Gas and electric stoves
gas stoves
The combustion of gas that occurs in the stove is a chemical reaction of the combination of methane with oxygen. And the science of the structure of matter describes the process of oxidation as follows. The methane molecule is closely spaced nuclei of a carbon atom and four hydrogen atoms, with its own electron cloud. The addition of oxygen to methane means the appearance of one nucleus of an oxygen atom near the mentioned five nuclei and the unification of the electron clouds of the initial substances (or rather, their molecules and atoms) into a common electron cloud. The system of nuclei and electrons obtained during oxidation has a lower internal energy than that of the two initial substances. Therefore, during oxidation, heat is released.
One of the characteristics of the combustion process of any gas is the speed of flame propagation in the gas. Its value depends on the heat capacity of the gas, the amount of heat released during combustion, and a number of other factors. If, for example, the rate of outflow of combustible gas from the burner exceeds the rate of propagation of the flame, then the flame may move away from the stove and, in the end, go out, since the combustible gas, diverging in all directions, will have a low concentration away from the stove.
Electric stoves
Today, electric stoves are gaining popularity at an incredible rate. After all, electric stoves are quite economical, many models come with an A class of energy consumption, and they are also fireproof. A large selection of electric stoves in the Unishop.by universal catalog at very competitive prices. At an electric stove, a fuel element, unlike a gas one, should in no case be combined with oxygen. Otherwise, the heating coil will burn out. This means that for the heater coil it is necessary to choose a metal that is resistant to oxidation even at elevated temperatures.
The required resistance of the heating element is easy to estimate based on the Joule-Lenz law. It is equal to the ratio of the square of the voltage to the power of the heater. And it turns out that this resistance is too great to make an element of well-conductive metals. Therefore, special alloys are used that do not oxidize when heated in air and have a high (for metals) resistivity.
In connection with the foregoing, let us dwell on the question, what determines the resistance of a metal to an electric current? There are a lot of free electrons in a metal. One has only to apply voltage, and they will rush through the metal, creating an electric current. Their run can be hindered by interaction with the ions that make up the crystal lattice of the metal (ions, not atoms, since some of the electrons that were part of the atoms have become free). However, one must keep in mind that an electron is not just a charged particle of very small size. An electron has the properties of both a particle and a wave. In some phenomena, the properties of an electron inherent in a particle are more pronounced, in others – inherent in a wave. The resistance of metals to electric current belongs to the latter. That is, we are dealing with the interaction of a crystal lattice with an electron wave, and not with the collision of electrons (particles) with ions (particles) of the lattice. And a wave can pass through an ideally regular crystal lattice, practically without being absorbed or scattered by it.
The resistance of metals increases with temperature. When determining the resistance required for a fuel element, it must be taken into account that this resistance must have the required value at its operating temperature. At room temperature, it is much lower, therefore, the starting current (until the coil heats up) is much larger than the operating current. The electrical wiring from the power board to the plate must be able to withstand these large inrush currents.