Heater

Halogen heater.

Image of an electric heater by forced convection

The heater or stove is an appliance that provides a continuous rapid flow of hot air to a room or container through a radiator that generates a heat source and a fan that quickly heats the air and transmits it to the place where it is.

There are different types of heaters, such as electric, gas, solar, gasoline, wood or coal.

The electric heater

An electric heater is a device that produces heat energy from electricity. The most widespread type is the "resistive" electric heater, where the generation of heat is due to the Joule Effect.

Other lesser-known electric heaters are "thermoelectrics", which exchange heat through a more complicated system: the Peltier Effect.

It is used to obtain heat comfortably and quickly.

Among the best-known applications of the Joule effect are the elements of stoves to heat the environment, the filaments of hair dryers, the resistances of irons for clothes, the stoves or stoves of the kitchens, the resistors in toasters and industrial ovens, heaters in kettles and fermenters, wires to prevent freezing in refrigerators and fogging on car rear windows, heaters in fish tanks and greenhouses, and many, many more applications.

Operation

Resistive heaters generate heat proportional to the square of the electrical current that flows through them. This relationship is known as Joule's Law.

Conducting materials (metals and alloys) are not "perfect conductors", but have an electrical resistivity to the passage of electrical current. The energy lost in conduction is dissipated as heat. The resistivity is a disadvantage when it is required to transport electrical energy, but it is desirable when it is sought to generate heat.

The microscopic explanation, but "classical", is that when there is a potential difference between the ends of a conducting wire, there is an electric field inside the material. This field accelerates the free charges of the material, until they collide (slowing down) with one of the fixed ions in the crystal lattice that forms the conductor. In these collisions, the charges give up their kinetic energy to the ions in the lattice, which corresponds to a dissipation of heat from the material to the surrounding medium.

A higher temperature there is greater agitation in the ions of the lattice. This causes the space where they move to be greater and, therefore, the frequency of the collisions of the charges with the ions is greater. Therefore, the resistivity in metallic conductors increases with temperature. The value of this resistivity depends on the type of metal atoms, their bonds, the amount and type of impurities, and other defects such as those due to mechanical deformation during the manufacture and shaping of the conductor.

Transmission of heat generated in the conductor

To prevent the conductor from melting, the heat generated by the Joule effect must be transferred. In order to improve this thermal transmission, in general the heaters have a greater area or contact surface with the environment that surrounds them. Depending on the application, heat is transferred in one or more of 3 possible ways.

• Driving (sherves, plates, dispensers, etc.)
• By convection (haired dryers, air heaters, etc.)
• Radiation (tatators, quartz stoves, etc.)

Construction

If the heat losses to the environment were less than the watts generated by the Joule effect, the temperature would continue to rise and the conductor could melt. Therefore, in the design of heaters (which work between approximately 50 and 1150 °C) it is important to calculate well the thermal balance in the filament; that the temperature control works well; and consider materials that are not as good conductors, that do not melt, oxidize, or fracture at the working temperature and atmosphere, and whose resistivity changes very little with temperature. Halogens

The set of alloys for heaters (Nichrome, Chromax, Constantan and Nickel-Copper-Zinc) are called "resistive materials".

Types of heaters

Currently in the market you can find different types of heaters. Normally the most used for the home are small heaters. The types of heaters that exist are the following: Electric heaters, convectors, ceramic, infrared, fan heaters and heating panels. All these are very suitable for use at home.

Both halogen (also called infrared) and quartz stoves emit almost the same level of heat. Halogen heaters are usually mobile and are used to heat a part of the room in an eventual way. Halogen heaters are a little more expensive than quartz heaters, they emit a lot of light and the heat emission is instantaneous, they usually have bases rotating and can be kept plugged in for long periods of time.

While quartz stoves are cheaper, they emit little light, take a few minutes to start emitting heat (although there is not much difference) and are designed to be plugged in for short periods of time. The mica radiator (mica panel, mica convector, quartz radiator, ceramic radiators or infrared stoves) is an electric heating system that has one or more quartz tubes (resistors) that are heated using electrical energy.

An electric emitter is an electric radiator, but with low consumption. Some include Wi-Fi to program them.

An oil radiator works by a process in which a thermal fluid (called "oil") is heated. This fluid (which we call oil) is specially formulated and is the one that distributes heat evenly through the radiator, transferring heat to the metal which, in this way, transports heat to the room. The heat then circulates around the room by natural convection, as any air blowing against the radiator is heated. This causes the entire room to eventually heat up as the cooler air will reach the bottom of the room, come into contact with the radiator and also heat up. They are low consumption since they only use an average of between 2,000 and 3,000 W of power, they keep the heat once they have been turned off, and their design is quite light.

Radiant panels spread heat by infrared electromagnetic radiation, by convection and some more recent models also by inertia, although this is not usually very common. Like the sun, radiant plates emit heat by radiation, transmitting it directly to the people, objects and walls of the room, creating an environment of maximum well-being and comfort. With radiation heating systems, heat losses through windows are minimized, since radiation does not pass through the glass. In this way, the same comfort is obtained with a lower air temperature, which provides healthier heat and energy savings of more than 25%. Radiation is a method of heat transfer that does not depend on any contact between the heat source and the heated object (such as air); Heat can be transmitted through space by thermal or infrared radiation.

A convector is a heating system that works by convection. Inside it has some resistors that, when connected to the electric current, heat the air that circulates through them and raise it, expelling it to the outside through some grilles.

The ceramic heater is a type of electric heater that, after connecting it to the electric current, heats the ceramic plates that it has inside and the fan of the heater distributes the heat generated.

Fan heaters are electric heaters that use a ventilation system to distribute the hot air produced, regardless of the way they heat it (although most are ceramic).