scholarly journals Investigation of Metal Air-Cooling Process as An Element of Thermal Processing

2019 ◽  
Vol 1 (2) ◽  
pp. 35
Author(s):  
Biryukov Alexey Borisovich ◽  
Gnitiev P. A.
Keyword(s):  
Heat Removal ◽  
Ceramic Fiber ◽  
Furnace Lining ◽  
Radiant Heat Transfer ◽  
Air Cooling ◽  
Ceramic Fibers ◽  
Technological Parameters ◽  
Conductivity Equation ◽  
Brick Lining ◽  
Coolant Delivery

<p>Background: Nowadays on metal tempering and annealing its air cooling (AC) is realized inside furnace with forced coolant delivery. Scientific tools lack for metal AC study and design is substantiated. The aim of this work is to investigate technological and design furnace parameters influence on metal AC duration, as well as disclosure of metal AC heat engineering regularities. Materials and method: For study mathematical model of metal AC is used. It bases on solving the differential non-stationary heat conductivity equation in one-dimensional form for cylindrical ingots and lining. Results: For three lining design types and different technological parameters operation acceleration possibility due to lining design change was studied. It is found that with ceramic fibers on walls and roof acceleration is 31-45% and with all lining made of ceramic fiber it is 44-52% as compared with fireclay brick lining. For a furnace with hearth of fireclay bricks and ceramic fiber on the walls and roof, convective component varies from 10 to 30%; for lining completely consisting of ceramic fibers it is 10 - 25%. When using fireclay brick lining parts their inner temperature is higher than for ceramic fiber up to 50 °C. Conclusions: Significant furnace lining materials type influence on metal AC intensity is proved. Heat removal mechanism on metal AC in furnace is disclosed, by establishing heat proportion directly removed from metal by convection. It is found that radiant heat transfer between metal and fireclay brick part of lining goes less intensively than with ceramic fiber part. </p>

scholarly journals Powder-in-Tube Reactive Molten-Core Fabrication of Glass-Clad BaO-TiO2-SiO2 Glass–Ceramic Fibers

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 395 ◽  
Author(s):  
Shuo Yang ◽  
Hanna Heyl ◽  
Daniel Homa ◽  
Gary Pickrell ◽  
Anbo Wang
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Second Harmonic ◽  
Picosecond Laser ◽  
Fused Silica ◽  
Ceramic Fiber ◽  
Powder Materials ◽  
Isothermal Heat Treatment ◽  
Ceramic Fibers ◽  
Powder In Tube

In this paper we report the fabrication of glass-clad BaO-TiO2-SiO2 (BTS) glass–ceramic fibers by powder-in-tube reactive molten-core drawing and successive isothermal heat treatment. Upon drawing, the inserted raw powder materials in the fused silica tubing melt and react with the fused silica tubing (housing tubing) via dissolution and diffusion interactions. During the drawing process, the fused silica tubing not only serves as a reactive crucible, but also as a fiber cladding layer. The formation of the BTS glass–ceramic structure in the core was verified by micro-Raman spectroscopy after the successive isothermal heat treatment. Second-harmonic generation and blue-white photoluminescence were observed in the fiber using 1064 nm and 266 nm picosecond laser irradiation, respectively. Therefore, the BTS glass–ceramic fiber is a promising candidate for all fiber based second-order nonlinear and photoluminescence applications. Moreover, the powder-in-tube reactive molten core method offers a more efficient and intrinsic contamination-free approach to fabricate glass–ceramic fibers.

Performance Evaluation of DRACS System for FHTR and Time Assessment of Operation Procedure

2013 ◽  
Author(s):  
Junya Nakata ◽  
Mikihiro Wakui ◽  
Michitsugu Mori ◽  
Hiroto Sakashita ◽  
Charles Forsberg
Keyword(s):  
Performance Evaluation ◽  
High Temperature ◽  
Cooling System ◽  
Heat Removal ◽  
Severe Accident ◽  
Air Cooling ◽  
Fluoride Salt ◽  
Nuclear Power Reactor ◽  
Decay Heat ◽  
Operation Procedure

The Fluoride-salt-cooled High-temperature Reactor (FHR) is a new concept of nuclear power reactor being investigated mainly in U.S. and China. The coolant is a liquid salt with a melting point of about 460°C and a boiling point of over 1400°C. As the baseline decay heat removal system, a passive Direct Reactor Air Cooling System (DRACS) is utilized. Though DRACS system has been developed in Sodium Fast reactors (SFR), there are some differences between both. For example, the system in FHR must decrease heat removal when temperatures are low to avoid freezing of the salt and blocking the flow of liquid. Therefore, considering its characteristics, a numerical investigation of DRACS system is needed to evaluate whether FHR has proper ability to remove decay heat and to be robust for a long-time cooling operation after even a severe accident. Furthermore, in addition to its performance evaluation, it is required to make up the operation plan of FHR considering features of this system. It is highly important, with the view of avoiding severe accident, to determine by when the system should be started up. In both countries mentioned above, Fluoride-salt-cooled High-temperature Test Reactor (FHTR) is currently in progress to build. Reviewing its design and system is a crucial step needed to develop the FHR technology. In this research, a performance of DRACS system under some thermal-hydraulic basic events was evaluated by numerical simulation. This paper also suggested the adequate operation procedure suitable for FHTR to avoid a severe accident.

scholarly journals The Impact of Environmental Factors on the Thermal Characteristic of a Lithium–ion Battery

Batteries ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 3 ◽  
Author(s):  
Gerd Liebig ◽  
Ulf Kirstein ◽  
Stefan Geißendörfer ◽  
Frank Schuldt ◽  
Carsten Agert
Keyword(s):  
Lithium Ion Battery ◽  
Thermal Characteristic ◽  
Thermal Characteristics ◽  
Heat Removal ◽  
Lithium Ion ◽  
Air Cooling ◽  
Heat Rejection ◽  
Study Results ◽  
Electrochemical Model ◽  
The Impact

To draw reliable conclusions about the thermal characteristic of or a preferential cooling strategy for a lithium–ion battery, the correct set of thermal input parameters and a detailed battery layout is crucial. In our previous work, an electrochemical model for a commercially-available, 40 Ah prismatic lithium–ion battery was validated under heuristic temperature dependence. In this work the validated electrochemical model is coupled to a spatially resolved, three dimensional (3D), thermal model of the same battery to evaluate the thermal characteristics, i.e., thermal barriers and preferential heat rejection patterns, within common environment layouts. We discuss to which extent the knowledge of the batteries’ interior layout can be constructively used for the design of an exterior battery thermal management. It is found from the study results that: (1) Increasing the current rate without considering an increased heat removal flux at natural convection at higher temperatures will lead to increased model deviations; (2) Centralized fan air-cooling within a climate chamber in a multi cell test arrangement can lead to significantly different thermal characteristics at each battery cell; (3) Increasing the interfacial surface area, at which preferential battery interior and exterior heat rejection match, can significantly lower the temperature rise and inhomogeneity within the electrode stack and increase the batteries’ lifespan.

Preparation and Microstructural Evolution of Sol-Gel-Derived Enstatite Fibers

2008 ◽  
Vol 368-372 ◽  
pp. 1007-1009
Author(s):  
M.T. Tsai ◽  
P.J. Tsai ◽  
H.C. Chang
Keyword(s):  
Microstructural Evolution ◽  
Sol Gel ◽  
Optical Transmittance ◽  
Ceramic Fiber ◽  
Visible Range ◽  
Metal Alkoxide ◽  
Ceramic Fibers ◽  
Bridging Ligands ◽  
Sol Gel Process ◽  
Infrared Studies

Homogeneous and transparent enstatite fibers were prepared via the sol-gel process of metal alkoxide precursors. The gel-to-ceramic conversion was characterized. The solution compositions had a significant influence on the microstructural evolution of gel fibers. Infrared studies indicated that bidentate bridging ligands were formed between acetate and metal ions, which enhanced spinnability remarkably. The as-drawn fibers were essentially microporous. On heating to 800 oC, enstatite ceramic fibers exhibited mesoporous structures with nanocrystals in size. The optical transmittance of enstatite ceramic fiber in the visible range was around 90 % after heating at 800 oC.

Facility for Continuous CVD Coating of Ceramic Fibers

1991 ◽  
Vol 250 ◽  
Author(s):  
Arthur W. Moore
Keyword(s):  
Boron Nitride ◽  
High Temperatures ◽  
Weight Ratio ◽  
High Strength ◽  
Ceramic Coatings ◽  
Ceramic Composites ◽  
Ceramic Fiber ◽  
Ceramic Fibers ◽  
Fiber Properties ◽  
Nitride Coatings

The development of new and improved ceramic fibers has spurred the development and application of ceramic composites with improved strength, strength/weight ratio, toughness, and durability at increasingly high temperatures. For many systems, the ceramic fibers can be used without modification because their properties are adequate for the chosen application. However, in order to take maximum advantage of the fiber properties, it is often necessary to coat the ceramic fibers with materials of different composition and properties. Examples include (1) boron nitride coatings on a ceramic fiber, such as Nicalon silicon carbide, to prevent reaction with the ceramic matrix during fabrication and to enhance fiber pullout and increase toughness when the ceramic composite is subjected to stress[l]; (2) boron nitride coatings on ceramic yarns, such as Nicalon for use as thermal insulation panels in an aerodynamic environment, to reduce abrasion of the Nicalon and to inhibit the oxidation of free carbon contained within the Nicalon[2]; and (3) ceramic coatings on carbon yarns and carbon-carbon composites to permit use of these high-strength, high-temperature materials in oxidizing environments at very high temperatures[3,4].

scholarly journals Mechanical Behavior of Reinforced Silty Sand: Focus on Application of Nano-Silica or Kaolin Coated Ceramic Fibers as a Reinforcement Material

2021 ◽  
Author(s):  
Mehdi Eshaghzadeh ◽  
Meysam Bayat ◽  
Rassoul Ajalloeian ◽  
Sayyed Mahdi Hejazi
Keyword(s):  
Fiber Surface ◽  
Friction Angle ◽  
Silty Sand ◽  
Ceramic Fiber ◽  
Fiber Reinforced ◽  
Ceramic Fibers ◽  
Coated Fiber ◽  
Direct Shear Tests ◽  
Stabilized Soil ◽  
Nanosilica Particles

Abstract Many studies have been done on the stabilization of weak soil using conventional chemical stabilizers such as lime, cement as well as modern materials such as nanoparticles; however, very few studies have examined the effect of coated fibers on the strength of stabilized soil. This paper presents the results of a series of direct shear tests on soil specimens treated with ceramic fiber, nanosilica, and kaolin. The effects of ceramic fibers, fiber length, nanosilica, and kaolin on the mechanical characteristics and shear strength of silty sand was investigated. The results show that the addition of fiber to silty sand resulted in a significant increase in the strength of the soil specimens. The dilative behavior of the soil specimen decreased with the addition of ceramic fibers. The cohesion of the fiber-reinforced specimens increased when the fiber surface was coated with nanosilica or kaolin particles. The friction angle of the coated fiber-reinforced specimens decreased with the addition of nanosilica particles; however, the friction angle of the coated fiber-reinforced specimens was practically independent of the kaolin content.

scholarly journals Contact crystallization of substances from solutions using evaporating refrigerants

2020 ◽  
Vol 15 (5) ◽  
pp. 7-15
Author(s):  
G. A. Nоsоv ◽  
M. E. Uvаrоv
Keyword(s):  
Aqueous Solutions ◽  
Crystallization Process ◽  
Heat Removal ◽  
Separation Process ◽  
Technological Parameters ◽  
Aggregate State ◽  
Initial Concentration ◽  
Liquid Phases ◽  
Compressor Power ◽  
Crystalline Suspension

Objectives. The aim of this study was to analyze the possibility of using contact crystallization with evaporating refrigerants for the isolation of substances from their aqueous solutions using salts [KNO3, NaI, and (NH2)2CO] as extraction examples and sucrose. Isobutane was used as a refrigerant.Methods. The analysis of the influence of the main technological parameters (i.e., solution’s cooling temperature, initial concentration, and compressed refrigerant vapor pressure) on the separation process and identification of its regularities was performed using mathematical dependencies previously developed by N.I. Gelperin and G.A. Nosov for each stage of the contact crystallization process. The authors studied the influence of these parameters on the yield of crystalline and liquid phases, refrigerant consumption, and compressor power.Results. The study showed that the use of evaporating refrigerants can significantly intensify the process of separating the mixture and spent refrigerant from the resulting crystalline suspension. This occurs owing to the evaporation of the liquid refrigerant that is in contact with the solution, which is accompanied by intense cooling. This process can be carried out at the temperature difference between the refrigerant and crystallizing mixture in the range of 0.5–1.0°C.Conclusions. Contact crystallization with evaporating refrigerants can be successfully applied to separate various substances from aqueous solutions. An important advantage of this process is the relatively low refrigerant consumption because heat removal from the solution is carried out as a result of changes in the aggregate state of the refrigerant. The use of contact crystallization can also considerably simplify the equipment.

scholarly journals Calculation and Experimental Study of Heat Exchange in a System of Plane-Parallel Channels with Surface Intensifiers

2021 ◽  
Vol 17 (2) ◽  
pp. 211-220
Author(s):  
S. I. Kaskov ◽  
Keyword(s):  
Experimental Study ◽  
Heat Exchange ◽  
Heat Removal ◽  
Air Cooling ◽  
Airflow Rate ◽  
Power Semiconductor ◽  
Average Temperature ◽  
Plane Parallel ◽  
Parallel Channels ◽  
The Difference

This paper presents the results of numerical investigation, calculation analysis and experimental study of heat exchange in a system of plane-parallel channels formed by rectangular fins, which are applied in a heat removal device using heat tubes for power semiconductor energy converters. Passive cooling (heat removal by radiation and natural convection) and active cooling (heat removal by radiation and forced convection) are investigated for various velocities of air cooling of fins by spherical vortex generators applied to its surface. A comparative analysis of the results is carried out for the average effective heat removal resistance and for the average temperature at the ends of the fins. The application of numerical modeling to solve such problems confirms the effectiveness of computational technologies. The difference between the results of the study ranges from 10 to 16% depending on the airflow rate.

scholarly journals The Influence of Technological Parameters on Durability of Products from ABS Plastic at Ultrasonic Welding

2019 ◽  
pp. 17-26
Author(s):  
S.S. Volkov ◽  
S.A. Korolev ◽  
D.S. Rozanov
Keyword(s):  
Welded Joint ◽  
Oscillation Amplitude ◽  
Heat Removal ◽  
Amplitude Distribution ◽  
Ultrasonic Welding ◽  
Optimal Choice ◽  
Welding Parameters ◽  
Technological Parameters ◽  
Welding Pressure

An ultrasonic welding method for round-shaped products made from ABS plastic is described in this paper. This method can eliminate roughness and waviness on the contact surface between the planimetric waveguide and the welded part, increase heat removal from the surface of the welded part in the subwaveguide zone and improve the efficiency of ultrasonic welding as well as the strength and quality of the welded joint. It is shown that a mushroom-shaped waveguide is the optimal choice for planimetric ultrasonic welding of ABS parts of the fan wheel type with regard to the uniformity of the oscillation amplitude distribution along the perimeter of the waveguide’s working end face. The optimal form of the waveguide’s working end face is defined that entails fixing the connecting parts relative to the waveguide’s axis along their diameter. It is established that at a certain combination of the ultrasonic welding modes for ABS plastic the rate of deformation at large welding pressures can turn out to be higher than at small pressures. This is caused by the competition of three factors: temperatures, static welding pressure and concentration of energy on the welded surfaces. It is determined that for welding ABS plastic the so-called soft modes of ultrasonic welding with small static welding pressure and oscillation amplitude of the waveguide’s end face should be used. In this case welding occurs only due to the distribution of microroughness, without dents from the waveguide on the surface of the welded material. Optimal welding parameters for ABS plastic are determined.

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