Coating, annular

Uncertainty in Correcting Atmospheric Data. The level of uncertainty with this method can be illustrated with results from atmospheric trials (57). After 4- to 6-h samples were collected in Southern California with CO -glycerol coated annular denuders during a late fall period, the N03" recovered... 

Figure 2. Vanadium pentoxide coated annular thermodenuder for the determination of NH3. (Reproduced with permission from reference 74. Copyright 1989 Pergamon Press.)...

For determination of Pb(C2H5)4 and other tetraalkyllead compounds in air by a diffusion technique employing an ICl-coated annular denuder, see [520] see also [442]. For determination of gaseous lead in exhaust gas by microwave-induced air-plasma emission spectrometry, see [532]. Methods for determination of Pb(C2H5)4 in hazardous waste incinerator flue gas were developed, based on gas chromatographic separation and detection by flame ionization or mass spectrometry [565]. 

The fluid dehvery in an air-spray system can be pressure or suction fed. In a pressure-fed system, the fluid is brought to the atomizer under positive pressure generated with an external pump, a gas pressure over the coating material in a tank, or an elevation head. In a suction system, the annular flow of air around the fluid tip generates sufficient vacuum to aspirate the coating material from a container through a fluid tube and into the air stream. In this case, the paint supply is normally located in a small cup attached to the spray device to keep the elevation differential and frictional pressure drop in the fluid-supply tube small. 

When metal inserts require hermetic sealing, consider coating them with a flexible elastomer such as an RTV rubber, polyurethane, or epoxy system. A second method is to design an annular space or reservoir at one end of the insert from which to dispense the flexible elastomers to effectively create a hermetic seal. Flexible sealants are also used to compensate for differences in the thermal coefficient of expansion between metal and plastic. 

Fan Spray 100-1000 High-pressure painting/coat ing, Annular combustors Good atomization, Narrow elliptical spray pattern High supply pressure... 

Fan spray atomizers have been widely used in the spray coating industry (Fig. 2.5), in some small annular gas turbine combustors, and in other special applications that require a narrow elliptical spray pattern rather than the normal circular pattern. In particular, fan spray atomizers are ideal for small annular combustors because they can produce a good lateral spread of fuel, allowing to minimize the number of injection ports. 

Design Parameters. With the assumption that the walls of the annulus are coated with a perfect collector for HN03, the efficiency of an annular denuder can be calculated (53) ... 

The measurement of FPN from the N03 recovered from a backup Teflon-nylon or nylon filter with the ADM is subject to some of the same potential sources of error as with the DDM. No loss of FPN passing through the annular denuder is expected on the basis of particle-loss measurements (55). Although HONO is efficiently removed ahead of the filter or filters, nearly all of the PAN would reach the nylon filter. Retention of PAN on nylon filters has been reported to be insignificant. Thus, relatively little error in FPN is expected with the ADM and CO -glycerol coated denuders. 

The efficiency of HN03 collection with a single annular denuder should be confirmed by each user with a known source of HN03, regardless of denuder coating used. On the basis of laboratory studies, Ferm and Sjodin (42) reported a technique that can be used to correct simultaneously for penetration of HN03 through the first of tandem denuders as well as for artifact N03" due to atmospheric species retained with low efficiency. 

Because of the labor-intensive nature of annular denuder sampling, alternative techniques deserve further scrutiny. The DDM, relying on Teflon-nylon filter packs (or nylon filters alone) and an anodized aluminum annular denuder ahead of one of a pair of modified dichotomous samplers (46), merits evaluation for the influence of potential interferents (e.g., HONO). The DDM with NaCl-coated denuders would probably be nearly free of interference from HONO, but this conclusion requires evaluation. Because coarse particulate N03 must be excluded to achieve improved accuracy for HN03 and fine particulate N03, supplementary samplers are needed to obtain improved estimates of total as well as coarse particulate... 

Applying fins coated with titania is an effective way to enhance the formaldehyde removal performance (Mo et al., 2008b). In order to compare the formaldehyde removal performance of annular photocatalytic reactors with and without the aforementioned fins, the PCO reactors without and with the fins operated in a sealed stainless steel chamber with formaldehyde in its air, respectively. Figure 4.15 shows the chamber formaldehyde concentration decay curves (a) an annular PCO reactor without fins, (b) an annular PCO reactor with six fins. It can be seen that the reactor with fins is more efficient than that without. The reason and the analysis are presented by Mo et al. (2008b) in detail. 

Eq. (8) shows the dependency of the critical thickness with mass m, radius rp, and velocity v0 of the inert particles coated with plastic and with the viscosity of the material that coats the sand fi. For the experimental conditions (total mass of sand, 30 g mass of plastic in the feed, 1 g sand particle diameter, between 0.6 and 1.2 mm sand density 2600 kg m-3, average velocity of the particles in the annular zones, 0.25ms-1 [7], the critical thickness predicted by Eq. (8) is 250 p,m. In this calculation, the viscosity of the plastic has been taken at its fusion temperature, 16 poises, because it is in the initial step of fusion when the stickiness of the plastic is maximum point. 

Annular flow is encountered in pipe extrusion dies, wire coating dies and film blowing dies. In the problem under consideration, a Power law fluid is flowing through an annular gap between two coaxial cylinders of radii kR and R, with k < 1 as schematically depicted in Fig. 5.15. The maximum in the velocity profile is located at r = j3R, where / is a constant to be determined. Due to the geometrical characteristics and ignoring entrance effects, the flow is unidirectional, i.e., u = (ur,ue,uz) = (0,0, wz(r)). 

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