Concentric cylinder cells

Dielectric dispersion of the solution was measured by using a transformer bridge, Ando Denki TR-IC model in the frequency range from 30 to 3M Hz. A platinum concentric cylinder cell was used in a thermostatted bath. The cell was calibrated with benzene. The concentration of the solution was 5 X 10 g ml to avoid the intermolecular interaction. The dipole moment of PBLG molecules was estimated by the Applequist-Mahr equation from the results of dielectric dispersion measurements. 

Fig. 15. Effects of turbulent shear stress level and exposure time on cell viability measured by trypan blue staining. Cells were sheared in a concentric cylinder viscometer [1]...

Fig. 17. Response of CRL-8018 hybridoma cells to increasing levels of well-defined laminar shear in the concentric cylinder viscometer for 10 min. Spinner flask cultures were seeded with cells from routine T-flask cultures that were 3 days old. Cell samples were taken from the spinner flask cultures during late-exponential growth and sheared in the viscometer [17]...

Soule et al. [141] constructed a sparged, concentric cylinder bioreactor for the cultivation of suspensions of Pirus malus. Growth was reduced under all rotational conditions. Sun and Linden [106] employed a rotating wall vessel (Rotary Cell Culture System, Synthecon, Houston, TX, USA) to cultivate suspensions of Taxus cuspidata under laminar flow conditions. Shear rates were... 

Electrochemical reactors (cells, tanks) are used for the practical realization of electrolysis or the electrochemical generation of electrical energy. In developing such reactors one must take into account the purpose of the reactor as well as the special features of the reactions employed in it. Most common is the classical reactor type with plane-parallel electrodes in which positive and negative electrodes alternate and all electrodes having the same polarity are connected in parallel. Reactors in which the electrodes are concentric cylinders and convection of the liquid electrolyte can be realized by rotation of one of the electrodes are less common. In batteries, occasionally the electrodes are in the form of two long ribbons with a separator in between which are wound up as a double spiral. 

Fig. 4.5.3 Cross section of a concentric cylinder flow cell. The directions z and y correspond, respectively, to the static magnatic field B0 and the gravitational field directions.

The monodisperse materials described hereafter were obtained with the Couette type cell designed by Bibette et al. [ 150,159]. It consists of two concentric cylinders (rotor and stator) separated by a very narrow gap (100 pm), allowing application of spatially homogeneous shear rates over a very wide range (from 0 to 14280 s ), with shearing durations of the order of 10 s. 

The device resembles a cylindrical differential mobility analyzer (DMA) in that a sample flow is introduced around the periphery of the annulus between two concentric cylinders, and charged particles migrate inward towards the inner cylinder in the presence of a radial electric field. Instead of being transmitted to an outlet flow, the sample is collected onto a Nichrome filament located on the inner cylinder. The primary benefit of this mode of size-resolved sampling, as opposed to aerodynamic separation into a vacuum, is that chemical ionization of the vapor molecules is feasible. Because there is no outlet aerosol flow, the collection efficiency is determined by desorption of the particles from the filament, chemical ionization of the vapor, separation in a mobility drift cell, and continuous measurement of the current produced when the ions impinge on a Faraday plate. 

Figure 6 (a) Annular cell made from two concentric cylinders of height H, inner radius... 

In the case of the thermal-conductivity, there are three main techniques those based on Equation (1) and those based on a transient application of it. Prior to about 1975, two forms of steady-state technique dominated the field parallel-plate devices, in which the temperature difference between two parallel disks either side of a fluid is measured when heat is generated in one plate, and concentric cylinder devices that apply the same technique in an obviously different geometry. In both cases, early work ignored the effects of convection. In more recent work, exemplified by the careful work in Amsterdam with parallel plates, and in Paris with concentric cylinders, the effects of convection have been investigated. Indeed, the parallel-plate cells employed in Amsterdam by van den Berg and his co-workers have the unique feature that, because the temperature difference imposed can be very small and the horizontal fluid layer very thin, it is possible to approach the critical point in a fluid or fluid mixture very closely (mK). 

A glass adsorption cell used for the static condenser method is shown in Fig. 14. The condenser is formed from two concentric cylinders separated by a 2 mm gap. 

Concentric Cylinder - Eberson cell Packed bed electrodes - fibre... 

A diagram of an electron capture detector is shown in figure 4.11. There are a large number of different detector designs, but the basic electron capture detector consists of a small chamber 1 or 2 ml in volume with two metal electrodes. The electrodes may be formed by concentric cylinders or by metal discs separated by a suitable insulator. The cell contains the radioactive source, usually electrically connected to the conduit through which the carrier gas enters and to the negative side of the power supply. A gauze "diffuser" is sometimes connected to the exit of the cell and to the positive side of the power supply. The electrode current is monitored by a suitable amplifier. 

It will be seen in the next and subsequent chapters that a wide variety of cell geometries (e.g. parallel plates, concentric cylinders, Swiss roll), types of electrode (e.g. plates, beds, porous, expanded metals and gauzes) and flow patterns are used in industrial electrochemistry. In most the flow is too complex to warrant a detailed fluid-mechanical calculation. Rather the normal approach to mass transport in electrolytic cells is to treat the cell as a unified whole and to seek expressions in terms of space-averaged quantities which permit some insight into the mass transport conditions within the cell. 

Similar cells based on cylindrical geometry have been proposed. In the stationary version, the electrolyte is pumped through a thin gap between two electrodes formed by the inside of a pipe and a concentric central cylinder. When the central electrode is rotated the cell is again self-pumping and the rotating cylinder cell has many of the attractions of the pump cell. It has been manufactured commercially for the removal of metal ions from dilute solutions. The cylinder cells have a poor space time yield compared with their disc counterparts but have the advantage that they may be modified to include a separator. 

---