Discrete Ordinates Radiation Model Research Articles

Irradiance penetration distribution and flashing light frequency simultaneously affected with microalgal cell absorption and CO2 bubble scattering in a raceway pond

In order to investigate light penetration and flashing light frequency for microalgal cell-CO2 bubble culture system in a raceway pond, user-defined function for CO2 mass transfer and bubble scattering models coupled with discrete ordinates radiation model were adopted to clarify simultaneous effects of microalgal cell absorption and CO2 bubble scattering. Light intensity along the microalgal suspension depth attenuated more rapidly with increased biomass concentration, decreased bubble generation diameter, increased CO2 gas content and incident light intensity. Ratio of light zone decreased from 81.13 % to 20.00 % when biomass concentration increased from 0 to 0.4 g/L because of light absorption and shading effects of microalgae. When bubble generation diameter increased from 0.1 to 1.6 mm, ratio of light zone increased from 37.95 % to 42.64 %, while microalgal flashing light cycle first decreased to a valley of 1.81 s at 0.8 mm and then increased. Local light intensity in the upper layers was more enhanced due to lots of CO2 bubbles gathering and reflecting more light with decreased bubble diameter and increased gas content. Light attenuated more rapidly in microalgal suspension with decreased bubble generation diameter and increased CO2 gas content because of increased bubble diffraction coefficient and contact area. When initial CO2 volume fraction increased from 0.02 to 0.2, flashing light frequency of microalgal cells decreased from 0.55 to 0.29 Hz and light zone time ratio φ decreased from 36.90 % to 18.40 %. At a biomass concentration of 0.1 g/L and a bubble flow rate of 0.1 m/s, the maximum light penetration and microalgal growth rate was achieved when bubble diameter, incident light intensity and gas content were optimally at 0.8 mm, 200 W/m2 and 0.02, respectively. This work provides data support and theoretical guidance for photobioreactor design and optimization of light energy utilization.

Numerical simulation of flow field and residence time of nanoparticles in a 1000-ton industrial multi-jet combustion reactor

In this work, by establishing a three-dimensional physical model of a 1000-ton industrial multi-jet combustion reactor, a hexahedral structured grid was used to discretize the model. Combined with realizable k–ε model, eddy-dissipation-concept, discrete-ordinate radiation model, hydrogen 19-step detailed reaction mechanism, air age user-defined-function, velocity field, temperature field, concentration field and gas arrival time in the reactor were numerically simulated. The Euler–Lagrange method combined with the discrete-phase-model was used to reveal the flow characteristics of particles in the reactor, and based on this, the effects of the reactor aspect ratios, central jet gas velocity and particle size on the flow field characteristics and particle back-mixing degree in the reactor were investigated. The results show that with the decrease of aspect ratio in the combustion reactors, the velocity and temperature attenuation in the reactor are intensified, the vortex phenomenon is aggravated, and the residence time distribution of nanoparticles is more dispersed. With the increase in the central jet gas velocities in reactors, the vortex lengthens along the axis, the turbulence intensity increases, and the residence time of particles decreases. The back-mixing degree and residence time of particles in the reactor also decrease with the increase in particle size. The simulation results can provide reference for the structural regulation of nanoparticles and the structural design of combustion reactor in the process of gas combustion synthesis.

A novel approach for volumetric solar receiver performance assessments

A novel design and an efficient operation of solar volumetric receivers remain critical for successfully integrating such receivers into solar energy harvesting devices. The performance of the solar volumetric receiver is highly dependent on the geometric connectivity of the actual pore-sites in the SiC open-cell foams. Although the performance of SiC foam receivers has been investigated previously considering the homogeneous foam structure, further studies are needed to explore the influence of the actual path of the pores and their connectivity on the flow and thermal performance of the receiver. Hence, the present study considers the novel design of a solar volumetric absorber incorporating the actual SiC foam receiver geometric features. Accordingly, the thermal and flow behavior of the working fluid within the receiver is examined considering the 3D connectivity of the pore sites. Moreover, the performance of the solar volumetric receiver is evaluated for different Reynolds numbers, solar concentrations, and foam porosities. A 3D-dimensional numerical investigation is carried out incorporating the interactions between convection, conduction, and radiation heat transfer for which the discrete ordinate radiation model is used. Porous SiC foam is placed in a channel having an optically transparent wall at the top and air is used as the working fluid extracting heat from foam. The overall heat transfer coefficient, normalized Nusselt number, and thermal effectiveness are evaluated for various operating conditions. Findings revealed that the receiver thermal performance improves at high Reynolds numbers. The convection heat transfer is found to be the apparent heat transfer mode within the porous SiC foam. In addition, the pumping power to overcome the flow resistance in the channel is considerably less than that of the rate of heat transfer gain.

Structural optimization to reduce the environmental crosswind negative influence on the performance of a solar chimney power plant system

The solar chimney power plant system (SCPPS) is a clean and pollution-free facility for generating electric power. To further improve the heat collection efficiency of SCPPS, reduce the influence of external unsteady environment crosswind, a bank of transparent baffles was proposed to be installed at the entrance of transparent cover in SCPPS. Combined with the discrete ordinates (DO) radiation model and solar load model in Fluent, the latitude and longitude of Hohhot and actual weather parameters were taken as boundary conditions. Numerical simulation of SCPPS model with external air domain and different number of baffles were carried out. The accuracy of numerical simulation was verified by experimental results. There are three different types of models discussed here: the SCPPS with no baffle, the SCPPS with one baffle, the SCPPS with two baffles. Under the condition of different baffle number, the distribution of temperature, velocity, pressure, turbulence and heat collecting efficiency were given to determine the optimal baffle number. The results show that the average temperature of chimney inlet with one baffle and two baffles are 0.92% and 3.92% higher than that with no baffle, respectively; the average velocity of chimney inlet with one baffle and two baffles are 11.83% and 18.70% higher than that with no baffle, respectively; the average collector efficiency of one baffle and two baffles are 28.45% and 58.52% higher than that of without baffle, respectively. Compared with without baffle and one baffle, adding two baffles can more effectively reduce the heat loss of SCPPS in Hohhot under different environmental crosswind speeds, and alleviate the negative effects of environmental crosswind.

Evaluating the different boundary conditions to simulate airflow and heat transfer in Double-Skin Facade

The CFD simulation accuracy mostly depends on the appropriate setting of boundary conditions and numerical simulation parameters. This study shows the influence of two types of boundary condition settings on the CFD simulation results of Double-Skin Facade (DSF) for a specific problem. These two boundary settings are the constant temperature on the DSF surfaces called Boundary A, and Boundary B is defined via solar radiation using the Discrete Ordinate radiation Model (DOM). The paper verified both the numerical simulations using the experimental data. Comparing the numerical results of two types of boundaries with experimental data shows that both cases underestimated the values lower than 5.2 K and 0.1 m/s for the temperature and velocity respectively at the regarded measured points. Boundary A gives more accurate temperature prediction results, while Boundary B shows velocity magnitude closer to the measurements in the middle height of the cavity; the average temperature and velocity differences between the two boundary types are 0.6 K and 0.003 m/s respectively which are negligible. Finally, the selection of boundary conditions depends on study purposes, however, when the DSF is equipped with blinds and if there is not enough data in hand but the exact value of solar irradiation, using the Boundary B approach is suggested; it can provide reasonable results associated with multi-type of thermal boundary conditions at the same time. Furthermore, if the goal is to investigate the flow pattern in the DSF, Boundary B is argued to perform better than the constant temperature boundary condition.

Study on the Solar Radiation and Heat Transfer of Cabin Fabric Using the Finite Volume Method

The heat transfer of different fabrics was investigated numerically in the cabin of an aircraft. The discrete ordinate (DO) radiation model was adopted to describe the solar radiation through the cabin window and the fabric’s reflection. The conjugate heat transfer between the air flow and the seat fabric was included to study the influence of the textile type and fabric thickness. Some important parameters such as the temperature, radiative heat flux, and heat transfer coefficient on the fabric surface were evaluated. The results showed that both altering of the textile type and thickness will bring about the variation of temperature on the cushion surface. The carbon fibre yarn seat and thinner padding fabric provide a much more enjoyable environment than others. The air circulation in the cabin can improves the thermal environment to some degree.

Intensification of MILD combustion of methane and hydrogen blend by the application of a magnetic field- a numerical study

The influence of an imposed magnetic field upon the behavior of a reacting flow under hydrogen-methane moderate or intense low oxygen dilution regime is investigated numerically. This is achieved through addition of a series of baffles close to the inlet nozzles of a well-characterized moderate or intense low oxygen dilution burner and applying variable intensity magnetic field therein. The resultant combusting flow under magneto-hydrodynamic effects is modeled using a standard RANS scheme with the inclusion of detailed chemistry (GRI. 2.1.1), eddy dissipation concept model with the volume fraction and time scale constants of 3 and 1, respectively, and the discrete ordinates radiation model. The simulation results show that application of the magnetic field allows significant reductions in the air preheating temperature often required for moderate or intense low oxygen dilution combustion. Examination of the radial distribution of different chemical spices (CH2O, OH, and CHO) shows that the imposed magnetic field results in thickening of the reacting flow and intensification of heat release.

Selection of a computational fluid dynamics (CFD) model and its application to greenhouse pad-fan cooling (PFC) systems

The use of pad-fan cooling (PFC) systems in greenhouses during summer is essential for improving crop production in tropical and subtropical regions. However, computational models have not been evaluated and compared for their ability to accurately simulate the temporal-spatial cooling generated by PFC systems. In addition, PFC systems generally have high electrical costs and provide uneven micro-climatic cooling, which is not conducive to crop growth. In the current study, four computational fluid dynamic (CFD) models (SST, Stke, Rngke, and Rke) combined with the Discrete Ordinate (DO) radiation model were compared for their ability to simulate the PFC cooling effects (wind speed, humidity, and temperature) in a greenhouse. After the best CFD model was identified, the significant factors (fan height or fan power density) which mostly affected the performance of the PFC system were determined. The results showed that, among the four CFD models, the SST model had the best simulation accuracy, i.e., it had both the smallest root mean squared error (RMSE) and the highest R2 when compared with measured indoor wind speeds and temperatures. And, fan power density significantly affected (p < 0.05) the cooling results of the PFC system in the greenhouse. After 15 min of cooling treatment, the indoor average relative humidity and temperature (65.42% and 27.46 °C) of mode b-B (with 1.25 W/m3 rated fan power density) and mode a-B (with rated 1.66 W/m3 fan power density) were significantly lower than those of modes c-B and d-B (with rated fan power densities < 1.25 W/m3) at 0.99 m fan height. We also found that mode b-B had the highest energy cooling efficiency of total active power (4.15 °C. m3J−1) among the four PFC modes. Therefore, mode b-B is recommended for the use of PFC systems in greenhouse cooling.

Simulation of Pool and Compartment Fire Using Flamelet Generated Manifold With/Without Radiation Coupling

One of the critical issues in fire dynamic simulation is the selection of suitable combustion model. Typically, combustion models based on infinite fast chemistry are used in fires. In this paper, the flamelet generated manifold (FGM) has been used as a combustion model and the fireFoam solver of OpenFOAM has been used. Two distinct FGMs, with and without radiation coupling, have been investigated to illustrate the role of radiation in simulations. The energy equation with discrete ordinates radiation model is used for coupling of FGM with radiation. These models will be examined in two scenarios of the pool and compartment fire. The FGM with the heat equation is in a good agreement with the experiments. In addition, the basic FGM has a deviation from the experimental results, in a pool fire scenario. The mean of vertical velocity of basic FGM and FGM with energy equation has 40 and 15 percent relative error, respectively, in the pool fire scenario. In the compartment fire, FGM model, with and without radiation coupling shows the same behavior and the velocity results have 9% relative error in the doorway. In general, the radiation coupling in pool fire is more important than compartment scenario.

NUMERICAL ANALYSIS OF NATURAL CONVECTION IN A HEATED ROOM AND ITS IMPLICATION ON THERMAL COMFORT

A heated room is numerically analyzed to study thermal comfort. Cold air flowing in from the inlet gets heated by a heat source (placed just below the inlet), before being distributed throughout the room. The presence of the heat source and a high Rayleigh number causes the flow of air to be buoyant and turbulent. Two RANS based turbulence models, RNG k-ε and k-ω SST turbulence models are used to model turbulence and the Discrete Ordinate (DO) radiation model is used to model radiation heat transfer between different surfaces in the room. In order to account for buoyant air movement, air is approximated as a Boussinesq fluid. Parameters that affect comfort such as comfort temperature, operative temperature, turbulence intensity, velocity and the temperature difference between the head and ankle level are investigated. It is found that the comfort temperature and operative temperature predicted in this study have similar profiles irrespective of the turbulence models. Predicted values of turbulence intensity and velocity were low, which shows a low risk of drought in the occupied zone. The two RANS models give results similar to earlier studies that were performed with different turbulence and radiation models, proving their robustness and viability for a variety of flow problems.

Three‐dimensional computational fluid dynamics modeling of baking of chhana podo (milk cake)

AbstractComputational Fluid Dynamics (CFD) modeling was used to study the air velocity distribution and analyze the unsteady heat transfer and temperature distribution pattern during baking of chhana podo (milk cake). At first, a 3‐D geometry of the baking oven was created, and discrete ordinates (DO) radiation model was employed to predict the distribution of temperature. The data on progressive changes in thermal properties of chhana podo dough during baking were fed into the CFD model. The DO model was found to be adequate to predict the distribution of temperature in the product, with root mean squared error (RMSE) of 1.122 and mean percent relative deviation modulus (%P) of 0.70. Similarly, the DO model was found to be adequate to predict the air temperature distribution in the oven, with RMSE of 1.842 and %P of 1.61. The distribution of air velocity inside the oven was predicted using k‐ω turbulence model. The air velocity near the oven door was 0.505 m/s, whereas it was 5.002 m/s near the fan. Simulation results provided some insights on the effect of spatial location on air velocity. The placement of chhana podo inside the oven was optimized based on this simulation. This CFD simulation has potential application in the design of ovens with enhanced heat transfer and thermal efficiency.Practical ApplicationsThe present work models the heat transfer during baking of chhana podo. Even though a lot of research works related to CFD to products such as bread are available, many studies have not comprehensively considered temperature distribution in the oven, air velocity distribution and heat transfer in the product. The thermo‐physical properties of the product were modeled with respect to temperature and given as inputs into the CFD model. The CFD simulation of air velocity distribution inside the baking chamber will be useful in optimizing the placement of product or dough for uniform baking. The air velocity and heat transfer simulations quantified the diffusion of heat inside the product. This CFD simulation study could be useful in optimization and design of baking ovens for various products. Also, simulation of the baking conditions of a product could be advantageous from the economic perspective.

Numerical Simulation of Solar Radiation and Conjugate Heat Transfer through Cabin Seat Textile

Abstract The solar radiation and the conjugate heat transfer through the cabin seat fabric were investigated numerically with a focus on a comparative analysis of various fabric solar reflectance or reflectivity (SR) and inlet cooling air velocity. For this purpose, 3D compressible Reynolds-averaged Navier–Stokes equations with the low Reynolds number turbulence model were utilized to simulate the airflow in the cabin. The discrete ordinate radiation model was adopted to describe the solar radiation. The conjugate heat transfer between the airflow and the fabric seats was included. The airflow temperature, radiative heat flux, and radiative heat transfer through the fabrics in a fixed cross section were studied. The results demonstrate that the increase in fabric SR leads to the increase in energy reflected to the atmosphere, which will bring about a lower temperature on the seat fabric. The decrease in emissivity and the energy absorbed results in the lower heat transfer and heat radiation and leads to the improvement of the cabin thermal environment. The high-temperature gradient near the seat causes the forced air circulation and is beneficial for the improvement of the thermal comfort. However, the cooling effect is not so obvious near the cabin seats when the inflow speed is increased.

Numerical modeling of heat losses in a line focusing solar compound parabolic concentrator with planar absorber

In this work, a three-dimensional steady state thermal model is developed for a compound parabolic concentrator of 2× concentration considering the effects of surface radiation and wall conduction. The performance of the compound parabolic concentrator is modeled to obtain the convective and radiative heat loss under the influence of different parameters such as absorber temperature, absorber emissivity, ambient temperature, external heat loss coefficient, aspect ratio and concentrator tilt. The turbulent natural convection in the concentrator is modeled using standard two equation k-ε turbulent model with enhanced wall treatment. For the surface radiation inside the concentrator, discrete ordinate radiation model is used. The thermo physical properties of air inside the cavity are assumed to be constant except the density which is modeled as incompressible ideal gas. The conduction at the walls is accounted by setting suitable wall thickness for reflectors, glass cover and end walls in the solver. This work clearly demonstrates the need for a three dimensional numerical simulation and coupled natural convection and radiation to exactly reproduce the velocity fields as would be obtained in experiments. The convective Nusselt number, radiative Nusselt Number and thermal stratification are obtained from the parametric study. This study on estimation of heat losses in compound parabolic concentrator is applicable to both solar thermal and solar photo-voltaic collectors with a view of modifying the concentrator design to optimize its thermal performance.

Evaluation of in-duct UV-C lamp array on air disinfection: A numerical analysis

In-duct ultraviolet germicidal irradiation systems are effective systems that are used in disinfection of pathogenic particles transported by air that moving through the ventilation systems. Proper design of these systems is quite important for energy consumption and disinfection performance. In this study, effect of four different lamp arrays within a square cross-section ventilation duct on the average UV dose, UV dose distribution and disinfection rate are examined by using computational fluid dynamics. The standard k-ε turbulence model and the discrete phase modeling are used to analyze airflow and particle distribution within the duct, respectively. Also, Discrete Ordinates (DO) radiation model is employed to obtain the irradiation field formed by each UV lamp. It is disclosed that UV lamp arrangement within duct significantly affects UV dose distribution.

Numerical Investigation of the Effects of Swirling Hot Co-Flow on MILD Combustion of a Hydrogen–Methane Blend

Abstract This paper examines the effects of swirl hot co-flow on the combustion behavior of a moderate or intense low oxygen dilution (MILD) burner fueled by a mixture of methane and hydrogen. Toward this goal, the realizable k-ɛ turbulence model, GRI. 2.11 reaction mechanism, and the discrete ordinates radiation model are incorporated into a computational modeling of the reactive flow. The numerical results are, first, favorably compared against the existing experimental data. Subsequently, a number of swirl co-flows are implemented, and structures of the resultant reactive flows are investigated systematically. The outcomes indicate that increasing the swirl velocity leads to the reduction of ignition delay and significantly enhances the reaction completion. The analysis of the spatial distribution of hydroxyl and formyl (OH and HCO) radicals reveals that swirling MILD combustion radially extends the reaction zone in comparison with the conventional MILD combustion. Yet, it reduces the length of the reactive region and allows for the occurrence of heat release in a shorter axial distance from the outlet fuel nozzle. Further, the addition of swirl reduces the production of carbon monoxide through its influences upon flow temperature and generation of formyl radical. However, it is found that swirling hot co-flow intensifies NOx emissions by strengthening of prompt and thermal mechanisms of NOx production. Reducing the temperature of the recycled flue gas is deemed to be an effective way of resolving this issue.

Rudimentary analysis for solar chimney enhancement

This paper presents fundamental results for solar chimney enhancement. Solar radiation proves to be an important factor in influencing the efficiency of the solar chimney power plant, but its effects on the ambient conditions outside the system has not been considered. Using the Discrete Ordinates radiation model on the semi-transparent collector component of the two-dimensional system, the work presented in this paper simulates the velocity and temperature inside the solar chimney as the ambient temperature of air outside is varied from 307 K to 314 K. At the highest ambient temperature, results show an increase in air velocity of 0.55 m/s at ground level and 1.85 m/s at a height of 1 m along the chimney. To further investigate of this study, a simulation model to include the ambient domain is proposed as a conclusion.

Experimental Validation of a Numerical Model of a Ventilated Façade with Horizontal and Vertical Open Joints

Commercial and residential building is one of the four major final energy consumption and end-use sectors. In this sector, cooling loads represent an important part of the energy consumption, and therefore, they must be minimized, improving the energy efficiency of buildings. Ventilated façades are one of the most widely used passive elements that are integrated into buildings, precisely with the aim of reducing these loads. This reduction is due to the airflow induced in the air cavity by the buoyancy forces, when the solar radiation heats the outer layer of the façade. In the open joint ventilated facades (OJVF), ventilation is attained through the open joints between the panels composing the outer layer. Despite the steadily growing research in the characterization of this type of system, few studies combine the numerical modelling of OJVF with experimental results for the assessment of the airflow in the ventilated cavities. This paper experimentally validates a numerical simulation model of an OJVF. Firstly, the façade performance has been experimentally assessed in a laboratory model determining the temperatures in the panels and air gap and measuring the flow field at the gap using particle image velocimetry (PIV) techniques. Secondly, a numerical model has been developed using advanced Computational Fluid Dynamics (CFD) simulation tools. Finally, an experimental validation of the numerical model has been done. Experimental and numerical results are compared in different planes inside the ventilated cavity. The discrete ordinates (DO) radiation model and the k-ε renormalisation group (RNG) turbulence model better adjust the simulated results to the experimental ones.

NUMERICAL ANALYSIS OF SOLAR TOWER SYSTEM UTILIZED WITH FLAT PLATE AND POROUS ABSORBER

The performance of solar updraft tower investigates numerically by comparing between two solar collectors with and without porous absorber flat plate. In this study, copper metal foam (10 and 40) PPI at the same porosity (0.9) are used as an absorber plate. The effect of the absorbing porous medium is studied to increase the air flow towards the updraft tower by tilting of the porous absorber at an angle (2° and 6°) from the horizontal line for (10 and 40) PPI and compared with the horizontal absorber flat plate. To simulate the physical quantities inside the porous medium, at steady state, symmetry, three dimensional, Darcy model and energy numerical model with local thermal equilibrium (LTE) assumption are adopted and numerical models is approximated by a RNG (Re-Normalization Group) k- ϵ turbulent model and discrete ordinates (DO) radiation model equations. The numerical study is analyzed by Fluent software package (version 18.2) to solve the governing equations. The results showed that the tilting of a porous absorber plate at an angle (2° and 6°) from the horizontal line lead to increase in the mass flow rate inside the solar updraft tower and the maximum performance is found by using 40 PPI at tilt angle 2°.The performance of solar updraft tower investigates numerically by comparing between two solar collectors with and without porous absorber flat plate. In this study, copper metal foam (10 and 40) PPI at the same porosity (0.9) are used as an absorber plate. The effect of the absorbing porous medium is studied to increase the air flow towards the updraft tower by tilting of the porous absorber at an angle (2° and 6°) from the horizontal line for (10 and 40) PPI and compared with the horizontal absorber flat plate. To simulate the physical quantities inside the porous medium, at steady state, symmetry, three dimensional, Darcy model and energy numerical model with local thermal equilibrium (LTE) assumption are adopted and numerical models is approximated by a RNG (Re-Normalization Group) k- ϵ turbulent model and discrete ordinates (DO) radiation model equations. The numerical study is analyzed by Fluent software package (version 18.2) to solve the governing equations. The results showed that the tilting of a porous absorber plate at an angle (2° and 6°) from the horizontal line lead to increase in the mass flow rate inside the solar updraft tower and the maximum performance is found by using 40 PPI at tilt angle 2°.

Hydrodynamic and thermodynamic enhancement of a solar chimney power plant

The present paper investigates the effect of geometrical parameters by using energy and exergy analysis and hydrophobic surfaces as an innovative method were proposed to enhance the performance of Solar Chimney Power Plant (SCPP). Furthermore, the best radiation model for SCPP simulation was represented. Hereupon, firstly large- scale SCPP using reverse fan model was validated based on Manzanares constructed power plant. For reducing the computational cost, nine different small scale 3-D models defined respect to prior experimental study under Tehran-Iran meteorological condition. The first and second laws of thermodynamics were studied, and an optimization was done for representing the best functional diameter, height and turbine pressure jump by the means of improvability rate and clarified optimization factor. Results show that the optimal state of chimney can be defined in relation to a certain condition; hence, the geometrical parameters under investigation should simultaneously be evaluated in system designs. Furthermore, applying the slip condition on walls to simulate hydrophobic surfaces was attempted to reduce shear stress on walls which led to roughly 11% performance enhancement. Consequently, Discrete Ordinates (DO) radiation model could be trusted based on its more factual outcomes with referred to prior experimental results of Heat flux method.

Numerical investigation of embedding some hot obstacles in a low speed reacting flow of the moderate or intense low-oxygen dilution in a jet-in-hot-coflow

Given the daily growth of pollutant emissions in this age of technology, every method that can increase the efficiency of the combustion as well as reduce the pollution is very important to consider. One way to reach this goal is moderate or intense low oxygen dilution. In the present work, this technology of turbulent nonpremixed CH4-H2 jet flames has investigated in various working conditions in Dally burner, numerically. In this regard, the finite volume method in OpenFOAM package has used with k-ε Re-Normalization Group as well as the discrete ordinates radiation model. Furthermore, the eddy dissipation concept for interaction between turbulence and chemistry in combination with the detailed reaction mechanism have been employed. At first, the results are compared with the experimental data and after validating the obtained results of the solution, the moderate or intense low-oxygen dilution combustion is investigated by putting some hot obstacles in the burner. The results show that the hot obstacle has a role similar to the hot spot and helps this condition of combustion to reduce the initial cost in order to preheat the hot oxidizer co-flow. This means that putting the hot obstacle in the burner causes to reduce the preheat temperature and the energy consumption per second up to 300 K and 17.9%, respectively, while it increases the turbulence intensity, reaction zone, outlet CO2 and H2O species while reduces NOx and CO emissions.