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Frank-Kamenetskii Theory
In combustion, Frank-Kamenetskii theory explains the Thermal runaway, thermal explosion of a homogeneous mixture of reactants, kept inside a closed vessel with constant temperature walls. It is named after a Russian scientist David A. Frank-Kamenetskii, who along with Nikolay Semyonov, Nikolay Semenov developed the theory in the 1930s. Problem description Sources: Consider a vessel maintained at a constant temperature T_o, containing a homogeneous reacting mixture. Let the characteristic size of the vessel be a. Since the mixture is homogeneous, the density \rho is constant. During the initial period of Combustion, ignition, the consumption of reactant concentration is negligible (see t_f and t_e below), thus the explosion is governed only by the energy equation. Assuming a one-step global reaction \text + \text \rightarrow \text + q, where q is the amount of heat released per unit mass of fuel consumed, and a reaction rate governed by Arrhenius law, the energy equation becomes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substances undergoing combustion vaporize, but when it does, a flame is a characteristic indicator of the reaction. While the activation energy must be overcome to initiate combustion (e.g., using a lit match to light a fire), the heat from a flame may provide enough energy to make the reaction self-sustaining. Combustion is often a complicated sequence of elementary radical reactions. Solid fuels, such as wood and coal, first undergo endothermic pyrolysis to produce gaseous fuels whose combustion then supplies the heat required to produce more of them. Combustion is often hot enough that incandescent light in the form of either glowing or a flame is produced. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
