Since the devices appeared on the market infrared heating slowly but surely gaining more and more popularity. The scope of their application is quite wide - from ordinary residential premises to industrial buildings high altitude. Naturally, the design and operating principle of an infrared heater is of considerable interest. We bring to your attention this article, where all questions regarding the operation of these devices will be discussed in detail.
Infrared heater: how does it work?
To get an idea of how infrared heating devices operate, let’s first understand the ways in which thermal energy can be transferred in a room’s space. There are only two of them:
- convection: any object whose temperature is higher than the surrounding air exchanges heat with it directly. The air, heated by this object, loses density and mass, due to which it rushes upward, displaced by a heavier cold flow. Thus, circulation begins in the space of the room air masses different temperatures.
- radiant heat: a surface having a temperature of more than 60 ºС begins to intensely emit electromagnetic waves in the range of 0.75-100 microns, carrying thermal energy. This is the basis for the work of infrared heaters, whose heating elements emit such waves.
The most comfortable range of infrared radiation for humans is from 5.6 to 100 microns, within which most infrared heaters operate. An exception is long-range devices installed on the ceilings of industrial buildings. They emit in the medium (2.5-5.6 µm) and short (0.75-2.5 µm) ranges and are located at a distance from the target of 3-6 m and 6-12 m, respectively. It is unacceptable to use such emitters in residential buildings.
When infrared rays hit surfaces within visibility, they increase their temperature. After this, the principle of convection comes into effect, heat begins to be transferred from the surfaces to the air of the room. Such heating is more uniform than during the operation of traditional convective systems, which is reflected in the figure:
Heater device
Before considering the design of an infrared heater, we note that these devices are produced in 2 types:
electric: they use heating elements various types: carbon spirals, tubular heating elements, halogen lamps and film micathermic panels.
gas: here IR rays are emitted by a heated ceramic element.
We will consider the design of the device using the example of a ceiling-mounted long-wave heater powered from the mains. It has a role heating element plays an aluminum plate with a built-in heating element of a special design. An anodized coating is applied to the surface of the plate, which improves the heat transfer of the surface. WITH reverse side reflector and layer installed thermal insulation material. The diagram below shows the design of ceiling heaters:
1 – metal body; 2 – ceiling mounting brackets; 3 – heating element; 4 – radiating plate made of aluminum; 5 – layer of thermal insulation with a reflector.
Other electrical infrared heating devices with other types of heating elements are structurally not much different from emitters hanging type. The only significant difference between them is the method of control. Wall-mounted and floor-mounted IR heaters have a built-in control unit with a thermostat and a tilt sensor. For ceiling-mounted devices, this unit is a remote unit mounted on the wall; it can control several devices simultaneously.
It must be said that the principle of operation of a gas infrared heater is similar to an electric one, only thermal energy is obtained in different ways.
In a gas appliance, the heating element is a ceramic plate, whose temperature can reach 900 ºС depending on the settings. The plate warms up gas burner, located in the end part of the housing, as shown in the diagram:
What is the secret of popularity?
Manufacturers declare the following advantages of infrared heaters:
- high efficiency and cost-effectiveness;
- absence of rotating parts and noise;
- a gentle warmth is generated that does not cause a deterioration in a person’s well-being;
- simple installation and connection.
As a rule, these are general phrases; something similar can be found in descriptions oil radiators or wall convectors. They do not answer the question - why are devices so attractive to users in real life? It turns out that everything is simple, the operation of a ceiling infrared heater, like a wall-mounted one, is possible in non-insulated buildings, in drafts and even on the street. The main thing is to be within the range of infrared radiation.
A device that emits infrared waves will create a zone of comfortable heat in front of it, leaving the rest of the room unattended. It will warm up after a few hours from heated objects. But the fact remains: in a room where 1 kW of heat is needed for heating, people install a 500 W infrared heater so that the radiant heat is distributed as widely as possible. It creates an illusion good heating, although in fact the temperature in the room remains dog-like, the laws of physics cannot be deceived.
If heating a room requires 1 kW of heat, then infrared emitters should be exactly this power, then there will be no illusions, a comfortable temperature will quickly be established in the entire room.
The devices also have other disadvantages. For example, the design of an infrared heater in a suspended design implies a wasteful consumption of about 10% of the heat accumulating under the ceiling. This is a convective transfer of energy from the heated body of the device to the surrounding air, which remains there, under the ceiling. Work wall heaters interfere various items, carbon and halogen devices irritate with their bright light, and micathermic ones - with a high price.
Conclusion
In general, infrared electric and gas heaters are perfect products and can heat private homes well. The main thing when buying is not to follow the lead of the sellers and choose a device for yourself required power, and then arrange it at home in the optimal way.
Infrared waves are not visible to the human eye. However, in essence, they are the same electromagnetic waves as visible light, and propagate in space according to the same laws. Therefore, such radiation can be emitted by a special illuminator and then captured optical device, in which the converter will turn invisible infrared waves into visible light.
An optical-electronic converter is used to convert infrared radiation into visible light. It converts infrared light into a stream of electrons, and the electrons, bombarding a special screen, cause it to glow in the visible range. The light emanating from the OEP is directed directly into the observer’s eye and recorded by a camera or video camera.
What should you pay attention to when selecting equipment for observation in the infrared range?
The quality of the image (brightness, contrast, sharpness, target detection range against the background of the landscape) depends both on the quality of the illuminator and on the NVD (generation of the image intensifier, quality of the optics). In addition to image clarity important factors when choosing a device for observation in the infrared range are:
- Weight and dimensions of the device;
- Reliable operation, durability;
- Device power consumption, type of power source;
- Protection of the device from moisture or dirt getting inside, resistance to shock and recoil;
- Price.
The choice should be made taking into account the specific objectives and purchase budget. Of course, for observation while hunting, you should look for a more compact and lightweight device, designed to withstand the load caused by the recoil of the weapon. And to ensure the protection of the territory, you can choose larger structures that have the ability to operate continuously for a long time.
presented on the Russian market
- . An observation device that visualizes radiation from the infrared part of the spectrum. The device is designed to operate using an infrared laser (solid-state or LED) with a wavelength of about 350...2000 nanometers as an emitter. The S-1+ photocathode used in the design allows you to see a clear image when observing a target at any distance within the capabilities of the device.
The device is easy to use. Compact dimensions and low weight allow you to observe without fatigue for a long time. The device has a comfortable handle. It can also be attached to a helmet-mask, freeing your hands for work. The device can withstand temperatures from -10ºC to +40ºC. Power supply - “little finger” 1.5-volt battery.
- . The device is capable of converting radiation from the infrared part of the spectrum with a wavelength from 320 to 1700 nanometers into visible light. Since it weighs only 250g, it can be used for long-term observation without causing hand fatigue. The ergonomic handle contributes to the comfort of observation. For more convenient observation, the device can be attached to a helmet mask and free your hands.
A more serious modification has also been developed for this model. It has a greater range of sensitivity to infrared radiation. The upper limit of the range is 2000 nanometers.
- . The camera is capable of detecting infrared radiation, which has a wavelength from 400 to 1700 nm. It can be used either directly for observation or attached to a microscope and for infrared microscopy, spectrography, forensic studies and other research work.
The camera's silicon CCD sensor has high sensitivity. It also implements the principle of electronic radiation amplification. The camera is powered by 4 AA batteries. There is also a built-in Charger. The AC adapter allows you to take 12V from a household electrical outlet, so you can work with the camera for a long time and in a comfortable environment. The product comes with a tripod and carrying bag.
- converts infrared waves with a wavelength of 350 - 1700 nm into visible radiation. In this design, an image intensifier tube with extended sensitivity is combined with an SSD camera. Thanks to the 4-inch LCD display, you can quickly monitor, and the video output allows you to record information on external media. The camera will be indispensable in infrared microscopy and forensic research. Power is supplied from 4 AA batteries. The camera's continuous operation time on one set of batteries is about 1.5 hours.
- Helmet-mask FM-1. This convenient accessory helps free your hands when working with SM-3R and Abris-M infrared surveillance devices. The mask mechanism has two fixed positions. In this case, it is possible to attach the device on the right or left side, depending on the preference of the observer. The position of the fixed device is also adjustable in three directions.
As you can see, today there are many devices on store shelves that allow you to monitor and record information in the near-infrared range. In this variety, any, even the most demanding buyer will find an option that suits him in terms of capabilities and cost.
Infrared rays have a different range, which facilitates their penetration into the human body in different layers. Their length can vary from 780 to 10,000 nm. For medicinal purposes, waves with a length of no more than 1400 nm are used, penetrating to a depth of 3 cm.
Concept of method
Infrared treatment involves exposing affected areas of the body to powerful light. It can be used either as a supplement or as a stand-alone therapy. Unlike IR rays, they do not contain ultraviolet radiation, which minimizes side effects.
During the procedure, narrow direction polarized light is used. The duration of one session depends on the complexity of the diagnosis and the expected result.
On average, one treatment procedure with infrared rays lasts from half an hour to 2 hours.
Long waves infrared radiation is a source of health and beauty. The video below explains this:
Its types
Therapy using infrared rays can be of two types:
- Local;
- General.
In the first case, the rays are directed to a specific area of the body, in the second - to the entire body. The duration of the session can be 15-30 minutes and occur up to two times a day. The course of treatment is usually 7-20 procedures.
If exposure to rays occurs on the face, it is necessary to protect the eyes with special pads or glasses.
Advantages and disadvantages
Due to its properties, infrared rays are actively used in modern medicine. Their effect on the body consists of the following processes:
- Stimulation of blood circulation, including the brain;
- Memory improvement;
- Normalization of blood pressure;
- Removing salts and toxins from the body;
- Blocking the effects of harmful fungi and microbes;
- Normalization of hormonal levels;
- Anti-inflammatory and analgesic effect;
- Improving immunity;
- Normalization of water-salt balance.
With all its advantages, this treatment method also has disadvantages. Thus, when using broad spectrum rays, it is observed and in some cases develops. Short beams are dangerous to the eyes. With prolonged use, cataracts, fear of light and other visual impairments may develop.
Indications for testing
The main indications for prescribing infrared treatment are:
- Diseases of the musculoskeletal system that are degenerative-dystrophic in nature;
- Complications of injuries, joint diseases, as well as infiltrates and contractures;
- Poorly healing wounds;
- Inflammatory processes in subacute and chronic forms;
- Various vision pathologies;
- Diseases of the ENT organs (including tonsillitis, for example, etc.)
- Burns (including) and;
- , and other skin diseases (including).
- Hair problems (cosmetology).
Contraindications
The procedure for treatment with infrared rays is contraindicated in the following cases:
- , having no content outflow;
- Exacerbation of diseases in chronic form;
- Availability ;
- Tuberculosis in open form;
- Blood diseases;
- Pregnancy and lactation;
- Individual intolerance.
Preparing for infrared treatment
No preparation is required before starting the procedure. If infrared rays are used in the field of cosmetology, the doctor may recommend additional facial cleansing before the scheduled procedure. Also at this stage, it is determined whether the patient has contraindications to the procedure.
In order for the rays to penetrate the skin better and not cause burns, the skin must be lubricated with a special gel. After which the immediate preparation of the treated body area occurs. At the end of the session, the remaining substances are removed from the surface of the skin, and the medicine against irritation and swelling.
How is the procedure performed?
In special institutions
During infrared therapy, no significant heat should be felt. When the treatment is carried out correctly, the patient feels a light and pleasant warmth. Thermal wraps using electric bandages, lamps with infrared rays, IR cabins and other equipment can be used for therapy.
In any case, working with rays warms up ambient air up to 50-60°C, which makes it possible to perform a session sufficiently long time. Thus, a visit to a cabin or capsule is allowed for 20-30 minutes, and with local effects on the body, the duration of the procedure increases to an hour.
This technique can be combined with other physiotherapeutic treatment. In this case, the procedures are prescribed both simultaneously and sequentially.
This video talks about IR treatment:
At home
Most often, for home treatment with these rays, a special infrared lamp. Plot skin, which is amenable to irradiation, is actively supplied with blood, and an increase in metabolic processes occurs on it. These changes in the body have a healing effect.
All medical devices that involve exposure to infrared rays on the body have their own standards and operating technologies, as well as limitations. That is why the technology of the session depends on the specific device.
Consequences and possible complications
Complications during therapy with infrared rays occur extremely rarely and are expressed in the following undesirable effects:
- Temporary visual impairment;
- Excitability;
- Anxiety.
When using rays in the field of dermatology and cosmetology, in rare cases the following may be observed:
- Excitement;
- Rapid eye fatigue;
- Migraine;
- Nausea.
Infrared device for home treatment
Recovery and care after therapy
At the end of the session, a red spot without clear contours may be observed on the treated area of skin (). It goes away on its own, usually 1-1.5 hours after the procedure.
IR sub-bands:
- Near IR (abbreviated as NIR): 0.78 - 1 µm;
- Short wavelength IR (abbreviated SWIR): 1 - 3 µm;
- Medium wavelength IR (abbreviated as MWIR): 3 - 6 µm;
- Long wavelength IR (abbreviated LWIR): 6 - 15 µm;
- Very long wavelength IR, abbreviated VLWIR: 15 - 1000 microns.
The infrared spectral range of 0.78 - 3 microns is used in fiber-optic communication lines (short for fiber-optic communication line), external monitoring devices for objects and equipment for conducting chemical analysis. In turn, all wavelengths from 2 microns to 5 microns are used in pyrometers and gas analyzers that monitor the level of pollution in a specific environment. The 3 - 5 µm interval is more suitable for systems that record images of objects with a high intrinsic temperature or in applications where the requirement for contrast is higher than for sensitivity. The spectral range 8 - 15 microns, which is very popular for special applications, is mainly used where it is necessary to see and recognize any objects located in fog.
All IR devices are designed in accordance with the IR transmittance schedule, which is given below.
There are two types of IR detectors:
- Photonic. Sensing elements consist of semiconductors various types, and can also include in their structure various metals, the principle of their operation is based on the absorption of photons by charge carriers, as a result of which the electrical parameters of the sensitive area change, namely: changes in resistance, the occurrence of a potential difference, photocurrent, etc. These changes can be recorded by measuring circuits formed on the substrate where the sensor itself is located . The sensors have high sensitivity and high response speed.
- Thermal. IR radiation is absorbed by the sensitive area of the sensor, heating it to a certain temperature, which leads to a change in physical parameters. These deviations can be recorded by measuring circuits made directly on the same substrate as the photosensitive area. The types of sensors described above have high inertia, significant response time and relatively low sensitivity in comparison with photon detectors.
Based on the type of semiconductor used, sensors are divided into:
- Own(undoped semiconductor with an equal concentration of holes and electrons).
- Impurity(doped n- or p-type semiconductor).
The main material of all photosensitive sensors is silicon or germanium, which can be doped with various impurities of boron, arsenic, gallium, etc. An impurity photosensitive sensor is similar to its own detector, with the only difference being that carriers from donor and acceptor levels can move into the conduction band, overcoming more low energy barrier, as a result of which this detector can operate with shorter wavelengths than its own.
Types of detector designs:
Under the influence of IR radiation, a photovoltaic effect occurs in the electron-hole transition: photons with an energy exceeding the band gap are absorbed by electrons, as a result of which they occupy places in the conduction band, thereby contributing to the emergence of a photocurrent. The detector can be made on the basis of both an impurity and an intrinsic semiconductor.
Photoresist. The sensitive element of the sensor is a semiconductor; the operating principle of this sensor is based on the effect of changing the resistance of a conductive material under the influence of IR radiation. Free charge carriers generated by photons in the sensitive region lead to a decrease in its resistance. The sensor can be made on the basis of both an impurity and an intrinsic semiconductor.
Photoemissive, also known as a “free carrier detector” or on a Schottky barrier.; To eliminate the need for deep cooling of impurity semiconductors, and in some cases to achieve sensitivity in the longer wavelength range, there is a third type of detector called photoemission detectors. In this type of sensor, a metal or metal-silicon structure is coated with impurity silicon. A free electron, which is formed as a result of interaction with a photon, enters the silicon from the conductor. The advantage of such a detector is that the response does not depend on the characteristics of the semiconductor.
Quantum well photodetector. The operating principle is similar to impurity detectors, in which impurities are used to change the structure of the bandgap. But in this type of detector, impurities are concentrated in microscopic regions where the band gap is significantly narrowed. The “well” formed in this way is called quantum. Registration of photons occurs due to the absorption and formation of charges in the quantum well, which are then drawn out by the field to another area. Such a detector is much more sensitive compared to other types, since an entire quantum well is not a single impurity atom, but from ten to one hundred atoms per unit area. Thanks to this, we can talk about a fairly high effective absorption area.
Thermocouple. The main element of this device is a contact pair of two metals with various jobs exit, resulting in a potential difference at the boundary. This voltage is proportional to the contact temperature.
Pyroelectric detectors made using pyroelectric materials and the operating principle of which is based on the appearance of a charge in the pyroelectric when a heat flow passes through it.
Microbeam detectors. Consists of a microbeam and a conductive base, which act as capacitor plates; the microbeam is formed from two tightly connected metal parts, having different coefficients thermal expansion. When heated, the beam bends and changes the capacity of the structure.
Bolometers (Thermistors) consist of a thermoresistive material, the operating principle of this sensor is based on the absorption of IR radiation by the material of the sensitive element, which leads to an increase in its temperature, which in turn causes a change electrical resistance. There are two ways to obtain information: measuring the current flowing in a sensitive area at a constant voltage and measuring voltage at a constant current.
Main settings
Sensitivity- the ratio of the change in the electrical quantity at the output of the radiation receiver caused by the radiation incident on it to the quantitative characteristic of this radiation. V/lk-s.
Integral sensitivity- sensitivity to non-monochromatic radiation of a given spectral composition. Measured in A/lm.
Spectral sensitivity- dependence of sensitivity on radiation wavelength.
Detection ability- the reciprocal value of the minimum radiation flux that causes a signal at the output equal to its own noise. It is inversely proportional square root from the area of the radiation receiver. Measured in 1/W.
Specific detection ability- Detection ability multiplied by the square root of the product of a frequency band of 1 Hz and an area of 1 cm 2. Measured in cm*Hz 1/2/W.
Response time- time required to establish an output signal corresponding to the input effect. Measured in milliseconds.
Working temperature- maximum sensor temperature and environment, in which the sensor is able to correctly perform its functions. Measured in °C.
Application:
- Space surveillance systems;
- ICBM launch detection system;
- In non-contact thermometers;
- In motion sensors;
- In IR spectrometers;
- In night vision devices;
- In homing heads.