scholarly journals Monitoring and Controlling Saturation Zones in Heap Leach Piles Using Thermal Analysis

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 115
Author(s):  
Omar Daud ◽  
Mauricio Correa ◽  
Humberto Estay ◽  
Javier Ruíz-del-Solar
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Radio Frequency ◽  
Irrigation System ◽  
Infrared Camera ◽  
Heap Leaching ◽  
Potential Danger ◽  
Mechatronic System ◽  
Heap Leach ◽  
Irrigation Flow

This manuscript describes a method that is based on the implementation and setup of a mechatronic system that can recognize and detect, through thermal analysis, the zones where heap leaching piles may become locally saturated. Such a condition could trigger the potential of liquefaction, generating local or general collapse in the pile. In order to reduce this potential danger, and therefore achieve full stability in the pile, the irrigation system must be properly controlled; for instance, in potentially saturated zones, the irrigation flow can be reduced or eliminated until the saturation has disappeared. The mechatronic system consists of a hexacopter, equipped with a thermal infrared camera mounted on its structure and pointing down to the ground, which is used to obtain the temperature information of the heat transfer between the heap pile and the environment. Such information is very useful, as the level of saturated zones can then be traced. The communication between the operator of the irrigation system and the mechatronic system is based on a radio-frequency link, in which geo-referenced images are transmitted.

Thermal Analysis of Railroad Bearings: Effect of Wheel Heating

2009 ◽  
Author(s):  
Constantine M. Tarawneh ◽  
Arturo A. Fuentes ◽  
Brent M. Wilson ◽  
Kevin D. Cole ◽  
Lariza Navarro
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Roller Bearing ◽  
Railroad Wheel ◽  
Fe Model ◽  
Wheel Pair ◽  
Tapered Roller Bearing ◽  
Excessive Heat ◽  
Tapered Roller ◽  
Railroad Bearings

Catastrophic bearing failure is a major concern for the railroad industry because it can lead to costly train stoppages and even derailments. Excessive heat buildup within the bearing is one of the main factors that can warn of impending failure. A question is often raised regarding the transfer of heat from a wheel during braking and whether this can lead to false setouts. Therefore, this work was motivated by the need to understand and quantify the heat transfer paths to the tapered roller bearing within the railroad wheel assembly when wheel heating occurs. A series of experiments and finite element (FE) analyses were conducted in order to identify the different heat transfer mechanisms, with emphasis on radiation. The experimental setup consisted of a train axle with two wheels and bearings pressed onto their respective journals. One of the wheels was heated using an electric tape placed around the outside of the rim. A total of 32 thermocouples scattered throughout the heated wheel, the axle, and the bearing circumference measured the temperature distribution within the assembly. In order to quantify the heat radiated to the bearing, a second set of experiments was developed; these included, in addition to the axle and the wheel pair, a parabolic reflector that blocked body-to-body radiation to the bearing. The appropriate boundary conditions including ambient temperature, emissivity, and convection coefficient estimates were measured or calculated from the aforementioned experiments. The FE thermal analysis of the wheel assembly was performed using the ALGOR™ software. Experimental temperature data along the radius of the heated wheel, the bearing circumference, and at selected locations on the axle were compared to the results of the FE model to verify its accuracy. The results indicate that the effect of thermal radiation from a hot wheel on the cup temperature of the adjacent bearing is minimal when the wheel tread temperature is at 135°C (275°F), and does not exceed 17°C (31°F) when the wheel tread is at 315°C (600°F).

scholarly journals Heat transfer simulation of the cure of thermoplastic particle interleaf carbon fibre epoxy prepregs

2018 ◽  
Vol 53 (15) ◽  
pp. 2053-2064 ◽  
Author(s):  
Tassos Mesogitis ◽  
James Kratz ◽  
Alex A Skordos
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Sensitivity Study ◽  
Process Models ◽  
Analysis Techniques ◽  
New Class ◽  
Thermosetting Polymers ◽  
Heat Transfer Simulation ◽  
Thermal Analysis Techniques ◽  
Semi Empirical

Thermochemical properties are needed to develop process models and define suitable cure cycles to convert thermosetting polymers into rigid glassy materials. Uncertainty surrounding the suitability of thermal analysis techniques and semi-empirical models developed for conventional composite materials has been raised for the new class of particle interleaf materials. This paper describes kinetics, conductivity, heat capacity and glass transition temperature measurements of HexPly® M21 particle interleaf material. Thermal models describing conventional, non-particle epoxy systems were fit to the data and validated through a thick-section cure. Results from curing experiments agree with heat transfer simulation predictions, indicating that established thermal analysis techniques and models can describe polymerisation and evolving material properties during processing of a material representing the class of interleaf toughened systems. A sensitivity study showed time savings up to about 20%, and associated energy-efficiency-productivity benefits can be achieved by using cure simulation for particle interleaf materials.

Endwall Heat Transfer Measurements in a Staggered Pin Fin Array With an Adiabatic Pin

2007 ◽  
Author(s):  
Forrest E. Ames ◽  
Chad A. Nordquist ◽  
Lindsay A. Klennert
Keyword(s):  
Heat Transfer ◽  
Turbulent Transport ◽  
Infrared Camera ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Skin Friction Coefficient ◽  
Vortex System ◽  
Flow Acceleration ◽  
Pin Fin ◽  
Pin Fin Array

Full surface endwall heat transfer distributions have been acquired in a staggered pin fin array with the use of an infrared camera. Values are presented at Reynolds numbers of 3000, 10,000 and 30,000 based on pin diameter and average velocity through adjacent pins. Average endwall Nusselt numbers agree closely with archival values at each Reynolds number. Locally averaged heat transfer levels show a substantial increase from the inlet through the first few rows and finally a nearly streamwise periodic condition in the second half of the eight row geometry. Increasing levels of heat transfer in the inlet region can be attributed to the leading edge vortex system, flow acceleration around pins, and the generation of turbulence. Distributions of turbulence intensity and turbulent scale are shown to help document the turbulent transport conditions through the array. Detailed endwall Nusselt number distributions are presented and compared at the three Reynolds numbers for the first four and last four rows. These detailed heat transfer distributions highlight the influence of the horseshoe vortex system in the entrance region and the wake generated turbulence throughout the pin fin array. Local velocity and turbulence distributions are presented together with local Stanton number and skin friction coefficient data to examine the aggressive nature of the turbulent mixing.

scholarly journals Improving the Heat Transfer Rate of Air Conditioning Condenser by Material Optimization

2021 ◽  
pp. 39-50
Author(s):  
A. A. Adegbola ◽  
O. A. Adeaga ◽  
A. O. Babalola ◽  
A. O. Oladejo ◽  
A. S. Alabi
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Heat Flux ◽  
Flow Rate ◽  
Transfer Rate ◽  
Air Conditioning ◽  
Static Pressure ◽  
Cfd Analysis ◽  
Condenser Tube ◽  
Total Heat Transfer

Air conditioning systems have condensers that remove unwanted heat from the refrigerant and transfer the heat outdoors. The optimization of the global exploit of heat exchanging devices is still a burdensome task due to different design parameters involved. There is need for more and substantial research into bettering cooling channel materials so as to ensure elevated performance, better efficiency, greater accuracy, long lasting and low cost heat exchanging. The aim of this research work is to improve the heat transfer rate of air conditioning condenser by optimizing materials for different tube diameters. Simulations using thermal analysis and Computational Fluid Dynamic (CFD) analysis were carried out to determine the better material and fluid respectively. The analysis was done using Analysis System software. Different parameters were calculated from the results obtained and graphs are plotted between various parameters such as heat flux, static pressure, velocity, mass flow rate and total heat transfer. The materials used for CFD analysis are R12 and R22, and for thermal analysis are copper and aluminium. From the CFD analysis, the result shows that R22 has more static pressure, velocity, mass flow rate and total heat transfer than R12 at condenser tube diameter 6 mm. In thermal investigation, the heat flux is more for copper material at condenser tube diameter 6 mm. Copper offers maximum heat flux. Also, refrigerant R22 scores maximum for the heat transfer criteria, but cannot be recommended due to toxicity

Thermal Analysis and Design Applications of the Spiral Groove Tubes in Condensers

2014 ◽  
Vol 1070-1072 ◽  
pp. 1705-1708
Author(s):  
Xiao Lu Wang ◽  
Da Yu Huang
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Tube Bundle ◽  
Spiral Groove ◽  
Analysis And Design ◽  
Grooved Tube ◽  
The Heat Transfer Coefficient

In this paper, condensation mechanism of the Freon refrigerants outside spiral grooved tube is discussed. The heat transfer coefficient of Freon refrigerants condensation outside spiral grooved tube is obtained. A calculation example of heat transfer coefficient on the tube bundle of condenser with baffle bars is presented. It shows the excellent thermal performance of the spiral groove tubes compared to smooth tubes.

Incipient Flow Boiling in a Vertical Channel With a Wavy Wall

2010 ◽  
Author(s):  
T. Netz ◽  
R. Shalem ◽  
J. Aharon ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
High Speed ◽  
Flow Boiling ◽  
Heated Surface ◽  
Vertical Channel ◽  
Infrared Camera ◽  
Heat Fluxes ◽  
Heated Wall ◽  
Boiling Incipience

In the present study, incipient flow boiling of water is studied experimentally in a square-cross-section vertical channel. Water, preheated to 60–80 degrees Celsius, flows upwards. The channel has an electrically heated wall, where the heat fluxes can be as high as above one megawatt per square meter. The experiment is repeated for different water flow rates, and the maximum Reynolds number reached in the present study is 27,300. Boiling is observed and recorded using a high-speed digital video camera. The temperature field on the heated surface is measured with an infrared camera and a software is used to obtain quantitative temperature data. Thus, the recorded boiling images are analyzed in conjunction with the detailed temperature field. The dependence of incipient boiling on the flow and heat transfer parameters is established. For a flat wall, the results for various velocities and subcooling conditions agree well with the existing literature. Furthermore, three different wavy heated surfaces are explored, having the same pitch of 4mm but different amplitudes of 0.25mm, 0.5mm and 0.75mm. The effect of surface waviness on single-phase heat transfer and boiling incipience is shown. The differences in boiling incipience on various surfaces are elucidated, and the effect of wave amplitude on the results is discussed.

Use of Saline Injection to Create Large Thermal Lesions During Radio Frequency Ablation Therapy: 2. Experimental Results

2001 ◽  
Author(s):  
Lissa P. Silver ◽  
Patrick S. Hamilton ◽  
Angela C. Ni ◽  
Roberto M. Aimi ◽  
Michael G. Curley
Keyword(s):  
Heat Transfer ◽  
Radio Frequency ◽  
Liver Tumors ◽  
Treatment Options ◽  
Left Ventricular ◽  
Electrode Site ◽  
Experimental Results ◽  
Interface Temperature ◽  
Invasive Treatment ◽  
Ablation Therapy

Abstract Tissue charring during radio frequency (RF) therapy causes an impedance rise and prevents further tissue heating from occurring, thereby limiting the size of lesions that can be created. The ability to create very large lesions would provide minimally invasive treatment options for deep tissue left ventricular arrythmias and otherwise-untreatable large liver tumors. Adding convection as a method of heat transfer by injecting saline at the RF electrode site acts to both clamp the electrode/tissue interface temperature and carry energy deeper into the tissue. We have developed a RF system that uses both conduction and convection simultaneously to both enhance the amount of heat transfer and prevent or greatly delay the onset of charring. Here we confirm the heat transfer augmentation of convection with experimental results in skeletal muscle, liver, and myocardium.

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