Mixing contact-driven

Figure C3.1.2. Stopped-flow apparatus with motor-driven syringes. Syringe plungers force tire reactants A and B tlirough a mixing chamber into a spectral cell. Kinetic data collection begins when tire effluent syringe plunger is pushed out to contact an activation switch, about a millisecond after tire initiation of mixing. (Adapted from Pilling M J and Seakins P W 1995 Reaction Kinetics (Oxford Oxford University Press)...

The lubrication requirements for single-screw type compressors are not severe, but in oil-flooded rotary units, the oxidizing conditions are extremely severe because fine droplets of oil are mixed intimately with hot compressed air. In some screw-type air compressors, the rotors are gear driven and do not make contact. In others, one rotor drives the other. The heaviest contact loads occur where power is transmitted from the female to the male rotor here the lubricant encounters physical conditions similar to those between mating gear teeth. This arduous combination of circumstances places a great demand on the chemical stability, and lubricating power, of the oil. 

P 21] Solutions of 10 M 4-(l-pyrenyl)butyric acid in ethanol and 10 M sulfuric acid in ethanol were contacted in a micro-mixing tee/micro channel flow configuration at room temperature and at 50 °C [91]. Pressure-driven feed was used. The glass surface of the micro channels was either tuned hydrophobic (by exposure to octadecyltrichlorosilane) or hydrophilic (by wetting with a sulfuric acid/hydrogen peroxide mixture). 

Gypsum may be a potential source of sulfur and sulfuric acid. Some European plants make Portland cement and sulfuric acid from gypsum or anhydrite. In the Muller-Kuhne process, gypsum is mixed with clay and silica in quantities necessary to make cement, along with coke to reduce CaSC>4 to CaO. In equipment similar to that for portland-cement manufacture, the SOi is driven off and converted to sulfuric acid by the contact process,... 

Both the contact efficiency of isobutane and olefin in the zones and the mixing efficiency of acid and hydrocarbon in these reactors are very important. The flow must be such that no isobutane recycle will bypass the reaction zone and no hydrocarbon will bypass the acid-hydrocarbon mixing zone. With this type of unit, a mixer driven by a 40-hp. motor is usually used in each of the zones. A reactor containing five such mixers can normally make 1500 bbl. per day of alkylate. The seven-zone reactors can make 3400 bbl. per day of alkylate. 

The region of the atmosphere that is in direct contact with the surface (on a timescale of 1 h or less) is commonly referred to as the boundary layer or mixed layer. Technically, the boundary layer refers to the region of the atmosphere that is dynamically influenced by the surface (through friction or convection driven by surface heating). Less formally, the boundary layer is used to represent the layer of high pollutant concentrations in source regions. The top of the boundary layer in urban areas is characterized by a sudden decrease in pollutant concentrations and usually by changes in other atmospheric features (water vapor content, thermal structure, and wind speeds). 

The basic unit operation on the pressure driven laminar flow platform is the contacting of at least two liquid streams at a microfluidic channel junction (see Fig. 7). This leads to controlled difflisional mixing at the phase interface, e g. for initiation of a (bio-) chemical reaction [105]. It can also be applied for the lateral focusing of micro-objects like particles or cells in the channel [95]. The required flow focusing channel network consists of one central and two S5munetric side channels, connected at a junction to form a common outlet channel. By varying the ratio of the flow rates, the lateral width of the central streamline within the common outlet channel can be adjusted very accurately. Consequently, micro-objects suspended in the liquid flowing... 

Applications have been developed whereby particles are driven acoustically from one fluid to another, making use of the laminar flow inherent in microfluidic systems. This precludes turbulence so fluids can be in physical contact with minimal mixing. Figure 4 shows the principle. A fluid containing particles is fed in through fluid 1 inlet, and the acoustic force drives the particles from fluid 1 to fluid 2. Fluid 2 can then be withdrawn from outlet 2 with the particles. The ability to wash cells and particles and to move them from one medium to another is a critical element of many forms of analysis and hence an important component of a lab-on-a-chip toolbox. A microfabricated device that works in a manner similar to that shown in Fig. 4 has been developed by Peterson et al. with applications including lipid and erythrocyte separation in... 

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