Average Radiation Flux Research Articles

Green Energy: An Ideal Energy Solution for Sustainable Development of Afar Region, Ethiopia

Green energy is the primary concern for the sustainable development of Ethiopia’s Afar region. The study’s goals are to present scientific evidence of the Afar region’s energy potential to researchers and industry sectors. We used solar shortwave, radiation transfer model, miniscale meteorological model for the Weather Research Forecast (WRF), and spatial and temporal simulation as research techniques. The data show that the Afar region has an energy potential of 239.9 W/m2 average solar radiation flux, 2.102 MW·h/m2 average annual solar density, 131.18 W/m2 average wind power density at h = 10 m , and 204.5 W/m2 average wind power density at h = 50 m . We discovered that solar energy and wind energy are potential energy sources in the Afar region for energy consumption such as solar cooking, solar lighting, and small DC applications.

A Linear Hybrid Concentrated Photovoltaic Solar Collector: A Methodology Proposal of Optical and Thermal Analysis

The photovoltaic cell surface in linear hybrid concentrated solar collectors receives non-uniform radiative flux, causing additional thermal stress due to hot spots and reducing its electrical performance and durability. The current study proposes a parametric methodology to determine the optimal receiver displacement required in a linear Cassegrain-type hybrid solar collector. The aim was to achieve a minimal non-uniformity distribution and a high radiative flux over the photovoltaic cells, considering optical errors close to real environment conditions and analyzing the heat transfer to determine the electrical and thermal efficiencies. The developed methodology was applied to analyze a case study with a receiver width of 0.125 m and rim angle of 80° and using a commercial silicon photovoltaic cell that supports up to 7000 W/m2. After applying the methodology, a hybrid solar collector with a concentration ratio of 13.0 and receiver displacement of 0.14 m is recommended. As a result, 5728 W/m2 of average radiative flux with non-uniformity lower than 4% was achieved. Thus, thanks to the proposed configuration, a low non-uniformity and high radiative flux were achieved, benefiting the photovoltaic cells’ life while improving their operation.

A Comparative Analysis of Flame Temperature, Radiation Behaviors, and NOx Emission of an Oil Burner Fueled With Nano Biodiesel Blend Fuel Containing Suspended Energetic and Non-energetic Metal Nanoparticles

Abstract This study presents a comparative experimental approach to analyze flame temperature, emissions, and radiation behaviors of an oil furnace fueled with nano biodiesel blend fuel containing suspended energetic and non-energetic nanoparticles (NPs). Iron NPs were used as energetic nanoparticles, and alumina (Al2O3) was selected as non-energetic NPs. A dilute homogeneous mixture (500 ppm) was provided from each NPs in B20 blend fuel. The fuels were burned in an oil burner subsequently, and infrared radiation (IR) images of flame, profiles of flame temperature, luminous and total radiation and NOx and CO emissions were gauged and compared. Measurements showed that both NPs improve the evaporation rate of fuel droplets and displace the peak of flame temperature to the flame upstream region. Moreover, nano biodiesel blend fuel containing energetic iron NPs elevates flame temperature while the non-energetic alumina NPs reduce the peak of flame temperature. In addition, both NPs strengthen the nucleation and growth of intermediate soot particles. These fuels containing suspended particles also lead to an increase in the intermediate soot particles content of flame and flame emissivity. This increases IR, luminous, and total flame radiation. The improvement of average flame radiative flux for nano biodiesel blend fuel containing energetic iron NPs and non-energetic alumina NPs is as high as 25% and 10%, respectively. Also, using energetic iron NPs and non-energetic alumina NPs in B20 fuel reduces the NOx emission by 13% and 11%, respectively.

Solar Energy Potential and Future Prospects in Afar Region, Ethiopia

The objective of the study is to provide scientific information of the solar potential of Afar region, for photovoltaic (PV) solar energy industry sectors. The afar region being exceptional solar potential with high average solar radiation flux 239.9W/m² (105.4% of average photon energy surface area of Ethiopia), and average annual solar density of 2.102MW•h/m² (105.5% of the average yearly solar density of Ethiopia). This finding requests the photovoltaic system as an alternative principal energy resource to substitute the present energy system in afar region. These comprehensive indication of the solar energy marketplace in Afar region, Ethiopia, key visions into its governing framework, energy sector, of photovoltaic (PV) industry segments. Therefore, the photovoltaic energy system has the best opportunity for basic energy application in the pastoral community for daily life consumption, such as solar lighting, for solar cooker, small devices and for air conditioning. These studies show that the Afar region gifted with significantly high monthly average daily solar radiation as a potential candidate for development of PV energy systems in Afar region. Therefore, the PV system has the power to run an evaporative air conditioning system effectively. These findings indicate that photovoltaic energy system as most promising energy in the Afar region.

A 28 kWe multi-source high-flux solar simulator: Design, characterization, and modeling

Singapore’s first multi-source high-flux solar simulator (HFSS) that comprises an array of seven 4-kWe xenon short-arc lamps close-coupled with ellipsoidal reflectors is designed, constructed, and characterized. An indirect mapping system that consists of a water-cooled Lambertian target, a CMOS camera, and a heat-flux gauge is adopted herein to experimentally characterize the performance of the developed HFSS. A calibration constant of 192.8 ± 9.6 kW m−2 (GS µs−1)–1 is determined and used to transform the raw-flux maps with grayscale values to the absolute-flux maps. Utilizing a series of flexible and precise adjusters, the variability of ± 1 mm in the x- and y-directions of the peak flux points of the radiation modules is measured. A peak flux of 7740 kW m−2 is measured for the sum of all 7 radiation modules. Average radiative fluxes of 4191 kW m−2 and 2933 kW m−2 can be observed from circular target areas of Ø40 mm and Ø60 mm, respectively, associated with promising electricity-to-target transfer efficiencies of 18.8% and 29.6%. A Monte Carlo ray-tracing (MCRT) model is calibrated by the experimental data. Based on the minimum root-mean-standard deviation between the measured and simulated results of the radiative power on the target, the optimal parameters of the MCRT model include the arc radius of 3.4 mm and the reflector surface error of 1.1 mrad.

Recent Studies on Two-Dimensional Radiative Transfer Problems in Anisotropic Scattering Media

In this work, an explicit formulation to solve two-dimensional radiative transfer problems in anisotropic scattering media is developed. A nodal technique along with the Analytical Discrete Ordinates (ADO) method are used to solve the discrete ordinates approximation of the radiative transfer equation, in Cartesian geometry. To make it possible, the discrete ordinates equations are transversally integrated over regions of the domain reducing the complexity of the model, yielding two one-dimensional equations for average angular intensities in x and y directions. The one-dimensional equations, with approximations for the unknown intensities on the contours of the regions, are then explicitly solved by the ADO method, with respect to the spatial variables, whose solutions are written in terms of eigenvalues and eigenfunctions. The phase function is expanded in terms of Legendre polynomials up to arbitrary order L, to model higher order anisotropy. The eigenvalue problem is derived for this general case and it preserves a relevant feature of the ADO method, which is the reduced order equal to half of the number of discrete directions. Numerical results for the average radiation density and radiative heat flux are presented, for test cases in which the degree of anisotropy can be up to twelve and the albedo assumes different values. A comparative analysis with results available in the literature allows the verification of the formulation and indicates a good performance of the proposed method in coarser meshes.

Effects of ambient conditions on concurrent-flow flame spread over a wide thin solid in microgravity

Two-dimensional numerical simulations were performed to study concurrent-flow flame spread over a thin solid in microgravity. The main variable is the ambient flow velocity. Results were validated against recent microgravity experiments (Saffire) where samples 41 cm wide were burned in two different flow velocities. The numerical results showed that, when flow velocity increases, the average radiative heat flux out of the solid surface in the pyrolysis region remains constant. The average convective heat flux decreases and the average radiative heat flux into the solid surface increases. The average net heat flux remains approximately constant. Additional simulations using different ambient pressures and oxygen percentages further showed that, while away from extinction conditions, the average net heat flux in the sample pyrolysis region and hence the average solid mass burning rate are insensitive to the ambient conditions (i.e., oxygen percentage, flow speed, pressure). Furthermore, the steady-state flame length is mainly controlled by the rate of oxygen entrainment into the gas-phase reaction zone and the average solid mass burning rate. Based on these observations, analytical model was developed to correlate the flame spread rate and flame length to ambient conditions. It predicts that, for concurrent-flow flame spread at steady state, the flame length and flame spread rate have linear dependency on the ambient pressure and the forced flow velocity, and a second order dependency on the ambient oxygen percentage. The proposed correlations were tested against numerical simulations as well as a collection of data from previous microgravity experiments in a wide range of ambient conditions.

Surface Warming During the 2018/Mars Year 34 Global Dust Storm.

The impact of Mars's 2018 Global Dust Storm (GDS) on surface and near‐surface air temperatures was investigated using an assimilation of Mars Climate Sounder observations. Rather than simply resulting in cooling everywhere from solar absorption (average surface radiative flux fell 26 W/m2), the globally averaged result was a 0.9‐K surface warming. These diurnally averaged surface temperature changes had a novel, highly nonuniform spatial structure, with up to 16‐K cooling/19‐K warming. Net warming occurred in low thermal inertia regions, where rapid nighttime radiative cooling was compensated by increased longwave emission and scattering. This caused strong nightside warming, outweighing dayside cooling. The reduced surface‐air temperature gradient closely coupled surface and air temperatures, even causing local dayside air warming. Results show good agreement with Mars Climate Sounder surface temperature retrievals. Comparisons with the 2001 GDS and free‐running simulations show that GDS spatial structure is crucial in determining global surface temperature effects.

Evaluation of urban ozone in the Brahmaputra River Valley

Ozone (O3), carbon monoxide (CO), nitrogen oxides (NOx = NO + NO2), methane (CH4) and non-methane hydrocarbons (NMHCs) were measured in Guwahati in the Brahmaputra River Valley (BRV) of northeastern India from January 1, 2013 to June 30, 2014. The current analysis shows that the annual mean concentrations of O3, CO, CO2, NOx, CH4, and NMHC in Guwahati were 10.5 (±6.30 ppb), 0.5 (±0.2 ppm), 411.7 (±37.5 ppm), 19.6 (±11.6 ppb), 2045(±417 ppb) and 173(±93 ppb), respectively. The pattern of O3concentrations in Guwahati indicated it was strongly influenced by local NOx sources with an adjacent national highway being the likely major source. Thus, the measured O3 values were reduced by local titration. Diel, weekly, and seasonal patterns for each of these gaseous species showed the strong influence of local sources. The mean ventilation coefficient was greater than >6000 m2s during the day in the pre-monsoon season indicating pollutant dispersion. The seasonally average solar radiation (SR) fluxes decreased in the order: pre-monsoon (180 W m−2), monsoon (176 W m−2), post-monsoon (148 W m−2) and winter (110 W m−2).The corresponding mean O3 concentrations were 14.8, 7.5, 6.4, and 10.1 ppb, respectively. In the pre-monsoon season, an impact of SR on the photochemical formation of O3was observed. High O3 winter concentrations were observed likely driven by local biomass burning providing reactive VOCs that contributed to ozone formation.

Experimental study on flux mapping for a novel 84 kWe high flux solar simulator

A novel 84 kWe high flux solar simulator with six instantaneous switch gates is designed in this study. Based on the indirect measurement method, a data acquisition and control software for the flux measurement is developed. A flux measurement algorithm is accomplished based on image processing method. In order to reduce random error, the least squares method is used to fit the average radiative flux and the average gray value. Then, the indirect flux measurement error is analyzed. The total errors of radiative flux and total radiative power for high flux solar simulator with all lamps in operation are ±10.57% and ±10.63%, respectively. The radiative flux mappings of solar simulator at different planes are obtained. The experimental results show that the radiative flux mapping is consistent with the ellipsoidal Gaussian distribution. The maximum system efficiency of 84 kWe high flux solar simulator is 38.1%. The maximum peak flux is 9.3 MW/m2 at the focal plane. The maximum average radiative flux on 5 cm diameter target is 5.2 MW/m2 at +1 cm plane. For a single short-arc xenon lamp, the maximum of peak flux, radiative power and system efficiency reach 1.2 MW/m2, 2.88 kW, and 41.1%, respectively.

Numerical study on the response of the largest lake in China to climate change

Abstract. Lakes are sensitive indicators of climate change. There are thousands of lakes on the Tibetan Plateau (TP), and more than 1200 of them have an area larger than 1 km2; they respond quickly to climate change, but few observation data of lakes are available. Therefore, the thermal condition of the plateau lakes under the background of climate warming remains poorly understood. In this study, the China regional surface meteorological feature dataset developed by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences (ITPCAS), MODIS lake surface temperature (LST) data and buoy observation data were used to evaluate the performance of lake model FLake, extended by simple parameterizations of the salinity effect, for brackish lake and to reveal the response of thermal conditions, radiation and heat balance of Qinghai Lake to the recent climate change. The results demonstrated that the FLake has good ability in capturing the seasonal variations in the lake surface temperature and the internal thermal structure of Qinghai Lake. The simulated lake surface temperature showed an increasing trend from 1979 to 2012, positively correlated with the air temperature and the downward longwave radiation while negatively correlated with the wind speed and downward shortwave radiation. The simulated internal thermodynamic structure revealed that Qinghai Lake is a dimictic lake with two overturn periods occurring in late spring and late autumn. The surface and mean water temperatures of the lake significantly increased from 1979 to 2012, while the bottom temperatures showed no significant trend, even decreasing slightly from 1989 to 2012. The warming was the strongest in winter for both the lake surface and air temperature. With the warming of the climate, the later ice-on and earlier ice-off trend was simulated in the lake, significantly influencing the interannual and seasonal variability in radiation and heat flux. The annual average net shortwave radiation and latent heat flux (LH) both increase obviously while the net longwave radiation and sensible heat flux (SH) decrease slightly. Earlier ice-off leads to more energy absorption mainly in the form of shortwave radiation during the thawing period, and later ice-on leads to more energy release in the form of longwave radiation, SH and LH during the ice formation period. Meanwhile, the lake–air temperature difference increased in both periods due to shortening ice duration.

Heat Transfer Model to Predict Temperature Distribution in the Ground

Knowledge of the temperature of the ground in time and space as well as its thermal properties gives basic information about physical phenomena concerning the transfer and accumulation of heat in the ground. It can be also used for evaluation of the heating possibilities of heat pumps; to proper design the size of the ground exchangers and the depth, at which they should be installed. For this purpose, a mathematical model based on the heat balance equation on the ground surface was developed. The basis of the model is the Carslaw-Jaeger equation regarding the temperature profile in the ground. The model was verified using experimental results for two different locations (different climatic conditions, moderate and arid climate)—the standard deviation is equal 0.62 K and 0.92 K, respectively. In this work, the impact of several parameters on the ground temperature profiles and thermal fluxes was determined. It was found that among the examined parameters the amplitude of the daily average solar radiation flux strongly effects on the total amount of heat transferred between the ground and the environment during the year, wherein the other parameters have a negligible effect.

Atmospheric components of the surface energy budget over young sea ice: Results from the N‐ICE2015 campaign

AbstractThe Norwegian young sea ice campaign obtained the first measurements of the surface energy budget over young, thin Arctic sea ice through the seasonal transition from winter to summer. This campaign was the first of its kind in the North Atlantic sector of the Arctic. This study describes the atmospheric and surface conditions and the radiative and turbulent heat fluxes over young, thin sea ice. The shortwave albedo of the snow surface ranged from about 0.85 in winter to 0.72–0.80 in early summer. The near‐surface atmosphere was typically stable in winter, unstable in spring, and near neutral in summer once the surface skin temperature reached 0°C. The daily average radiative and turbulent heat fluxes typically sum to negative values (−40 to 0 W m−2) in winter but then transition toward positive values of up to nearly +60 W m−2 as solar radiation contributes significantly to the surface energy budget. The sensible heat flux typically ranges from +20–30 W m−2 in winter (into the surface) to negative values between 0 and −20 W m−2 in spring and summer. A winter case study highlights the significant effect of synoptic storms and demonstrates the complex interplay of wind, clouds, and heat and moisture advection on the surface energy components over sea ice in winter. A spring case study contrasts a rare period of 24 h of clear‐sky conditions with typical overcast conditions and highlights the impact of clouds on the surface radiation and energy budgets over young, thin sea ice.

A 6-focus high-concentration photovoltaic-thermal dish system

Abstract We present the design, optical characterization and full-system modeling of a novel 6-focus, high-concentration photovoltaic-thermal solar polygeneration system, aiming at an energy-efficient and cost-effective utilization of the solar resource. Essential to this system is a compact, modular solar dish concentrator design optimized for mass-production, structural rigidity, and scalability, with a high geometric concentration ratio of 1733× at each of its six receivers. Every receiver comprises 36 triple-junction CPV cells, interconnected in a unique hybrid parallel-serial scheme that mitigates mismatch losses caused by non-uniform irradiance distributions. Cogeneration is enabled by using high-performance microchannel heat exchangers, allowing the extraction of low grade heat for secondary thermal processes. The tested prototype achieves an average solar radiative flux of 1374 suns on each of the receivers. By optimizing several design parameters, the CPV-thermal system can deliver a solar-to-electricity conversion efficiency of 28.5% in PV-only mode and 26.6% in cogeneration mode while extracting heat at 89.8 °C, and a power of 12.1 kW el and 11.3 kW el /21.5 kW th respectively, matching the performance of state of the art CPV commercial systems, while striving towards a reduction of the investment costs.

Solar Radiation at Surface for Typical Cities in the Arid and Semi-Arid Area in Xinjiang, China Based on Satellite Observation

Xinjiang, a region of China with arid and semi-arid areas, has abundant solar incidence with 166.5×104 km2 and diverse underlying surface. The meager number of surface radiation observatories cannot meet the need for efficient exploration of solar energy. In this study we classified Xinjiang into three regions: southern Xinjiang, northern Xinjiang and Tu-Ha region and applied satellite data to provide the surface solar radiation’s temporal distribution for 10 typical cities. The study is focused on seasonal, annual and variations of all sky downward shortwave radiation flux at surface based on 24-year satellite dataset GEWEX-SRB from the WCRP/GEWEX (World Climate Research Program/Global Energy and Water Cycle Experiment) from 1984 to 2007. The results are as follows. In general, the monthly average solar radiation flux for the cities in the Tu-Ha region was the largest followed by the south Xinjiang and northern Xinjiang. The solar radiation in the most northern cities were less than 150.0 W/m2 in winter, the minimum is 138.7 W/m2, while the other cities were greater than 150.0 W/m2. The maximum of monthly solar flux for the Tu-Ha region, southern and northern Xinjiang was 400.0 W/m2.

Aerosol direct shortwave radiative forcing effect based on SBDART model in the Pearl River Delta, Guangdong (China)

Aerosols play an important role in the energy budget of the earth-atmosphere system. In this paper, we studied aerosol shortwave direct radiative forcing (DRF) effects in Pearl River Delta based on SBDART and a 'two-layer-single-wavelength' model. Simulation results indicated that the underlying surface type and solar zenith angle have significant impacts on aerosol radiative forcing. The comparison between aerosol radiative forcing effects on urban asphalt surface and vegetation shows cooling and warming effects of aerosol shortwave radiative forcing on urban asphalt are much more apparent than that on vegetation, implying aerosols over asphalt-predominated cities will impact the local climate. Then we estimated variations of average DRF and net radiation flux with solar zenith angle in the Pearl River Delta. DRF indicates warming at solar zenith angles of 0°, 20°, 40° and 60°, but cooling at 80°. Net radiation flux increases with a decrease in aerosol optical thickness (AOT) at low elevation, but with an increase in AOT above 5 km.

MATHEMATICAL MODEL FOR DETERMINING OF HOURLY AVERAGE TOTAL SOLAR RADIATION ON TILTED SURFACE OF TWO DIFFERENT CITIES (MANSOURA AND RIYADH)

The main drawback of solar energy utilization in any application based on calculated hourly average solar radiation flux incident on a horizontal plane is the clearness index of the specific location. A mathematical model using MATLAB program was functioned to compute the hourly average solar radiation flux incident on a horizontal surface of Mansoura University (latitude and longitude angles, and altitude above the sea level, respectively, are 31.045oN, 31.365oE, and 6.0 m) and King Saud University (24.725N, 46.617E, and 611 m). The hourly average solar radiation measured on a horizontal surface at the same locations and times was used with that calculated for the average day of each month throughout a whole year in order to determine the clearness index (KT). The split of total solar radiation measured on a horizontal surface into its beam and diffuse components is of interest in two contexts. Firstly, methods for calculating total solar radiation on surfaces of other orientation from data on a horizontal surface require separate treatments of beam and diffuse solar radiation. Secondly, estimates of the longtime thermal performance of most concentrating solar collectors must be based on estimates of availability of beam solar radiation. The measured data of hourly average solar radiation on tilted surface was validated against that computed by Duffie and Beckman model using coefficient of determination (R2), correlation coefficient (r), and root mean square error (RMSE). The obtained results revealed that, the validation between the measure and calculated data was highly agreement as the (R2) and (r) were high and the (RMSE) was low.

Characterization of a 6 kW high-flux solar simulator with an array of xenon arc lamps capable of concentrations of nearly 5000 suns.

A systematic methodology for characterizing a novel and newly fabricated high-flux solar simulator is presented. The high-flux solar simulator consists of seven xenon short-arc lamps mounted in truncated ellipsoidal reflectors. Characterization of spatial radiative heat flux distribution was performed using calorimetric measurements of heat flow coupled with CCD camera imaging of a Lambertian target mounted in the focal plane. The calorimetric measurements and images of the Lambertian target were obtained in two separate runs under identical conditions. Detailed modeling in the high-flux solar simulator was accomplished using Monte Carlo ray tracing to capture radiative heat transport. A least-squares regression model was used on the Monte Carlo radiative heat transfer analysis with the experimental data to account for manufacturing defects. The Monte Carlo ray tracing was calibrated by regressing modeled radiative heat flux as a function of specular error and electric power to radiation conversion onto measured radiative heat flux from experimental results. Specular error and electric power to radiation conversion efficiency were 5.92 ± 0.05 mrad and 0.537 ± 0.004, respectively. An average radiative heat flux with 95% errors bounds of 4880 ± 223 kW ⋅ m(-2) was measured over a 40 mm diameter with a cavity-type calorimeter with an apparent absorptivity of 0.994. The Monte Carlo ray-tracing resulted in an average radiative heat flux of 893.3 kW ⋅ m(-2) for a single lamp, comparable to the measured radiative heat fluxes with 95% error bounds of 892.5 ± 105.3 kW ⋅ m(-2) from calorimetry.

SILAM and MACC reanalysis aerosol data used for simulating the aerosol direct radiative effect with the NWP model HARMONIE for summer 2010 wildfire case in Russia

Persistent high pressure conditions over the European part of Russia during summer 2010 were responsible for an extended period of hot and dry weather, creating favourable conditions for severe wildfires. The chemical transport model SILAM is used to simulate the dispersion of smoke aerosol for this case. Aerosol fields from SILAM are compared to the Monitoring Atmospheric Composition and Climate (MACC) reanalysis. Moreover, the model output is compared to in situ and remote sensing measurements, paying particular attention to the most intense fire period of August 7 to 9, when the plume reached the Baltic countries and Finland. The maximum observed aerosol optical depth was more than 4 at 550 nm during this time. The aerosol distributions from the SILAM run and the MACC reanalysis are subsequently used in meteorological simulations using the Hirlam Aladin Research for Mesoscale Operational Numerical Weather Prediction in Euromed (HARMONIE) model. The modelling results show a significant reduction of the daily average shortwave radiation fluxes at the surface (up to 125 W/m2) and daily average near-surface temperature (up to 4 °C) through the aerosol direct radiative effect. The simulated near-surface temperature and vertical temperature profile agree better with the observations, when the aerosol direct radiative effect is considered in the meteorological simulation. The boundary layer is more stably stratified, creating poorer dispersion conditions for the smoke.

Effect of pulverized anthracite coal particles injection on thermal and radiative characteristics of natural gas flame: An experimental study

Natural gas is increasingly used as a clean fuel. In many industrial combustion systems, such as industrial furnaces and boilers, a large portion of heat is transferred by radiation. The use of natural gas in such industrial systems leads to a decrease in radiative heat transfer. The addition of solid reactant particles into flame is widely proposed in the literature as a method to enhance radiation from non-luminous flames, with a preponderance of research on hydrogen flame. The present study explores how the injection of pulverized anthracite coal particles into natural gas diffusion flame, as a non-luminous one, affects the thermal and radiative properties of natural gas. A novelty of our research method is the exploitation of yellow chemiluminescence of soot particles together with infrared photography to locate radiative particles and discover their qualitative distribution. The IR filter used in our technique was tested with Thermo Nicolet Avatar 370 FTIR Spectrometer for its spectral transmittance to be determined. The results indicate that the injection of coal particles into natural gas flame leads to a rise in the soot content of flame. Having the advantage of high absorptivity and emissivity coefficients in the near IR region, the soot particles in turn increase the flame luminosity and, more importantly, its emissivity coefficient. Also, the heat released from the combustion of particles increases the average temperature of flame about 29°C. These raise the radiative heat transfer and thermal efficiency of flame as much as 43% and 21%, respectively. It is noteworthy that the average temperature difference and emissivity coefficient, respectively, account for 17% and 83% of the enhancement of the average radiation flux.