scholarly journals Heat transfer to small cylinders and flat strips immersed in a fluidized bed

2021 ◽  
Author(s):  
Dennis Rosero
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Carbon Steel ◽  
Fluidized Bed ◽  
High Carbon Steel ◽  
Heat Treating ◽  
Operating Conditions ◽  
Vertical Position ◽  
Steel Wires ◽  
Flat Strip

Fluidized bed heat treating systems have been used to heat treat low carbon steel wires for a number of years. Extending this application to high carbon steel wires and metal straps has been implemented with very little success due to the lack of knowledge of heat transfer coefficients or, alternatively, Nusselt number for small cylinders and flat strips. The objective of this study was to provide reliable data for predicting a suitable Nusselt number for small horizontal cylinders and flat strips at various orientations under conditions typically encountered in heat treating fluidized bed systems. In this study, resistively heated small cylinders and flat strips ranging in diameter from 1.27 to 9.53mm and in width from 6.25 to 25.4mm respectively were immersed in a 311mm in diameter lab-scale fluidized bed. The bed consisted of fine alumina oxide sand of mean particle size ranging from 145 to 330[micro]m fluidized by air at ambient temperatures. The fluidized bed unit was capable of fluidizing rates ranging from 0.14 to 23 G/Gmf. The cylinder and flat strip samples were positioned horizontally in the bed. The flat strip samples were rotated around the length's center axis in 15° increments from a 0° horizontal position to a 90° vertical position. The results showed that published correlations over-predict small cylinder Nusselt numbers over the entire fluidizing range; furthermore, their trends did not agree. Flat strip results demonstrated highest heat transfer rates at a vertical position. A correlation that predicts the mean Nusselt number within ±15% for both geometries was developed for operating conditions covered by the experiments.

scholarly journals Heat transfer to small cylinders and flat strips immersed in a fluidized bed

2021 ◽  
Author(s):  
Dennis Rosero
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Carbon Steel ◽  
Fluidized Bed ◽  
High Carbon Steel ◽  
Heat Treating ◽  
Operating Conditions ◽  
Vertical Position ◽  
Steel Wires ◽  
Flat Strip

Fluidized bed heat treating systems have been used to heat treat low carbon steel wires for a number of years. Extending this application to high carbon steel wires and metal straps has been implemented with very little success due to the lack of knowledge of heat transfer coefficients or, alternatively, Nusselt number for small cylinders and flat strips. The objective of this study was to provide reliable data for predicting a suitable Nusselt number for small horizontal cylinders and flat strips at various orientations under conditions typically encountered in heat treating fluidized bed systems. In this study, resistively heated small cylinders and flat strips ranging in diameter from 1.27 to 9.53mm and in width from 6.25 to 25.4mm respectively were immersed in a 311mm in diameter lab-scale fluidized bed. The bed consisted of fine alumina oxide sand of mean particle size ranging from 145 to 330[micro]m fluidized by air at ambient temperatures. The fluidized bed unit was capable of fluidizing rates ranging from 0.14 to 23 G/Gmf. The cylinder and flat strip samples were positioned horizontally in the bed. The flat strip samples were rotated around the length's center axis in 15° increments from a 0° horizontal position to a 90° vertical position. The results showed that published correlations over-predict small cylinder Nusselt numbers over the entire fluidizing range; furthermore, their trends did not agree. Flat strip results demonstrated highest heat transfer rates at a vertical position. A correlation that predicts the mean Nusselt number within ±15% for both geometries was developed for operating conditions covered by the experiments.

Heat Transfer to Small Horizontal Cylinders Immersed in a Fluidized Bed

2006 ◽  
Vol 128 (10) ◽  
pp. 984-989 ◽  
Author(s):  
J. Friedman ◽  
P. Koundakjian ◽  
D. Naylor ◽  
D. Rosero
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Manufacturing Industry ◽  
Steel Wire ◽  
Small Diameter ◽  
Heat Treating ◽  
Packed Bed ◽  
Horizontal Cylinders

Heat transfer to horizontal cylinders immersed in fluidized beds has been extensively studied, but mainly in the context of heat transfer to boiler tubes in coal-fired beds. As a result, most correlations in the literature have been derived for cylinders of 25-50mm diameter in vigorously fluidizing beds. In recent years, fluidized bed heat treating furnaces fired by natural gas have become increasingly popular, particularly in the steel wire manufacturing industry. These fluidized beds typically operate at relatively low fluidizing rates (G∕Gmf<5) and with small diameter wires (1-6mm). Nusselt number correlations developed based on boiler tube studies do not extrapolate down to these small size ranges and low fluidizing rates. In order to obtain reliable Nusselt number data for these size ranges, an experimental investigation has been undertaken using two heat treating fluidized beds; one a pilot-scale industrial unit and the other a lab-scale (300mm diameter) unit. Heat transfer measurements were obtained using resistively heated cylindrical samples ranging from 1.3 to 9.5mm in diameter at fluidizing rates ranging from approximately 0.5×Gmf (packed bed condition) to over 10×Gmf using aluminum oxide sand particles ranging from dp=145-330μm (50–90 grit). It has been found that for all cylinder sizes tested, the Nusselt number reaches a maximum near 2×Gmf, then remains relatively steady (±5-10%) to the maximum fluidizing rate tested, typically 8-12×Gmf. A correlation for maximum Nusselt number is developed.

Heat Transfer to Flat Strips Immersed in a Fluidized Bed

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Christopher Penny ◽  
Dennis Rosero ◽  
David Naylor ◽  
Jacob Friedman
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Nusselt Number ◽  
Fluidized Bed ◽  
Manufacturing Industry ◽  
Particle Diameter ◽  
Orientation Angle ◽  
Heat Treating ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Heat transfer to objects immersed in a fluidized bed has been studied extensively across a relatively large range of geometries, though most work has looked at cylinders, a geometry important in power generation fluidized bed applications. As the power generation industry has been the primary stimulant to fluidized bed heat transfer research, very little information is available regarding geometries significant in heat treating applications. In this work, heat transfer to thin flat strips immersed in a fluidized bed is examined. This geometry is important in the steel strap manufacturing industry where many manufacturers use environmentally damaging molten lead baths to heat-treat their product. In order to determine the feasibility of a fluidized bed heat treating system as an alternative to the more hazardous lead-based process, an experimental investigation has been conducted in which Nusselt number data for flat strips with widths in the range of 6.35–25.4 mm are obtained using a laboratory-scale fluidized bed (310 mm diameter). Aluminum oxide sand particles in the range of dp=145–330 μm (50–90 grit) are used as the fluidized media within the fluidized operating range from 0.15Gmf to approximately 10Gmf. The strip orientation angle θo was also varied to establish the position from which maximum heat transfer is obtained. It was found that a decrease in particle diameter, an increase in fluidizing rate, and an increase in sample diameter resulted in an increase in Nusselt number. It was also observed that for the smaller samples tested, a maximum Nusselt number plateau was reached, at approximately G/Gmf=2.5. Finally, it was shown that an increase in θo (from 0 deg to 90 deg) resulted in an increase in Nusselt number. A correlation for the maximum Nusselt number was developed, providing excellent agreement within ±15%.

Heat Transfer to Small Cylinders Immersed in a Fluidized Bed

2005 ◽  
Author(s):  
Jacob Friedman ◽  
Polo Koundakjian ◽  
Dennis Rosero
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Manufacturing Industry ◽  
Steel Wire ◽  
Small Diameter ◽  
Heat Treating ◽  
Packed Bed ◽  
Pilot Scale

Heat transfer to horizontal cylinders immersed in fluidized beds has been extensively studied, but mainly in the context of heat transfer to boiler tubes in coal-fired beds. As a result, most correlations in the literature have been derived for cylinders of 25–50mm diameter in vigorously fluidizing beds. In recent years, fluidized bed heat treating furnaces fired by natural gas have become increasingly popular, particularly in the steel wire manufacturing industry. These fluidized beds typically operate at relatively low fluidizing rates (G/Gmf < 5) and with small diameter wires (1–6mm). Nusselt number correlations developed based on boiler tube studies do not extrapolate down to these small size ranges and low fluidizing rates. In order to obtain reliable Nusselt number data for these size ranges, an experimental investigation has been undertaken using two heat treating fluidized beds; one a pilot-scale industrial unit and the other a lab-scale (300mm diameter) unit. Heat transfer measurements were obtained using resistively heated cylindrical samples ranging from 1.3 mm to 9.5 mm in diameter at fluidizing rates ranging from approximately 0.5 × Gmf (packed bed condition) to over 10 × Gmf using aluminum oxide sand particles ranging from dp = 145–330 μm (50 to 90 grit). It has been found that for all cylinder sizes tested, the Nusselt number reaches a maximum near 2 × Gmf, then remains relatively steady (± 5–10%) to the maximum fluidizing rate tested, typically 8–12 × Gmf. A correlation for maximum Nusselt number is developed.

UNS G10600

Alloy Digest ◽  
1991 ◽  
Vol 40 (3) ◽  
Keyword(s):  
Fracture Toughness ◽  
Carbon Steel ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Carbon Steel ◽  
Heat Treating ◽  
High Carbon ◽  
Steel Mills

Abstract UNS No. G 10600 is a high-carbon steel of low hardenability. It may be used in the as-rolled, annealed, normalized or quenched and-tempered condition, depending on the desired properties. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, machining, and joining. Filing Code: CS-129. Producer or source: Carbon steel mills.

The Mould Flux Heat Conduction Performance Designing of High Carbon Steel for Thin Slab Continuous Casting

2014 ◽  
Vol 1033-1034 ◽  
pp. 1313-1316
Author(s):  
Hui Rong Li ◽  
Li Gen Sun ◽  
Li Qun Ai
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Carbon Steel ◽  
Continuous Casting ◽  
Orthogonal Experiment ◽  
High Carbon Steel ◽  
Thin Slab ◽  
High Carbon ◽  
Slab Continuous Casting ◽  
Mould Flux

Heat transfer of the mould flux between the mould and the strand is very complicated, especially for the high carbon steel thin slab continuous casting. In this research the orthogonal experiment has been carried out, and the results showed that: the effect for the heat flux form strong to weak is: R>Na2O>F>MgO>BaO. and in the experiment range, with the R increasing, when the R, Na2O content and the F- content are increasing, the heat flux would be decreasing; with the MgO content increasing, the crystallization temperature would getting fluctuant; with the BaO content increasing, the heat flux would getting fluctuant, when its content is around 6%, the heat flux is reach its summit.

Dynamic simulation of the circulating fluidized bed loop performance under the various operating conditions

2019 ◽  
Vol 233 (7) ◽  
pp. 901-913 ◽  
Author(s):  
Seongil Kim ◽  
Sangmin Choi ◽  
Jari Lappalainen ◽  
Tae-Ho Song
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Heat Transfer Rate ◽  
Dynamic Simulation ◽  
Transfer Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Operating Conditions ◽  
Temperature Behavior ◽  
Furnace Temperature

In a circulating fluidized bed boiler, the large thermal mass and flow characteristics of the solids strongly affect the transient response of the circulating fluidized bed loop temperature, which determines the heat transfer rate to steam flow. Therefore, it is essential to interpret the dynamic response of the solid behavior in the circulating fluidized bed loop for the stable and efficient operation of the circulating fluidized bed boiler. In this study, the dynamic simulation of the solid behavior along with the flue gas flow in a circulating fluidized bed loop was performed by applying the core-annulus approach for the solid-gas flow inside the furnace and selected models for other physical phenomena of the fluidized bed. The circulating fluidized bed loop of a commercial boiler was selected as the target system. Especially, the model simulates the characteristics of the solid behavior, such as the local solid mass distribution, and the solid flow inside the furnace and the circulating solid according to the various operating conditions. These aspects are difficult to measure and quantify in a real power plant. In this paper, the simulated furnace temperature behavior as the representative performance parameter of the circulating fluidized bed loop was discussed along with the qualitative operation experiences reported in the literature. The operating conditions include the feed rate of fuel and air, the particle size, the solid inventory and the solid circulation rate. Furnace temperature behavior was reproduced through the simulation for each operating case in the literature and was analyzed with the solid behavior along with the combustion rate and heat transfer rate of the circulating fluidized bed loop. The simulation enables quantitative evaluation of the effect of the solid behavior on the temperatures of the furnace and return part in the various operating conditions.

Optimization of Lead Patenting Process for High Carbon Steel Wires

2017 ◽  
Vol 87 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Shamsher Singh Bargujer ◽  
Narender M. Suri ◽  
Rajendra M. Belokar
Keyword(s):  
Carbon Steel ◽  
High Carbon Steel ◽  
High Carbon ◽  
Steel Wires

The Influence of Die Approach and Bearing Part of Die on Mechanical-Technological Properties of High Carbon Steel Wires / Wpływ Części Roboczej I Kalibrującej Ciągadła Na Własności Mechaniczno-Technologiczne Drutów Ze Stali Wysokowęglowej

2012 ◽  
Vol 57 (4) ◽  
pp. 1105-1110 ◽  
Author(s):  
J. Adamczyk ◽  
M. Suliga ◽  
J.W. Pilarczyk ◽  
M. Burdek
Keyword(s):  
Carbon Steel ◽  
High Carbon Steel ◽  
Effective Strain ◽  
Total Elongation ◽  
Strength Properties ◽  
Drawing Process ◽  
Technological Properties ◽  
High Carbon ◽  
Steel Wires ◽  
Bearing Part

In this work the influence of the die approach and bearing part of die on mechanical-technological properties of high carbon steel wires has been assessed. The drawing process of φ5.5 mm wires to the final wire of φ2.9 mm was conducted in 6 passes, by means of a multi-die drawing machine Koch type. The drawing speeds in the last passes were: 7 m/s. For wires drawn according to four variants the investigation of mechanical-technological properties has been carried out, in which yield strength, tensile strength, uniform and total elongation, reduction of area, the number of twists and the number of bends were determined. On the basis of numerical analyses wire drawing process, the influence of geometry of die on redundant strain and effective strain has been determined. The investigations have shown the essential influence of geometry of die on mechanical-technological properties of high carbon steel wires. It has been shown that the increase of strength properties in wires drawn with high die angle is related to the occurrence in their bigger effective strain.

Effect of roller die drawing on structure, texture and other properties of high carbon steel wires

1998 ◽  
Vol 4 (4) ◽  
pp. 727-731 ◽  
Author(s):  
Jan W. Pilarczyk ◽  
Henryk Dyja ◽  
Bogdan Golis ◽  
Elzbieta Tabuda
Keyword(s):  
Carbon Steel ◽  
High Carbon Steel ◽  
High Carbon ◽  
Steel Wires
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