Region mixture

A 2-value smaller than 1 means that there is an excess of fuel in the mixture. In this case the air/fuel mixture is called rich. If more air is in the mixture than needed for a complete fuel combustion (2 > 1) the term lean mixture is used. Ideally the combustion is complete at 2 = 1. Real fuel cannot be combusted without an increase in CO and soot at 2-values smaller than 1.05. Due to changing operation conditions, for example a soiled burner, wear of the nozzle or leaky flaps, change of gas quality or changes of temperature and air pressure in the ambient atmosphere, the air/fuel ratio and thus flue gas composition can change over time. In order to minimize the risk of intoxication (see also chapter 5333), explosion and pollution real (uncontrolled) fuel burners are adjusted to operate far beyond this limit in the excess (lean mixture) region. However, unfortunately effi-... 

We add N2 uniformly to the mixture, moving along the B-C line towards 100 % N2. The least amount of N2 before air can safely be added is found by locating state C just when the addition of air no longer intersects the flammable mixture region. This is shown by the process B —> C and C —> A in Figure 4.16(b) ... 

COMMENTS. (1) The turbine work produced is very small. It does not pay to install an expansion device to produce a small amount of work. The expansion process can be achieved by a simple throttling valve. (2) The compressor handles the refrigerant as a mixture of saturated liquid and saturated vapor. It is not practical. Therefore, the compression process should be moved out of the mixture region to the superheated region. 

Fig. 17. The character of etching of platinum foils in ethylene/oxygen mixtures is a function of gas phase composition. Under excess fuel conditions between 500 and 700°C, carbon films containing platinum particles form on top of the foil. TEM micrograph of a carbon film formed after 40 h of treatment at 587°C in a fuel excess O2/C2H4 mixture (region IV). (Reprinted with permission from (55). Copyright 1985 American Chemical Society.)...

The two calculation methods in Section 4.2 enable prediction of the three-phase (Lw-H-V) gas mixture region extending between the two quadruple points Qi and Q2 in Figure 4.1. Section 4.3 provides a method to use the techniques of Section 4.2 to locate both quadruple points on a pressure-temperature plot. Section 4.3 also discusses equilibrium of three condensed phases [aqueous liquid-hydrate-hydrocarbon liquid (Lw-H-Lhc)] Determination of equilibrium from condensed phases provides an answer to the question, Given a liquid... 

An example showing a constrained mixture region with lower bounds and upper bounds is illustrated in Figure 8.11. We see that for this particular case, the following constraints apply ... 

FIGURE 8.11 Constrained mixture region with upper and lower bounds. 

The influence of oxidation processes on particle temperature is demonstrated by the fact that hot particles work preferably as an ignition source in the poor mixture region of gas-air or vapour-air mixtures, i.e. in a concentration range below the stoichiometric mixture. In the rich mixture region above the stoichiometric mixture, particles are not very efficient as ignition sources, due to the lack of oxygen. 

Fig. 3.16.2 Separation of phases for a binary mixture. Region inside curve represents the domain of heterogeneous phases.

In the mixture region W 4 the convective terms and tangential mass transfer due to molecular diffusion play the primary role (molecular diffusion along the radial coordinate can be neglected). 

For the example of superheated water, the subsonic branch of the adiabat terminates inside the mixture region so only liquid-vapor mixture downstream states are possible. Is it possible to obtain downstream states which are pure vapor, t.e., a complete evaporation wave The possibility of such waves is suggested by the existence of the inverse process, the complete liquefaction shock [12] that is, shocks from a pure vapor to a pure liquid state. This process can only occm in a fluid of high molar specific heat, a retrograde fluid in which the saturation boundary on the vapor side has positive slope in T-s coordinates. 

Fig. 6.5 Phase diagrams of side-chain association. The binodal (solid line), the spinodals (borderline of the gray areas), microphase separation transition Une (broken line), critical solution points (white circles), and Lifshitz points (black circles) are shown. The homogeneous mixture region, microphase region, and the macroscopicaUy unstable region are indicated by H, M, and U, respectively. Parameters are fixed at wa = 1000, f = 200, = 10, A.q = 1.0, and tjfi = 1.0. The...

Figure 1.12. Liquid-Kquid-vapor phase diagram for benzene (l)-isopropil alcohol(2)-water(3) mixture. Region of two liquid phases Reg is shaded, cr, critical point dotty lines, sep-aratrixes thin hues, hquid-liquid tie-hnes, vapor line.

Figme 1.13. Some types of liquid-liquid phase diagrams for three-component mixtures. Region of three liquid phases Reg is shaded. Thin line, tie-line liquid-liquid cr, critical points. 

Figure 6.16. Trajectories of heteroazeotropic distiUation (a) distillate from azeocolumn to decanter for separation toluene(l)-ethanol(2)-water(3) mixture (b) distillate from azeocolumn to decanter and a recycle stream of the entrainer from decanter to azeocolumn for separation benzene(l)-isopropanol(2)-water(3) mixture (c) distillate from azeostripping to decanter and a recycle stream of the entrainer from decanter to azeostripping for separation benzene(l)-isopropanol(2)-water(3) mixture (d) distillate from azeocolumn to decanter and a recycle stream of the entrainer from decanter to azeocolumn for separation acetic add(l)-n-butyl acetate (2)-water(3) mixture (e) bottom from azeocolumn to decanter for separation butanol(l)-acetone(2)-water(3) mixture and (f) side product from azeocolumn to decanter for separation butanol(l)-acetone(2)-water(3) mixture. Regions of two liquid phases Regi,i 1,2 are shaded.

Figme 6.17. Trajectories of heteroextractive distillation (a) distillate from azeocolumn to decanter and a stream of the entrainer from decanter and additional entrainer to azeocolumn for separation vinyl acetate(l)-methanol(2)-water(3) mixture (b) distillate from azeocolumn to decanter and a stream of the entrainer from decanter and additional entrainer to azeocolumn for separation chloroform(l)-acetone(2)-water(3) mixture. Regions of two Kquid phases Reg/,i /,2 are shaded. 

Fig. 11 Typical mixture region expansion behavior In the under water thermite billet tests (data taken from COMET 1-26).

A contour plot of the macroscopic melt density (ap) is shown at the end of the fall phase for RUNl, 0.3 s, in Fig. 3. An interesting feature is the appearance of a steam-water chimney in the Interior of the mixture region, which can be seen in Figs. 3 and 4, with the vapor volume fraction at 0.3 s. The axial average steam volume fraction... 

In RUN4A the subcooled boiling model, surface entrainment model, and surface tracking were used. The melt distribution at time of bottom contact for this case is shown in Fig. 5, where it is apparent that the overall mixture region is considerably larger than in RUNl. The time of bottom contact is also later, 0.4s vs 0.3s. A steam chimney is still present, but steam is now being generated near the main melt mass at the tank bottom, as seen in Fig. 6. 

Another parameter used to assess mixing is the steam volume fraction in the mixture region. The usual experimental procedure for the FITS experiments was either to use measurements of water level swell to estimate the steam volume fraction in the entire tank, which was then... 

The mixture region vapor volume fraction in RUN4A is 0.5, vs 0.065 in RUNl. 

It appears that the global parameters obtained for the mixture region, namely the Sauter diameter (from which total surface area of the melt can be found), the water/melt mass ratio, and the vapor volume fraction, form a sufficient set of parameters to characterize a coarse mixture. Further analysis on the physical explosion of mixtures should then allow a definition of what combination of coarse mixture parameters can lead to a propagating FCI. 

It should be noted that many of the parameters available from IFCI calculations are difficult to observe experimentally for instance, the actual water/melt mass ratio in the mixture region requires determination of the spatial distribution of the three-phase system. Another example is the calculation of a steam chimney forming in the mixture region, which has not been observed directly in experiments, although its presence has been suggested. It appears important to somehow measure the spatial variation of the three-phase mixture experimentally, both to verify the calculational results and to accurately determine the characteristics of the actual mixture region. 

---