scholarly journals Improving the Hydraulic Effects Resulting from the Use of a Submerged Biofiter to Enhance Water Quality in Polluted Streams

2021 ◽  
Vol 18 (23) ◽  
pp. 12351
Author(s):  
Atef A. El-Saiad ◽  
Hany F. Abd-Elhamid ◽  
Zeinab I. Salama ◽  
Martina Zeleňáková ◽  
Erik Weiss ◽  
...  
Keyword(s):  
Water Quality ◽  
Flow Rate ◽  
Water Depth ◽  
Empirical Equation ◽  
Flow Behavior ◽  
The Self ◽  
Constant Flow ◽  
Purification Process ◽  
Constant Flow Rate ◽  
Case Comparison

Water scarcity is one of the most serious problems facing many countries. In addition, water pollution could lose more water. A submerged biofilter (SB) is used to enhance the self-purification process in polluted streams. However, most previous studies have focused on the efficiency of SB to remove pollutants and there is a lack of studies investigating the hydraulic changes in streams. The current paper aimed to study the hydraulic effects of SB on the flow behavior in streams and how to improve it. An empirical equation for determining the flow rate through SB was developed. Different cases were studied to improve the hydraulic effects resulting from the use of SB. The effect of increasing SB length was tested using different SB lengths. The results showed that increasing the length increased the upstream water depth (h1) and relative heading up (h1/h2). In the second case, comparison between continuous and fragmented SB was tested. The results showed that a fragmented biofilter increased the upstream water depth and the relative heading up. Case three tested the effect of SB height. Different SB heights were tested with a fixed length and constant flow rate. The results revealed that the upstream water depth and relative heading up decreased when the biofilter height decreased. Case four tested the effect of SB with a fixed volume and constant flow rate. In this case, the length and height of SB were changed where the volume was fixed. The results showed that the relative heading up decreased when the SB height decreased and the length increased, which revealed that the SB height can improve the hydraulic impacts. Finally, the use of SB to improve the water quality in polluted streams led to an increase of the relative heading up, which can be reduced by decreasing the height of SB.

Pumpless Fuel Supply Using Pressurized Fuel Regulated by Autonomous Flow-Rate Regulation Valves

2012 ◽  
Vol 9 (3) ◽  
Author(s):  
Il Doh ◽  
Young-Ho Cho
Keyword(s):  
Fuel Cells ◽  
Flow Rate ◽  
Electrical Power ◽  
Initial Pressure ◽  
Flow Regulation ◽  
Present System ◽  
Constant Flow ◽  
Constant Flow Rate ◽  
Fuel Supply ◽  
Fuel Flow

A pumpless fuel supply using pressurized fuel with autonomous flow regulation valves is presented. Since micropumps and their control circuitry consume a portion of the electrical power generated in fuel cells, fuel supply without micropumps makes it possible to provide more efficient and inexpensive fuel cells than conventional ones. The flow regulation valves in the present system maintain the constant fuel flow rate from the pressurized fuel chamber even though the fuel pressure decreases. They autonomously adjust fluidic resistance of the channel according to fuel pressure so as to maintain constant flow rate. Compared to previous pumpless fuel supply methods, the present method offers more uniform fuel flow without any fluctuation using a simple structure. The prototypes were fabricated by a polymer micromolding process. In the experimental study using the pressurized deionized water, prototypes with pressure regulation valves showed constant flow rate of 5.38 ± 0.52 μl/s over 80 min and 5.89 ± 0.62 μl/s over 134 min, for the initial pressure in the fuel chamber of 50 and 100 kPa, respectively, while the other prototypes having the same fluidic geometry without flow regulation valves showed higher and gradually decreasing flow rate. The present pumpless fuel supply method providing constant flow rate with autonomous valve operation will be beneficial for the development of next-generation fuel cells.

scholarly journals Axisymmetric three-dimensional gravity currents generated by lock exchange

2018 ◽  
Vol 851 ◽  
pp. 507-544 ◽  
Author(s):  
Roberto Inghilesi ◽  
Claudia Adduce ◽  
Valentina Lombardi ◽  
Federico Roman ◽  
Vincenzo Armenio
Keyword(s):  
Froude Number ◽  
Flow Rate ◽  
Rapid Development ◽  
Three Dimensional ◽  
Gravity Currents ◽  
Constant Flow ◽  
Axially Symmetric ◽  
Grashof Number ◽  
Constant Flow Rate ◽  
Dimensional Gravity

Unconfined three-dimensional gravity currents generated by lock exchange using a small dividing gate in a sufficiently large tank are investigated by means of large eddy simulations under the Boussinesq approximation, with Grashof numbers varying over five orders of magnitudes. The study shows that, after an initial transient, the flow can be separated into an axisymmetric expansion and a globally translating motion. In particular, the circular frontline spreads like a constant-flow-rate, axially symmetric gravity current about a virtual source translating along the symmetry axis. The flow is characterised by the presence of lobe and cleft instabilities and hydrodynamic shocks. Depending on the Grashof number, the shocks can either be isolated or produced continuously. In the latter case a typical ring structure is visible in the density and velocity fields. The analysis of the frontal spreading of the axisymmetric part of the current indicates the presence of three regimes, namely, a slumping phase, an inertial–buoyancy equilibrium regime and a viscous–buoyancy equilibrium regime. The viscous–buoyancy phase is in good agreement with the model of Huppert (J. Fluid Mech., vol. 121, 1982, pp. 43–58), while the inertial phase is consistent with the experiments of Britter (Atmos. Environ., vol. 13, 1979, pp. 1241–1247), conducted for purely axially symmetric, constant inflow, gravity currents. The adoption of the slumping model of Huppert & Simpson (J. Fluid Mech., vol. 99 (04), 1980, pp. 785–799), which is here extended to the case of constant-flow-rate cylindrical currents, allows reconciling of the different theories about the initial radial spreading in the context of different asymptotic regimes. As expected, the slumping phase is governed by the Froude number at the lock’s gate, whereas the transition to the viscous phase depends on both the Froude number at the gate and the Grashof number. The identification of the inertial–buoyancy regime in the presence of hydrodynamic shocks for this class of flows is important, due to the lack of analytical solutions for the similarity problem in the framework of shallow water theory. This fact has considerably slowed the research on variable-flow-rate axisymmetric gravity currents, as opposed to the rapid development of the knowledge about cylindrical constant-volume and planar gravity currents, despite their own environmental relevance.

scholarly journals A Hybrid Computational and Analytical Model of Inline Drip Emitters

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Jaya Narain ◽  
Amos G. Winter V
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Flow Behavior ◽  
Computational Time ◽  
Matrix Formulation ◽  
Element Analysis ◽  
Constant Flow Rate ◽  
Patch Load ◽  
Pressure Resistance ◽  
Time Required

This paper details a hybrid computational and analytical model to predict the performance of inline pressure compensating drip irrigation emitters. Pressure compensating emitters deliver a constant flow rate over a range of applied pressures to accurately meter water to crops. Flow rate is controlled within the emitter via a fixed resistance tortuous path, and a variable flow resistance composed of a flexible membrane that deflects under changes in pressure, restricting the flow path. A pressure resistance parameter was derived using an experimentally validated computational fluid dynamics (CFD) model to describe the flow behavior in tortuous paths. The bending mechanics of the membrane were modeled analytically and refined by deriving a correction factor using finite element analysis (FEA). A matrix formulation that calculates the force applied by a line or a patch load of any shape on a rectangular membrane, along which there is a prescribed deflection, was derived and was found to be accurate to be 1%. The combined hybrid computational–analytical model reduces the computational time of modeling emitters from hours to less than 30 min, dramatically lowering the time required to iterate and select optimal designs. The model was validated experimentally using three commercially available drip emitters and was accurate to within 12% of the experimental results.

Effect of Rotating Electromagnetic Field on the Conductivity of Aqueous NaCl Solution

2011 ◽  
Vol 391-392 ◽  
pp. 1080-1084
Author(s):  
Nan Li ◽  
Feng Chai ◽  
Lei Chen ◽  
Shu Kang Cheng
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Fields ◽  
Flow Rate ◽  
Constant Flow ◽  
Nacl Solution ◽  
Flow Loop ◽  
Constant Flow Rate

Effect of rotating electromagnetic field on the conductivity of aqueous NaCl solution was investigated by experiments. NaCl solution was circulated at a constant flow rate in the flow loop with a rotating-electromagnetic generating device for a period of time. Then conductivity of NaCl solution was measured at different NaCl solution contractions and rotating electromagnetic fields. Simultaneously, the conductivity was determined for NaCl solution untreated magnetically, as a reference. It was found that the rotating electromagnetic field influenced conductivity of aqueous NaCl solution and made it increased. The mechanism of the effect of the rotating electromagnetic field on conductivity of NaCl solution was also discussed.

Factors Affecting the Efficiency of Absorption Oil Filtration at Constant Flow Rate

1961 ◽  
Author(s):  
Walter J. Ewbank ◽  
C. B. Threlkeld ◽  
C. E. Mitchell ◽  
R. G. Hamilton
Keyword(s):  
Flow Rate ◽  
Constant Flow ◽  
Factors Affecting ◽  
Constant Flow Rate ◽  
Oil Filtration
Sign in / Sign up

Export Citation Format

Share Document