Algebraic Reynolds Mass Flux Model

The Reynolds mass flux model can also be further simplified by letting the convection terms of u c on the left side of Eq. (3.24) equal to the molecular diffusion and turbulent diffusion in terms of u d on the right side, then under steady condition, Eq. (3.25a) becomes 

The number of unknown quantities and equations of this model is the same as the Reynolds mass flux model except using Eq. (3.31) to replace Eq. (3.25a) for calculating m c in order to reduce the load of computation. 

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The hybrid Reynolds mass flux model and algebraic Reynolds mass flux model, which only need to solve simpler Eq. (1.8) instead of complicated Eq. (1.23), may be a proper choice for multiple tray computation if their simulated results are very close to the standard Reynolds mass flux model. For comparison, the simulated column trays in Sect. 4.1.1.1 for separating n-heptane and methylcyclohexane are used. Li [17] simulated concentration profiles of all trays at different levels above the tray floor, among which the tray number 8 and tray number 6 are shown in Fig. 4.17a and b. 

Reyuolds mass flux model at 70 mm above the tray floor, b standard Reynolds mass flux model at 20 mm above the tray floor, c hybrid Reynolds mass flux model at 70 mm above the tray floor, d hybrid Reynolds mass flux model at 20 mm above the tray floor, e algebraic Reynolds mass flux model at 70 mm above the tray floor, and f algebraic Reynolds mass flux model at 20 mm above the tray Hoot... 

The verification of algebraic Reynolds mass flux model as well as the comparison with hybrid model is shown in Fig. 4.45. At low F factor, these two models are in agreement with experiment, but at high F factor the algebraic Reynolds mass flux model shows greater deviation from the experimental data. 

Li [7] simulated the packed column as described in Sect. 4.2.1 by using Reynolds mass flux model instead of two-equation model and compared their difference. The simulated results for three forms of Reynolds mass flux model (standard, hybrid, and algebraic) are given in subsequent sections. 

Fig. 4.45 Comparison of algebraic and hytoid Reynolds mass flux models with experimental data, a F factor = 0.758 m s (kg b F factor = 1.02 m s (kg and c F fac-...

Abstract In this chapter, the two CMT models, i.e., c — Eci model and Reynolds mass flux model (in standard, hybrid, and algebraic forms) are used for simulating the chemical absorption of CO2 in packed column by using MEA, AMP, and NaOH separately and their simulated results are closely checked with the experimental data. It is noted that the radial distribution of Di is similar to a, but quite different from fit. It means that the conventional assumption on the analogy between the momentum transfer and the mass transfer in turbulent fluids is unjustifled, and thus, the use of CMT method for simulation is necessary. In the analysis of the simulation results, some transport phenomena are interpreted in terms of the co-action or counteraction of the turbulent mass flux diffusion. 

The model equations are the same as the standard Reynolds mass flux except u equations are changed to the following algebraic form ... 

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