This article is intended for general familiarization with the combustion process. The main attention will be paid to the diversity of the types of this phenomenon. In particular, we will focus on laminar, turbulent, heterogeneous and other types of combustion. Let's talk separately about the fire.
Introduction
Before we start talking about the main topic of the article, about the types of combustion, let's get acquainted with the definition of the term.
Combustion is a chemical-physical process; a complex phenomenon in the transformation of substances that are the initial participants in an exothermic reaction into a combustion product. Accompanied by a relatively large and intense release of heat. The chemical energy stored in the form of a reserve and residing in the components of the initial mixtures can also be removed and take the form of radiation of heat and/or light. The luminous zone is called the front or the flame.
Combustion chemical reactions most often “move” along a branched-chain type mechanism with a constant progression of self-acceleration. The latter is due to the release of heat in the reaction. Unlike other typesoxidation and reduction reactions, combustion has a large thermal effect, and the activation energy potential causes a large dependence between the reaction rate and temperature. To start the flow of this phenomenon, the presence of an initiator is necessary. Humanity uses the potential of this process and all its types. Long-burning boilers, rocket and car engines, various burners and much more became possible thanks to the study and study of combustion.
Classification
Types of combustion are classified according to different criteria. For example, determining the type of process depends on the speed at which the combustion mixture moves. This difference makes it possible to distinguish between slow (deflagration) and detonation types of combustion. Waves of the first type are capable of propagating at subsonic speeds, and the chemical reaction is maintained by heating the reagents that form the shock wave. Heating, in turn, is responsible for the movement of the wave from the source (its propagation). Slow combustion is laminar and turbulent. Detonation always occurs in a turbulent form. Types of combustion of gases, solids and liquids may have some features of the process. However, this is not an important factor in determining the conditions for their classification.
Flame
Types of combustion and combustion conditions cause many different types of the main object of this article. A person uses them depending on the field of activity,starting from everyday life and ending with the design of space rockets.
Flames are part of the combustion process. However, it is important to remember that against the background of laminar or turbulent fire, smoldering, etc., it is rather a description of a specific area of \u200b\u200bfire. The flame denotes a luminous zone formed during the g-tion. The combustion of natural gas can cause the temperature in the air to rise to two thousand Kelvin.
The flame formed by the combustion of carbon fuel is capable of interacting with electromagnetic fields. This indicates the presence of charged particles. In fact, it has been proven that a flame can have the "behavior" of a weakly ionized plasma. The phenomenon responsible for the generation of ions is called chemionization.
Laminar combustion form
Speaking about the types of combustion, we should mention the concept of laminar g-tion. It is observed in the case of a low flow rate of the mixture. In this way, the candle burns out, and gas stoves work with low fuel consumption. However, the gas in this case is mixed with other substances, which causes a constant movement of the flame front relative to the initial mixtures with specifically specified speed conditions, which, in turn, depends on the temperature, pressure, and reaction reagents. Ignition conditions do not play a role here.
Turbulent combustion form
Turbulent flow is "work" on a mixture that can be defined as turbulent. This reaction is the most difficult to study, and it is also extremely common in practical applications.mechanisms and devices. To date, there is no complete theory of turbulent combustion, which would be fully capable of describing this process.
There are many problems associated with the study of turbulent combustion. For example, the mutual influence of combustion on turbulence and vice versa leads to the fact that the process of combustion can either be intensified due to heat release (in excess of the norm) or decrease. The latter is due to the increase in viscosity with increasing temperature.
Heterogeneous combustion
Another type of combustion of substances is a heterogeneous reaction. These processes are the opposite of homogeneous. Such combustion occurs in a heterogeneous system, that is, a system containing more than 1 phase (an example is gas and liquid). This also includes processes occurring under the conditions of the phase separation boundary. Very often, heterogeneous combustion means a chemical reaction during which its reagent (fuel) evaporates, and the process occurs in different gas phases. An example is the combustion of coal in air. Here, carbon is able to react with oxygen molecules and form carbon monoxide, which, in turn, can burn out in the gas phase and cause the creation of carbon dioxide. There are several types of heterogeneous combustion, which may differ in mechanism.
Special Species
Smoldering is a special form of slow combustion. It is maintained due to the heat released in the reaction of O2 molecules with hot condensed matter. Reactionoccurs on the surface of the reagent and accumulates in the condensation phase.
Solid-phase g-tion are processes occurring in powders of inorganic and organic nature. These phenomena are classified as autowave and exothermic. They are not accompanied by a noticeable release of gases.
Combustion in porous media is characterized by the fact that the medium itself, such as a ceramic matrix, is heated due to the consumption of a certain part of the heat. In turn, the initial mixture is heated by the matrix. Here the product is recovered.
Flameless combustion also exists.
Fire
Fire is often considered a type of combustion.
Fire is a process that a person does not control. It is not a type of combustion, but nevertheless, a fire causes a lot of material damage, and is also extremely dangerous for the life of animals, including humans. In the course of the discovery and study of fire and its properties, the problem of fire became relatively common in people's lives. Among the methods of struggle, preventive measures and direct protection remain the main ones to this day. The last function is performed by rapid response units - fire services. There are many special alerts. You can call these services by dialing 101. In addition to the main number, since 2013 a call to the 112 line has also been added. The most commonly used fire fighting materials are water, sand, a fire extinguisher, tarpaulins and asbestos materials.
