Spectral optical characteristics of nanoparticles for effective extinction of black body radiation with high temperatures
Introduction
Fires are characterized by a number of parameters — the area of the fire, the temperature of an open fire surface, and others. The main damaging factors of fires are the direct effect of flame and heat radiation from a fire [1]. A direct effect of thermal radiation with high temperatures on objects and people is main interest. As a result of the absorption of thermal radiation energy, objects are heated, burned and destroyed. People are dying or getting burns of the body and upper respiratory tract of different degrees of severity.
Up to 50% of heat input from a heat source comes from thermal radiation [1], [2], [3], [4], [5], [6]. Note, that the surrounding air is transparent (diathermic) for thermal radiation, so the air temperature rises a little bit when radiation passes through it.
The characteristic temperatures of different types of fires (oil and gas, forest, metals, etc.) vary in the approximate range of about 1000–2000 K. Instead of fires, the implementation of high-temperature technological processes (metal melting, gas and plasma metal cutting, rolling mills, forging presses) is carried out in the industry with realization of the characteristic temperatures in the same range. The intensity of thermal radiation depends on the temperature and area of the source and the degree of blackness of its surface. Radiation from all of the above radiation sources can be simulated with a black body (BB) radiation with a sufficient degree of accuracy [1,5,6].
The purpose of passive protection application against the effects of intense radiation from a fire is to protect people's lives and their escape routes, to ensure safety of firefighters involved in extinguishing a fire, and to minimize material damage. Radiation source shielding is the most common and effective way to protect against thermal radiation [7]. Screens are used both for shielding radiation sources and for protecting workplaces from the radiation screen according to the laws of geometric optics. Some screens were made of various effects.
Radiation, interacting with the substance of the transparent and semitransparent screens, basically bypasses the stage of conversion to thermal energy and propagates inside the silicate, quartz, metallized glasses, as well as films. Fire-resistant glasses [8] provide protection and fire safety of people's lifes, protects the infrastructure of the building and limits damage from fire. However, it needs to improve the extinction properties of existed glass screens. It is necessary to achieve a significant attenuation of radiation, first of all, in the infrared region of the spectrum, in which from 50 to 90% of its radiation energy is concentrated depending on the radiation temperatures in the range 1000–2000 K.
For this purpose, it is proposed to investigate of optical properties and select nanoparticles (NPs), immersed in glass, that can effectively attenuate the energy of optical radiation in the visible (VIS) and infrared (IR) regions. A comparative investigation and analysis of the optimal parameters of various NPs for effective attenuation of optical radiation from BB with temperature of about 1000–2000 K is still missing.
The spectral optical characteristics of single NPs in glass (quartz), depending on the radiation wavelength and the parameters of NPs for the effective attenuation (absorption, scattering and extinction) of optical radiation from various natural or technology sources with a temperature of the radiator surface with an interval of 1000–2000 K based on computer simulation have been investigated.
Section snippets
Methods and materials
Recent years, numerous scientific investigations have been focused on the research of the unique optical properties of NPs [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22]. The surface plasmon resonance of radiation on a NP determines the optical properties and the efficiency of absorption and scattering of radiation by a NP.
A preliminary analysis of optical properties of different homogeneous (metallic) NPs showed practical impossibility to use them for
Results and discussion
Fig. 1, Fig. 2, Fig. 3 show the dependences of the BB normalized optical radiation intensity Iλn on the wavelength λ (1) for three values of temperature TS = 1000, 1500, 2000 K with the locations of the maximum values of intensity Iλn(ТS) = 1 at λmax on the λ axis in accordance with (3). The positions λmax for different TS are indicated by solid vertical lines in Fig. 1, Fig. 2, Fig. 3. It should be noted that the radiation wavelength varies inside wide spectral interval of 200–7000 nm with a
Conclusions
The strongly enhanced extinction of BB visible and infrared radiation by NPs in a wide spectral interval of 200-6000 nm is of scientific and technical interest. The selection of single NP for extinction of radiation from BB requires the simultaneous fulfillment of the following conditions - the dependence of NP Kext on λ should be maximally close to the dependence Inλ(λ), ≈λmax, the use of NPs with maximal value of and fulfillment of the condition Kabs > Ksca, P1 > 1.
The
CRediT authorship contribution statement
V.K. Pustovalov: Conceptualization, Methodology, Writing - original draft, Investigation. L.G. Astafyeva: Software, Visualization, Investigation.
Declaration of Competing Interest
The authors declare no conflicts of interest.
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