Holub slit model

In the case of trickle flow, it has been shown that under certain conditions the slit-flow approximation yields a very satisfactory set of constitutive equations for the gas-liquid and the liquid-solid drag forces [20, 21]. As a matter of fact, the slit flow becomes well representative of the trickle-flow regime when the liquid texture is contributed by solid-supported liquid Aims and rivulets. This generally occurs at low liquid flow rates that allow the transport of film-like liquids [20]. We will assume, without proof though, that such hypotheses also hold in the case of artificial-gravity operation. The validity of these assumptions and of the several others outlined above will be evaluated later in terms of model versus experiment comparisons. Choosing the drag force closures of the simplified Holub slit model [20], the equations system becomes ... 

Equations (11.7)-(11.9) are an adapted form of the slit model of Holub et al. [20] to a trickle bed experiencing artificial-gravity conditions. 

The reactor is inserted in region A of the solenoid bore (Fig. 11.1). Experiments are first made to measure the liquid holdup, the pressure drop and the wetting efficiency in the absence of magnetic fields. A sufficient time is allowed for the system to reach steady state before measurements are acquired. Experimental data are compared with the predictions of the Holub et al. [20] modeL Eigures 11.3a and b show the experimental data versus Holub s model for the trickle-flow regime with the magnetic field off. The slit model restores the hydrodynamic behavior pretty well in terms of pressure-drop and liquid-holdup variations. 

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