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Basic properties of infrared radiation. Infrared radiation: influence on the human body, the effect of rays, their properties, benefits and harms, possible consequences

What is infrared radiation? The definition states that infrared rays are electromagnetic radiation that obeys optical laws and is of the nature of visible light. Infrared rays have a spectral range between red visible light and short-wave radio emission. For the infrared region of the spectrum there is a division into short-wave, medium-wave and long-wave. The heating effect of such rays is high. The accepted abbreviation for infrared radiation is IR.

IR radiation

Manufacturers report different information about heating devices designed according to the principle of radiation in question. Some may indicate that the device is infrared, while others may indicate that it is long-wave or dark. All this in practice relates to infrared radiation; long-wave heaters have the lowest temperature of the radiating surface, and waves are emitted in greater mass in the long-wave zone of the spectrum. They also received the name dark, since at temperature they do not give off light and do not shine, as in other cases. Medium wave heaters have a higher surface temperature and are called gray heaters. The light type is a short-wave device.

The optical characteristics of a substance in the infrared regions of the spectrum differ from the optical properties in ordinary everyday life. Heating devices that people use every day emit infrared rays, but you cannot see them. The whole difference is in the wavelength, it varies. An ordinary radiator emits rays, which is how the room is heated. Infrared radiation waves are present in human life naturally; the sun emits them.

Infrared radiation belongs to the category of electromagnetic radiation, that is, it cannot be seen with the eyes. Wavelengths range from 1 millimeter to 0.7 micrometers. The biggest source of infrared rays is the sun.

IR rays for heating

The presence of heating based on this technology allows you to get rid of the disadvantages of the convection system, which is associated with the circulation of air flow in the premises. Convection raises and carries dust, debris, and creates a draft. If you install an electric infrared heater, it will work on the principle of solar rays, the effect will be similar to solar heat in cool weather.

Infrared wave is a form of energy, it is a natural mechanism borrowed from nature. These rays are capable of heating not only objects, but also the air space itself. The waves penetrate the air layers and heat objects and living tissues. Localization of the source of the radiation in question is not so important; if the device is on the ceiling, the heating rays will reach the floor perfectly. It is important that infrared radiation allows you to leave the air moist, it does not dry it out, as other types of heating devices do. The performance of devices based on infrared radiation is extremely high.

Infrared radiation does not require large energy costs, so there are savings for domestic use of this development. IR rays are suitable for working in large spaces; the main thing is to choose the right ray length and set up the devices correctly.

Harm and benefits of infrared radiation

Long infrared rays hitting the skin cause a reaction in nerve receptors. This ensures the presence of heat. Therefore, in many sources, infrared radiation is called thermal radiation. Most of the emitted energy is absorbed by moisture, which is contained in the upper layer of human skin. Therefore, the skin temperature rises, and due to this, the entire body is heated.

There is an opinion that infrared radiation is harmful. This is wrong.

Research shows that long-wave radiation is safe for the body, moreover, it has benefits.

They strengthen the immune system, stimulate regeneration and improve the condition of internal organs. These rays with a length of 9.6 microns are used in medical practice for therapeutic purposes.

Shortwave infrared radiation works differently. It penetrates deep into the tissue and warms the internal organs, bypassing the skin. If you irradiate the skin with such rays, the capillary network expands, the skin turns red, and signs of a burn may appear. Such rays are dangerous for the eyes, they lead to the formation of cataracts, disrupt the water-salt balance, and provoke seizures.

A person gets heatstroke due to short-wave radiation. If you increase the temperature of the brain by even a degree, then signs of shock or poisoning already appear:

  • nausea;
  • rapid pulse;
  • darkening in the eyes.

If overheating occurs by two degrees or more, then meningitis develops, which is life-threatening.

The intensity of infrared radiation depends on several factors. The distance to the location of heat sources and the temperature indicator are important. Long-wave infrared radiation is important in life, and it is impossible to do without it. Harm can only occur when the wavelength is incorrect and the time it affects a person is long.

How to protect a person from the harm of infrared radiation?

Not all infrared waves are harmful. Shortwave infrared energy should be avoided. Where is it found in everyday life? Body temperatures above 100 degrees should be avoided. This category includes steelmaking equipment and electric arc furnaces. In production, employees wear specially designed uniforms that have a protective shield.

The most useful infrared heating device was the Russian stove; the heat from it was therapeutic and beneficial. However, no one uses such devices now. Infrared heaters have become firmly established, and infrared waves are widely used in industry.

If the spiral that gives off heat in an infrared device is protected by a heat insulator, then the radiation will be soft and long-wave, and this is safe. If the device has an open heating element, then the infrared radiation will be hard, short-wave, and this is dangerous to health.

In order to understand the design of the device, you need to study the technical data sheet. There will be information about the infrared rays used in a particular case. Pay attention to what the wavelength is.

Infrared radiation is not always clearly harmful; only open sources, short rays and prolonged exposure to them emit danger.

You should protect your eyes from the source of the waves, and if discomfort occurs, move away from the influence of infrared rays. If unusual dryness appears on the skin, it means that the rays are drying out the lipid layer, and this is very good.

Infrared radiation in useful ranges is used as treatment; physiotherapy methods are based on working with rays and electrodes. However, all effects are carried out under the supervision of specialists; you should not treat yourself with infrared devices. The duration of action must be strictly determined by medical indications, based on the goals and objectives of treatment.

It is believed that infrared radiation is unfavorable for systematic exposure to small children, so it is advisable to carefully select heating devices for the bedroom and children's rooms. You will need the help of specialists to set up a safe and effective infrared network in your apartment or house.

You shouldn’t give up modern technologies because of prejudices due to ignorance.

Infrared (IR) radiation is a type of electromagnetic radiation that occupies the spectral range between visible red light (INFRAred: BELOW red) and shortwave radio waves. These rays create heat and are scientifically known as thermal waves. These rays create heat and are scientifically known as thermal waves.

All heated bodies emit infrared radiation, including the human body and the Sun, which in this way warms our planet, giving life to all life on it. The warmth that we feel from a fire near a fire or fireplace, a heater or warm asphalt is all a consequence of infrared rays.

The entire spectrum of infrared radiation is usually divided into three main ranges, differing in wavelength:

  • Short wavelength, with wavelength λ = 0.74-2.5 µm;
  • Medium wave, with wavelength λ = 2.5-50 µm;
  • Long wavelength, with wavelength λ = 50-2000 µm.

Near or short-wave infrared rays are not hot at all; in fact, we don’t even feel them. These waves are used, for example, in TV remote controls, automation systems, security systems, etc. Their frequency is higher, and accordingly their energy is higher than that of far (long) infrared rays. But not at such a level as to harm the body. Heat begins to be created at mid-infrared wavelengths, and we already feel their energy. Infrared radiation is also called “thermal” radiation, because radiation from heated objects is perceived by the human skin as a sensation of heat. In this case, the wavelengths emitted by the body depend on the heating temperature: the higher the temperature, the shorter the wavelength and the higher the radiation intensity. For example, a source with a wavelength of 1.1 microns corresponds to molten metal, and a source with a wavelength of 3.4 microns corresponds to metal at the end of rolling and forging.

Of interest to us is the spectrum with a wavelength of 5-20 microns, since it is in this range that more than 90% of the radiation produced by infrared heating systems occurs, with a radiation peak of 10 microns. It is very important that it is at this frequency that the human body itself emits infrared waves of 9.4 microns. Thus, any radiation at a given frequency is perceived by the human body as related and has a beneficial and, even moreover, healing effect on it.

With such exposure to infrared radiation on the body, the effect of “resonance absorption” occurs, which is characterized by the body’s active absorption of external energy. As a result, one can observe an increase in a person’s hemoglobin level, an increase in the activity of enzymes and estrogens, and, in general, a stimulation of a person’s vital activity.

The effect of infrared radiation on the surface of the human body, as we have already said, is useful and, on top of that, pleasant. Remember the first sunny days at the beginning of spring, when after a long and cloudy winter the sun finally came out! You feel how it pleasantly envelops the illuminated area of ​​your skin, face, palms. I no longer want to wear gloves and a hat, despite the rather low temperature compared to the “comfortable” one. But as soon as a small cloud appears, we immediately experience noticeable discomfort from the interruption of such a pleasant sensation. This is the very radiation that we so lacked throughout the winter, when the Sun was absent for a long time, and we, willy-nilly, carried out our “infrared post”.

As a result of exposure to infrared radiation, you can observe:

  • Acceleration of metabolism in the body;
  • Restoration of skin tissue;
  • Slowing down the aging process;
  • Removing excess fat from the body;
  • Release of human motor energy;
  • Increasing the body's antimicrobial resistance;
  • Activation of plant growth

and many many others. Moreover, infrared irradiation is used in physiotherapy to treat many diseases, including cancer, as it promotes the expansion of capillaries, stimulates blood flow in the vessels, improves immunity and produces a general therapeutic effect.

And this is not at all surprising, because this radiation is given to us by nature as a way of transmitting heat and life to all living things that need this warmth and comfort, bypassing empty space and air as intermediaries.

There are different sources of infrared radiation. Currently, they are found in household appliances, automation and security systems, and are also used for drying industrial products. Infrared light sources, when used correctly, do not affect the human body, which is why the products are very popular.

History of discovery

For many centuries, outstanding minds have been studying the nature and action of light.

Infrared light was discovered in the early 19th century through the research of astronomer W. Herschel. Its essence was to study the heating abilities of various solar areas. The scientist brought a thermometer to them and monitored the increase in temperature. This process was observed when the device touched the red border. V. Herschel concluded that there is a certain radiation that cannot be seen visually, but can be determined using a thermometer.

Infrared rays: application

They are widespread in human life and have found their application in various fields:

  • Warfare. Modern missiles and warheads, capable of independently aiming at a target, are equipped with which are the result of the use of infrared radiation.
  • Thermography. Infrared radiation is used to study overheated or supercooled areas. Infrared images are also used in astronomy to detect celestial bodies.
  • Life The operation of which is aimed at heating interior items and walls has gained great popularity. They then release heat into the space.
  • Remote control. All existing remote controls for TV, furnaces, air conditioners, etc. equipped with infrared rays.
  • In medicine, infrared rays are used to treat and prevent various diseases.

Let's look at where these elements are used.

Infrared gas burners

An infrared burner is used to heat various rooms.

At first it was used for greenhouses and garages (that is, non-residential premises). However, modern technologies have made it possible to use it even in apartments. Popularly, such a burner is called a solar device, since when turned on, the working surface of the equipment resembles sunlight. Over time, such devices replaced oil heaters and convectors.

Main features

An infrared burner differs from other devices in its heating method. Heat is transferred through means that are not noticeable to humans. This feature allows heat to penetrate not only into the air, but also onto interior items, which subsequently also increase the temperature in the room. The infrared emitter does not dry out the air, because the rays are primarily directed at interior items and walls. In the future, heat will be transferred from walls or objects directly to the space of the room, and the process occurs in a few minutes.

Positive sides

The main advantage of such devices is quick and easy heating of the room. For example, it will take 20 minutes to heat a cold room to a temperature of +24ºС. During the process, there is no air movement, which contributes to the formation of dust and large contaminants. Therefore, an infrared emitter is installed indoors by those people who have allergies.

In addition, infrared rays, when hitting a surface with dust, do not cause it to burn, and, as a result, there is no smell of burnt dust. The quality of heating and durability of the device depends on the heating element. Such devices use a ceramic type.

Price

The price of such devices is quite low and accessible to all segments of the population. For example, a gas burner costs from 800 rubles. A whole stove can be purchased for 4,000 rubles.

Sauna

What is an infrared cabin? This is a special room that is built from natural types of wood (for example, cedar). Infrared emitters are installed in it, acting on the tree.

During heating, phytoncides are released - useful components that prevent the development or appearance of fungi and bacteria.

Such an infrared cabin is popularly called a sauna. The air temperature inside the room reaches 45ºС, so it is quite comfortable to be in it. This temperature allows the human body to be warmed evenly and deeply. Therefore, heat does not affect the cardiovascular system. During the procedure, accumulated toxins and waste are removed, metabolism in the body is accelerated (due to the rapid movement of blood), and tissues are also enriched with oxygen. However, sweating is not the main feature of an infrared sauna. It is aimed at improving well-being.

Impact on humans

Such premises have a beneficial effect on the human body. During the procedure, all muscles, tissues and bones are warmed up. Accelerating blood circulation affects metabolism, which helps saturate muscles and tissues with oxygen. In addition, the infrared cabin is visited to prevent various diseases. Most people leave only positive reviews.

Negative effects of infrared radiation

Sources of infrared radiation can cause not only positive effects on the body, but also cause harm to it.

With prolonged exposure to rays, the capillaries expand, which leads to redness or burns. Sources of infrared radiation cause particular harm to the organs of vision - this is the formation of cataracts. In some cases, a person experiences seizures.

Short rays affect the human body, causing a deterioration in the brain's temperature by several degrees: darkening of the eyes, dizziness, nausea. A further increase in temperature can lead to the formation of meningitis.

Deterioration or improvement of the condition occurs due to the intensity of the electromagnetic field. It is characterized by temperature and distance to the source of thermal energy radiation.

Long waves of infrared radiation play a special role in various life processes. Short ones have a greater effect on the human body.

How to prevent the harmful effects of infrared rays?

As mentioned earlier, short-term thermal radiation has a negative effect on the human body. Let's look at examples in which IR radiation is dangerous.

Today, infrared heaters that emit temperatures above 100ºC can be harmful to health. Among them are the following:

  • Industrial equipment emitting radiant energy. To prevent negative impacts, special clothing and heat-protective elements should be used, as well as preventive measures should be taken among working personnel.
  • Infrared device. The most famous heater is the stove. However, it has long gone out of use. Increasingly, electric infrared heaters are being used in apartments, country houses and cottages. Its design includes a heating element (in the form of a spiral), which is protected by a special heat-insulating material. Such exposure to rays does not harm the human body. The air in the heated zone is not dried. You can heat the room in 30 minutes. First, infrared radiation heats objects, and then they heat the entire apartment.

Infrared radiation is widely used in various fields, from industrial to medicine.

However, they should be handled with care, as the rays can have a negative effect on humans. It all depends on the wavelength and distance to the heating device.

So, we found out what sources of infrared radiation exist.

Infrared radiation is the part of the solar radiation spectrum that is directly adjacent to the red part of the visible spectrum. The human eye is unable to see in this region of the spectrum, but we can feel this radiation as heat.

Infrared radiation has two important characteristics: the wavelength (frequency) of the radiation and the intensity of the radiation. Depending on the wavelength, three regions of infrared radiation are distinguished: near (0.75−1.5 micrometers), middle (1.5 - 5.6 microns) and far (5.6−100 microns). Taking into account the physiological characteristics of humans, modern medicine divides the infrared region of the radiation spectrum into 3 ranges:

  • wavelength 0.75-1.5 microns - radiation penetrating deep into human skin (IR-A range);
  • wavelength 1.5-5 microns - radiation absorbed by the epidermis and connective tissue layer of the skin (IR-B range);
  • wavelength more than 5 microns - radiation absorbed on the surface of the skin (IR-C range). Moreover, the greatest penetration is observed in the range from 0.75 to 3 microns and this range is called the “therapeutic transparency window”.

Figure 1 (original source - Journal of Biomedical Optics 12(4), 044012 July/August 2007) shows the absorption spectra of IR radiation for water and tissue of human organs depending on the wavelength. It is noted that the tissue of the human body consists of 98% water and this fact explains the similarity of the absorption characteristics of infrared radiation in the spectral region of 1.5-10 microns.

If we take into account the fact that water itself intensively absorbs IR radiation in the range of 1.5-10 microns with peaks at wavelengths of 2.93, 4.7 and 6.2 microns (Yukhnevich G.V. Infrared spectroscopy of water, M, 1973), then the most effective for heating and drying processes should be considered IR emitters that emit in the middle and far infrared spectrum with a peak radiation intensity in the wavelength range of 1.5-6.5 μm.

The total amount of energy emitted per unit time by a unit of radiating surface is called the emissivity of the IR emitter E, W/m². The radiation energy depends on the wavelength λ and the temperature of the emitting surface and is an integral characteristic, since it takes into account the radiation energy of waves of all lengths. Emissivity related to the wavelength interval dλ is called radiation intensity I, W/(m²∙μm).

Integrating expression (1) allows us to determine the emissivity (specific integral radiation energy) based on the experimentally determined radiation intensity spectrum in the wavelength range from λ1 to λ2:

Figure 2 shows the emission intensity spectra of NOMAKON™ IKN-101 IR emitters, obtained at different nominal electrical powers of the emitter: 1000 W, 650 W, 400 W and 250 W.

With an increase in the power of the emitter and, accordingly, the temperature of the emitting surface, the intensity of the radiation increases, and the radiation spectrum shifts to shorter wavelengths (Wien's displacement law). In this case, the peak radiation intensity (85-90% of the spectrum) falls in the wavelength range of 1.5-6 microns, which corresponds to the optimal physics of the infrared heating and drying process for this case.

The intensity of infrared radiation and, accordingly, the specific radiation energy decreases with increasing distance from the radiation source. Figure 3 shows the curves of changes in the specific radiation energy of NOMAKON™ IKN-101 ceramic emitters depending on the distance between the emitting surface and the measurement point normal to the emitting surface. The measurements were carried out with a selective radiometer in the wavelength range of 1.5-8 μm, followed by integration of the radiation intensity spectra. As can be seen from the graph, the specific radiation energy E, W/m² decreases in inverse proportion to the distance L, m to the radiation source.

In order to understand the principle of operation of infrared emitters, it is necessary to imagine the essence of such a physical phenomenon as infrared radiation.

Infrared range and wavelength

Infrared radiation is a type of electromagnetic radiation that occupies the range from 0.77 to 340 microns in the spectrum of electromagnetic waves. In this case, the range from 0.77 to 15 microns is considered short-wave, from 15 to 100 microns - medium wave, and from 100 to 340 - long-wave.

The short-wave part of the spectrum is adjacent to visible light, and the long-wave part merges with the region of ultrashort radio waves. Therefore, infrared radiation has both the properties of visible light (it propagates in a straight line, is reflected, refracted like visible light) and the properties of radio waves (it can pass through some materials that are opaque to visible radiation).

Infrared emitters with a surface temperature from 700 C to 2500 C have a wavelength of 1.55-2.55 microns and are called “light” - in wavelength they are closer to visible light, emitters with a lower surface temperature have a longer wavelength and are called "dark".

Infrared radiation sources

Generally speaking, any body heated to a certain temperature emits thermal energy in the infrared range of the electromagnetic wave spectrum and can transfer this energy through radiant heat exchange to other bodies. Energy transfer occurs from a body with a higher temperature to a body with a lower temperature, while different bodies have different emissive and absorptive abilities, which depend on the nature of the two bodies, the state of their surface, etc.

Electromagnetic radiation has a quantum-photonic character. When interacting with matter, a photon is absorbed by the atoms of the substance, transferring its energy to them. At the same time, the energy of thermal vibrations of atoms in the molecules of the substance increases, i.e. radiation energy turns into heat.

The essence of radiant heating is that the burner, being a source of radiation, generates, forms in space and directs thermal radiation into the heating zone. It falls on enclosing structures (floors, walls), technological equipment, people in the irradiation zone, is absorbed by them and heats them up. The radiation flux, absorbed by surfaces, clothing and human skin, creates thermal comfort without increasing the ambient temperature. The air in heated rooms, while remaining almost transparent to infrared radiation, is heated due to “secondary heat”, i.e. convection from structures and objects heated by radiation.

Properties and applications of infrared radiation

It has been established that exposure to infrared radiation heating has a beneficial effect on humans. If thermal radiation with a wavelength greater than 2 microns is perceived mainly by the skin with the resulting thermal energy being conducted inside, then radiation with a wavelength of up to 1.5 microns penetrates the surface of the skin, partially heats it, reaches the network of blood vessels and directly increases the temperature of the blood. At a certain intensity of heat flow, its impact causes a pleasant thermal sensation. In radiant heating, the human body releases most of its excess heat by convection to the surrounding air, which has a lower temperature. This form of heat transfer has a refreshing effect and has a beneficial effect on well-being.

In our country, the study of infrared heating technology has been carried out since the 30s, both in relation to agriculture and industry.

Conducted medical and biological studies have made it possible to establish that infrared heating systems more fully meet the specifics of livestock buildings than convective central or air heating systems. First of all, due to the fact that with infrared heating the temperature of the internal surfaces of the fences, especially the floor, exceeds the air temperature in the room. This factor has a beneficial effect on the thermal balance of animals, eliminating intense heat loss.

Infrared systems, working in conjunction with natural ventilation systems, ensure a reduction in relative air humidity to standard values ​​(on pig farms and calf barns to 70-75% and below).

As a result of the operation of these systems, the temperature and humidity conditions in the premises reach favorable parameters.

The use of radiant heating systems for agricultural buildings allows not only to create the necessary microclimate conditions, but also to intensify production. In many farms in Bashkiria (collective farm named after Lenin, collective farm named after Nurimanov), the production of offspring significantly increased after the introduction of infrared heating (increasing farrowing in winter by 4 times), and the safety of young animals increased (from 72.8% to 97.6%).

Currently, the infrared heating system has been installed and has been operating for one season at the Chuvash Broiler enterprise in the suburbs of Cheboksary. According to reviews from farm managers, during the period of minimum winter temperatures -34-36 C, the system worked uninterruptedly and provided the required heat for raising poultry for meat (floor housing) for a period of 48 days. They are currently considering the issue of equipping the remaining poultry houses with infrared systems.