scholarly journals Effects of flotation operational parameters on froth stability and froth recovery

2021 ◽  
Vol 121 (1) ◽  
Author(s):  
M. Ostadrahimi ◽  
S. Farrokhpay ◽  
K. Gharibi ◽  
A. Dehghani ◽  
M. Aghajanloo
Keyword(s):  
Exponential Model ◽  
Change Model ◽  
Operational Parameters ◽  
Air Velocity ◽  
Froth Stability ◽  
Height Change

SYNOPSIS The effect of flotation operational parameters on froth stability and froth recovery was studied. Froth stability was measured using a special column. To determine the froth recovery, the froth height change model and froth height exponential model were used. It was found that since the interactions between the pulp and froth zones affect the time of froth formation, the exponential model is more suitable than the froth height change method for determining the froth recovery. The results showed that superficial air velocity and collector dosage have, respectively, the highest and lowest effect on the froth recovery, while froth recovery decreases sharply with increasing froth height. Keywords: froth stability, froth recovery, superficial air velocity, collector dosage, frother dosage.

scholarly journals Thermodynamic Evaluation of the Forced Convective Hybrid-Solar Dryer during Drying Process of Rosemary (Rosmarinus officinalis L.) Leaves

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5835
Author(s):  
Hamed Karami ◽  
Mohammad Kaveh ◽  
Iman Golpour ◽  
Esmail Khalife ◽  
Robert Rusinek ◽  
...  
Keyword(s):  
Energy Utilization ◽  
Exergy Loss ◽  
Thermodynamic Evaluation ◽  
Drying Process ◽  
Operational Parameters ◽  
Air Velocity ◽  
Solar Dryer ◽  
Energy And Exergy ◽  
Four Levels ◽  
Rosmarinus Officinalis L

This study aimed to examine the energy and exergy indices of the rosemary drying process in a hybrid-solar dryer (HSD) and the effects of air-drying parameters on these thermodynamic indices. Drying experiments were carried out at four levels of air temperature (40, 50, 60, and 70 ∘C) and three levels of air velocity (1, 1.5, and 2 m/s). Energy and exergy were calculated by application of the first and second laws of thermodynamics. Based on the principal laws, energy efficiency, exergy losses, and exergetic improvement potential rate, were evaluated. The results showed that the energy utilization ratio (EUR) ranged from 0.246 to 0.502, and energy utilization (EU) ranged from 0.017 to 0.060 (kJ/s). Exergy loss and efficiency varied from 0.009 to 0.028 (kJ/s) and from 35.08% to 78.5%, respectively, and increased with increased temperature and air velocity. It was found that the exergy loss rate was affected by temperature and air velocity because the overall heat transfer coefficient was different under these conditions. By comparison, with increasing temperature and air velocity, the exergy efficiency increased. Because most energy is used to evaporate moisture, this behavior may be explained by improved energy utilization. The drying chamber sustainability index ranged from 0.0129 to 0.0293. This study provides insights into the optimization process of drying operations and operational parameters in solar hybrid dryers that reduce energy losses and consumption.

scholarly journals Drying and color in punamuña leaves (Satureja boliviana)

DYNA ◽  
2021 ◽  
Vol 88 (216) ◽  
pp. 31-37
Author(s):  
David Choque-Quispe ◽  
Betsy Suri Ramos-Pacheco ◽  
Aydeé Marilú Solano-Reynoso ◽  
Carlos Alberto Ligarda-Samanez ◽  
Yudith Choque-Quispe ◽  
...  
Keyword(s):  
Activation Energy ◽  
Arrhenius Equation ◽  
Color Difference ◽  
Exponential Model ◽  
Drying Kinetics ◽  
Diffusivity Coefficient ◽  
Air Velocity ◽  
Peruvian Andes ◽  
Increasing Temperature ◽  
Fick Equation

Drying allows water to be removed and food to be preserved, however, this operation can degrade color. Punamuña leaves are aromatic and used for medicinal purposes in the Peruvian Andes. This research aimed to determine and model the drying kinetics, the diffusivity coefficient (Def), the activation energy (Ea), and the color of punamuña leaves. A horizontal dryer was used at 40, 50, and 60 °C and airspeed of 1.0 and 0.5 m / s; drying kinetics was modeled with 10 models. Def was determined with the Fick equation, Ea with the Arrhenius equation; the color was determined in the L* a* b* space. It was found that the triple exponential model with six parameters better represented the drying kinetics (R2> 99.73 and E <3.04%); Def increased with temperature and air velocity. Ea was found between 43.62 to 44.52 kJ/mol for speeds of 1.0 to 0.5 m/s respectively; L* and a*/b* decreased, the color difference ΔE * increased with increasing temperature and lower air velocity

scholarly journals Numerical analysis of Darrieus vertical axis wind turbine using omni-direction guide vane

2021 ◽  
Vol 2054 (1) ◽  
pp. 012090
Author(s):  
K Sathiyamoorthy ◽  
N Nandha Sri Varma ◽  
M Showrinath
Keyword(s):  
Numerical Analysis ◽  
Performance Analysis ◽  
Guide Vane ◽  
Vertical Axis ◽  
Equation Model ◽  
Transient Simulation ◽  
Vertical Axis Wind Turbine ◽  
Operational Parameters ◽  
Air Velocity ◽  
The Moment

Abstract The performance of Darrieus turbine is studied in this paper with the attachment of ODGV to enhance its performance. The angles of guided vanes are chosen from the literature as α=20° beta=55°. According to this hypothesis the airfoil section of S1046 chosen for performance analysis. The K-ε SST 2 equation model is used for generating the moment for 5 blades turbine with the radius of 0.25m in the 2D configuration. The Chord length is chosen as 78mm and Air velocity is considered as 6m/s for the entire transient simulation. The study of performance and operational parameters have been done on turbine with presence and absence of ODGV.

scholarly journals Experimental investigation of pre-drying data for some medicinal herbs in forced convection

2019 ◽  
pp. 465-465
Author(s):  
Tibor Poós ◽  
Evelin Varju
Keyword(s):  
Medicinal Plants ◽  
Forced Convection ◽  
Active Agent ◽  
Ambient Air ◽  
Drying Rate ◽  
Operational Parameters ◽  
Air Velocity ◽  
Fluidized Bed Dryer ◽  
Wild Carrot ◽  
Volume Decrease

The special active agent content of herbs makes them suitable for healing and health preservation. The key element in the processing of herbs and spices is drying. Before drying, the medicinal plants should be stored under appropriate conditions to avoid deterioration of quality where one of the possible methods is pre-drying with ambient air. This work defines the determination of main operational parameters at forced convection drying with ambient air like drying rate, volume decrease, maximum drying air velocity and porosity for various medicinal plants (common yarrow - Achillea collina, giant goldenrod - Solidago gigantea, wormwood - Artemisia, walnut leaf - Juglandis folium, wild carrot - Daucus carota). To determine the drying rate, a convective dryer was used where the average drying rate of common yarrow and wild carrot were the highest followed by giant goldenrod, walnut leaf and wormwood. Measurements were made on a pilot plant fluidized bed dryer to determine the volume decrease and the maximum drying air velocity. The volume decrease was determined as a function of time and moisture content. It was found that the maximum drying air velocity for each medicinal plant was between 1.8 and 2.2 m/s. In addition, for each herb the porosity was measured by an air pycnometer.

scholarly journals TO THE PROBLEM OF DETERMINING AIR VELOCITY FIELD IN TUNNEL STRUCTURES OF A SUBWAY LINE USING CIRCULAR MODELS AS A METHOD OF TOPOLOGICAL DECOMPOSITION

2020 ◽  
Vol 2 ◽  
pp. 129-137
Author(s):  
Timofey S. Oshchepkov ◽  
Lavrenty A. Kiyanitsa ◽  
Ivan V. Lugin
Keyword(s):  
Discrete Model ◽  
Air Distribution ◽  
Operational Parameters ◽  
Air Velocity ◽  
Air Filters ◽  
Piston Effect ◽  
Circular Model ◽  
Air Stream ◽  
Public Areas ◽  
Suspended Dust

Underground subway structures represent crowded public areas; therefore, they are subject to high requirements for maintaining the standard microclimate parameters at stations and in tunnels, including the content of suspended dust in the air. To maintain dust concentration within specifications, it is proposed to use air filters installed in station ventilation connections in the stream of air from the piston effect of trains. To study the piston effect by aerogasdynamic computational methods, a method is proposed for the topological decomposition of a subway line - transition froma complete linear model to a closed circular model by isolating several lines and closing them into a circle, which allows reducing the size of discrete model of the design section, while maintaining the influence of neighboring lines and stations as well as calculation accuracy. As a result of a numerical experiment, the parameters of transient air distribution from the piston effect of trains and the structure of air stream at the places of filter installation are determined for further study of their geometric, structural and operational parameters.

scholarly journals Parameter Optimization of Flat Plate Liquid Desiccant Dehumidification System using Taguchi Method

2019 ◽  
Vol 8 (6) ◽  
pp. 5026-5029
Keyword(s):  
Taguchi Method ◽  
Flat Plate ◽  
Signal To Noise Ratio ◽  
Solution Concentration ◽  
Operational Parameters ◽  
Liquid Desiccant ◽  
Air Velocity ◽  
Signal To Noise ◽  
Liquid Desiccant Dehumidification ◽  
Experimental Findings

In this research paper, Taguchi method, an influential technique for the optimization of operational parameters, is used to analyse the dehumidification parameters for a flat plate liquid desiccant dehumidification system. An orthogonal array using analysis of variance (ANOVA) and signal to noise ratio (S/N) are applied to find the dehumidification parameters of a liquid desiccant dehumidification system (LDDS). Calcium chloride (CaCl2) is used as a liquid desiccant solution. In this study, desiccant flow rate, air velocity and desiccant solution concentration are kept as operating parameters to find out the optimal relative humidity for room comfort. Experimental findings have shown proficient agreement with this approach.

Electron sources: Past, present, and future

1993 ◽  
Vol 51 ◽  
pp. 764-765
Author(s):  
David C Joy
Keyword(s):  
Glass Tube ◽  
Source Size ◽  
Electron Gun ◽  
Operating Parameters ◽  
Operational Parameters ◽  
Electron Sources ◽  
Difficult Decision ◽  
Probe Size ◽  
Wide Range ◽  
Overall Performance

The electron source is the most important component of the Scanning electron microscope (SEM) since it is this which will determine the overall performance of the machine. The gun performance can be described in terms of quantities such as its brightness, its source size, its energy spread, and its stability and, depending on the chosen application, any of these factors may be the most significant one. The task of the electron gun in an SEM is, in fact, particularly difficult because of the very wide range of operational parameters that may be required e.g a variation in probe size of from a few angstroms to a few microns, and a probe current which may go from less than a pico-amp to more than a microamp. This wide range of operating parameters makes the choice of the optimum source for scanning microscopy a difficult decision.Historically, the first step up from the sealed glass tube ‘cathode ray generator’ was the simple, diode, tungsten thermionic emitter.

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