Principles Of Heat And Mass Transfer 7th Edition Solution Manual ((NEW))
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From the TG data it can be seen that NG evaporates more than diazomethane. The mass of NG decreases because of the evaporation at the rate of 0.73% for a heating rate of 10 °C/min. With a heating rate of 20 °C/min, the mass of the evaporate of NG decreases by 4.6%. The highest mass loss was observed at a heating rate of 40 °C/min [6]. Evaporation of the amide group of NG took place at higher temperatures. The vapor pressure of NG increases with temperature, which also enhances the vaporization of the compounds. The vapors of NG and DMN were previously found to evaporate in an almost linear relationship with the heating rate [6, 24].
To facilitate the determination of the thermally induced volatilization of NG and DMN, a comparative method was proposed, which combines the existing data from the TGA, DLS, and function of the gas chromatograph for calibration compounds estimated from the literature [48, 49, 50, 51]. This method is suitable for determining the vapor pressure of the compounds of an unknown nature. The role of the heating rate is limited to improving the accuracy of the results. Earlier, we used the TG data to determine the vapor pressure of NG, DMN, DNN, and DMNP [32]. The vapor pressure data presented here in Table 4 are reliable, since the volatile products from the thermal decomposition of the compounds were analyzed, which made it possible to exclude the influence of the humidity and temperature of the material on the vapor pressure. These data are consistent with the findings of the previous study [6]. The sums are in agreement with the results previously obtained for NG and DMN obtained by the infrared method [52].
In the DLS method, the sample is placed in a glass ampoule and weighed. The ampoule is then sealed with an internal thermocouple. The mass of the sample should be constant. It should be noted that during DLS the sample is heated in an atmosphere free of volatile compounds (in order to avoid losses to the atmosphere or the conduction of heat by volatile components [53]). d2c66b5586