Mixed phase pipe

A system in which the liquid and gas/ vapour phases are uniformly mixed. In pipe flow, "homogeneous" also implies no slip between the phases and complete vapour/ liquid equilibrium (see 9 3 1)... 

Stirred tank reactors (STR) are the most frequently used reactors in lab-scale ozonation, partially due to the ease in modeling completely mixed phases, but they are very seldom used in full-scale applications. There are various modifications with regard to the types of gas diffusers or the construction of the stirrers possible. Normally lab-scale reactors are equipped with coarse diffusers, such as a ring pipe with holes of 0,1-1.0 m3 diameter. The k/ a-values are in the range of 0.02 to 2.0 s (see Table 2-4 ), which are considerably higher than those of bubble columns. From the viewpoint of mass transfer, the main advantage of STRs is that the stirrer speed can be varied, and thus also the ozone mass transfer coefficient, independently of the gas flow rate. 

Combustion may also occur in mixed-phase systems (solids with liquids, solids with gases, liquids with gases). The theory of mixed-phase combustion is a much less studied subject, and consequently flammability data are almost exclusively determined by experimental testing. The primary hazard with most oxidant delivery systems is that of mixed-phase combustion the oxidant is a gaseous material which may support combustion of the system which is either a liquid (oils, greases, coolants) or a solid (piping, valves, instruments). 

Acoustic/ultrasonic techniques that have been developed into flow-monitoring instruments are Doppler, cross-correlation, and transit-time methods. An ultrasonic Doppler flowmeter has been applied to single-phase turbulent flows and mixed-phase (solid/liquid or gas/liquid) flows. The crosscorrelation technique is mainly for mixed-phase flows, whereas the transit-time method has been applied to single-phase flows, either liquid or gas, in large pipes. 

Mixed phase downflow fixed bed reactors can operate in several flow regimes. These bear resemblance to flow regimes in two phase flow in pipes. These flow regimes are the gas continuous ("trickle bed"), bubble flow, pulse flow and gas continuous blurring regime or spray flow. Many maps have been proposed in the... 

This problem only occurs when the drum is elevated above the partial condenser. The fundamental difficulty is excessive riser pipe diameter. To avoid slug flow in such a riser a mixed-phase velocity of at least 20 ft/s is needed. 

There are many variants on this simple theme. For instance, many other methods for mixing have found use. In a design offered by Lurgi, the phases are mixed in what is essentially an axial flow pump, and then pass down a relatively long pipe where the turbulence of flow keeps the phases mixed while the extraction takes place. In another design, the individual phases are pumped and then join and pass through a static mixer. There are no particular physicochemical reasons for preferring one type of mixer to... 

A direct numerical relationship between heat and momentum fluxes, as for the simple Reynolds analogy for a single phase, is not obtained in this case because of a basic and significant difference in heat transfer coefficient definitions. For singlephase flow in pipes, the mixed mean or integrated average temperature is used in... 

The limiting factors for successful soil mixing treatment include the presence of boulders and subsurface utilities such as underground wires or piping. Depth to the water table may adversely impact the vapor extraction components effectiveness because vapor phase off-gas systems cannot process liquid streams. The vendor claims that depth to the water table may also influence lateral migration of processing gases. 

The. Homogeneous Equilibrium Model (HEM) assumes uniform mixing of the phases across the. pipe diameter, no phase slip (mechanical equilibrium), thermal equilibrium between, the..phases and complete vapour/ liquid, equilibrium. "Homogenous" in the context of the HEM refers to the flow in the vent line. 

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