Flow-through system, dynamic

Recently it has been shown that rotating coiled columns (RCC) can be successfully applied to the dynamic (flow-through) fractionation of HM in soils and sediments [1]. Since the flow rate of the extracting reagents in the RCC equipment is very similar to the sampling rate that is used in the pneumatic nebulization in inductively coupled plasma atomic emission spectrometer (ICP-AES), on-line coupling of these devices without any additional system seems to be possible. 

The use of dynamic, flow-through test chambers is common in the study of emissions from sources of indoor air pollution [39]. They are also widely used in the study of indoor sinks. Some of the earlier work on sinks examined the surfaces of the test chambers themselves and showed that chamber sink effects can be important [21]. Researchers routinely evaluate test chamber systems for sink effects [34,40]. A recent paper on the measurement of SVOC emissions showed how the chamber sink effect can be exploited [41]. In this study, SVOCs adsorbed on chamber walls were removed by heating, flushed out, and quantified to give SVOC emission rates. 

Over the years constmction of the dynamic chamber has been modified. For studies conducted recently, the chamber is generally constmcted as follows. The dynamic flow-through chamber system is cylindrical in nature and built from Plexiglas material. Chamber dimensions may vary but are generally about 23 cm inner diameter (i.d.) and 46 cm. in height. The entire closed system is lined on the inside with 2 mil fluorinated ethylene propylene (FEP) Teflon and stainless steel fittings in order to minimize chemical reactions with sample flow. 

Figure 1. Schematic of dynamic flow-through chamber system configured to measure emissions from a swine waste treatment lagoon.

The following mass balance equation may be used for the dynamic flow-through chamber system and applied to any target gaseous substance of known concentration ... 

As with any type of experimental procedure, it is desirable to compare data acquired in field studies with controlled laboratory studies and/or related models. Various comparisons with models, as well as other measurement techniques, have been made with data collected via the dynamic flow-through chamber system. Some results are presented in the following discussion. 

For model comparisons with the dynamic flow-through chamber system, Aneja et al., (200Id) developed a mass transport model based on the quiescent thin film concept (Danckwerts,... 

The dynamic flow-through chamber system has been successfully developed in response to a need to measure emissions of nitrogen, sulphur, and carbon compounds for a variety of field applications. Moreover, similar chamber systems have also been deployed to measure uptake of nitrogen, sulphur, ozone, and hydrogen peroxide gases by crops and vegetation to examine... 

RLE A combination of static and dynamic (flow-through) solvent extraction at a higher pressure and usually also elevated temperatures Organic solvent(s) dispersant, drying agent, or sorbent Special extraction vessel PLE system... 

In fluid dynamics fluids are in motion. Generally, they are moved from place to place by means of mechanical devices such as pumps or blowers, by gravity head, or by pressure, and flow through systems of piping and/or process equipment. The first step in the solution of flow problems is generally to apply the principles of the conservation of mass to the whole system or to any part of the system. First, we will consider an elementary balance on a simple geometry, and later we shall derive the general mass-balance equation. 

Acoustosizer IIs (Colloidal Dynamics, Warwick, USA) with a built-in conductivity meter and thermometer was used to measure the potential and conductance of solutions of phosphoric and oxalic acid solutions in mixed (water-ethanol and water-methanol) solvents and of Ti02 dispersions (1-10 % by mass). The apparatus was kept in a fume-hood. A flow-through system and stirrer prevented sedimentation of dispersions. An external thermostat was used to keep the solutions and dispersions at 25 1 °C. 4 mL of 1 M acid was added in 0.1 mL portions to 170 mL of initial solution or... 

Because of this heat generation, when adsorption takes place in a fixed bed with a gas phase flowing through the bed, the adsorption becomes a non-isothermal, non-adiabatic, non-equilibrium time and position dependent process. The following set of equations defines the mass and energy balances for this dynamic adsorption system [30,31] ... 

Fluid power equipment is designed to reduce friction as much as possible. Since energy cannot be destroyed, some of the energy created by both static pressure and velocity is converted to heat energy as the fluid flows through the piping and components within a hydraulic system. As friction increases, so does the amount of dynamic and static energy that is converted into heat. 

In the SI system, the theoretical unit of v is m2/s or the commonly used Stoke (St) where 1 St = 0.0001 m2/s = 100 cSt = 100 centiStoke. Similarly, 1 centiStoke = 1 cSt = 0.000001 m2/s = 0.01 Stoke = 0.01 st. The specific gravity of water at 20.2°C (68.4°F) is almost 1. The kinematic viscosity of water at 20.2°C (68.4°F) is for all practical purposes equal to 1 cSt. For a liquid, the kinematic viscosity will decrease with higher temperature. For a gas, the kinematic viscosity will increase with higher temperature. Another commonly used kinematic viscosity unit is Saybolt universal seconds (SUS), which is the efflux time required for 60 mL of petroleum product to flow through the calibrated orifice of a Saybolt universal viscometer, as described by ASTM-D88. Therefore, the relationship between dynamic viscosity and kinematic viscosity can be expressed as... 

The design of a cross-flow filter system employs an inertial filter principle that allows the permeate or filtrate to flow radially through the porous media at a relatively low face velocity compared to that of the mainstream slurry flow in the axial direction, as shown schematically in Figure 15.1.9 Particles entrained in the high-velocity axial flow field are prevented from entering the porous media by the ballistic effect of particle inertia. It has been suggested that submicron particles penetrate the filter medium and form a dynamic membrane or submicron layer, as shown in... 

In some cases, where the wall of the reactor has an appreciable thermal capacity, the dynamics of the wall can be of importance (Luyben, 1973). The simplest approach is to assume the whole wall material has a uniform temperature and therefore can be treated as a single lumped parameter system or, in effect, as a single well-stirred tank. The heat flow through the jacket wall is represented in... 

A centrifugal pump is used to pump a liquid in steady turbulent flow through a smooth pipe from one tank to another. Develop an expression for the system total head A/t in terms of the static heads on the discharge and suction sides zd and zs respectively, the gas pressures above the tanks on the discharge and suction sides Pd and Ps respectively, the liquid density p, the liquid dynamic viscosity p, the gravitational acceleration g, the total equivalent lengths on... 

Common Features of Processes Performed in Flow-Through Dynamic Systems... 

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