Spray temperature

Porofore concentration does not determine the yield of microspheres as much as the spraying temperature. In particular, the best choice of entry and chamber temperatures are 480 and 220 °C, respectively (Table 2) 28). 

K. Alternatively, one may start with an aqueous ultrasonically dispersed suspension of titania containing HAuCLj, and proceed in the same way,125 but at a spray temperature of 673 K the gold particle size was larger (20 nm). All samples contained Au° and AU2O3 the presence of AU2O3 is surprising after such a temperature of treatment (Section 4.1.1). 

Measurements have been made of the combustion characteristics of an air blast kerosene spray flame and of droplet sizes within the spray boundary of isothermal sprays. Specific techniques were used to measure velocity, temperature, concentration, and droplet size. Velocities measured by laser anemometer in spray flames in some areas are 400% higher than those in isothermal sprays. Temperature profiles are similar to those of gaseous diffusion flames. Gas analyses indicate the formation of intermediate reactants, e.g., CO and Hg, in the cracking process. Rosin-Rammler mean size and size distribution of droplets in isothermal sprays are related to atomizer efficiency and subsequent secondary atomizer/vaporization effects. 

The Effect of Evaporation Conditions on Film Morphology. Two extreme modes of operation were examined evaporation sufficiently rapid to avoid any accumulation of solution on the surface of the KBr disc during the run, and evaporation so mild that liquid accumulated on the disc surface and then evaporated completely. Evaporation control variables included ultrasonic nozzle power, spray temperature, gas flow rate around the disc, oven temperature, and pressure. With accumulation... 

Spray drying involves converting the atomized liquid droplets into dry powders by hot air. This one-step process is capable of making particles of size suitable for inhalation.The particle size and size distribution of the powder can be manipulated by the concentration of the feed solution, the spray temperature, cyclone efficiency, and chemical nature of the feed. ... 

Note of the author The procedure mistakenly recommends the temperatnre (see above) as 60.8 + 9°F. Such a recommendation does not make mnch sense becanse when a deviation is recognized as being of 9°, one cannot pretend that the principal fignre is measnred with a precision of 0.1°. This notation is misleading and confusing. In fact, the recommendation simply suggests to have water spray temperature between 52 and 70°F. The precise figure of 60.8° is superficial and nnnecessary. 

The simulation duration was 40 ms, which is sufficient for most of the spray droplets away from the nozzle to reach the freezing temperature. This is illustrated in Fig. 16.3, which shows the spray at 40 ms in a vertical cross-sectional plane through the nozzle. It can be seen that most of the droplets in the lower half of the spray have already reached the freezing temperature and thus do not break up or coalesce anymore. In fact, as shown in Fig. 16.4, the average temperature of the entire spray has reached the freezing temperature of 291 K after 23 ms, whereas the average spray temperature is 283 K at the end of the simulation. In the same figure, the maximum and minimum drop temperatures are also shown. The maximum... 

Fig. 16.4 Cocoa butter (CB) spray temperatures. The average spray temperature reaches the freezing temperature at 23 ms...

Table IS.3 Recommended nominal size of chippings and target rates of spread binder at spraying temperature for single surface dressings...

The organization determined that a water wash spray temperature of 50°C (122°F) water is sufircient for proper cleaning of the silo. Equipment to cool the hot supply will be installed for safer operation temperatures (see Fig. 3.15 for time vs. temperature to bum human tissue). 

The mechanical characteristics of the bagasse-rubber roofing products are shown in Table 5. Results are for the initial material and following 1,000 hours of weatherometer exposure with cyclic UV, water spray, temperature, and humidity. The tensile strength retention of 97% is considered excellent. 

While weather fastness may be evaluated by exposing the sample to actual outdoor conditions for a prolonged time, accelerated tests are more commonly used in industry. In an accelerated weathering test, the specimens are exposed to cycles of different atmospheric factors such as light, dark, water spray, temperature change and... 

The viscosity of paints and lacquers that are applied by spraying (using for example a spray gun) ranges from 0.04 to 0.12 Pas. For hot sprays that are applied at about 75 °C, the viscosity should be adjusted to about 0.2 Pas at room temperature, so that it will be less than 0.1 Pas at the spraying temperature. The viscosity of hot plastic paints that are sprayed at temperatures around 150 °C should be less than 0.15 Pas. The viscosity of the paint is usually adjusted by addition of solvent. The viscosity of the bulk paint has to be so low for spray operations, since it will substantially increase on evaporation of the solvent during the spraying process (from the time it leaves the spray nozzle to the time when it hits the substrate on which it is to be coated). The increase in viscosity depends on the solvent volatility. 

Spray properties are mostly determined with optical measurement techniques. For the analysis of the droplet diameter Shadowgraphic methods, laser diffraction or Phase Doppler Anemometry (PDA) have been used elsewhere [1, 2, 11, 18]. Droplet velocities can be measured with Shadowgraphy, Particle Image Velocimetry (PIV), or PDA [1, 6, 19]. The determination of the spray temperature is possible with Global Rainbow Thermometry (GRT), Planar Laser Induced Fluorescence (PLIF), and Differential Infrared Thermography (DIT) [20-22]. 

Pressure measurements inside the nozzle capillary are done with a transducer (Wagner, Type P-05). The pressure is measured at three locations in the nozzle capillary, at the nozzle inlet (0 mm), in the middle between nozzle inlet and outlet (9 mm), and at nozzle outlet (18 mm). The measurements last for 10 s and data is recorded in a frequency of 0.1 Hz. Measurements of the spray temperature are... 

Fig. 16.25 Spray temperature in dependence on liquid temperature water steel nozzle,...

---