Residence guided flow

P 40] A similar protocol was made for the 2x2 multi-reaction mode. Using a special script to guide flow over 700 or 1000 s, depending on the individual reaction, a residence time of 120 s was achieved for each reaction. The other features of the protocol are identical with ]P 39]. 

Residence Time Distribution for Guided Flow in Channels... 

The influence of channels, i.e. flow-guiding internal structures, also accounts for the overall residence time distribution in the square. This will be demonstrated by the observation of particles emitted at the structure inlet. The path of such an... 

The same calculation was executed for a structure with the same outer dimensions but without flow-guiding internal structures, i.e. channels (Figure 4.96). The particles were emitted at the same positions as before but they did not follow the same routes as before because no guiding elements were present. In fact some parts of the square were not even reached by these particles, showing that the residence time in these areas is theoretically infinite. 

Obviously the characteristic distribution of the structured square, as expected, is much closer to the ideal plug flow reactor than to the laminar flow reactor. This desired behavior is a result of the channel walls, which are flow-guiding elements and pressure resistors to the flow at the same time. Two of the streamlines are projecting with a residence time of more than 0.4 s. These are the streamlines passing the area close to the wall of the distribution area, which introduces a larger resistance to these particles due to wall friction. This could, for example, be accounted for by a different channel width between the near wall channels and the central channels. 

Argon or helium at a pressure of 100 Torr is bubbled through JP-10, generating a reactant flow that is 5% JP-10. The reactant mix is metered into the flow-tube through a leak valve where the pressure drops to a few tori-celli. The flow properties of the reactor have been discussed in detail previously. Briefly, the total pressure in the heated zone of the flow-tube varies from 3 to 1.2 Torr over the temperature range from 300 to 1700 K, while the residence time drops from 4.5 to 1.5 ms. The flow-tube exhaust is dumped into a temperature-stabilized ( 200 °C) ionization source where the pressure is 1 Torr. The analyte molecules can be ionized either by EI or by methane Cl. The ions are then mass analyzed by the tandem guided ion-beam quadrupole mass spectrometer described in the above-referenced publications. 

With other short-time dryers, the product motion is in the form of a vortex flow driven by the hot gas which increases the residence time. This can be achieved with hot gas jets tangentially entering the drying area (vortex flow dryers such as helical flow tube with nozzles and annular flow dryer [5.77]), with displacement internals including gas guide vanes (spiral tube pneumatic dryer [5.78, 5.79]), or with tapered inclined perforated screen (cyclone dryer [5.80]). The convex dryer [5.81, 5.82] combines the functions of drying and classifying. With a... 

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