scholarly journals Impacts of increasing the airflow rate on load-haul-dump heat spread at an underground mine

2021 ◽  
Vol 882 (1) ◽  
pp. 012049
Author(s):  
D R Kaiyandra ◽  
R Yulianti ◽  
P N Hartami
Keyword(s):  
Air Temperature ◽  
Process Mining ◽  
Ventilation Network ◽  
Airflow Rate ◽  
Mining Equipment ◽  
Ansys Fluent ◽  
Mining Companies ◽  
Tunnel Model ◽  
Reduced Temperature ◽  
Heat Spreading

Abstract In the mining process, mining companies use various mining equipment to extract valuable materials. One of them is a load-haul-dump (LHD) machine. Although this equipment is very helpful in the production process, it also has drawbacks. This equipment emits heat that can affect air temperature in the mine tunnel and cause a decrease in the comfort of mineworkers, which then impacts the mine productivity. One of the methods that can be carried out to overcome this problem is to increase the amount of airflow by changing the ventilation network. Therefore, this study aims to determine the impacts of increasing airflow on the heat spread of the operated LHD machines. The results of this study are to provide a method for reduced temperature visually and can be used as a recommendation for temperature reduction in the future. To examine the heat spreading, the researchers applied a tunnel model made using CFD software that is ANSYS Fluent and use VentSim software to simulate the network changes. The results indicated that the increase of the airflow rate could reduce the temperature on the work front when the LHD machines are operating and can affect the heat spread.

scholarly journals Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4743
Author(s):  
Tomasz Janoszek ◽  
Zbigniew Lubosik ◽  
Lucjan Świerczek ◽  
Andrzej Walentek ◽  
Jerzy Jaroszewicz
Keyword(s):  
Numerical Calculations ◽  
Mining Institute ◽  
Ventilation Network ◽  
Underground Excavation ◽  
In Situ Tests ◽  
Ansys Fluent ◽  
Aerosol Emission ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

scholarly journals 2D Numerical Simulation Study of Airfoil Performance

2021 ◽  
Author(s):  
Nasser Shelil
Keyword(s):  
Experimental Data ◽  
Wind Tunnel ◽  
Air Temperature ◽  
Wind Turbines ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
Ansys Fluent

Abstract. The aerodynamic characteristics of DTU-LN221 airfoil is studied. ANSYS Fluent is used to simulate the airfoil performance with seven different turbulence models. The simulation results for the airfoil with different turbulence models are compared with the wind tunnel experimental data performed under the same operating conditions. It is found that there is a good agreement between the computational fluid dynamics (CFD) predicted aerodynamic force coefficients with wind tunnel experimental data especially with angle of attack between −5° to 10°. RSM is chosen to investigate the flow field structure and the surface pressure coefficients under different angle of attack between −5° to 10°. Also the effect of changing air temperature, velocity and turbulence intensity on lift and drag coefficients/forces are examined. The results show that it is recommended to operate the wind turbines airfoil at low air temperature and high velocity to enhance the performance of the wind turbines.

scholarly journals Heat Transfer Enhancement in Air Cooled Gas Turbine Blade Using

2021 ◽  
Vol 8 (3) ◽  
pp. 52-69
Author(s):  
Dr. Farhan Lafta Rashid Rashid ◽  
Dr. Haider Nadhom Azziz Azziz ◽  
Dr. Emad Qasem Hussein Hussein
Keyword(s):  
Temperature Distribution ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Air Temperature ◽  
Air Flow ◽  
Three Dimensions ◽  
Internal Diameter ◽  
Wall Surface ◽  
Gas Turbine Blade ◽  
Ansys Fluent

In this paper, an investigation of using corrugated passages instead of circular crosssection passages was achieved in conditions simulate the case in the gas turbine blade coolingusing ANSYS Fluent version (14.5) with Boundary conditions: inlet coolant air temperature of300 K with different air flow Reynolds numbers (191000, 286000 and 382000). Thesurrounding constant hot air temperatures was (1700 K). The numerical simulations was done bysolving the governing equations (Continuity, Reynolds Averaging Navier-stokes and Energyequation) using (k-ε) model in three dimensions by using the FLUENT version (14.5). Thepresent case was simulated by using corrugated passage of 3 m long, internal diameter of 0.3 m,0.01 m groove height and wall thickness of 0.01 m, was compared with circular cross sectionpipe for the same length, diameter and thickness. The temperature, velocity distributioncontours, cooling air temperature distribution, the inner wall surface temperature, and thermalperformance factor at the two passages centerline are presented in this paper. The coolant airtemperature at the corrugated passage centerline was higher than that for circular one by(12.3%), the temperature distribution for the inner wall surface for the corrugated passage islower than circular one by (4.88 %). The coolant air flow velocity seems to be accelerated anddecelerated through the corrugated passage, so it was shown that the thermal performance factoralong the corrugated passage is larger than 1, this is due to the fact that the corrugated wallscreate turbulent conditions and increasing thermal surface area, and thus increasing heat transfercoefficient than the circular case.

Deposition of Ellipsoidal Fibers in Nasal Cavity: Influence of Non-Creeping Flow Conditions

2019 ◽  
Author(s):  
Mehdi Aboulhasan Tash ◽  
Mohammad Mehdi Tavakol ◽  
Omid Abouali ◽  
Goodarz Ahmadi
Keyword(s):  
Nasal Cavity ◽  
Flow Condition ◽  
Hot Spot ◽  
Hydrodynamic Forces ◽  
Physical Activities ◽  
Creeping Flow ◽  
Airflow Rate ◽  
Ansys Fluent ◽  
Aspect Ratios ◽  
Deposition Fraction

Abstract In this study, deposition fraction of ellipsoidal particles in a 3D-Model of the nasal cavity (right airway) of a 24-year-old healthy woman was simulated for laminar and turbulent inhalation flow rates. The geometry used included the main nasal cavity from the nostril to the beginning of nasopharynx and was constructed in the Ansys-ICEM software from a CT scan image. The numerical simulations of governing equations were obtained using the Ansys-Fluent software. The mean airflow was assumed to be incompressible and steady. For turbulence modeling, the Realizable k-ε model was employed and the Lagrangian trajectory analysis method was used for particle tracking. For evaluating the ellipsoidal particle motions, several user-defined functions (UDFs) were developed and linked to the discrete phase model of the Ansys-Fluent code. The developed UDFs solve for the coupled translational and rotational equations of motion for ellipsoidal fibers and also accounts for the stochastic modeling of turbulence velocity fluctuations. The hydrodynamic forces and torques were calculated based on the non-creeping formulations for various ellipsoidal fibers. Laminar flow condition was assumed for breathing rate of 5.0 lit/min for the rest or light physical activities and turbulent flow condition was assumed for airflow rate of 20 lit/min for high physical activities. To investigate the dispersion and deposition of particles in the model of the human nasal cavity, various fibers with a semi-minor axis of 1, 3, 5 and 10 μm and various aspect ratios were considered. Using the non-creeping flow formulation for hydrodynamic forces and torques, the simulation results showed slight differences in the total deposition fraction of ellipsoidal fibers compared with the corresponding creeping flow model. Small fibers deposit roughly uniformly in the nasal cavity with no hotspot region. For the large inertial fibers, however, the nasal valve is a hot spot region, where the deposition rate reaches to its peak.

Process optimization of paddy drying in cross-flow aerated drying cum storage bin

2020 ◽  
Vol 44 (03) ◽  
pp. 7-15
Author(s):  
Sruthi N. U. ◽  
U. C. Lohani ◽  
N. C. Shahi ◽  
J. P. Pandey
Keyword(s):  
Air Temperature ◽  
Specific Energy Consumption ◽  
Cross Flow ◽  
Moisture Diffusivity ◽  
Airflow Rate ◽  
Experimental Conditions ◽  
Heating Chamber ◽  
Drying Time ◽  
Drying Rates ◽  
Drying Conditions

A cross-flow aerated drying cum storage bin was developed and the drying conditions for paddy was optimised. The drying cum storage bin consisted of a cylindrical outer drum with two inner basins having perorated walls made of galvanised iron to hold paddy, and a central perforated vertical duct. A blower (1.5 kW) connected at the base supplies air to the heating chamber (with 1 kW heater coil) and moves vertically through the central duct. The hot air passes horizontally through the grain bulk taking the moisture and moves towards the perforated walls of the bin and exit through the space between the drum and the basins. Drying experiments were conducted with bed thickness of 15 cm to study the drying characteristics of paddy and evaluate the performance of the dryer. Paddy was dried from 18 to 12% (wb) moisture content with the independent parameters selected being drying air temperature (35, 40 and 45 °C) and airflow rate (15, 21 and 27 m3 /h). The drying time varied 1.5 to 4.75 hours over the entire experimental conditions. The analysis of drying rates for both top and bottom bins showed minimum variation indicating uniform drying throughout the depth of the bin. The estimated optimum conditions of drying were 45°C temperature and 27 m3 /h airflow rate. The predicted values of responses at optimised conditions were 1.51 hours of drying time, 6.05x10-7 m2 /s of effective moisture diffusivity, 0.078 W/m2 K of heat transfer coefficient, and 8.23x105 kJ/kg of specific energy consumption. Further, exergy analysis indicated that exergy loss increased with increase in drying air temperature and airflow rate.

Heat and Mass Transfer Characteristics of a Finned-Tube Evaporator Under Frosting Conditions

2001 ◽  
Author(s):  
Y. H. Kim ◽  
Y. J. Park ◽  
Y. C. Kim ◽  
S. C. Shim ◽  
S. K. Oh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Air Temperature ◽  
Early Stage ◽  
Finned Tube ◽  
Airflow Rate ◽  
Air Velocity ◽  
Frost Formation ◽  
Transfer Characteristics

Abstract An experimental study was performed to investigate the heat and mass transfer characteristics of a finned-tube evaporator coil utilized in a domestic refrigerator under frosting conditions. Airside heat transfer coefficient was measured as a function of air temperature, humidity ratio, air velocity, and evaporating temperature. In addition, frost thickness was monitored and measured by visualization tests during frosting operation. Based on the experimental results, the degradation of heat transfer performance due to frost formation was explored as a function of operating parameters. The rate of frost formation on the evaporator increases at relatively high humidity, high airflow rate, low inlet air temperature and low refrigerant temperature. As the frost thickness increases, airflow rate gradually decreases, while the capacity increases at the early stage of frost formation and then significantly drops.

A Gray-Box Based Virtual SCFM Meter in Rooftop Air-Conditioning Units

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Daihong Yu ◽  
Haorong Li ◽  
Yuebin Yu
Keyword(s):  
Real Time ◽  
Air Temperature ◽  
First Principles ◽  
Air Conditioning ◽  
Low Cost ◽  
Fault Detection And Diagnosis ◽  
Operating Conditions ◽  
Airflow Rate ◽  
Fault Diagnostics ◽  
True Value

Knowledge of supply airflow rate (SCFM) measurement in packaged rooftop air-conditioning units (RTUs) is vital for improving energy management and indoor air quality and facilitating real-time automated control and fault detection and diagnosis. Despite the importance of SCFM measurement in RTUs, the conventional SCFM metering devices are very vulnerable. The credibility of SCFM measurement would be compromised dramatically after a long-term use in adverse duct work surroundings. Moreover, application of conventional SCFM meters in RTUs is very costly in regard to procurement, installation, and periodic maintenance. A cost-effective and accurate nonconventional first principles based SCFM meter in RTUs was proposed previously to virtually monitor SCFM measurement. In order to overcome the deficiencies of the first principles based virtual SCFM meter in model implementation and fault diagnostics, experiments with a wider combination and coverage are investigated in this study. It is found that a gray-box based virtual SCFM meter can be obtained with available system information (outside air damper status) and low-cost temperature measurements (direct measurement of a manufacturer-installed supply air temperature sensor (SATmfr,meas) and outside air temperature). Further experiment evaluations demonstrate that the gray-box based virtual SCFM meter could predict the true value of SCFM very accurately (the uncertainty is ±5.9%) with significantly enhanced applicability in model implementation and capability in fault diagnostics. Additionally, the gray-box based virtual SCFM meter also inherits good characteristics of the first principles based virtual SCFM meter, such as high cost-effectiveness, good robustness against variations in multivariable operating conditions, and applicability to similar RTUs. This innovative virtual meter could serve as a permanent monitoring tool to indicate real-time SCFM measurement and/or to automatically detect and diagnose an improper quantity of SCFM for RTUs.

Computational Fluid Dynamics Simulation of Ventilation Effect of a Large Cross-Section Cable Tunnel

2013 ◽  
Vol 353-356 ◽  
pp. 1404-1410
Author(s):  
Jun Sheng Chen ◽  
Shu Zhuo Liu ◽  
Ying Guang Fang ◽  
Hai Hong Mo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Temperature Distribution ◽  
Cross Section ◽  
Air Temperature ◽  
Influential Factors ◽  
Dynamics Simulation ◽  
Airflow Rate ◽  
Large Cross Section ◽  
Finite Element Software

The finite element software ADINA was employed in this paper to study the ventilation effect of a large cross-section cable tunnel by using a computational fluid dynamics method. The temperature and ventilation zoning inside a cable tunnel were determined according to the characteristics of the large cross-section cable tunnel. With the ambient tunnel characteristics and tunnel cross-section layout being taken into consideration, a three-dimensional model for large cross-section cable tunnels was established; the computations indicate that the main influential factors of ventilation effect of large cross-section cable tunnels are intake airflow rate, intake air temperature, exhaust airflow rate, ventilation duration, tunnel length, fire door layout, and so on. The average air velocity in the tunnel was about 60 % of the intake airflow rate. The intake air temperature has much impact on tunnel temperature distribution within a range of 30 m away from the tunnel origin, as shown by a significant cooling effect when intake air temperature falls; whereas the intake air temperature has less impact on tunnel temperature distribution beyond 30 m from the tunnel origin.

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