG tube on ECT signals were measured using a small mock-up tank (2 m high and 0.7 m in diameter) in which were introduced two SG tubes similar with the ones used in the Monju FBR (one tube is ferromagnetic and made of 2.25Cr–1Mo alloy, while the other one is made of SUS321 and is austenitic). Defects, SG support plates (on both helical and straight part of the tube) and welds were added to tubes and the ECT signal was measured before and after sodium draining. Variations in the sodium layer thickness and consequently its effect on ECT signals were measured by filling and draining the tank three times in order to recreate each time new layers of sodium. The paper describes the experimental conditions and the ECT results for both types of SG tubes by comparing the defects, SG support plates and weld signals before and after draining of sodium. Additionally, sodium structures were examined visually using a VideoScope camera, confirming the recorded ECT signals. The paper also presents details about sodium layer thickness measurements in several parts of SG tubes (near defect, SP, weld, bend, helical tube, straight tube) by scratching and collecting the sodium on a small area of 20mm×20mm. The volume of sodium drops is also estimated. The measurement results showed that there are significant differences in the sodium layer thickness depending on the SG tube material.

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