Residence time meaning

The StabUity or persistence of a poUutant in the atmosphere depends on the poUutant s atmospheric residence time. Mean residence times and principal atmospheric sinks for a variety of species are given in Table 2. Species like SO2, (NO and NO2), and coarse particles have lifetimes less than... 

Residence time, mean The average time spent by the molecules in a vessel. Mathematically, it is the first moment of the effluent concentration from a vessel with impulse input, or ... 

Also assume that the pilot- and full-scale vessels will operate at the same temperature. This means that A(o-out,bout, . )and/i/2 will be the same for the two vessels and that Equation (1.49) will have the same solution for provided that 7 is held constant during scaleup. Scaling with a constant value for the mean residence time is standard practice for reactors. If the scaleup succeeds in maintaining the CSTR-like environment, the large and small reactors will behave identically with respect to the reaction. Constant residence time means that the system inventory, pV, should also scale as S. The inventory scaleup factor is defined as... 

Residence time, mean, is the average time spent by all molecules in the... 

Mean residence time, mean dissolution time, mean absorption time... 

Short residence time means that this desired product is continuously removed from the reactor before any over oxidation can occur. 

Mean Residence Time Mean residence time (MRT) is the average time for all dmg molecules to exist in the body. MRT is another measure of... 

The stability or persistence of a pollutant in the atmosphere depends on the pollutant s atmospheric residence time. Mean residence times and principal atmospheric sinks for a variety of species are given in Table 2. Species like S02, NO (NO and N02), and coarse particles have lifetimes less than a day thus important environmental impacts from these as primary pollutants are usually within close proximity to the emissions sources. In the presence of high concentrations of NO, the residence time of 03 is on the order of seconds to hours. In the relatively nonpolluted environment of the free troposphere, from approximately 1500 m to the top of the troposphere ( 12 km), the 90-day lifetime applies. Consequently, given the right conditions, 03 could have important environmental impact far downwind from its source. In fact, concentrations of 03 near the NAAQS limit have been transported from the Gulf Coast of the United States to the Northeast over a several-day period (9). 

There is a range of sources for atmospheric COS and these seem fairly evenly balanced (see Figure 17). This coupled with its long residence time mean that it has a constant concentration throughout the atmosphere. It is typically found at concentrations close to 500 ppt... 

Mean time between two jump attempts, residence time Mean exchange time between two adjacent molecules Average time that a particle which is foimd at site i, has already spent in the single-file system... 

Similarity in residence times means equal residence times in the small-scale and large-scale equipment. This is a requirement that is often not fulfilled in extrusion processes. When using an extruder as a reactor, however, particular attention should be given to this point. 

Modified residence time (mean residence time related to mass of catalyst or solid reactant) kg s m ... 

As is normal in such cases, as soon as a result appears promising, the demands increase Thus the 650 kg/h achieved were not acceptably high, and since the model we had built was a 1 6 scale model and the capacity required in full scale was 24 t/h, we were asked to prove that the unit would perform as well with 4 t/h. The scale factor of 1 6 was based on the cross section of the upper elutriator tube, in which velocities similar to those in the full scale version were maintained. Since we had not really thought of how the dispersing device was to be scaled up (loading ratio , residence time , mean transport distance ), all we could do was again set the system up and run it ... 

Since the F factor is generally about 2-5, the residence time of fluid element is then reduced by 4-25 folds. The shorter residence time means the faster the fluid circulation and quicker the interfacial mass renewal. The circulations of the fluid element without Marangoni convection and with Marangoni convection are shown schematically in Fig. 8.24. It is shown that by the help of Marangoni convection, the path of circulation is smaller (I < L) and the residence time is shorten (f < T) because the renewal of interfacial concentration is faster. Nevertheless, the I and t are statistic average length and time, which are still unknown. 

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