Radiant heaters

The flow field created within the protection zone depends mainly on the density difference between supply air and room air (Fig. 10.90). With vertical flow the supply air should be isothermal or cooler than ambient air. If it were warmer, the extension of the controlled flow would be reduced due to buoyancy effects, resulting in the supply air not reaching the operator s breathing zone. As the. supply air cannot be used for heating, the operator s thermal comfort should be maintained, preferably with radiant heaters in cold environments. If the supply air temperature is lower than the room air, the denser supply air accelerates down to the operator, and for continuity reasons the supply flow contracts. Excessive temperature differences result in a reduced controlled flow area with thermal discomfort, and should only be used in special cases. 

Environmentally Responsive Work-stations (ERWs). Workers in open-office areas have direct, individual control over both the temperature and air-flow. Radiant heaters and vents are built directly into their furniture and are controlled by a panel on their desks, which also provides direct control of task lighting and of white noise levels (to mask out nearby noises). A motion sensor in each ERW turns it off when the worker leaves the space, and brings it back on when he or she returns. 

Overhead radiant heaters 3.1-41 850-900 Flueless High level or ceiling mounted... 

Immersion heaters. An immersion heater consisting of a radiant heater encased in a silica sheath, is useful for the direct heating of most acids and other liquids (except hydrofluoric acid and concentrated caustic alkalis). Infrared radiation passes through the silica sheath with little absorption, so that a large proportion of heat is transferred to the liquid by radiation. The heater is almost unaffected by violent thermal shock due to the low coefficient of thermal expansion of the silica. 

A flat-bottomed cylindrical vessel, 2 m in diameter, containing boiling water at 373 K, is mounted on a cylindrical section of insulating material, l m deep and 2 m ID at the base of which is a radiant heater, also 2 m in diameter, with a surface temperature of 1500 K. If the vessel base and the heater surfaces may be regarded as black bodies and conduction though the insulation is negligible, what is the rate of radiant heat transfer to the vessel How would this be affected if the insulation were removed so that the system was open to the surroundings at 290 K ... 

Deglor [Detoxification and glassification of residues] A process for vitrifying wastes, such as fly ash, by heating to 1,400°C in an electric furnace. Some of the heat is provided by radiant heaters, some by passage of electricity through the melt. Developed and piloted by ABB in Switzerland from the 1980s, commercialized in Japan in 1996. 

ISO 11907-4 1998 Plastics - Smoke generation - Determination of the corrosivity of fire effluents - Part 4 Dynamic decomposition method using a conical radiant heater... 

Figure 2. Schematic of valve manifold assembly, microreactor, radiant heater, and high pressure assembly depicting vacuum and high pressure operation.

In a house used for investigating indoor air pollution that had natural gas fueled applicances (a convective heater, a radiant heater, and a range with four burners), both the surface reaction of N02 and the direct combustion emissions contributed significantly to the measured indoor HONO. When an appliance was operational, the contribution of direct emissions was the more important source (Spicer et al., 1993). 

These latter pieces of equipment may be called bulb-to-bulb distillation units. A commercial form is the Kugelrohr apparatus (Aldrich). The material to be distilled is placed in a suitably sized round-bottomed flask (one-third full) and attached to the receiver flask train (Fig. 2.120). This arrangement is connected to a horizontal drive shaft which enables the bulbs to be gently rocked by a safe air-or vacuum-operated oscillating motor, which speeds distillation and prevents bumping. The distillation flask may be heated up to 225 °C in an i.r.-radiant heater. The hollow drive shaft may be connected to a vacuum pumping system and the apparatus operates down to 1 x 10 5mmHg. 

Finally release the press and remove the die body (A) and the upper steel pellet from the face of the disc and then remove the disc itself with tweezers (the disc should never be handled with the fingers), and mount it in the specially designed holder. These latter operations are best conducted under a radiant heater. The disc holder is located in position in the sample beam path of the spectrophotometer if required a blank potassium bromide disc, similarly prepared, is introduced into the reference beam path. 

Providing that care has been taken in the disc preparation the final disc should be slightly opaque due to the presence of the sample (the blank disc should be transparent). Should the disc show a number of white spots, it is probable that the mixture has been unevenly ground. If the disc shows a tendency to flake, then excessive grinding of the powder is indicated. If after being removed from the die the disc becomes cloudy this is indicative of the uptake of water to avoid this difficulty it is necessary to ensure that the die is evacuated for a sufficiently long period and that the removal of the disc from the die is carried out under a radiant heater. 

The cells are emptied by attachment of one of the ports to a vacuum line incorporating a suitable trapping system, cleaned by several rinses with neat solvent and then with dichloromethane. Solvent is removed by a short period of suction and the cell is finally dried under a radiant heater and stored in a desiccator. Prolonged passage of air through the cell must be avoided otherwise fogging of the cell windows from atmospheric moisture may occur. 

Wafers are transported, in Inconel trays, on a moving belt through a reactant gas flow while being heated from below by quartz radiant heaters. Reactant gases are introduced through a unique disperser head design. Details of the gas introduction are shown in Figure 2. 

Barometric pressure is detected by bellows against a reference, which is provided by a sealed-in vacuum. Exposing the instrument to direct sunlight, radiant heaters, or to direct drafts, such as from open windows or doors, should be avoided. Air temperature is measured with a platinum resistance thermometer. It is placed in a long tube that has been painted white on the outside to reflect solar radiation. A small blower pulls ambient air into the tube and across the thermometer. 

The test apparatus consists of a 0.914 x 0.610 x 0.914 m enclosure (see Figure 14.12). A radiant heater with a diameter of 76 mm is used to provide a constant radiant heat flux of 25kW/m2 to the specimen surface. The specimen measures 76 x 76 mm and is oriented vertically. 

Both compact and expanded wallcoverings can exhibit blistering at the embossing stage with the former this is attributable to residues of solvents from printing inks and lacquers, which may evaporate explosively when exposed to the radiant heaters (in bad instances, solvent vapours may accumulate and... 

Infrared radiant heaters provide an increase in the efficiency of heat transfer, exceeding that of oven heaters. Infrared heaters are useful in rapid heating of localized areas of a substrate. However, the rate of heat transfer is dependent, to some extent, on the color of the workpiece. The darker the part, the more rapid the heating.19 Radiant heaters are also more expensive and maintenance-dependent than air circulating ovens. 

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