Radiative Properties Of Materials Research Articles

Dust-Induced Regulation of Thermal Radiation in Water Droplets

Accurate and fast prediction of thermal radiation properties of materials is crucial for their potential applications. However, some models assume that the media are made up of pure water droplets, which do not account for the increasing deviations caused by volcanic eruptions, pollution, and human activities that exacerbate dust production. The distinct radiation properties of water and dust particles make it challenging to determine the thermal radiation properties of water droplets containing dust particles. To address this issue, we investigate the influence of dust particles on light transmission and energy distribution in water droplets using the multiple sphere T-matrix method. By considering different droplet and dust diameters, volume fractions, and position distributions, we analyze how extinction regulation is achieved in dust-containing water droplets. Our results reveal the significant role of dust particles in the thermal radiation effect and provide insights into the electromagnetic properties of colloidal suspensions. Moreover, the dust-induced reestablishment of energy balance raises concerns about environmental management and climate change. This research highlights the importance of accounting for dust particles in atmospheric models and their potential impact on radiative balance.

Analysis on influence factors for transmission measurements of absorbing and scattering media based on the internal optical-path of FTIR spectrometer

Fouriertransforminfrared(FTIR) spectrometer is commonly used to obtain spectral radiation characteristic parameters of various materials based on transmission or reflection mode. The analysis model for transmission measurements of absorbing and scattering media is established based on the internal optical-path of FTIR spectrometer. According to the experimental phenomenon observed in transmission measurements, the influence of several factors on measuring transmission spectra is studied, including geometric parameters of the measurement optical-path and spectral radiation properties of materials. Based on the verification of calculation model, the relationship between the detected transmittance by the internal optical-path of FTIR spectrometer and the optical thickness of materials is proposed in a similar form as Beer’s law. This study has certain guiding significance for the subsequent use of FTIR spectrometer in the measurements of radiation properties for absorbing and scattering materials.

Cryogen-free apparatus for rapid thermal emissivity measurements at low temperature

Thermal radiation is a significant way of heat transfer among insulation parts. For minimization of heat leakage, the radiative properties of materials are essential for the design of cryogenic devices. Emissivity is a key element of radiation properties of materials. However, such experimental data are always not sufficient, especially at cryogenic temperature. In order to measure the radiative properties of material surfaces, a measurement device was presented. The device is based on a two-stage Gifford-McMahon refrigerator and the dismountable sample test rod has independent vacuum environment, which allows the sample to be replaced rapidly. In emissivity measurement, the temperature of examined samples can be controlled precisely between 15.4 K to room temperature.

Thermomechanical behavior of semitransparent bodies with cavities under thermal radiation

UDC 539.3 A mathematical model for the description of coupled processes of radiative heat exchange, heat conduction, and deformation in semitransparent bodies under thermal radiation is generalized for the case of these bodies with closed structural cavities. The model is based on the phenomenological theory of radiation and theory of quasistatic thermoelasticity in the description of radiation properties of materials by spectral characteristics and taking into account properties of the medium on cavities. As an example, we investigate the thermostressed state of a hollow sphere filled by gas under homogeneous radiation from a heated external spherical surface. A large number of elements of modern devices of electronic, electrovacuum, and vacuum equipment have cavities of structural and functional application. In the process of manufacture and operation, they are often subjected to complex actions, among which thermal action is the most important. That is why, in recent years, the

Radiative properties of materials with surface scattering or volume scattering: A review

Radiative properties of rough surfaces, particulate media and porous materials are important in thermal engineering and many other applications. These properties are often needed for calculating heat transfer between surfaces and volume elements in participating media, as well as for accurate radiometric temperature measurements. In this paper, recent research on scattering of thermal radiation by rough surfaces, fibrous insulation, soot, aerogel, biological materials, and polytetrafluoroethylene (PTFE) is reviewed. Both theoretical modeling and experimental investigation are discussed. Rigorous solutions and approximation methods for surface scattering and volume scattering are described. The approach of using measured surface roughness statistics in Monte Carlo simulations to predict radiative properties of rough surfaces is emphasized. The effects of various parameters on the radiative properties of particulate media and porous materials are summarized.

Method for measurement of radiation, transmission, and reflection coefficients of semitransparent materials

Basic principles and results of testing a technique for determining the radiation properties of materials are presented.

Study of the ignitability and thermal radiation properties of materials based on polymers

Study of the ignitability and thermal radiation properties of materials based on polymers

New materials in solar energy utilization

The radiation properties of materials determine to a large degree the performance of solar exchangers, while the physical properties determine design variables such as thicknesses of sections, etc. New materials are becoming available, and new modifications of old materials are being developed, which are of immediate and potential importance in reducing the cost of use of solar energy, and increasing the temperature range over which solar exchangers can operate. Notable among these materials are plastics for cover use or for reflecting surfaces, selective surfaces, glasses with particular properties advantageous for cover materials or reflectors, and the honeycomb absorber that limits reradiation and convection.