scholarly journals Microfluidics made easy: A robust low-cost constant pressure flow controller for engineers and cell biologists

2016 ◽  
Vol 10 (3) ◽  
pp. 034107 ◽  
Author(s):  
Nicholas Mavrogiannis ◽  
Markela Ibo ◽  
Xiaotong Fu ◽  
Francesca Crivellari ◽  
Zachary Gagnon
Keyword(s):  
Constant Pressure ◽  
Low Cost ◽  
Pressure Flow ◽  
Flow Controller

scholarly journals Damping Pressure Pulsations in a Wave-Powered Desalination System

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Brandon J. Hopkins ◽  
Nikhil Padhye ◽  
Alison Greenlee ◽  
James Torres ◽  
Levon Thomas ◽  
...  
Keyword(s):  
Constant Pressure ◽  
Low Cost ◽  
Pressure Fluctuations ◽  
Cost Effective ◽  
Coastal Communities ◽  
Pressure Pulsations ◽  
Pressure Flow ◽  
Reliable Source ◽  
Effective Option ◽  
Elastic Pipes

Wave-driven reverse osmosis desalination systems can be a cost-effective option for providing a safe and reliable source of drinking water for large coastal communities. Such systems usually require the stabilization of pulsating pressures for desalination purposes. The key challenge is to convert a fluctuating pressure flow into a constant pressure flow. To address this task, stub-filters, accumulators, and radially elastic-pipes are considered for smoothing the pressure fluctuations in the flow. An analytical model for fluidic capacitance of accumulators and elastic pipes are derived and verified. Commercially available accumulators in combination with essentially rigid (and low cost) piping are found to be a cost-effective solution for this application, and a model for selecting accumulators with the required fluidic-capacitance for the intended system is thus presented.

Turbulent Spot in 3-D Constant Pressure Flow

1995 ◽  
pp. 279-286
Author(s):  
M. Jahanmiri ◽  
A. Prabhu ◽  
R. Narasimha
Keyword(s):  
Constant Pressure ◽  
Turbulent Spot ◽  
Pressure Flow

The freely recovering arc in a constant-pressure flow

1974 ◽  
Vol 7 (16) ◽  
pp. 2254-2265 ◽  
Author(s):  
G R Jones ◽  
S R Naidu
Keyword(s):  
Constant Pressure ◽  
Pressure Flow

Large Eddy Simulation of High Reynolds Number Nonreacting and Reacting JP-8 Sprays in a Constant Pressure Flow Vessel With a Detailed Chemistry Approach

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Luis Bravo ◽  
Sameera Wijeyakulasuriya ◽  
Eric Pomraning ◽  
Peter K. Senecal ◽  
Chol-Bum Kweon
Keyword(s):  
Large Eddy Simulation ◽  
Internal Combustion Engines ◽  
Constant Pressure ◽  
Engine Performance ◽  
Spray Combustion ◽  
Pressure Flow ◽  
Detailed Chemistry ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Lift Off

In military propulsion applications, the characterization of internal combustion engines operating with jet fuel is vital to understand engine performance, combustion phasing, and emissions when JP-8 is fully substituted for diesel fuel. In this work, high-resolution large eddy simulation (LES) simulations have been performed in-order to provide a comprehensive analysis of the detailed mixture formation process in engine sprays for nozzle configurations of interest to the Army. The first phase examines the behavior of a nonreacting evaporating spray, and demonstrates the accuracy in predicting liquid and vapor transient penetration profiles using a multirealization statistical grid-converged approach. The study was conducted using a suite of single-orifice injectors ranging from 40 to 147 μm at a rail pressure of 1000 bar and chamber conditions at 900 K and 60 bar. The next phase models the nonpremixed combustion behavior of reacting sprays and investigates the submodel ability to predict auto-ignition and lift-off length (LOL) dynamics. The model is constructed using a Kelvin Helmholtz–Rayleigh Taylor (KH–RT) spray atomization framework coupled to an LES approach. The liquid physical properties are defined using a JP-8 mixture containing 80% n-decane and 20% trimethylbenzene (TMB), while the gas phase utilizes the Aachen kinetic mechanism (Hummer, et al., 2007, “Experimental and Kinetic Modeling Study of Combustion of JP-8, Its Surrogates, and Reference Components in Laminar Non Premixed Flows,” Proc. Combust. Inst., 31, pp. 393–400 and Honnet, et al., 2009, “A Surrogate Fuel for Kerosene,” Proc. Combust. Inst., 32, pp. 485–492) and a detailed chemistry combustion approach. The results are in good agreement with the spray combustion measurements from the Army Research Laboratory (ARL), constant pressure flow (CPF) facility, and provide a robust computational framework for further JP-8 studies of spray combustion.

Pressure Buildup for Wells Produced at a Constant Pressure

1981 ◽  
Vol 21 (01) ◽  
pp. 105-114 ◽  
Author(s):  
C.A. Ehlig-Economides ◽  
H.J. Ramey
Keyword(s):  
Constant Pressure ◽  
Variable Rate ◽  
Reservoir Pressure ◽  
Well Test ◽  
Well Test Analysis ◽  
Pressure Flow ◽  
Value Analysis ◽  
Pressure Buildup ◽  
Constant Flow Rate ◽  
Constant Rate

Abstract Conventional well test analysis has been developed primarily for production at a constant flow rate. However, there are several common reservoir production conditions which result in flow at a constant pressure instead of a constant rate. In the field, wells are produced at constant pressure when fluids flow into a constant-pressure separator and during the rate decline period of reservoir depletion. In geothermal reservoirs, produced fluids may drive a backpressured turbine. Open wells, including artesian water wells, flow at constant atmospheric pressure.Most of the existing methods for pressure buildup analysis of wells with a constant-pressure flow history are empirical. Few are based on sound theory. Hence, there is a need for a thorough treatment of pressure buildup behavior following constant-pressure production.In this work, the method of superposition of continuously changing rates was used to generate an exact solution for pressure buildup following constant-pressure flow. The method is general. Storage and skin effects were incorporated into the theory, and both bounded and unbounded reservoirs were considered. Buildup solutions were graphed using conventional techniques for analysis. Horner's method for plotting buildup data after a variable-rate flow was found to be accurate in a majority of cases. Also, the method by Matthews et al. for determining the average reservoir pressure in a closed system was determined to be correct for buildup following constant-pressure flow. Introduction When a flowing well is shut in, the pressure in the wellbore increases with time as the pressures throughout the reservoir approach a static value. Analysis of the pressure increase, or pressure buildup, often provides useful information about the reservoir and the wellbore itself. Techniques exist for determination of wellbore storage, skin effect, reservoir permeability and porosity, and either the initial reservoir pressure or the volumetric average reservoir pressure at the time the well was shut in. Effects of fractures penetrated by or near the wellbore also can be detected, as well as nearby faults or reservoir drainage boundaries.Most of the techniques for pressure buildup analysis were developed for wells which, prior to shut-in, were produced at a constant rate. When the production rate before shut-in changes rapidly, conventional analysis is often suspect. If the exact rate history is known, the theory of superposition in time of constant-rate solution leads to the method derived by Horner which compensates for changing production rates. This method results in long calculations. However, in the same paper Horner proposed a simplified procedure in which the last established rate was assumed constant and the flow time was set equal to the cumulative production divided by the last established rate. Other methods for analysis of pressure buildup after a variable-rate production history were proposed by Odeh et al.A special case of variable-rate production results when a well is produced at constant pressure. The first published application of pressure buildup analysis for a well produced at constant pressure prior to shut-in was by Jacob and Lohman. Their graph of residual drawdown vs. total time divided by shut-in time results in a semilog straight line. SPEJ P. 105^

Ocean Energy On-Demand Using Underocean Compressed Air Storage

2007 ◽  
Author(s):  
Richard J. Seymour
Keyword(s):  
Constant Pressure ◽  
Low Cost ◽  
Salt Dome ◽  
Compressed Air ◽  
Recovery Efficiency ◽  
Ocean Energy ◽  
On Demand ◽  
Storage Chamber ◽  
Air Supply ◽  
Design Challenge

Renewable ocean energy sources are typically highly variable and uncontrolled, resulting in the production of low value electricity. Storing energy in the form of compressed air is a mature technology on land. Utilizing hydrostatic pressure at depth in the ocean to maintain constant pressure in the air supply chamber offers large recovery efficiency advantages. If salt dome caverns are not available, the design challenge is the development of a low cost bottom-founded air storage chamber.

High-Speed Rainbow Schlieren Deflectometry of N-Heptane Sprays Using a Common Rail Diesel Injector

2016 ◽  
Author(s):  
Eileen M. Mirynowski ◽  
Ajay K. Agrawal ◽  
Joshua A. Bittle
Keyword(s):  
High Speed ◽  
Fuel Injection ◽  
Constant Pressure ◽  
Operating Conditions ◽  
Common Rail ◽  
Fuel Injector ◽  
Pressure Flow ◽  
Schlieren Technique ◽  
Fuel Sprays ◽  
Rainbow Schlieren

More precise measurements of the fuel injection process can enable better combustion control and more accurate predictions resulting in a reduction of fuel consumption and toxic emissions. Many of the current methods researchers are using to investigate the transient liquid fuel sprays are limited by cross sensitivity when studying regions with both liquid and vapor phases present (i.e. upstream of the liquid length). The quantitative rainbow schlieren technique has been demonstrated in the past for gaseous fuel jets and is being developed here to enable study of the spray near the injector. In this work an optically accessible constant pressure flow rig and a modern common rail diesel injector are used to obtain high speed images of vaporizing fuel sprays at elevated ambient temperatures and pressures. Quantitative results of full-field equivalence ratio measurements are presented as well as more traditional measurements such as vapor penetration and angle for a single condition (13 bar, 180°C normal air) using nheptane injected through a single hole (0.1mm diameter) common rail fuel injector at 1000 bar fuel injection pressure. This work serves as a proof of concept for the rainbow schlieren technique being applied to vaporizing fuel sprays and full details of the image processing routine are provided. The ability of the imaging technique combined with the constant pressure flow rig make this approach ideal for generating large data sets in short periods of time for a wide range of operating conditions.

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