scholarly journals Numerical simulation and experimental study on hematite production by oxidation of mill scale

2021 ◽  
Vol 1195 (1) ◽  
pp. 012044
Author(s):  
M T Aldiramadan ◽  
J Nabilah ◽  
M Ridwan ◽  
D S Khaerudini
Keyword(s):  
Waste Product ◽  
Thermal Characteristics ◽  
Ambient Air ◽  
Experimental Result ◽  
Mill Scale ◽  
Storage Media ◽  
Degree Of Oxidation ◽  
Pi Theorem ◽  
Recycle And Reuse ◽  
Oxide Derivative

Abstract Mill scale is a waste product from steel hot rolling processes and containing a high amount of FeO and Fe3O4. It is crucial to recycle and reuse this waste for the recovery into a metallic iron or its single oxide derivative. One of the end products of mill scale oxidation is hematite which has multitude of uses in various application. In this present study, mill scale is converted to hematite by roasting a mixture of mill scale at a specific set of conditions at 900°C for a varied time under ambient air environment by addition of pelletized limestone as a heat storage media. In this work, the Dimensionless Degree of Oxidation Prediction Model (DDOPM) has been constructed to gain hematite purity approach in the resulting powder by using Matlab. The Buckingham Pi Theorem is used to find dimensionless parameters considering the effect of different parameters including the geometric factor of tubular horizontal furnace used, characteristic of mill scale, ambient air factor, and thermal characteristics of limestone. The degree of oxidation from experimental result was obtained from XRF analysis and compared to the result of DDOPM to show the correlation between the experimental and numerical.

Small and Full-Scale Modeling for the Application of Wall Solar Chimneys

2016 ◽  
Author(s):  
David Park ◽  
Francine Battaglia
Keyword(s):  
Natural Ventilation ◽  
Velocity Ratio ◽  
Thermal Conditions ◽  
Ambient Air ◽  
Full Scale ◽  
Scale Model ◽  
Small Scale ◽  
Solar Chimney ◽  
Window Position ◽  
Pi Theorem

A solar chimney is a natural ventilation technique that has a potential to save energy consumption as well as to maintain the air quality in the building. However, studies of buildings are often challenging due to their large sizes. The objective of the current study was to determine relationships between small- and full-scale solar chimney system models. In the current work, computational fluid dynamics (CFD) was utilized to model different building sizes with a solar chimney system, where the computational model was validated with the experimental study of Mathur et al. The window, which controls entrainment of ambient air, was also studied to determine the effects of window position. Correlations for average velocity ratio and non-dimensional temperature were consistent regardless of window position. Buckingham pi theorem was employed to further non-dimensionalize the important variables. Regression analysis was conducted to develop a mathematical model to predict a relationship among all of the variables, where the model agreed well with simulation results with an error of 2.33%. The study demonstrated that the flow and thermal conditions in larger buildings can be predicted from the small-scale model.

A Comparison of Cover Coat Methods for Electronic Flexible Printed Circuit (E-FPC) Based on Peeling Strength

2011 ◽  
Vol 421 ◽  
pp. 489-492 ◽  
Author(s):  
Suradet Tantrairatn ◽  
Paphakorn Pitayachaval ◽  
Sirisak Rangklang ◽  
Jiraphon Srisertpol
Keyword(s):  
Waste Product ◽  
Experimental Result ◽  
Machine Method ◽  
Electrical Circuits ◽  
Printed Circuit ◽  
Printed Circuits ◽  
Acceptable Range ◽  
Peeling Strength ◽  
Flexible Printed Circuit

In electronic flexible printed circuit (E-FPC) manufacturing procedure, the cover laminating process in which the line circuit (copper wire) is covered with hot cover layer on the printed circuits is importance process. This process will help to increase elasticity, strength and corrosion protection to the product therefore this process can affect directly to quality of the printed circuit. The process for laminating printed circuits can be classified into two methods by coating with industry iron and hot bar machine. This article compares the quality of the electrical circuit between industry iron and hot bar machine methods in the cover coating process by using Peeling Strength to indicate the quality in the same temperature and time condition. The experimental result illustrates the electrical circuits using the hot bar machine method give Peeling Strength value in the acceptable range and the laminating surface of circuits is smooth and uniform. On the other hand, Peel Strength value of electrical circuits using the industry iron method is unsteady and lower than the acceptable range. Moreover the result circuit product has wrinkled coating surface and become the waste product.

Thermophysical properties and thermal characteristics of phase change emulsion for thermal energy storage media

Energy ◽  
2016 ◽  
Vol 117 ◽  
pp. 562-568 ◽  
Author(s):  
Tsuyoshi Kawanami ◽  
Kenichi Togashi ◽  
Koji Fumoto ◽  
Shigeki Hirano ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Thermophysical Properties ◽  
Thermal Characteristics ◽  
Storage Media

Biomechanical properties and thermal characteristics of frozen versus thawed whole bone

2020 ◽  
Vol 234 (8) ◽  
pp. 874-883
Author(s):  
Ignace J Brazda ◽  
Jacob Reeves ◽  
G Daniel G Langohr ◽  
Meghan C Crookshank ◽  
Emil H Schemitsch ◽  
...  
Keyword(s):  
Steady State ◽  
Thermal Characteristics ◽  
Ambient Air ◽  
Biomechanical Properties ◽  
Mechanical Tests ◽  
Mineral Density ◽  
Cross Sectional ◽  
Three Point Bending ◽  
Transverse Cracking ◽  
Steady State Temperature

Biomechanics research often requires cadaveric whole bones to be stored in a freezer and then thawed prior to use; however, the literature shows a variety of practices for thawing. Consequently, this is the first study to report the mechanical properties of fully frozen versus fully thawed whole bone as ‘proof of principle’. Two groups of 10 porcine ribs each were statistically equivalent at baseline in length, cross-sectional area, and bone mineral density. The two groups were stored in a freezer for at least 24 h, thawed in air at 23 °C for 4 h while temperature readings were taken to establish the time needed for thawing, and once again returned to the freezer for at least 24 h. Mechanical tests to failure using three-point bending were then done on the ‘frozen’ group immediately after removal from the freezer and the ‘thawed’ group when steady-state ambient air temperature was reached. Temperature readings over the entire thawing period were described by the line-of-best-fit formula T = (28.34t − 6.69)/(t + 0.38), where T = temperature in degree Celsius and t = time in hours, such that frozen specimens at t = 0 h had a temperature of −17 °C and thawed specimens at t = 1.75 h reached a steady-state temperature of 20 °C–23 °C. Mechanical tests showed that frozen versus thawed specimens had an average of 32% higher stiffness k, 34% higher ultimate force Fu, 28% lower ultimate displacement δu, 40% lower ultimate work Wu, 43% higher elastic modulus E, 37% higher ultimate normal stress σu, and 33% higher ultimate shear stress τu. Whole ribs failed at midspan primarily by transverse cracking (16 of 20 cases), oblique cracking (three of 20 cases), or surface denting (one of 20 cases), each having unique shapes for force versus displacement graphs differentiated mainly by ultimate force location.

Thermal Behaviors in a Square Duct with U-Ribbed Tape Inserts

2014 ◽  
Vol 931-932 ◽  
pp. 1208-1212
Author(s):  
Chitakorn Khanoknaiyakarn ◽  
Sompol Skullong ◽  
Pongjet Promvonge ◽  
Nuthvipa Jayranaiwachira
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Performance Enhancement ◽  
Thermal Characteristics ◽  
Longitudinal Vortex ◽  
Experimental Result ◽  
Airflow Rate ◽  
Constant Heat ◽  
Square Duct ◽  
The One

This paper presents an experimental study on thermal characteristics in a constant heat-fluxed square-duct heat exchanger with U-ribbed tape inserts. The experiments are carried out by varying airflow rate for Reynolds number ranging from 4000 to 38,000. The insertion of the U-ribbed tape is performed with an axial rib-pitch set to four times duct-height (4H) at a single attack angle, α=45° and the ribbed tape is diagonally inserted in the square duct in order to generate longitudinal vortex flows. Effects of five blockage ratios (e/H=0.1, 0.15, 0.2, 0.25 and 0.3) on heat transfer and friction loss are experimentally investigated. The experimental result shows that the insertion of the U-ribbed tape at e/H=0.3 provides the highest heat transfer and friction factor values but the one at e/H=0.25 yields the highest thermal performance enhancement.

scholarly journals Study of heat transfer and pressure drop characteristics of air heat exchanger using PCM for free cooling applications

2016 ◽  
Vol 20 (5) ◽  
pp. 1543-1554 ◽  
Author(s):  
Sivakumar Kalaiselvam ◽  
Kanchipuram Sureshkumar ◽  
Vijeykishoor Sriram
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Phase Change Materials ◽  
Thermal Characteristics ◽  
Ambient Air ◽  
Dynamics Modeling ◽  
Tube Heat Exchanger ◽  
High Heat Transfer ◽  
Free Cooling

Free cooling is the process of storing the cool energy available in the night ambient air and using it during the day. The heat exchanger used in this work is a modular type which is similar to the shell and tube heat exchanger. The shell side is filled with Phase Change Materials (PCM) and air flow is through the tubes in the module. The modules of the heat exchanger are arranged one over other with air spacers in between each module. The air space provided in between the module in-creases the retention time of the air for better heat transfer. Transient Computational Fluid Dynamics modeling is carried out for single air passage in a modular heat exchanger. It shows that the PCM phase transition time in the module in which different shape of fins is adopted. The module with rectangular fins has 17.2 % reduction in solidification compared with the plain module. Then steady state numerical analysis is accomplished to the whole module having the fin of high heat transfer, so that pressure drop, flow and thermal characteristics across the module and the air spacers are deter-mined for various air inlet velocities of 0.4 to 1.6 m/s. To validate the computational results, experiments are carried out and the agreement was found to be good.

Issues in Vapor Phase Lubrication of Magnetic Data Storage Media

2005 ◽  
Author(s):  
Andrew J. Gellman ◽  
Yang Yun
Keyword(s):  
Data Storage ◽  
Vapor Phase ◽  
Ambient Air ◽  
Magnetic Data ◽  
Vapor Phase Lubrication ◽  
Initial Oxidation ◽  
Storage Media ◽  
Airborne Contamination ◽  
Langmuir Hinshelwood Mechanism ◽  
Kinetics Of

Vapor phase lubrication (VPL) integrates media lubrication with the vacuum processing steps used throughout most of the hard disk media fabrication process. This avoids exposure of the unlubricated a-CHx overcoat surface to the ambient air and airborne contamination. In vapor lubrication the a-CHx surface can be oxidized under controlled conditions immediately prior to lubricant adsorption. The kinetics of a-CHx oxidation have been studied using x-ray photoemission spectroscopy in an apparatus that allows oxidation of freshly deposited a-CHx films. The dissociative sticking coefficient of oxygen is ∼10−6 and the initial oxidation kinetics can be described by a Langmuir-Hinshelwood mechanism.

scholarly journals Investigation of Hydrogen Storage Characteristics of MgH2 Based Materials with Addition of Ni and Activated Carbon

Inorganics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 12 ◽  
Author(s):  
Eli Grigorova ◽  
Diana Nihtianova ◽  
Boyko Tsyntsarski ◽  
Ivanka Stoycheva
Keyword(s):  
Activated Carbon ◽  
Hydrogen Storage ◽  
Surface Composition ◽  
Positive Impact ◽  
Waste Product ◽  
Absorption Capacity ◽  
Storage Media ◽  
Selected Area Electron Diffraction ◽  
Before And After ◽  
Polyethylene Production

Magnesium-based materials are promising as hydrogen storage media due to their high theoretical hydrogen absorption capacity, abundance and low price. The subject of this study are the hydrogen sorption characteristics of the composites 80 wt % MgH2-15 wt % Ni-5 wt % activated carbon (synthesized from polyolefin wax, a waste product of polyethylene production at low pressure which will be denoted further in the text as POW) and 90 wt % MgH2-5 wt % Ni-5 wt % POW, prepared by ball milling under argon atmosphere. Structure, phase and surface composition of the samples before and after hydrogenation are determined by XRD and TEM. The maximum absorption capacity value of the composites at a temperature 573 K and after 60 min. of hydrogenation are 5.3 wt % H2 for the material with higher Ni content and 5.5 wt % H2 for the other sample. The presence of both additives—nickel and activated carbon derived from POW—has a positive impact on hydrogenation kinetics and the capacity achieved. The results from TEM characterization, e.g., the polycrystalline SAED (selected area electron diffraction) show the presence of graphite, Mg and monoclinic Mg2NiH4.

Vapor Phase Lubricant Adsorption on Magnetic Data Storage Media

2005 ◽  
Author(s):  
Yang Yun ◽  
Andrew J. Gellman
Keyword(s):  
Data Storage ◽  
Vapor Phase ◽  
Ambient Air ◽  
Magnetic Data ◽  
Vapor Phase Lubrication ◽  
Storage Media ◽  
Airborne Contamination ◽  
Hydrogenated Amorphous ◽  
Processing Steps ◽  
Vapor Lubrication

Vapor phase lubrication (VPL) integrates media lubrication with the vacuum processing steps used throughout most of the hard disk media fabrication process. This avoids exposure of the unlubricated hydrogenated amorphous carbon (a-CHx) overcoat to the ambient air and airborne contamination. In vapor lubrication the a-CHx surface can be oxidized under controlled conditions immediately prior to lubricant adsorption. The interaction between lubricants and a-CHx films can be tailored by controlled oxidation of the a-CHx in vapor phase lubrication.

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