Heat-proving the heater

Heat-proving the heater Optimizing air flow to maximize combustion efficiency. 

If it is variable, set the outside air intake quantity to the winter value. Set the desired temperature up to a maximum, leaving the humidity setting alone. It will be appreciated that as the room temperature rises during the heating test the rh tends to fall. However, since the humidity setting remains unaltered the humidifying system will be called upon to operate until at one condition it is working at peak winter rate. Due to the faster characteristic of heaters, the rh will be found to fall but absolute moisture should be found to steadily rise. The duration of the test is normally about 3 h and final conditions should be held for half an hour to prove the moisture source. 

At a reactor temperature of 300 °C the temperature gradient between reactor centre and edge was about 40 °C and thus not acceptable. Different heat sources had been studied. The best solution proved to be a commercial heating plate used in Ceran top stoves. For libraries of 10 cm diameter a heating plate of 1,2 kW and outer diameter of 17 cm has been used. This heat source heats an air pad, which in turn heats the reactor bottom mounted above the heater (see Fig. 7.9 below). With this setup the temperature gradient has been reduced to <4°C at 300 °C (Fig. 7.3), which was found acceptable for a primary screening technique. 

To prove the possibility of the appearance of a T-S effect L vov [20] modelled the curve J = /(PcOa) for decomposition of single crystals of CaCOa, using the same software as had been used for dehydration reactions. The heat spent for decomposition was assumed to be compensated in part at the expense of heater radiation and thermal conductivity of the excess CO2 present in the reactor. The result of modelling [20] under these conditions (1,000 K) was that the T-S effect could be observed only when the emittance e became lower than... 

Should this prove insufficient, or in cases where Joule s heat cannot be used for some reasons, special heating devices must be employed. Heating devices installed outside the electrolyzer are suitable for open containers and not too high temperatures. Such heaters are installed before the first cell in an arrangement of cascades with a circulation of the electrolyte. The electrolytic cell can also be provided with a steam heating jacket. 

Another type of reactor using a simple injector is a reactor with a dome type cover.In this case, the injector is installed on the bottom plate of the reactor. Figure 11 shows the typical configuration of this type of reactor. In this case the dome is usually heated to a proper temperature by a separate heater to prevent precursor condensation on it. It is rather difficult to expect uniform deposition of a thin film from this asymmetrical gas injection geometry. However, it has actually been proved that good thickness and compositional uniformity are obtained over the 8 wafer surface for Ta O thin films. Figure 12 shows the typical variation in thickness of a Ta O thin film using this reactor. 

Stirrer-heater. Heating is continued at 8S°C until CO evolution ceases, generaUy requiring between 15 and 30 min. It is important to stop heating the reaction mixture as soon as the reaction is complete. Otherwise, a darkening occurs that imparts an undesirable color to the product. Purification to remove this discoloration has proved to be difficult. ... 

Should high temperature be necessary for pyrolysis or to accelerate a reaction, the TLC plate is laid on an aluminium plate, itself lying on an asbestos mat. The layer is then heated with an infra red heater at a distance of 10—20 cm. The so-called quartz surface evaporator (30 cm diameter) has proved most useful in our work (Firm 70). The heating spirals reach temperatures up to 800° C and, like the quartz reflector, are not attacked by the usual acid vapours. Heidbbink [284] has recommended in connection with pyrolysis of the substances, that the chromatograms should be previously placed in a atmosphere of gas, e. g., CI2, Brg NOg. 

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