Combustible characteristic constant

Table 9-1 Combustible Characteristic Constant for the Swift-Epstein Equation1...

I he experimental investigation of the combustion of sprays is complicated by the many variables involved. Common sprays are composed of a wide range of droplet sizes distributed unevenly in the spray cone. Turbulence of the air and the relative motion of the droplets through the air are poorly defined. The burning of an isolated droplet itself presents a difficult problem, although much progress has been made in this field in the past few years. To study the effect of any single variable on the combustion characteristics of a spray, other variables must be held constant. This paper reviews those fields of effort in which work has been done to simplify the complex physical aspects of this problem. 

APIRP 45 has three main objectives—the synthesis, purification, and properties of hydrocarbons their engine combustion characteristics and hydrocarbons for superpurification and physical-constants measurement. 

The study on the spray combustion characteristics of 10% CPO blended with diesel fuel was conducted in a constant-volume combustion chamber. With the fixed experimental conditions such as spray ambient pressure and injection events, the effects of 10% CPO diesel at the injection line pressure of 100 MPa on spray combustion and flame stmcture were investigated using a photo diode and ICCD camera. Two-color method was also employed to predict combustion flame temperatures and KL factors. 

Design Methods for Calciners In indirect-heated calciners, heat transfer is primarily by radiation from the cyhnder wall to the solids bed. The thermal efficiency ranges from 30 to 65 percent. By utilization of the furnace exhaust gases for preheated combustion air, steam produc tion, or heat for other process steps, the thermal efficiency can be increased considerably. The limiting factors in heat transmission he in the conductivity and radiation constants of the shell metal and solids bed. If the characteristics of these are known, equipment may be accurately sized by employing the Stefan-Boltzmann radiation equation. Apparent heat-transfer coefficients will range from 17 J/(m s K) in low-temperature operations to 8.5 J/(m s K) in high-temperature processes. 

In the so-called "wrinkled flame regime," the "turbulent flame speed" was expected to be controlled by a characteristic value of the turbulent fluctuations of velocity u rather than by chemistry and molecular diffusivities. Shchelkin [2] was the first to propose the law St/Sl= (1 + A u /Si) ), where A is a universal constant and Sl the laminar flame velocity of propagation. For the other limiting regime, called "distributed combustion," Summerfield [4] inferred that if the turbulent diffusivity simply replaces the molecular one, then the turbulent flame speed is proportional to the laminar flame speed but multiplied by the square root of the turbulence Reynolds number Re. ... 

The photodecomposition and thermodecomposition of nitromethane have been extensively studied as model systems in combustion, explosion and atmosphere pollution processes[l]. On another hand, nitromethane was selected as a model solvent in experiments aimed at examining non hydrogen-bonded solvent effects in a general acid-base theory of organic molecules [2.3]. This selection is based on the electronic and structural characteristics of nitromethane that has a high dielectric constant, and at the same time cannot form hydrogen bonds with solute molecules. 

In the fluidized bed gasifier, crushed coal is introduced into a fluidized bed of char together with oxygen or air and steam. Coal undergoes drying, devolatilization, gasification and combustion at essentially constant temperature of about 1000 C because of the rapid mixing characteristics of fluidized beds. 

F. Maslonlsa, Determination of the Laminar Combustion Velocity of Gas Mixtures from Values of Explosion Times Found in Determination of Explosion Characteristics , Petrochemia 18 (3), 99-103 (1978) CA 90,57473 (1979) [Good agreement between expti and calcd data is reported for vinyl ethylene using the equation 7 Ty — a constant, where 7 is the laminar combustion vel and Tv is the expln time (or time to expin )]... 

It is difficult to see in the characteristics and properties of the three earths of Becher any substantial improvement on the tria prima of Paracelsus and his successors, other than the avoidance of the use of the three names which were in common use in two different meanings. For the three principles of that name, as chemists of that school took great pains constantly to explain, were not the same as the common substances so named. Nevertheless, the new name terra pinguis or fatty earth for the older sulphur, as the substance which departs in combustion, certainly gave the stimulus which incited Stahl and his followers to develop the influential phlogistic hypothesis and Becher thus played a not unimportant part in the history of chemical theory. 

For some reactions the rate constant kj can be very large, leading potentially to very rapid transients in the species concentrations (e.g., [A]). Of course, other species may be governed by reactions that have relatively slow rates. Chemical kinetics, especially for systems like combustion, is characterized by enormous disparities in the characteristic time scales for the response of different species. In a flame, for example, the characteristic time scales for free-radical species (e.g., H atoms) are extremely short, while the characteristic time scales for other species (e.g., NO) are quite long. It is this huge time-scale disparity that leads to a numerical (computational) property called stiffness. 

Figure 15.1 shows families of solutions to the model problem for different values of X and different initial conditions. The family of solutions can be thought of as a manifold of solutions, all of which, regardless of the initial condition, tend toward the slowly varying y = t2 + 1 solution. In chemical kinetics, the behavior illustrated in Fig. 15.1 is exhibited by certain species, like the free radicals. After initial very rapid transients such as a combustion ignition, the free-radical concentrations often vary slowly, with their behavior controlled by steady-state or partial-equilibrium conditions. The faster the characteristic scales, the more rapidly the fast-time-constant species come into equilibrium with the major species (i.e., approach a slowly varying solution). 

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