scholarly journals Silo discharge: influence of the particle shape on the velocity profiles

2021 ◽  
Vol 249 ◽  
pp. 03029
Author(s):  
Florencia Escudero ◽  
Marcela Camila Villagrán Olivares ◽  
Rodolfo Uñac ◽  
Ana María Vidales ◽  
Jesica Benito
Keyword(s):  
Flow Rate ◽  
Work Group ◽  
Free Fall ◽  
Velocity Profiles ◽  
Spherical Particles ◽  
Theoretical Formulation ◽  
Silo Discharge ◽  
Funnel Flow ◽  
Rate Formulation ◽  
Group 1

Experiments on the discharge of a silo with an inclined outlet are performed using flattened seeds in order to evaluate the validity of a previous theoretical formulation developed in our work group [1]. In that description, funnel flow regime is assumed to be based on a free fall parabolic arc. The shape of this arc is described with a parameter which is the only one involved in the flow rate formulation. An experimental analysis of the behavior of this parameter is carried out based on the geometry and shape of the grains within the silo. Also, video analysis of the silo discharge is performed in order to investigate the velocity profiles at the outlet of the hopper for these non-spherical particles. Experiments are contrasted with analytical predictions derived from the proposed formulation in order to assess and discuss its validity for the case of flattened particles.

Effect of fiber length, flow rate, and concentration on velocity profiles of cellulosic fiber suspensions

2013 ◽  
Vol 224 (10) ◽  
pp. 2301-2310 ◽  
Author(s):  
E. J. Tozzi ◽  
D. M. Lavenson ◽  
M. J. McCarthy ◽  
R. L. Powell
Keyword(s):  
Flow Rate ◽  
Fiber Length ◽  
Velocity Profiles ◽  
Fiber Suspensions ◽  
Cellulosic Fiber

Experimental and DEM studies of velocity profiles and residence time distribution of non-spherical particles in silos

2020 ◽  
Vol 373 ◽  
pp. 510-521 ◽  
Author(s):  
Shahab Golshan ◽  
Behrad Esgandari ◽  
Reza Zarghami ◽  
Bruno Blais ◽  
Khashayar Saleh
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Velocity Profiles ◽  
Spherical Particles

Effect of magnesium loading on magnesium delivery to the juxtamedullary end-descending limb

1985 ◽  
Vol 248 (1) ◽  
pp. F145-F151
Author(s):  
D. R. Roy
Keyword(s):  
Flow Rate ◽  
Magnesium Concentration ◽  
Group 4 ◽  
Intravenous Magnesium ◽  
Group 3 ◽  
Group 2 ◽  
Magnesium Excretion ◽  
Plasma Magnesium ◽  
Normal Controls ◽  
Group 1

Previous micropuncture and microperfusion studies in acutely hypermagnesemic rats have yielded conflicting results with respect to magnesium transport in Henle's loop. The following experiments were performed to reexamine, by micropuncture of papillary end-descending limb, whether magnesium undergoes intratubular secretion in magnesium-loaded rats. Group 1 animals served as normal controls; group 2 animals received an acute intravenous magnesium load; group 3 animals were orally magnesium loaded for 3 wk before receiving an acute intravenous magnesium load during micropuncture; group 4 animals were acutely thyroparathyroidectomized and water loaded before receiving an acute magnesium load. Fractional magnesium delivery to the end-descending limb did not differ from the corresponding value observed in the superficial proximal tubule in normal animals (67 +/- 5.3 vs. 76 +/- 7.6%). Acute magnesium loading raised plasma magnesium concentration and fractional magnesium excretion more than twofold but did not change fractional magnesium delivery to the end-descending limb or superficial nephron significantly from control values (75 and 73%). Chronic oral magnesium loading raised daily urinary magnesium excretion threefold (183 vs. 53 mumol X day-1 X 100 g body wt-1, P less than 0.05), but acute magnesium loading in this group did not significantly alter fractional delivery to the end-descending limb (85 +/- 10%, NS). Increasing intratubular flow rate while acutely raising plasma magnesium concentration (group 4) also did not induce intratubular magnesium secretion. The absence of significant changes in fractional magnesium delivery to the end-descending limb during magnesium loading suggests that intratubular magnesium secretion, if at all present, is very small and of questionable significance.

scholarly journals Disentangling the Free-Fall Arch Paradox in Silo Discharge

2015 ◽  
Vol 114 (23) ◽  
Author(s):  
S. M. Rubio-Largo ◽  
A. Janda ◽  
D. Maza ◽  
I. Zuriguel ◽  
R. C. Hidalgo
Keyword(s):  
Free Fall ◽  
Silo Discharge

scholarly journals On-Sun Performance Evaluation of Alternative High-Temperature Falling Particle Receiver Designs

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Clifford K. Ho ◽  
Joshua M. Christian ◽  
Julius E. Yellowhair ◽  
Kenneth Armijo ◽  
William J. Kolb ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Particle Temperature ◽  
Free Fall ◽  
Mass Flow Rates ◽  
Mesh Structures ◽  
Free Falling ◽  
The Impact

This paper evaluates the on-sun performance of a 1 MW falling particle receiver. Two particle receiver designs were investigated: obstructed flow particle receiver versus free-falling particle receiver. The intent of the tests was to investigate the impact of particle mass flow rate, irradiance, and particle temperature on the particle temperature rise and thermal efficiency of the receiver for each design. Results indicate that the obstructed flow design increased the residence time of the particles in the concentrated flux, thereby increasing the particle temperature and thermal efficiency for a given mass flow rate. The obstructions, a staggered array of chevron-shaped mesh structures, also provided more stability to the falling particles, which were prone to instabilities caused by convective currents in the free-fall design. Challenges encountered during the tests included nonuniform mass flow rates, wind impacts, and oxidation/deterioration of the mesh structures. Alternative materials, designs, and methods are presented to overcome these challenges.

scholarly journals Evaluation of Process Conditions for Ultrasonic Spray-Freeze Drying of Transglutaminase

2020 ◽  
Vol 58 (1) ◽  
pp. 38-48
Author(s):  
Hilal Isleroglu ◽  
Izzet Turker
Keyword(s):  
Enzyme Activity ◽  
Flow Rate ◽  
Freeze Drying ◽  
Desirability Function ◽  
Spherical Particles ◽  
Optimum Process ◽  
Process Conditions ◽  
Plate Temperature ◽  
Ultrasonic Spray ◽  
Spray Freeze Drying

In this study, a commercial transglutaminase enzyme was dried using an ultrasonic spray freeze drying method and the effects of the process conditions were optimized to maximize the final transglutaminase activity. Accordingly, process parameters affecting enzyme activity were selected, such as nozzle frequency (48 and 120 kHz), flow rate (2, 5 and 8 mL/min) and plate temperature for secondary drying (25, 35 and 45 °C). Moreover, the effects of different pH values (pH=2.0 and 9.0) and high temperature (80 °C) on enzyme activity, physical properties and particle morphology of transglutaminase were discussed. According to the results, transglutaminase preserved its activity despite ultrasonic spray freeze drying. Sonication enhanced the enzyme activity. Using the desirability function method, the optimum process conditions were determined to be flow rate 3.10 mL/min, plate temperature 45 °C and nozzle frequency 120 kHz. The predicted activity ratio was 1.17, and experimentally obtained ratio was 1.14±0.02. Furthermore, enzyme produced by ultrasonic spray freeze drying had low moisture values (2.92-4.36 %) at 8 h of drying. When the morphological structure of the transglutaminase particles produced by ultrasonic spray freeze drying under the optimum conditions was examined, spherical particles with pores on their surfaces were observed. In addition, flow properties of the transglutaminase powders were considered as fair under most conditions according to the Carr index.

Development of Pulse Ultrasonic Doppler Method for Flow Rate Measurements of Power Plant: Characteristics of Sound Pressure Distributions and Evaluation of the Hybrid Ultrasonic Flowmetering System Using TOF and UDM

2006 ◽  
Author(s):  
Hiroshige Kikura ◽  
Yuto Inoue ◽  
Masanori Aritomi ◽  
Michitsugu Mori
Keyword(s):  
Velocity Profile ◽  
Ultrasonic Velocity ◽  
Flow Rate ◽  
Time Of Flight ◽  
Velocity Profiles ◽  
Instantaneous Velocity ◽  
Rate Measurement ◽  
Flow Rate Measurement ◽  
Doppler Method ◽  
Flow Metering

A multi-beam pulse ultrasonic Doppler method has been developed for a new type of flow metering system. This new system is a hybrid of the time-of-flight type ultrasonic flowmeter and the ultrasonic velocity profile type flowmeter, having the advantages of these two types. Our final purpose is to apply the hybrid ultrasonic flow metering system to an accurate flow rate measurement of feed- or recirculation- water in nuclear power plants. The pulse ultrasonic Doppler method (UDM) has the capability to obtain instantaneous velocity profiles along an ultrasonic beam. The principle of the UDM flowmeter, which is one of the ultrasonic velocity profile type flowmeters, is based on the integration of an instantaneous velocity profile over a pipe diameter. The multi-beam system is expected to eliminate installation problems such as those of entry length, and also to follow transient flow rate more precisely by increasing the number of ultrasonic transducers. However, it needs reflectors for receiving ultrasonic Doppler signals. On the other hand, the time-of-flight (TOF) ultrasonic flow metering system does not need any reflector, but it needs profile factors (PFs) which depend on velocity profiles. PF is one of the important experimental coefficients for the accurate flow rate measurement. Therefore PFs must be corrected according to the changes in flow conditions. In the present study, we investigated to what degree the hybrid ultrasonic flow metering system can adjust the profile factors of the time-of-flight ultrasonic flow meters by using the multi-beam pulse ultrasonic Doppler method in metallic wall piping.

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