Pressure and Temperature as Parameters for Controlling Difficult-to-Initiate Combustible Mixtures
A. A. Vasilyev1,2, V. A. Vasilyev1
1Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: ammonia, chemical reaction rate, activation energy, ignition delay, detonation cell, critical initiation energy, nitrogen oxides
Abstract
From the standpoint of explosion safety of flammable mixtures, critical initiation energy data are most important, allowing for an analysis of the relative hazard of various mixtures. Critical energies E* are defined as the minimum initiator energies that ensure ignition and subsequent propagation of combustion and detonation waves in the mixture under study: the lower the E*, the more hazardous the mixture. Traditionally, initiation energy increases significantly when mixtures are diluted with nitrogen (replacing oxygen with air), when moving away from stoichiometry toward concentration limits, and when the initial pressure decreases. The effect of temperature is less clear and has not been studied in sufficient detail. In this paper, the role of the initial mixture temperature is analyzed using the example of a difficult-to-initiate ammonia-oxygen-nitrogen mixture, not only stoichiometric but also lean and rich compositions. The most interesting and important gas-dynamic and kinetic parameters of combustion, explosion, and detonation are presented. A significant difference in the behavior and values of most system parameters was established, indicating a lack of similarity in the chemical processes taking place.
|
