Thermal Radiation Intensity Research Articles

Modeling the Optimal Distance Between Pipes in a Solar Water Heating Collector

This study proposes a mathematical model based on normal distribution to determine the optimal distance between pipes in a solar water heating collector. The model takes into account key system parameters such as material thermal conductivity, heat losses, and solar radiation intensity. Experimental data collected for model validation confirm its accuracy and adequacy. The main results show that the maximum efficiency (η) of the solar water heating collector is achieved at a pipe spacing of approximately 0.0469 m. The analytical method demonstrates a smooth decrease in efficiency when deviating from the optimal distance, whereas the experimental data indicate a high sensitivity of the system to changes in this parameter. Thus, the proposed model is a useful tool for designers, allowing for precise prediction of optimal system parameters and increased efficiency. Further research and experiments are planned to improve model accuracy and expand its applicability.

Simulation study of multi-layer titanium nitride nanodisk broadband solar absorber and thermal emitter

Solar energy has always been a kind of energy with large reserves and wide application. It is well utilized through solar absorbers. In our study, the finite difference time domain method (FDTD) is used to simulate the absorber composed of refractory metal materials, and its absorption performance and thermal emission performance are obtained. The ultra-wide band of 200 nm–3000 nm reaches 95.93% absorption efficiency, of which the bandwidth absorption efficiency of 2533 nm (200 nm–2733 nm) is greater than 90%. The absorption efficiency in the whole spectrum range (200 nm–2733 nm) is 97.17% on average. The multilayer nanodisk structure of the absorber allows it to undergo strong surface plasmon resonance and near-field coupling when irradiated by incident light. The thermal emission performance of the absorber enables it to also be applied to the thermal emitter. The thermal emission efficiency of 95.37% can be achieved at a high temperature of up to 1500 K. Moreover, the changes of polarization and incident angle do not cause significant changes in absorption. Under the gradual change of polarization angle (0°–90°), the absorption spectrum maintains a high degree of consistency. As the incident angle increases from 0° to 60°, there is still 85% absorption efficiency. The high absorption efficiency and excellent thermal radiation intensity of ultra-wideband enable it to be deeply used in energy absorption and conversion applications.

A dynamic thermal radiation insulation method for directional solidification of polysilicon

To simplify the structure and reduce the high energy consumption of thermal insulation structures for polysilicon directional solidification equipment, an innovative cavity structure with a mirror and diffuse reflector was designed for thermal insulation. This method uses an internal thermal radiation cavity instead of a traditional insulation layer. Compared with the traditional insulation material, its volume was only 16.6 % of the crucible volume, and the energy consumption was reduced by 8.6 %. A mathematical model of the thermal radiation exchange in the cavity was established and solved analytically. Because of the design of mirror and reflector, the self-adjustment of the thermal radiation intensity and angle in the cavity was theoretically verified. It could automatically “trail” the temperature change on the sidewalls of the melt (crucible), and the dynamic thermal compensation was equivalent to an adiabatic construction. Three comparison experiments with a large ingot (0.9 m × 0.9 m × 0.35 m) were performed. When the cavity height to width ratio was greater than 3.33, the thermal compensation was poor and the quality of the ingot is lower than that of the others. The experiments showed that refractory brick and polished brass are a good combination for creating a cavity.

Comprehensive assessment of emergency fire risks during oil and gas well drilling

The study aims to perform a comprehensive assessment of emergency fire risks when drilling oil and gas wells for open flowing of the well with gas flare combustion and the combustion caused by diesel fuel spills. The object is a well site of the oil and gas condensate field in the Irkutsk region. A retrospective analysis of emergency situations during oil and gas well drilling identified the most frequent types of accident - fires at oil and gas production facilities, open fountains and emissions from wells. Scenarios for these accidents were developed and event trees were built. Using them, options with the greatest possible damage caused by a fire were identified. The intensity of thermal radiation was estimated at various distances from the center of the flare with open flowing of the well with the gas flare combustion. The intensity of thermal radiation during a fire caused by diesel fuel spills was calculated for the destruction of three RVS-50 tanks. Safe distances from the accident site and possible fatal injuries to the personnel were identified.

Evaluating the Combustion Performance of the Usual Timbers in Furniture Using a Grey Correlation Method Based on Thermolysis, Ignition, and Flame Spread

Timber is the most widely used material for furniture in view of its characteristics of light mass, high strength, easy processing, coloring, and decorative appearance. However, the flammability of wood has been frequently associated with increased fire intensity and the rapid spread of fire in buildings. In this paper, the combustion performance of six kinds of common furniture timber was investigated based on thermogravimetric analysis at 25–500 °C, cone calorimetry with 50 kW/m2 thermal radiation intensity, and flame spread experiments with 3 kW/m2 thermal radiation intensity. The ignition, weight loss, thermogenesis, smoke, and flame spread characteristics of these timbers were obtained. Subsequently, a comprehensive index system including thermal stability, heat release ability, smoke production capacity, and flame spreading speed was constructed to evaluate the combustion performance of the selected timbers. In addition, a grey correlation method relying on the game theory to assign weight was proposed for the quantitative analysis of the relevant evaluation indexes. As a result, the combustion performance of the six kinds of timber, which was defined as a specific value from poor to good, was as follows: pine (0.8696) > Chinese fir (0.8568) > Oriented Strandboard (OSB) (0.8425) > density board (0.8122) > plywood (0.8087) > elm (0.7909). Timber with poor combustion performance contributes to the reduction in fire risk in buildings. Our suggestions are of great significance for selecting furniture timber from the perspective of the prevention and control of building fires.

Experimental and numerical study of combustion in pipe cutting operations with hydrogen-blending gas

This study investigated the flame combustion of gas-containing pipe cutting operations by combining experimental and numerical simulation techniques. Based on the empirical flame length formula and experimental and numerical simulation flame length data, a flame length formula for gas outlet with large aspect ratio was proposed. In the experimental phase, cutting experiments were conducted with cutting slit lengths of 1–11 cm for pipe pressures of 10–550 Pa and hydrogen doping ratios of 0%, 10%, and 20%. The flame lengths were then measured. A hydrogen-doped natural gas combustion model based on the vortex dissipation conceptual model and Grimech-3.0 mechanism was established to simulate the experimental conditions. The flame lengths derived from the numerical simulation were in good agreement with the experimentally measured flame lengths, with an average error of 7.02%. This indicates that the reliability of the numerical model can be verified. The effects of hydrogen doping ratio, tube pressure, and cutting slit length on flame length and thermal radiation range were investigated using the control variable method. The results demonstrated that hydrogen doping reduced flame length and flame length away from the flame. Furthermore, an increase in pipe pressure and single cut length also resulted in an increase in flame length. It was observed that under normal operating conditions, a safe intensity of thermal radiation could be maintained within the operating distance when the operator wore protective clothing.

Redshift and Photon Energy Attenuation Constant in Vacuum

There obtained an estimate of the minimum value of the photon energy attenuation constant in vacuum α: α = 8 · 10–19 m–1 based on quantum concepts of the structure of vacuum and data on the red shift of the emitter spectra of distant galaxies. Presumably, the cosmic microwave radiation is partly the thermal vacuum radiation heated by the photon fluxes from the infinite universe. Despite the universe infinity, the sky is dark precisely due to the photon’s energy absorption from distant and ultra-distant galaxies in vacuum, and not only the photon absorption during various interactions with the gas or dust components of intergalactic clusters. Thus, the emission spectrum of these ultra-distant objects is transformed into the microwave range, which complements the intensity of thermal radiation in this range. The inconsistency of alternative explanations for the red shift is shown: the Doppler effect in the cosmological model of the expanding universe and the Big Bang, and the gravitational shift.

Study on combustion characteristics of glass fiber/phenolic resin composites

In order to study the combustion characteristics of glass fiber/phenolic resin composites, a conical calorimeter was used to explore the combustion characteristics of glass fiber/phenolic resin composites in an aircraft frame under different thermal radiation intensities, and the fire hazard of the materials was evaluated by evaluation index, and the limiting oxygen index at different temperatures was explored by combining the high temperature oxygen index meter. The test results show that when the ambient temperature increases from 20 °C to 220 °C, the limiting oxygen index first increases from 86.6 % to 93.7 %, and then decreases to 84.4 %. The oxygen consumption and CO2 release increase with the increase of thermal radiation intensity during combustion, and the release of CO decreases with the increase of thermal radiation. The heat release rate curve of the test material has only 1 enhancement peak. The heat radiation intensity increased from 50 kW/m2 to 70 kW/m2, and the peak heat release rate of the test material combustion increased from 64.7 kW/m2 to 100.7 kW/m2. The rate of mass loss of materials accelerates with the increase of thermal radiation intensity; As the intensity of thermal radiation increases, the fire hazard of the material increases.

Infrared thermography detection of grouting defects in post-tensioned tendon ducts under active thermal excitation

The efficacy of employing infrared thermography (IRT) for concrete bridge deck inspection has been well established. Although an IRT detection method during construction stage under hydration heat excitation had been proposed in old works, it is also essential to be applicated in the existing large amounts of bridges in service, while it can be challenging due to factors, such as the substantial depth of the ducts and the variation in duct materials. Therefore, this study presents an IRT detection method for grouting defects in post-tensioned tendon ducts under the stimulation of a shortwave infrared heater. The investigation explores the influence of different factors, such as duct depth, length, grouting compactness level, and duct material, on the detection results and the corresponding heating durations required. Results indicate that with a thermal radiation intensity of approximately 550 W/m2 with a heating duration of 45 mins and followed by a cooling period of 90 mins to 130 mins, the detection of fully grouted void defects within 350 mm long ducts made of polyvinyl chloride (PVC) at burial depths of 50, 70, and 90 mm is feasible. For the best detection results, grouting void defects buried at a depth of 50 mm should be detected after a maximum heating duration of 75 mins and 90 mins corresponding to the PVC ducts and metal ducts. The detection effectiveness is higher for PVC ducts than for metal ducts. Furthermore, an environmental impact analysis should be carried out in the future to make this method into practice.

The significant role of Darcy–Forchhiemer with integrated hybrid nanoparticles (Graphene and TiO 2) on dusty nanofluid flow subjected to heat conduction

The thermal analysis of two-phase models that deal with the fluid and dusty phases has been considered. This study instigates the flow of a non-miscible, dusty hybrid nanofluid over a stretching cylinder with Darcy–Forchheimer permeability in the presence of thermal radiation. The mathematical model is based on the single-phase nanofluid model, which features modified thermophysical characteristics. This innovative flow model explores how important it is to enhance the concentration of dust particles in fluid dynamics. Hybrid nanoparticles are substituted for nanoparticles in a conventional case to accelerate the heat transfer rate of the fluid. Therefore, in this study, the magnetohydrodynamic flow of hybrid nanofluids and heat transfer of non-Newtonian dusty fluids with suspensions of hybrid nanoparticles have been examined. The appropriate dimensionless variables are used to convert the governing periodic model into a non-dimensional form. The finite-difference-based bvp5c algorithm is used through Matlab for numerical analysis of the set of obtained ordinary differential equations. The graphs explored the influences of relatable factors over the profiles of mass, heat, and velocity transfers. It is observed that with intensifying values of Eckert number (Ec) and Biot number (Bi), the temperature of both phases increased at a significant level, and the velocity decreased with increasing intensity of the magnetic field. The computational results of velocity, core temperature, and intensity dispersion are significant for both aspects. Furthermore, it is observed that both the fluid and dust phases exhibit declining behavior as a result of the impact of porosity, mass concentration, and magnetism on the flow stream. Moreover, it is noticed that both the dust phase temperature θ p ( η ) and fluid phase temperature θ ( η ) intensified with the high intensity of magnetic field and thermal radiation. The missile nozzles, nuclear power plants for aerospace and gaseous-core nuclear rocket systems, and the radiation are considered for evaluating heating significance.

ON THE ISSUE OF COMPREHENSIVE ASSESSMENT OF THE IMPACT OF THERMAL RADIATION AT WORKPLACES, TAKING INTO ACCOUNT AIR POLLUTION

Problem statement. The research demonstrates that existing methods for determining the distribution of thermal radiation intensity using nomograms and formulas contain significant errors. This is due to the adoption of a number of simplifications regarding numerous interdependent parameters, including the temperature inside furnaces, the size of openings and shafts, etc. As a result, there is a need for measurements of thermal radiation intensity at distances of 5−10 meters and beyond. The purpose of the article. The objective of the article is to propose a concept for a new experimental methodology to investigate the intensity of radiation exposure to workers at their workplaces. Simultaneously, in order to address the issues of thermal protection for workers, actual measurement data of thermal radiation levels are necessary for each workstation under real working conditions within the workspace. Conclusion. It is important to characterize the composition of the gas environment, as its impurities can distort the distribution of radiant energy through interference and diffraction effects, which need to be considered for microclimate optimization. The presence of dust particles complicates the straight-line heat transfer through scattering and scintillation of rays, requiring further improvement of models. Turbulence, impurities, and atmospheric heterogeneity are important factors that need to be further investigated and taken into account in heat transfer process modeling. Scintillation affects the quality of radiation transmission, necessitating further study of this phenomenon. Local atmospheric composition peculiarities require the development of models that consider these variations. The obtained experimental data will contribute to improving the accuracy of modeling and enhancing working conditions. Further refinement of measurement techniques is necessary for obtaining reliable information.

ОЦЕНКА ВОЗМОЖНОСТИ ЭСКАЛАЦИИ ПОЖАРА ПРИ ХРАНЕНИИ МОТОРНЫХ ТОПЛИВ В ПОЛИМЕРНЫХ ЭЛАСТИЧНЫХ РЕЗЕРВУАРАХ

Due to the increase in oil production and production of petroleum products, as well as their transportation and storage, the range and sizes of reservoirs are increasing. For this purpose, polymer tanks are widely used at Russian enterprises of the fuel and energy complex, including mobile tank farmsand oil depots for the operational storage of oil and petroleum products. However, the polymer materials from which the tanks are made are flammable, which increases their fire hazard level. An assessment of the possibility of fire escalation has been carried out using the example of an oil depot model for storing motor fuels in polymer elastic tanks. The results 
 of calculating the dangerous factors of a spill fire during depressurization of polymer elastic tanks with gasoline and diesel fuel, as well as a graph of the dependence of the intensity of thermal radiation during the ignition of these tanks, are presented in tabular form, and an event tree is constructed. The parameters characterizing the possible escalation of a fire at a motor fuel storage site under quasi-stationary conditions have been determined.
 A methodology is proposed that allows assessing the possibility of realizing the escalating nature of a fire at facilities for storing and handling motor fuels in polymer elastic tanks, and recommendations are also given to prevent the progressive nature of the development of negative events and reduce damage in case of fire.

The Influence of the Heat Transfer Mode on the Stability of Foam Extinguishing Agents

The mass loss mechanisms of an aqueous film-forming foam (AF foam), an AR/AFFF water-soluble film-forming foam extinguishing agent (AR foam), and a Class A foam extinguishing agent (A foam) at different levels of thermal radiation, thermal convection, and heat conduction intensity were studied. At a relatively low thermal radiation intensity, the liquid separation rate of the AF, AR, and A foams is related to the properties of the foam itself, such as viscosity and surface/interface tension, which are relatively independent of the external radiation heat flux of the foam. At low radiation intensity (15 kW/m2 and 25 kW/m2), the liquid separation rate of the AF and A foams is relatively stable. When the heat flux intensity is 35 kW/m2, the liquid separation rate of the AF and A foams increases notably, which may be mainly due to the rapid decrease in foam viscosity. And the mass loss behavior is dominated by liquid separation in the AF, AR, and A foams under the influence of thermal radiation and thermal convection. Under the same experimental conditions, the liquid separation rate of AF is the fastest. There is no significant difference in the evaporation rates of the three kinds of foam in the same heat conduction condition. In addition, the AR and A foams usually have a 25% longer liquid separation time (t) under thermal radiation and thermal convection, and the thermal stability is better than AF foam. The temperature reached by the AF foam layer under thermal convection was lower than that of the AR and A foams, and the time for the foam layer to reach the highest temperature under heat conduction was longer than that of the AR and A foams.

Gas-Flow-Rate Inversion Based on Experiments and Simulation of Flame Combustion Characteristics in a Drilling Blowout

Accurately estimating the gas-flow rate at a wellhead to invert the formation pressure and production capacity information can be the basis for subsequent well-killing parameter design following oil and gas-well drilling blowout and ignition. Based on the multicomponent characteristics of the blowout gas and the turbulence intensity of the blowout flame, as well as the effects of complex factors such as environmental wind direction, wind speed, and wellhead structure, a numerical model for actual drilling blowout ignition is established. Jet-flame experiments are conducted under blowout conditions to verify the accuracy of the model. The temperature and radiation fields and flame morphologies of the well jet flow flame under different lateral wind speeds, well jet flow rates, and wellhead diameters are analyzed. Previous studies have found that as the lateral wind speed increases, the maximum temperature and maximum thermal radiation intensity of the blowout flame first decrease and then increase. However, as the amount of well jet increases, although the flame influence area increases, the maximum temperature does not increase significantly, and the maximum thermal radiation intensity actually decreases. Based on experimental and numerical simulation datasets, a high-yield gas-well jet volume prediction method based on the flame height and thermal radiation intensity of the well jet flow is constructed, which has important engineering application value for achieving successful well killing following well jet ignition.

Study on the Engineering Application of LNG Accident Consequence Model in the Design of Terminal Sump

In order to provide a theoretical basis for the design of the LNG terminal sump, this paper proposes a suitable mathematical model and solution method by analyzing the physical process of evaporation diffusion and thermal radiation of the sump. Combined with the engineering practice, a lot of calculations have been carried out on the vapor diffusion concentration and pool fire thermal radiation intensity of the terminal sump, and the correlations between the vapor concentration and thermal radiation intensity and their influencing factors have been quantitatively calculated. Based on the analysis of the calculation results, it is concluded that the vapor concentration and thermal radiation value at the fire control room of the wharf are strongly related to the equivalent diameter of the sump and the distance from the fire control room to the sump. Among them, the distance from the fire control room to the sump is more closely related to the vapor concentration, and the equivalent diameter of the sump is more closely related to the thermal radiation; Keeping 19.2~33.8meters between the fire control room and the sump can basically ensure that the vapor concentration at the fire control room does not exceed the standard; In order to ensure that the thermal radiation at the fire control room does not exceed the standard, the distance between the fire control room and the sump should not be less than 15meters, and the equivalent diameter of the sump should not be greater than 7meters. The research methods and conclusions proposed in this paper can provide useful reference for engineering designers, and also build a bridge for mutual reference and application for theoretical research and engineering practice.

Optimized Machine Learning Model for Fire Consequence Prediction

This article focuses on using machine learning to predict the distance at which a chemical storage tank fire reaches a specified thermal radiation intensity. DNV’s Process Hazard Analysis Software Tool (PHAST) is used to simulate different scenarios of tank leakage and to establish a database of tank accidents. Backpropagation (BP) neural networks, random forest models, and the optimized random forest model K-R are used for model training and consequence prediction. The regression performance of the models is evaluated using the mean squared error (MSE) and R2. The results indicate that the K-R regression prediction model outperforms the other two machine learning algorithms, accurately predicting the distance at which the thermal radiation intensity is reached after a tank fire. Compared with the simulation results, the model demonstrates higher accuracy in predicting the distance of tank fire consequences, proving the effectiveness of machine learning algorithms in predicting the range of consequences of tank storage area fire events.

Steering Thermal Radiation

Thermal radiation is a physical phenomenon exhibiting dual characteristics of both light and heat. Sunlight, serving as the primary source of energy, emanates as thermal radiation from a high-temperature surface at 5,700 K. It is also responsible for the feeling of warmth experienced when individuals congregate and non-contact measurement of body temperature. Thus, thermal radiation exists everywhere in our daily life. However, in the early 20th century, thermal radiation posed a challenge to physicists. The endeavor to elucidate the spectrum of thermal radiation led to the concept of light as photons, therefore signaling the advent of quantum physics. It is known that thermal radiation uniformly emits, irrespective of its direction and polarization, with the spectrum dictated by Planck’s law. Yet, this commonplace should be modified when thermal radiation encounters the principle of nanophotonics. Herein lies the ability to modulate the intensity of thermal radiation across desired wavelengths, directions, and polarizations. In this article, we will delve into the latest research findings concerning the manipulation of thermal radiation and its promising applications.

Hunting Resource Management by Population Size Control by Remote Sensing Using an Unmanned Aerial Vehicle

The study was carried out on the territory of the Kemerovo region-Kuzbass (Western Siberia, Russia). The purpose of the study was to obtain information on the species diversity and population of big-game animals. The monitoring was carried out on the forest territories of the region’s administrative districts. In the course of remote sensing using an unmanned aerial vehicle, the presence of all types of animals under consideration, except for the bear, was recorded. The deviation of the population number determined using the traditional method of digital technologies varied up to 50%. It was established that environmental measures organized and carried out by the regional administration and hunting farms improved the situation and stabilized the population of the main group of game animals. It was found that when using a sufficiently high sensitivity of the thermal imager (the used thermal imager had a very high sensitivity class ≤ 60 mK at 300 K), long-haired animals, which are characterized by a lower intensity of thermal radiation (for example, wolves) are identified and recognized in the images. The larger the animal and the worse the thermal insulation layer (wool or feathers), the easier it is to identify it in infrared images and the lower the sensitivity requirements of thermal imagers. The ability to recognize and record smaller animals and birds requires additional research on existing technologies. Our research has confirmed the validity of digital remote monitoring methods for managing the wildlife of hunting farms and nature conservation areas of the Siberian Taiga territories.

Оценка опасности теплового излучения водородного пламени

Today, due to the rapid development of the hydrogen power industry, fire safety of hydrogen-containing facilities becomes a matter of great importance. Risk assessment for the hydrogen power facilities is one of the key objectives of the development. To find the solution, the information on the intensity of hydrogen flare radiation must be obtained. At the same time, such information published in literary sources is often incomplete and sometimes even contradictory. Therefore, the study aims to review the literary sources published in Russian and international journals. The basic value required to assess fire hazard is the intensity of the surface radiation of hydrogen flame. The study considered four types of the flame; i.e., the gaseous jet flame, the jet flame of liquid hydrogen, the flame in the liquid hydrogen pool, and the fireball. Remarkably, the intensity of the surface thermal radiation of hydrogen flame is significantly lower when compared with the hydrocarbon flame. For fire hazard calculations, the intensity of the surface thermal radiation of jet flame of gaseous hydrogen can be adopted as equal to 33 kW/m2. The surface thermal radiation intensity value for the hydrogen fireball can be adopted as equal to 330 kW/m2. The intensity of the surface thermal radiation at liquid hydrogen combustion (for both jet flame and pool fire) can be adopted as equal to 80 kW/m2.

Влияние скорости воздушного потока на тепловое излучение от углеводородного пожара в резервуаре для хранения нефти

Purpose. The article assesses the effect of air flow velocity on the intensity of thermal radiation from a fire in a vertical steel tank with a floating roof of 65 000 m3 capacity (VSTWFR-65000) with crude oil. The indicators of hazardous fire factors - open flame, smoke and temperature at different wind speeds – have been studied. Methods. The method of numerical modeling in the Fire Dynamics Simulator software package, as well as the method of processing the obtained research results have been used in the study. Findings. The dependence of the flame inclination angle at different air flow speeds has been obtained. The simulation results have been shown: smoke distribution at different wind speeds, as well as temperature change at a distance from the fire source depending on the air flow velocity. Research application field. The results of the study can be used in the development of design documentation for measures to ensure fire safety of a tank farm with floating roof tanks, as well as in adjusting fire extinguishing plans. Conclusions. Based on the simulation results it has been found that with an increase in the air flow velocity the intensity of thermal radiation initially increases and then decreases. It has been found that at an air flow velocity of 9 m/s the maximum thermal radiation reaches 23.43 kW/m2 at the nearest point of the adjacent tank in the projection from the central axis of the burning tank. At an air flow velocity of 6.5 m/s the temperature at the top of the adjacent tank reaches 176 °C, and at 9 m/s – 426 °C, which is higher than the autoignition temperature of oil, which is within 222–256 °C, there by creating a threat of fire spread. The study has defined the maximum distances from the burning VSTWFR-65000 for the safe presence of people, amounting to 47.3; 48.9; 50.2; 53.4; 55.7; 56.8; 59.4 m for wind speed of classes 0, 1, 2, 3, 4, 5 and 6 respectively.