Direct fluid injection, schematic

Figure 4i Schematic illustration of the Direct Fluid Injection (DFI) process. An ideal expansion through a pinhole orifice (top) and expansion through a capillary restriction (bottom).

Figure 8.22 Schematic diagram of the Suprex MPS/225 integrated aupercritical fluid extractor, cryogenically focused interface and supercritical fluid chromatogra d>. The bold lines represent the direction of fluid flow in the load and inject positions.

Figure 5.8 Schematic representation of a chip-based solid phase extraction-MEKC device, (a) Layout of the entire device and (b) expanded view of the extraction region of the device. The dotted lines represent the direction of fluid flow during extraction the solid lines signify flow during elution/injection (Narrow channels are 55 pm wide, column chamber is 210 pm wide, with all channels 15 pm deep.) [87].

Fig. 13.15 Schematic representation of the flow pattern in the central portion of the advancing front between two parallel plates. The coordinate system moves in the x direction with the front velocity. Black rectangles denote the stretching deformation the fluid particles experience. [Reprinted by permission from Z. Tadmor, Molecular Orientation in Injection Molding, J. Appl. Polym. Sci., 18, 1753 (1974).]...

While the flow of a fluid through a packed bed at a given velocity, v, is a coimnon situation in practice, the description of the problem is quite complicated even in a one-dimensional space with fluids of uniform properties. This is due to the fact that mixing takes place both longitudinally (in the direction of flow) and transversely (perpendicular to the flow). Suppose at i=0 a dot of traced fluid (such as dye) of concentration c, rather than over the entire face, is injected. This situation is schematically shown in Fig. 3.2. As the dot moves from left (face 1) to right (face 2) with the flow, it will spread in the direction of flow and perpendicular to the flow. At face 2 the dot is transformed into an ellipse with concentration varying across it. There are several methods to obtain partial differential equations describing the concentration behaviour of the mixed zone as a function of time and position, to model the phenomenon shown in Fig. 3.2. 

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