scholarly journals The flow limiting operator: a new approach to environmental control in flow bioreactors

RSC Advances ◽  
2020 ◽  
Vol 10 (52) ◽  
pp. 31056-31064
Author(s):  
Jeffrey Horbatiuk ◽  
Lubna Alazzawi ◽  
Carolyn A. Harris
Keyword(s):  
High Throughput ◽  
Flow Rate ◽  
Environmental Control ◽  
Fluid Velocity ◽  
New Approach ◽  
Pulsation Amplitude

FLO is a high-throughput bioreactor for testing biomaterials in more physiologically similar environments including pulsation amplitude, flow rate, and pressure waveforms which is done through the manipulation of fluid velocity.

New approach to maintaining liquid flow rate stability in national primary standard

2021 ◽  
pp. 101930
Author(s):  
N.I. Mikheev ◽  
V.M. Molochnikov ◽  
D.V. Kratirov ◽  
O.A. Dushina ◽  
A.A. Paereliy ◽  
...  
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Primary Standard ◽  
New Approach ◽  
National Primary Standard

Determination of Safe Pumping Temperature for Waxy Crude Pipelines

2006 ◽  
Author(s):  
Jinjun Zhang ◽  
Jianlin Ding ◽  
Kang Xu ◽  
Huajun Fan
Keyword(s):  
Flow Rate ◽  
Pour Point ◽  
Heating Temperature ◽  
Safety Margin ◽  
Low Flow ◽  
Stable Operation ◽  
Inlet Temperature ◽  
New Approach ◽  
Point Temperature ◽  
Waxy Crude

Flow risk of a hot waxy crude pipeline mainly comes from restart failure, i.e. oil gelation resulted from prolonged pipeline shutdown, and unstable operation at low flow rate. Once the unstable operation happens, the friction loss of the pipeline increases with decreasing flow rate and finally flow may cease if treated improperly. To avoid these flow risks, the pumping temperature of the crude is generally required to be kept above a minimum allowable temperature, and conventionally the pour point temperature is taken. This practice is effective but quite rough. Obviously, to control the inlet temperature of a heating station at the pour point temperature implies different safety margin for winter and summer operation. For large throughput hot oil pipelines, reduction of the heating temperature even by a little bit may save a great amount of fuel. Therefore, how to save fuel while ensuring safe operation has been a valuable topic for long time. On the other hand, many factors impacting the flow safety are stochastic and with uncertainty, so analysis without considering this feature can hardly yield convincible results, though this has been the common case for many years. In this paper, by taking the stochastic feature into account, a Stable Operation Index (SOI) and a Pipeline Restartability Index (PRI) were proposed to assess the flow safety of a pipeline concerning the low-flowrate stable operation and restartability after shutdown. Combining these two indexes, a Pipeline Flow Safety Index (PFSI) was adopted to assess the flow risks of hot waxy crude pipelines. On this basis a new approach to quantitatively determining the safe pumping temperature was developed and illustrated by a case study. Encouraging results show that this new approach has the potential to replace the simple rule of pour point as a guide to determining the safe pumping temperature of waxy crude pipelines.

scholarly journals New Approach for High-Throughput Screening of Drug Activity on Plasmodium Liver Stages

2006 ◽  
Vol 50 (4) ◽  
pp. 1586-1589 ◽  
Author(s):  
Audrey Gego ◽  
Olivier Silvie ◽  
Jean-François Franetich ◽  
Khemaïs Farhati ◽  
Laurent Hannoun ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
High Throughput ◽  
High Throughput Screening ◽  
Scanning System ◽  
New Approach ◽  
Drug Activity ◽  
Hepatic Cells ◽  
High Throughput Drug Screening ◽  
Prophylactic Drugs

ABSTRACT Plasmodium liver stages represent potential targets for antimalarial prophylactic drugs. Nevertheless, there is a lack of molecules active on these stages. We have now developed a new approach for the high-throughput screening of drug activity on Plasmodium liver stages in vitro, based on an infrared fluorescence scanning system. This method allowed us to count automatically and rapidly Plasmodium-infected hepatocytes, using different hepatic cells and different Plasmodium species, including Plasmodium falciparum. This new technique is well adapted for high-throughput drug screening and should facilitate the identification of new antimalarial compounds active on Plasmodium liver stages.

Mechanical Impact Effects of Fluid Hammer Effects on Drag Reduction of Coiled Tubing

2021 ◽  
pp. 1-10
Author(s):  
Yongsheng Liu ◽  
Xing Qin ◽  
Yuchen Sun ◽  
Zijun Dou ◽  
Jiansong Zhang ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Drag Reduction ◽  
Flow Rate ◽  
Fluid Velocity ◽  
Fluid Pressure ◽  
Great Influence ◽  
Radial Force ◽  
Fluid Flow Rate ◽  
Normal Contact ◽  
Coiled Tubing

Abstract Aiming at the oscillation drag reduction tool that improves the extension limit of coiled tubing downhole operations, the fluid hammer equation of the oscillation drag reducer is established based on the fluid hammer effect. The fluid hammer equation is solved by the asymptotic method, and the distribution of fluid pressure and flow velocity in coiled tubing with oscillation drag reducers is obtained. At the same time, the axial force and radial force of the coiled tubing caused by the fluid hammer oscillator are calculated according to the momentum theorem. The radial force will change the normal contact force of the coiled tubing which has a great influence on frictional drag. The results show that the fluid flow rate and pressure decrease stepwise from the oscillator position to the wellhead position, and the fluid flow rate and pressure will change abruptly during each valve opening and closing time. When the fluid passes through the oscillator, the unit mass fluid will generate an instantaneous axial tension due to the change in the fluid velocity, thereby converting the static friction into dynamic friction, which is conducive to the extend limit of coiled tubing.

scholarly journals A new design way for cylindrical blades with adjustable inlet blade angles

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401983017
Author(s):  
Jing Yan ◽  
Xiaobing Liu ◽  
Li Peng ◽  
Jianan Li
Keyword(s):  
Flow Rate ◽  
Leading Edge ◽  
Design Flow ◽  
Improve Performance ◽  
Plan View ◽  
Pump Design ◽  
New Approach ◽  
Traditional Design ◽  
Inlet Angle ◽  
Blade Leading Edge

A new approach for cylindrical blade design is presented in this article. Authors of this article analyzed the main reasons which are responsible for the low efficiency of untwisted blades and found out that the shock losses along the blade leading edge are much higher than those of twisted blades. Furthermore, based on the analysis, this article proposed a new design approach that is different from the traditional one. This new approach can reduce hydraulic losses at blade leading edge and improve performance and efficiency of cylindrical blades. In the traditional design process, to draw blade projection in plan view, an incidence at intersection of blade leading edge and inner streamline on the meridional section is selected for calculating blade inlet angle accurately. Because the incidence and the blade inlet angle at the intersection of blade leading edge and outer streamline are formed automatically, the blade inlet angles at this point are not suitable for oncoming flow direction, generating noticeable shock losses at this place. In the new design program, blade inlet angles at both intersection points formed by blade leading edge and the outer, inner streamlines are accurately calculated. This makes the shock losses generated by blade leading edge be minimized. Moreover, in conventional design, the projection of blade pressure side into plan view consists of only one plane curve. In the new design way, projection of blade surface in plan view is composed of two curves joined smoothly and continuously. Two impellers with fundamentally identical geometrical parameters were designed and manufactured, and the only difference is that their cylindrical blades were calculated and configured by applying a traditional design method or a the new approach. Test findings from an open loop indicate that in a wide load range from 0.8 to 1.2 times design flow rate, both head and efficiency of the new pump were raised. Over the operating range, efficiency of the new pump increased by 0.5% to 2.7%. Particularly, for higher flow rate, pump performance was improved significantly, and the increase of efficiency at pump design point arrived at 2.7%. The results suggest that the new approach presented in this article offers an effective and useful means to improve performance of low specific speed pumps.

Comprehensive analysis of the thermohydraulic performance of cooling networks subject to fouling and undergoing retrofit projects

2020 ◽  
pp. 0958305X2094531
Author(s):  
Hebert Lugo-Granados ◽  
Lázaro Canizalez-Dávalos ◽  
Martín Picón-Núñez
Keyword(s):  
Pressure Drop ◽  
Water Flow ◽  
Flow Rate ◽  
Fluid Velocity ◽  
Water Flow Rate ◽  
Volumetric Flow Rate ◽  
Cooling Capacity ◽  
Point Of View ◽  
Rate Distribution

The aim of this paper is to develop guidelines for the placing of new coolers in cooling systems subject to retrofit. The effects of the accumulation of scale on the flow system are considered. A methodology to assess the interconnected effect of local fluid velocity and fouling deposition is developed. The local average fluid velocity depends on the water flow rate distribution across the piping network. The methodology has four main calculation components: a) the determination of the flow rate distribution across the piping network, b) the prediction of fouling deposition, c) determination of the hydraulic changes and the effect on fouling brought about by the placing of new exchangers into an existing structure, and d) the calculation of the total cooling load and pressure drop of the system. The set of disturbances introduced to the system through fouling and the incorporation of new coolers, create network responses that eventually influence the cooling capacity and the pressure drop. In this work, these interactions are analysed using two case studies. The results indicate that, from the thermal point of view, the incorporation of new heat exchangers is recommended in series. The limit is the point where the increase of the total pressure drop causes a reduction in the overall volumetric flow rate. New coolers added in parallel create a reduction of pressure drop and an increase in the overall water flow rate; however, this increase is not enough to counteract the reduction of fluid velocity and heat capacity removal.

scholarly journals Volumetric flow rate in simulations of microfluidic devices

2018 ◽  
Vol 180 ◽  
pp. 02046
Author(s):  
KristÍna Kovalčíková ◽  
Martin Slavík ◽  
Katarína Bachratá ◽  
Hynek Bachratý ◽  
Alžbeta Bohiniková
Keyword(s):  
External Force ◽  
Flow Rate ◽  
Laboratory Experiments ◽  
Fluid Velocity ◽  
Volumetric Flow Rate ◽  
Microfluidic Devices ◽  
Fixed Set ◽  
Volumetric Rate ◽  
Simulation Parameter ◽  
Set Up

In this work, we examine the volumetric flow rate of microfluidic devices. The volumetric flow rate is a parameter which is necessary to correctly set up a simulation of a real device and to check the conformity of a simulation and a laboratory experiments [1]. Instead of defining the volumetric rate at the beginning as a simulation parameter, a parameter of external force is set. The proposed hypothesis is that for a fixed set of other parameters (topology, viscosity of the liquid, …) the volumetric flow rate is linearly dependent on external force in typical ranges of fluid velocity used in our simulations. To confirm this linearity hypothesis and to find numerical limits of this approach, we test several values of the external force parameter. The tests are designed for three different topologies of simulation box and for various haematocrits. The topologies of the microfluidic devices are inspired by existing laboratory experiments [3 - 6]. The linear relationship between the external force and the volumetric flow rate is verified in orders of magnitudes similar to the values obtained from laboratory experiments.

Addressing the siphoning effect in new shunt designs by decoupling the activation pressure and the pressure gradient across the valve

2013 ◽  
Vol 11 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Tobias A. Mattei ◽  
Martin Morris ◽  
Kathleen Nowak ◽  
Daniel Smith ◽  
Jeremy Yee ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Fluid Velocity ◽  
Component System ◽  
The Past ◽  
Benchmark Tests ◽  
Final Design ◽  
Actual Flow Rate ◽  
Actual Flow ◽  
Labview Program

Object Although several improvements have been observed in the past few years in shunt technology, currently available systems still present several associated problems. Among these, overdrainage along with its complications remains one of the great challenges for new shunt designs. To address the so-called siphoning effect, the authors provide a practical example of how it is possible to decouple the activation pressure and the pressure gradient across the valve through a 3–key component system. In this new shunt design, the flow is expected to depend only on the intracranial pressure and not on the pressure gradient across the valve, thus avoiding the so-called siphoning effect. Methods The authors used computer models to theoretically evaluate the mechanical variables involved in the operation of the newly designed valve, such as the fluid's Reynolds number, proximal pressure, distal pressure, pressure gradient, actual flow rate, and expected flow rate. After fabrication of the first superscaled model, the authors performed benchmark tests to analyze the performance of the new shunt prototype, and the obtained data were compared with the results predicted by the previous mathematical models. Results The final design of the new paddle wheel valve with the 3–key component antisiphoning system was tested in the hydrodynamics laboratory to prove that the siphoning effect did not occur. According to the calculations obtained using the LabVIEW program during the experiments, each time the distal pressure decreased without an increase in the proximal pressure (despite the range of the pressure gradient), the pin blocked the spinning of the paddle wheels, and the calculated fluid velocity through the system tended to zero. Such a situation was significantly different from the expected flow rate for such a pressure gradient in a siphoning situation without the new antisiphon system. Conclusions The design of this new prototype with a 3–key component antisiphoning system demonstrated that it is possible to decouple the activation pressure and the pressure gradient across the valve, avoiding the siphoning effect. Although further developments are necessary to provide a model compatible to clinical use, the authors believe that this new prototype illustrates the possibility of successfully addressing the siphoning effect by using a simple 3–key component system that is able to decouple the activation pressure and the pressure gradient across the valve by using a separate pressure chamber. It is expected that such proof of concept may significantly contribute to future shunt designs attempting to address the problem of overdrainage due to the siphoning effect.

Sign in / Sign up

Export Citation Format

Share Document