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Service diagnosis and repairs
Published in A.C. Bryant, Refrigeration Equipment, 2007
When the symptoms of plant operation indicate a complete blockage, and no temperature difference is obvious at the filter drier, it is natural to suspect that the expansion valve or perhaps a solenoid valve is at fault. The simple expedient of applying a cloth dipped in hot water will determine the presence of moisture. Warming up the expansion valve will melt the ice in the valve and the flow of refrigerant will resume, but only until such time as the temperature at the expansion valve is low enough to form ice and restrict the liquid flow once more. A blowtorch should never be used for this purpose, for obvious reasons.
Critical Condition of AP/HTPB Explosion Induced in Near Flame Area of Fire
Published in Combustion Science and Technology, 2022
Jianbo Yu, Jianping Li, Qi Zhang
Fire temperature generated by different substances combustion is different. For example, the combustion temperature of paper is about 473K, the building fire temperature is about 673K, the alcohol combustion temperature is 873K, the coal combustion temperature is 1100K, and the maximum temperature of gas lamp or alcohol blowtorch is even more than 2000K. Therefore, in order to simulate the change of temperature and explosion process of AP/HTPB solid propellant at different fire temperatures, using the cook-off model in this study, the cook-off simulation of chemical reaction and temperature change in solid propellant with mass fraction of 90% AP and 10% HTPB was carried out at cook-off of 473K, 573K, 600K, 673K, 800K, 1000K, 1200K, 1400K, 1600K, 1800K and 2000K respectively. Figure 5 shows the change of temperature contours during cook-off at the 1200K fire temperature. The fire temperature and the temperature on the outside wall of the AP/HTPB device at the time when explosion is initiated are listed in Table 3.
Seasonal pollution characteristics, source apportionment and health risks of PM2.5-bound polycyclic aromatic hydrocarbons in an industrial city in northwestern China
Published in Human and Ecological Risk Assessment: An International Journal, 2021
Guozhen Zhang, Kejing Ma, Lijuan Sun, Pengfei Liu, Yongli Yue
Factor 4 accounted for 15.9% of the total PAHs. The profiles had high loadings of BkF, BaP and PYR and moderate loadings of FLA and CHR, which exist in the exhaust emissions of diesel engines. Therefore, factor 4 is considered diesel exhaust (Harrison et al. 1996; Guarieiro et al. 2014; Shao et al. 2014). A similar profile, with high loadings of BkF, BaP and BghiP, was observed in PM2.5-bound PAHs in Shanghai (Wang, Lin, et al. 2015). The seasonal contribution of PAHs in autumn and winter was significantly higher than that in spring and summer, mainly because Baiyin is a highly industrialized city. Diesel is the main energy source for large trucks and construction equipment used in industrial activities such as industrial ore transshipment, mining blowtorch use, boiler combustion, sintering, copper smelting and copper convertion, and the poor performance of diesel engines at low temperatures leads to an increase in diesel consumption in autumn and winter. Furthermore, due to the decreased temperatures in autumn and winter, the boundary layer height declines, and meteorological diffusion worsens, which decreases the transfer of PAHs from the particle phase to the gas phase. Overall, the combination of dry climatic conditions and low temperature is more conducive to the accumulation and persistence of PAHs in PM2.5.
Robert Hare's Theory of Galvanism: A Study of Heat and Electricity in Early Nineteenth-Century American Chemistry
Published in Ambix, 2018
More specifically, Hare made three widely cited and discussed instruments: the oxyhydrogen blowtorch (1801), the calorimotor (1819), and the deflagrator (1821).7 The oxyhydrogen blowtorch combined oxygen and hydrogen gases in a portable blowtorch that burned at significantly highly temperatures than other devices: it “melted lime and magnesia,” and allowed for the study of different types of chemical reactions, as these newly liquefied substances could be combined with other materials.8 (It also introduced Hare to the nastiness of priority disputes and charges of provincialism when in 1819 Cambridge University professor Edward Clarke claimed to have invented the blowtorch.)9 In contrast to the blowtorch, Hare modified the voltaic pile (or battery) to create the calorimotor and deflagrator, investigative apparatuses designed to illuminate the relationship between heat and electricity. As Joule wrote, “There are few facts in science more interesting than those which establish a connexion between heat and electricity. Their value, indeed, cannot be estimated rightly, until we obtain a complete knowledge of the grand agents upon which they shed so much light.”10