Air Pressure in the Bulk of Granular Solid Discharged From a Bin

1969 ◽  
Vol 91 (2) ◽  
pp. 382-384 ◽  
Author(s):  
A. Wlodarski ◽  
A. Pfeffer
Keyword(s):  
Granular Material ◽  
Flow Rate ◽  
Pressure Difference ◽  
Solid Particles ◽  
Air Pressure ◽  
Rate Equations ◽  
Small Laboratory ◽  
Laboratory Apparatus ◽  
Surrounding Atmosphere ◽  
Granular Solid

Air pressure different from that in the surrounding atmosphere develops in the bulk of granular material flowing out of an open bin through the bottom orifice. When measured on the axis of a small laboratory apparatus the differences have been found to oscillate about a mean changing along the bin and reaching its maximum/negative/well above the orifice. Pressure difference at a given point inside the bed depends upon the orifice size, and upon the size of solid particles. Equalization of the air pressure just above the orifice with that of the air outside the bin influences flow rate of the material. It is suggested that the overlooking of these effects is to some extent responsible for the great variety of flow rate equations so far proposed.

The Purification Experiments of Cold Rolling Emulsion by Hydrocyclone

2010 ◽  
Vol 37-38 ◽  
pp. 1529-1533
Author(s):  
Liang Ma ◽  
Hong Liang Pan ◽  
Hua Lin Wang ◽  
Qiang Yang ◽  
Jian Gang Wang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Pressure Difference ◽  
Separation Efficiency ◽  
Removal Rate ◽  
Optimal Operation ◽  
Solid Particles ◽  
Rolled Sheet ◽  
Operation Condition ◽  
Inlet Flow Rate ◽  
Relationship Of

This article focuses on the separation of ferrous impurities from emulsion with micro-hydrocyclone. The relationship of flow rate, pressure and separation efficiency is studied to determine the optimal operation condition. Results show the separation efficiency and the pressure difference increase with the inlet flow rate of the micro-hydrocyclone. When the inlet pressure is 0.4MPa, pressure difference △Pio is 0.26Mpa and the average inlet particle size is 2.719μm, the separation efficiency of the solid particles is 76% and the removal rate of solid particles with the size above 5.5μm is 85.64%, which contributes to the improvement of the quality of cold rolled sheet.

EXTRACTION OF MINUTE GAS BUBBLES FROM LIQUIDS FLOWING IN A SIMULATED CARDIOPULMONARY BYPASS SYSTEM BY A VENTURI-ASPIRATOR UNIT

2002 ◽  
Vol 02 (03n04) ◽  
pp. 297-312
Author(s):  
WEN-JEI YANG ◽  
AMR EID ◽  
R. ECHIGO
Keyword(s):  
Cardiopulmonary Bypass ◽  
Flow Rate ◽  
Whole Blood ◽  
Pressure Difference ◽  
Gas Bubbles ◽  
Blood Oxygenation ◽  
Straight Tube ◽  
Suction Pressure ◽  
Total Flow ◽  
Total Flow Rate

An experimental study is performed to extract minute gas bubbles from liquids flowing in a simulated cardiopulmonary bypass system using a Venturi-aspirator unit. In other words, oxygen bubbles in oxygenated blood are simulated by air bubbles in water with AP30 (about same viscosity as whole blood). This study is intended to determine the feasibility of using a Venturi aspirator unit to extract minute gas bubbles from a simulated cardiopulmonary bypass system. Testing of the Venturi-type bubble extraction is carried out using three different test sections. Two Venturis are used, and a straight tube configuration is used as a control. The two Venturis are similar, with the exception that one has a longer inlet cone which causes the entering liquid to accelerate at a slower rate. Results are obtained for effectiveness of the aspirator unit as functions of total flow rate, extraction suction, suction pressure difference, and hydraulic head. It is concluded from the study that:(i) The effectiveness of the Venturis is typically between 90 and 100 percent. It increases with an increase in suction or suction pressure difference but decreases with an increase in total flow rate.(ii) The Venturi is most suitable for extraction of minute gas bubbles, especially for use with AP30 (whole blood), which yields substantially higher effectiveness than water.(iii) It is anticipated that a Venturi-aspirator unit can be superior to other bubble separation device as the cardiopulmonary bypass system for applications in extra corporeal blood oxygenation.

Parametric study on pressure-based packed bed adsorption system for air dehumidification

2021 ◽  
pp. 095440892110073
Author(s):  
V Sureshkannan ◽  
TV Arjunan ◽  
D Seenivasan ◽  
SP Anbuudayasankar ◽  
M Arulraj
Keyword(s):  
Genetic Algorithm ◽  
Taguchi Method ◽  
Flow Rate ◽  
Uptake Rate ◽  
Air Flow ◽  
Packed Bed ◽  
Air Pressure ◽  
Dew Point ◽  
Adsorption System ◽  
Air Flow Rate

Compressed air free from traces of water vapour is vital in many applications in an industrial sector. This study focuses on parametric optimization of a pressure-based packed bed adsorption system for air dehumidification through the Taguchi method and Genetic Algorithm. The effect of operational parameters, namely absolute feed air pressure, feed air linear velocity, and purge air flow rate percent on adsorption uptake rate of molecular sieve 13X-water pair, are studied based on L25 orthogonal array. From the analysis of variance, it has been found that absolute feed air pressure and purge air flow rate percent were the parameters making significant improvement in the adsorption uptake rate. A correlation representing the process was developed using regression analysis. The optimum adsorption conditions were obtained through the Taguchi method and genetic algorithm and verified through the confirmation experiments. This system can be recommended for the industrial and domestic applications that require product air with the dew point temperature below 0°C.

Oral Air Pressure and Nasal Air Flow Rate on Levator Veli Palatini Muscle Activity in Patients Wearing a Speech Appliance

1995 ◽  
Vol 32 (5) ◽  
pp. 382-389 ◽  
Author(s):  
Takashi Tachimura ◽  
Hisanaga Hara ◽  
Takeshi Wada
Keyword(s):  
Flow Rate ◽  
Muscle Activity ◽  
Neural Control ◽  
Air Flow ◽  
Air Pressure ◽  
Electromyographic Activity ◽  
Air Flow Rate ◽  
Circular Area ◽  
Pharyngeal Bulb ◽  
Levator Veli Palatini

This study was designed to determine if levator veli palatini muscle activity can be elicited by simultaneous changes in oral air pressure and nasal air flow when a speech appliance is in place. The speech appliances routinely worn by 15 subjects were each modified experimentally by drilling a hole in the vertical center of the pharyngeal bulb. The air flow rate into the nasal cavity through the opening in the bulb was altered by changing the circular area of the opening in the bulb from the occluded condition (Condition I), to circular area of 12.6 mm2 (4 mm in diameter; Condition II), and then to 38.5 mm2 (7 mm in diameter; Condition III). Electromyographic activity was measured from the levator veli palatini muscle with changes in nasal air flow rate and oral air pressure. Levator veli palatini muscle activity was correlated with changes in nasal air flow and oral air pressure. Increases in levator veli palatini muscle activity were associated with increases in nasal air flow rate compared to oral air pressure changes. The results indicated that aerodynamic variables of nasal air flow and oral air pressure might be involved in the neural control of speech production in individuals wearing a speech appliance, even if the subjects exhibit velopharyngeal incompetence without using a speech appliance. Also, the stimulating effect of bulb reduction therapy on velopharyngeal function might be achieved through the change in aerodynamic variables in association with the bulb reduction.

scholarly journals Determination of Permeability and Inertial Coefficients of Sintered Metal Porous Media Using an Isothermal Chamber

2018 ◽  
Vol 8 (9) ◽  
pp. 1670 ◽  
Author(s):  
Wei Zhong ◽  
Xiang Ji ◽  
Chong Li ◽  
Jiwen Fang ◽  
Fanghua Liu
Keyword(s):  
Porous Media ◽  
Steady State ◽  
Flow Rate ◽  
Pressure Difference ◽  
Testing Time ◽  
Sintered Metal ◽  
Steady State Method ◽  
Volume Limit ◽  
Inertial Coefficient

Sintered metal porous media are widely used in a broad range of industrial equipment. Generally, the flow properties in porous media are represented by an incompressible Darcy‒Forchheimer regime. This study uses a modified Forchheimer equation to represent the flow rate characteristics, which are then experimentally and theoretically investigated using a few samples of sintered metal porous media. The traditional steady-state method has a long testing time and considerable air consumption. With this in mind, a discharge method based on an isothermal chamber filled with copper wires is proposed to simultaneously determine the permeability and inertial coefficient. The flow rate discharged from the isothermal chamber is calculated by differentiating the measured pressure, and a paired dataset of pressure difference and flow rate is available. The theoretical representations of pressure difference versus flow rate show good agreement with the steady-state results. Finally, the volume limit of the isothermal chamber is addressed to ensure sufficient accuracy.

A Numerical Analysis on the System Impedance in a Fan Cooling System

2003 ◽  
Author(s):  
Dong-Il Kim ◽  
Ki-So Bok ◽  
Han-Bae Lee
Keyword(s):  
Numerical Analysis ◽  
Pressure Drop ◽  
Flow Rate ◽  
Pressure Difference ◽  
Cooling System ◽  
Computational Time ◽  
Computational Domain ◽  
Impedance Curve ◽  
Fan Cooling ◽  
Large Investment

To seek the fan operating point on a cooling system with fans, it is very important to determine the system impedance curve and it has been usually examined with the fan tester based on ASHRAE standard and AMCA standard. This leads to a large investment in time and cost, because it could not be executed until the system is made actually. Therefore it is necessary to predict the system impedance curve through numerical analysis so that we could reduce the measurement time and effort. This paper presents how the system impedance curve (pressure drop curve) is computed by CFD in substitute for experiment. In reverse order to the experimental principle of the fan tester, pressure difference was adopted first as inlet and outlet boundary conditions of the system and then flow rate was calculated. After determining the system impedance curve, it was compared with experimental results. Also the computational domain of the system was investigated to minimize computational time.

The Effect of Boundary Layer Separation on Accuracy of Flow Measurement Using the Gibson Method

2007 ◽  
Author(s):  
F. Z. Sierra ◽  
A. Adamkowski ◽  
G. Urquiza ◽  
J. Kubiak ◽  
H. Lara ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Cross Section ◽  
Flow Rate ◽  
Pressure Difference ◽  
Proper Time ◽  
Effective Cross Section ◽  
Boundary Layer Separation ◽  
Water Hammer ◽  
Time Interval ◽  
Geometry Factor

The Gibson method utilizes the effect of water hammer phenomenon (hydraulic transients) in a pipeline for flow rate determination. The method consists in measuring a static pressure difference, which occurs between two cross-sections of the pipeline as a result of a temporal change of momentum from t0 to t1. This condition is induced when the water flow in the pipeline is stopped suddenly using a cut-off device. The flow rate is determined by integrating, within a proper time interval, the measured pressure difference change caused by the water hammer (inertia effect). However, several observations demonstrate that changes of pipeline geometry like diameter change, bifurcations, or direction shift by elbows may produce an effect on the computation of the flow rate. The paper focuses on this effect. Computational simulations have shown that the boundary layer separates when the flow faces sudden changes like these mentioned to above. The separation may reduce the effective cross section area of flow modifying a geometry factor involved into the computation of the flow rate. The remainder is directed to quantify the magnitude of such a factor under the influence of pipeline geometry changes. Results of numerical computations are discussed on the basis of how cross section reductions impact on the geometry factor magnitude and consequently on the mass flow rate.

scholarly journals SENSIBILIDADE DE GOTEJADORES À OBSTRUÇÃO POR PARTÍCULAS DE AREIA

Irriga ◽  
2018 ◽  
Vol 23 (2) ◽  
pp. 194-203
Author(s):  
Acácio Perboni ◽  
José Antonio Frizzone ◽  
Rubens Duarte Coelho ◽  
Rogério Lavanholi ◽  
Ezequiel Saretta
Keyword(s):  
Turbulent Flow ◽  
Flow Rate ◽  
Flow Regimes ◽  
Solid Particles ◽  
Automated System ◽  
Particle Sizes ◽  
Initial Flow ◽  
Water Flow Velocity ◽  
Sand Particles ◽  
Micro Irrigation

SENSIBILIDADE DE GOTEJADORES À OBSTRUÇÃO POR PARTÍCULAS DE AREIA     ACÁCIO PERBONI1; JOSÉ ANTONIO FRIZZONE2; RUBENS DUARTE COELHO2; ROGÉRIO LAVANHOLI3 E EZEQUIEL SARETTA4   1 Professor, IFMT, Campo Novo do Parecis - MT, [email protected] 2 Professor, Departamento de Engenharia de Biossistemas, ESALQ/USP, Piracicaba - SP, [email protected]; [email protected] 3 Doutorando, Departamento de Engenharia de Biossistemas, ESALQ/USP, Piracicaba - SP, [email protected] 4 Professor, UFSM, Cachoeira do Sul - RS, [email protected]     1 RESUMO   O objetivo deste trabalho foi avaliar a influência do tamanho e concentração de partículas de areia e da velocidade de fluxo da água nas linhas na sensibilidade à obstrução de um modelo de gotejador do tipo cilíndrico, não regulado, com vazão nominal de 2 L h-1. Foram realizados ensaios de obstrução com areia misturada em água destilada, combinando os seguintes fatores: três faixas granulométricas de partículas de areia, três concentrações de areia e três velocidades de fluxo de água no tubo. A vazão de 32 gotejadores foi medida a cada doze minutos por meio de um sistema automatizado. Nos ensaios com faixa granulométrica de 0,105 a 0,25 mm, ocorreu a obstrução nas concentrações de 250 e 500 mg L-1, para os regimes de escoamento de transição e turbulento. Já na faixa granulométrica de 0,25 a 0,5 mm, ocorreu obstrução nas concentrações de 100, 250 e 500 mg L-1, para os regimes de escoamento de transição e turbulento. A obstrução de gotejadores ocorreu de forma aleatória nas oito linhas. Após obstruídos os gotejadores não desobstruíram com o passar do tempo de ensaio.   Palavras-chave: microirrigação, partículas sólidas inertes, granulometria, concentração     PERBONI, A.; FRIZZONE, J. A.; COELHO, R. D.; LAVANHOLI, R.; SARETTA, E. SENSITIVITY OF DRIPPERS TO CLOGGING CAUSED BY SAND PARTICLES     2 ABSTRACT   The purpose of this research was to assess the influence of concentration and size of sand particles, and water flow velocity in laterals on the sensitivity of drippers to clogging. A cylindrical integrated non-pressure compensating dripper of 2 L h-1 nominal flow rate was used. Experiments were undertaken using distilled water and sand particles, according to the following levels: (a) three ranges of particles sizes; (b) three concentrations of particles; and, (c) three flow velocities in the laterals. The flow rate of 32 drippers was measured at every 12 minutes by an automated system. Within the range of particle sizes from 0.105 to 0.25 mm, clogging of emitters was observed under transient and turbulent flow regimes, and under particles concentration of 250 and 500 mg L-1. Within the range of particles sizes from 0.25 to 0.5 mm, clogging was observed for all concentrations under transient and turbulent flow regimes. Clogging of emitters occurred as a random phenomenon. Once clogged, emitters did not recover their initial flow rate.    Keywords: micro irrigation, inert solid particles, particle size, concentration

On the Mass Flow Rate of Granular Material in Silos with Lateral Exit Holes

2012 ◽  
pp. 261-266
Author(s):  
Abraham Medina ◽  
G. Juliana Gutiérrez-Paredes ◽  
Satyan Chowdary ◽  
Anoop Kumar ◽  
K. Kesava Rao
Keyword(s):  
Granular Material ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate
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