![\"Solar](\"http:\/\/nomacon.by\/wp-content\/uploads\/ir-spektr.jpg\")
<\/a>According to DIN 5031, depending on the wavelength, three regions of infrared radiation are distinguished: near IR-A (0.75-1.4 \u03bcm), middle IR-B (1.4 - 3.0 \u03bcm) and far IR-C ( 3.0-80 \u03bcm). Taking into account the physiological characteristics of humans, modern medicine characterizes these areas of the spectrum as follows (see Figure 2):<\/p>\n\n\n\n
- wavelength 0.75-1.4 microns - radiation penetrating deep into the human skin (IR-A range<\/strong>);<\/li>
- wavelength 1.4-3 microns - radiation absorbed by the epidermis and the connective tissue layer of the skin (IR-B range<\/strong>);<\/li>
- wavelength over 3 microns - radiation absorbed on the skin surface (IR-C range<\/strong>).<\/li><\/ul>\n\n\n\n
![\"Three](\"http:\/\/nomacon.by\/wp-content\/uploads\/graphic-absoeption.png\")
Fig. 2<\/figcaption><\/figure><\/div>\n\n\n\n In this case, the greatest penetration is observed in the range from 0.75 to 3 microns and this range is called the "window of therapeutic transparency" of radiant infrared heating of the human body.<\/p>\n\n\n\n
Figure 2 (original source - Journal of Biomedical Optics 12 (4), 044012 July \/ August 2007) shows the absorption spectra of infrared radiation for water and tissue of human organs, depending on the wavelength. It is noted that the tissue of the human body consists of water on 98% and this fact explains the similarity of the absorption characteristics of infrared radiation in the spectral range of 1.4-10 microns.<\/p>\n\n\n\n
If we take into account the fact that water itself intensively absorbs infrared radiation in the range of 1.4-10 microns with peaks at wavelengths of 2.93, 4.7 and 6.2 microns (see Figure 2 and Yukhnevich G.V. Infrared spectroscopy of water, M, 1973), then the most effective for heating and drying processes should be considered infrared emitters, emitting in the middle and far infrared spectrum with a peak of radiation intensity in the wavelength range of 1.5-7.0 microns.<\/p>\n\n\n\n
The total amount of energy emitted per unit time by a unit of emitting surface is called emissivity<\/strong>, or specific radiation energy<\/strong> IR emitter E<\/em><\/strong>, W \/ m2<\/sup>... Radiation energy depends on wavelength \u03bb<\/em><\/strong>, \u03bcm and temperature of the emitting surface T<\/em><\/strong>, \u00b0 C and is an integral characteristic, since it takes into account the radiation energy of all wavelengths of a given spectral range of radiation.<\/p>\n\n\n\n
Emissivity per wavelength interval d\u03bb<\/em><\/strong> are called radiation intensity I<\/em><\/strong>, W \/ (m2<\/sup>\u2022 \u03bcm).<\/p>\n\n\n\n
![\"Radiation](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-form1.png\")
<\/figure><\/div>\n\n\n\nIntegration of expression (1) makes it possible to determine the specific radiation energy based on the spectrum of radiation intensity determined either by calculation or experimentally I = f (\u03bb)<\/em><\/strong> in the wavelength range from \u03bb1<\/sub><\/em><\/strong> before \u03bb2<\/sub><\/em><\/strong>.<\/p>\n\n\n\n
![\"Specific](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-form2.png\")
<\/figure><\/div>\n\n\n\n![\"Radiation](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-ris3.jpg\")
<\/a>Fig. 3<\/figcaption><\/figure><\/div>\n\n\n\n Figure 3 shows the spectra of the radiation intensity of infrared emitters NOMAKON<\/strong> TSC-101, obtained at various nominal electric power of the emitter, which is 1000 W, 650 W and 400 W. The emitters had a unified standard size of the radiating surface in plan, equal to 245x60 mm.<\/p>\n\n\n\n
The tests were carried out at the Institute of Physics of the National Academy of Sciences of Belarus. The infrared radiation spectra were measured on an upgraded SDL-2 spectro-measuring complex (LOMO, St. Petersburg, USSR) using an MDR-23 registration monochromator. The distance from the ceramic emitters to the monochromator slit was 500 mm. A module from ORIEL INSTRUMENTS (USA) was used as a photodetector, the sensitivity of which did not depend on the radiation wavelength. With an increase in the power of the emitter and, accordingly, the temperature of the emitting surface, the radiation intensity increases, and the radiation spectrum shifts to the region of shorter wavelengths (Wien's displacement law)<\/strong>... In this case, the peak of the radiation intensity (not less than 80 % spectrum) falls on the wavelength range of 1.5-6.0 microns, which corresponds to the physics of the infrared heating and drying process that is optimal for this case.<\/p>\n\n\n\n
The spectral nature of infrared radiation, when each wavelength range corresponds to a certain value of the radiation energy I = f (\u03bb)<\/em><\/strong>, can be described using the well-known Planck equation depending on the absolute temperature of the radiating surface Tabs<\/em>1<\/sub>, \u00b0 K<\/em><\/strong>, emissivity (emissivity) of the radiating surface \u03b51<\/sub><\/em><\/strong> and the current radiation wavelength \u03bbi<\/em><\/sub><\/em><\/strong>, \u03bcm<\/p>\n\n\n\n
![\"The](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-form3.png\")
<\/figure><\/div>\n\n\n\nWhere C1<\/sub> = 0.374 * 10-15<\/sup> W \u2022 m2<\/sup>, C2<\/sub> = 0.4388 * 10-2<\/sup> m \u2022 K<\/em><\/strong> - Planck's constant equations.<\/p>\n\n\n\n
Maximum value of radiation intensity Imax1<\/sub><\/em><\/strong> corresponding to the wavelength \u03bbmax1<\/sub><\/em><\/strong> can be calculated by formula (3) and the value itself \u03bbmax1<\/sub><\/em><\/strong> can be determined by the Wien equation<\/p>\n\n\n\n
![\"Wien's](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-form4.png\")
<\/figure><\/div>\n\n\n\nWhere b0<\/sub> = 2.898 * 10-3<\/sup> m \u2022 K<\/em><\/strong> Is the constant of Wien's equation.<\/p>\n\n\n\n
Thus, having determined for the source of infrared radiation the values \u03b51<\/sub><\/em><\/strong> and Tabs<\/em>1<\/sub><\/em><\/strong> for a given operating mode and calculating the spectrum of radiation intensity I = f (\u03bb)<\/em><\/strong> according to formula (3), it is possible to determine the value of the specific radiation energy E<\/em><\/strong>, W \/ m2<\/sup> on the radiating surface, integrating the values I<\/em><\/strong> in the wavelength range from \u03bb1<\/sub><\/em><\/strong> before \u03bb2<\/sub><\/em><\/strong> according to expression (2).<\/p>\n\n\n\n
For infrared ceramic and quartz emitters at a temperature of the emitting surface not exceeding plus 720-860 \u00b0 \u0421 and the degree of emissivity of the emitting surface equal to \u03b51<\/sub> = 0,85-0,96 <\/em><\/strong>, i.e. close to an absolutely black body, the procedure for calculating the specific radiation energy with sufficient accuracy can be performed using the Stefan-Boltzmann formula obtained by integrating the Planck equation in the radiation wavelength range from 0 to \u221e<\/em><\/strong> :<\/p>\n\n\n\n
![\"Stefan-Boltzmann](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-form5.png\")
<\/figure><\/div>\n\n\n\nWhere C0<\/sub> = 5.671 * 10-15<\/sup> W \/ (m2<\/sup>\u2022 K4<\/sup>)<\/em><\/strong> Is the constant of the Stefan-Boltzmann equation.<\/p>\n\n\n\n
Figure 4 shows the characteristics of infrared radiation for ceramic emitters of the NOMAKON IKN-101 brand, obtained using expressions (3) - (5) with the degree of emissivity of the emitting surface \u03b51<\/sub> = 0,96<\/em><\/strong> and temperature of the emitting surface Tiz<\/em>1<\/sub> <\/em><\/strong>, \u00b0 C which corresponds to the electric power of the emitter Piz<\/em>1<\/sub><\/em><\/strong> , W according to the technical characteristics presented in the table on the website page.<\/p>\n\n\n\n
Calculated values of specific surface radiation energy Eiz<\/em>1<\/sub> <\/em><\/strong>, W \/ cm2<\/sup> and the wavelength of the maximum spectral radiation intensity \u03bbmax1<\/sub><\/em><\/strong>, \u03bcm are important characteristics for determining in the future the modes of operation of infrared electric heaters.<\/p>\n\n\n\n
Analysis of the distribution of the radiation intensity by wavelengths (see Figure 4) in a wide range of values of the electric power of the emitters and the temperature of the emitting surface shows that the main radiation energy is generated in the wavelength range of 1.0-10 \u03bcm and includes the energy of the near (0 , 75-1.4 microns), medium (1.4-3 microns) and far (3-80 microns) radiation ranges. In this case, the wavelengths of 0-1.0 microns of the near and 10-80 microns of the far radiation ranges do not play a practical role in the process of infrared heating. Thus, the use of these emitters is justified for materials that absorb radiation well in the wavelength range of 1.0-10 microns with an absorption maximum at the peak of the maximum spectral radiation intensity in the wavelength range of 1.5-7.0 microns.<\/p>\n\n\n\n
![\"Spectral](\"http:\/\/nomacon.by\/wp-content\/uploads\/ir-ris4.jpg\")
<\/a>Fig. four<\/figcaption><\/figure><\/div>\n\n\n\n Characteristics of the emissivity of ceramic and quartz emitters<\/h2>\n\n\n\n
The development of methods for engineering calculation of infrared heating processes is of decisive importance in the design of equipment for technological processes, as well as for the selection of electric heaters and heating systems for industrial and domestic heating. <\/p><\/blockquote><\/figure>\n\n\n\n
The methods presented below are based on a detailed analysis of the emissivity of the ceramic and quartz emitters developed by us, on the generalization of their measured and calculated basic characteristics depending on the size, shape and design features of the radiation surface.<\/p>\n\n\n\n
The principle of operation of emitters is shown in Figure 5. <\/strong><\/p>\n\n\n\n
Ceramic emitters of the NOMACONTM IKN-100, IKN-200 and IKN-300 series are installed in a metal case with a reflector-reflector. Quartz emitters of the NOMAKON IKN-400 series have their own metal case. The description of the emitters, as well as their structural and connection dimensions, are presented on the corresponding pages of the site.<\/p>\n\n\n\n
In the process of heating the radiation surface of ceramic emitters, as well as quartz tubes-emitters of quartz emitters, fluxes of radiant heat are formed, directed both outward from the heater into the environment and into the inside of the heater to the reflector-reflector and the housing.<\/p>\n\n\n\n
![\"The](\"http:\/\/nomacon.by\/wp-content\/uploads\/ir-ris5.jpg\")
<\/a><\/figure><\/div>\n\n\n\nPartially reflected from the inner metal surfaces, infrared rays return to the emitting surface, further heating it and increasing the surface radiation energy outward Eiz<\/em>1<\/sub> <\/em><\/strong>... Partial absorption of radiation causes heating of the reflector and housing. Additionally, the reflector and the heater body are heated from the inside by convective currents of hot air washing over the radiator. Thus, in a steady-state heating mode, the loss of heat energy Qp<\/em>1<\/sub> <\/em><\/strong>, W, i.e. that part of the energy that was not used to generate infrared radiation will be determined by heat losses to the environment from the heated heater body and heat losses from the heated air from the emitter. At the same time, the ambient infrared background radiation with a specific power will affect the emitting surface Eos<\/em>1<\/sub> <\/em><\/strong>, W \/ m2<\/sup>.<\/p>\n\n\n\n
In the steady-state heating mode, the emitter consumes the nominal electrical power Piz<\/em>1<\/sub> <\/em><\/strong>, W and at the same time the energy conservation equation for the heater (energy balance) will take the form:<\/p>\n\n\n\n
![\"Heater](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-form6.png\")
<\/figure><\/div>\n\n\n\nWhere Fiz<\/em>1<\/sub> <\/em><\/strong>, m2<\/sup> Is the estimated area of the radiation surface of the emitter.<\/p>\n\n\n\n
Calculated radiation surface area<\/h3>\n\n\n\n
For the calculated area of the radiation surface of ceramic emitters of the NOMAKON TSC-100, TSC-200 and TSC-300 series, the geometric area of the outer surface of the ceramic emitters is taken from which radiant heat is mainly generated outward from the heater into the environment, and also on which the main reception of the background (reflected) radiation from the environment. It should be noted that the electric wire heating coil embedded in the ceramics is located the closest (at a distance of 1.5-2 mm) to the calculated radiating surface, marked in yellow in Figure 5.<\/p>\n\n\n\n
The calculated area of the radiation surface of quartz emitters of the NOMACONTM IKN-400 series is taken to be the geometric area of the outer surface of quartz tubes-emitters from which radiant heat is mainly generated outward from the heater into the environment, and also on which the background (reflected) radiation from the environment is received. Wednesday. In this case, the surface of only those tubes in which the wire electric heating coil is installed is taken into account. The calculated radiation surface of the TSC-400 series emitters is marked in yellow in Figure 5.<\/p>\n\n\n\n
The calculated values of the radiation surface for all series and standard sizes of the emitters are given in the tables "Technical characteristics" on the corresponding pages of the site.<\/p>\n\n\n\n
Specific electrical power consumption<\/h3>\n\n\n\n
Since the radiation surface and the heating electric spiral are structurally related to each other, it is possible to assume that for TSC emitters of the same design (series), but different standard sizes (brands), the heating and infrared radiation generation modes will be identical, provided that the consumed electrical power per unit surface is equal radiation. Expression for calculating the specific electrical power consumption Poud<\/em>1<\/sub> <\/em><\/strong>, W \/ m2<\/sup> will take the form:<\/p>\n\n\n\n
![\"Expression](\"http:\/\/nomacon.by\/wp-content\/uploads\/ik-harakteristiki-form7.png\")
<\/figure><\/div>\n\n\n\nOn the pages of emitters of the same series, there are universal graphs of their heating, depending on the consumed specific electrical power.<\/p>\n\n\n\n
Radiating surface temperature<\/strong><\/h3>\n\n\n\n
It is a definable parameter when calculating infrared heating modes. The "Specifications" tables on the emitter pages show the measured values of the emitting surface temperature Tiz<\/em>1<\/sub> <\/em><\/strong>, \u00b0 C depending on the rated electric power of the emitters Piz<\/em>1<\/sub> <\/em><\/strong>, W, or specific electrical power consumption Poud<\/em>1<\/sub> <\/em><\/strong>, W \/ m2<\/sup>.<\/p>\n\n\n\n
Measurements of the temperature of the emitting surface of the TSC emitters were carried out by two methods. <\/p>\n\n\n\n
- Contact method<\/strong> made it possible to continuously record heating and cooling curves using thermocouple microsensors of temperature rigidly fixed on the radiation surface (thermocouple TXA (K) with a measuring junction diameter of 0.5 mm) (see Figure 6). <\/li>
- Contactless pyrometric method<\/strong> measuring the temperature of the radiating surface by its thermal radiation was used in a steady state to determine the emissivity (emissivity) of the radiating surface \u03b51<\/sub><\/em><\/strong><\/li><\/ul>\n\n\n\n
- wavelength 1.4-3 microns - radiation absorbed by the epidermis and the connective tissue layer of the skin (IR-B range<\/strong>);<\/li>