High-temperature gases

Note 2 Precooling of high temperature gases will be necessary to prevent rapid evaporation of fine droplets. 

SiO or SiS are generated when O2 or H2S are passed over heated Si at about 1500 K in an AI2O3 furnace. The high temperature gases are condensed on a helium cooled copper mirror together with an excess of argon. 

Hanson, R. K. and Kuntz-Falcone, P. A., "Temperature Measurement Technique for High-Temperature Gases Using a Tunable Diode Laser" Applied Optics, 1978, 17, 2477. 

The gas turbine is driven by high-temperature gases from a combustion space, as indicated in Fig. 8.11. The entering air is compressed (supercharged) to a pressure of several bars before combustion. The centrifugal compressor operates on the same shaft as the turbine, and part of the work of the turbine serves to drive the compressor. The unit shown in Fig. 8.11 is a complete power plant, as are Otto and Diesel engines. The gas turbipe is just one part of the assembly and performs the same function as the steam turbine in a steam power plant (Fig. 8.1). 

Disadvantages of water as a coolant are the low boiling temperature and the influence of corrosion. For operation at high temperatures, gases are preferable as... 

At the end of the hydrodynamic phase, the radius of the cavity is equal to the radius of the zone vaporised and melted by the shock wave. The high-pressure and high-temperature gases that fill this cavity then expand adiabatically, pushing back the surrounding rocks, while the shock propagates far ahead. 

Gas turbines efficiency is higher with high temperature gases... 

When solid fuels are introduced into a high temperature furnace, they are heated by the high-temperature gases and walls of the furnace. The moisture in the wastes is first released at about 100°C (212°F) the volatile matter begins to decompose at about 200°C (392°F) and transports to the outside of the particles. The volatile... 

Corrosion of automobile exhaust systems by direct reaction of the metal with high-temperature gases and by condensation of water and absorption of the oxides of sulfur and nitrogen to produce aqueous acid environments... 

Spectroscopic methods depend on the spectral line intensity emitted by the media of interest. Tliese techniques have been used for temperature measurement in high-temperature gases [48]. TTie wavelength involved is generally shorter than those in the infrared band. 

Grey, J. "Probe Measurements in High Temperature Gases and Dense Plasmas." In Measurements in Heat Transfer, edited by E. R. G. Eckert and R. J. Goldstein, 2nd ed. Washington, DC Hemisphere Publishing, 337-374, 1976. 

Temperatures produced when a burning composition is confined are also higher, because high temperature gases and radiant energy cannot escape. 

Drellishak, K. S. Partition functions and thermodynamic properties of high temperature gases, Ph. D. Northwestern Univ. 1%3... 

Deflagrations and detonations are of importance in any study of the hazards associated with flammable materials as they produce high-temperature gases. These gases and the pressures they produce may be harmful to humans and surrounding structures. Their behavior is considered in this and the following sections. 

Phase Transition The chemical potential of gases therefore decreases especially fast with increase in temperature. Their tendency to transform decreases most strongly so that, by comparison to other states, the gaseous state becomes more and more stable. This simply means that, as a result of temperature increase, all other states must eventually transform into the gaseous state. At high temperatures, gases possess the weakest tendency to transform and therefore represent the most stable form of matter. 

It is impossible to prevent some degree of interaction between a metallic component and high-temperature gases, so the common term prevention is not strictly applicable. What is meant is a reduction of the interaction to a very low value. The use of cheap low-grade fuels limits the options of improving the corrosion environment. About 30% of annual corrosion costs may be saved with the use of preventive measures. Three common methods are employed to prevent hot ash corrosion for both coal- and oil-fired furnaces. The use of highly resistant surfaces, the ranoval of the undesired contaminants in the fuels, and the use of additives are the most practical methods in this respect. The first two methods are identical for both types of furnaces. The type of preventive additives used in coal-fired furnaces differs from those utilized in oil-fired furnaces. 

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