High heat of combustion

It is a spontaneously flammable gas having an extremely high heat of combustion. 

A third screening smoke-type is white phosphoms [7723-14-0] (WP), P (see Phosphorus and THE phosphides), which reacts spontaneously with air and water vapor to produce a dense cloud of phosphoms pentoxide [1314-56-3]. An effective screen is obtained as the P2O5 hydrolyzes to form droplets of dilute phosphoric acid aerosol. WP produces smoke in great quantity, but it has certain disadvantages. Because WP has such a high heat of combustion, the smoke it produces from bulk-filled munitions has a tendency to rise in pillarlike mass. This behavior too often nullifies the screening effect, particularly in stiU air. Also, WP is very brittle, and the exploding munitions in which it is used break it into very small particles that bum rapidly. 

The solid fuel composition is, therefore, concerned with the pursuit of higher I p involving both flame temperature elevation and molecular weight reduction. Concomitantly, it is desirable to have high heat of combustion, which also dictates the combustion chamber temperature. The actual composition is, therefore, set on the basis of the energy quantum inherent in the various constituents. 

C06-0057. Acetylene (C2 H2) Is used In welding torches because it has a high heat of combustion. When 1.00 g of acetylene bums completely in excess O2 gas at constant volume, it releases 48.2 kJ of energy, (a) What Is the balanced chemical equation for this reaction (b) What is the molar energy of combustion of acetylene (c) How much energy is released per mole of O2 consumed ... 

Several of the combustion-related properties of hydrogen in air, such as its wide flammability limits (4-75 vol%), wide detonation range (20-65 vol%), very low spark ignition energy (0.02 mJ), high heat of combustion (121 kJ/g) and high flame temperature (2050°C) combine to emphasise the high fire-related hazards of the... 

The density of the elements is also an important parameter with regard to obtaining a high heat of combustion in a reactor of limited volume. The volumetric heat of combustion (kj m" ) shows differences compared to the mass-based heat of combustion (kj kg" ). For example, the volumetric heat of combustion of Zr is the highest of the fuel elements and that of Ti is the next highest when oxidized by oxygen gas. 

Beryllium (Be) is a gray-colored brittle metal. Be bums in air to form BeO or B03N2, releasing a high heat of combustion. However, Be and its compounds are known as highly toxic materials. 

Theoretical Basis. Heterogeneous fuels are suspensions of finely divided metals or metal compounds in appropriate liquid fuels and represent one approach for using the low molecular weight metals (and certain of their derivatives) that have high heats of combustion with typical rocket oxidizers. The theoretical basis for the interest in metal-containing fuels is discussed in the introduction. Glassman (16) showed that all... 

The combustion temperature of metallized pyrolants is high due to the high heat of combustion of metal particles, and the molecular mass of the combustion pro-... 

The heat of explosion Q can be increased by adding to the explosive composition another fuel which has a high heat of combustion AHc. Such fuels can be found with the lighter elements of the periodic table as shown in Table 5.17. 

In the United States the practice is to use the high heat of combustion in boiler combustion calculations. In Europe the low heal value is used. 

Because boranes have high heats of combustion, they were once considered as potential lightweight, high-energy rocket fuels, but they proved to be too expensive to prepare. Nevertheless, boranes continue to be of interest to chemists because of their unusual structures and bonding. 

The two most common reactions of sigma-covalently bonded organometallic compounds are oxidation and hydrolysis (see Chapter 1). These compounds have very high heats of combustion because of the stabilities of their oxidation products, which consist of metal oxide, water, and carbon dioxide, as shown by the following reaction for the oxidation of diethyl zinc ... 

Fig. 6 WHB with staged wastewater injection 02 oxygen flow, W, high heat of combustion wastewater, WM low heat of combustion wastewater, CW cooling water...

These are not frequently used monomers. There exists a clear connection between the strain of various members in the series of cyclic hydrocarbon molecules and their heats of combustion (see Table 1). The high heats of combustion of the first members are the consequence of the C—C bond angle deviation from 109°28. In cyclohexane, the most stable cycloalkane which can exist in the chair conformation, the C—C bond angle value deviates very little from that observed in unstrained compounds. Cyclopentane exhibits the smallest deviation of the C—C bond angle from the theoretical value. Its higher heat of combustion is due to steric interactions of pairs of neighbouring hydrogen atoms. A similar situation is observed with cycloheptane [12a]. 

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