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Showing 14 results for Burner

Amir Karimdoost Yasuri,
Volume 3, Issue 1 (5-2019)
Abstract

Abstract

Research Subject: Other waste incinerators and other high-temperature systems designed to dispose of garbage are referred to as heat treatment systems. The burning of waste materials, such as garbage, converts them into ashes collected on the waste floor, exhaust gases, very small particles and, most importantly, heat, which can be used to generate electrical power.

 

Research Approach:

In this research, firstly, the energy and exergy efficiencies of a waste incineration cycle, along with utilization of Lorestan petrochemical waste as an additional fuel for waste incineration, are investigated. In this way, the amount of energy needed to produce the required water vapor to disable the catalyst Ziegler-Nata was calculated for the production of linear stylistic polyethylene. Subsequently, a simple model for the inactivation reaction of Ziegler-Nata catalysts was presented using the steam generated by the waste incinerator, and then the mathematical equations for these reactions were obtained using the primary reaction law. By introducing these reactions into the reaction model, a new equation for the reaction model was obtained that covers the moments after the time of deviation to an acceptable level. This indicates the overcoming of inactivation reactions on the reactions of active centers production in the final stages of the reaction.

Main Results: The energy and exergy efficiencies of the waste incineration cycle along with the use of Lorestan petrochemical waste as an additional waste gas were investigated and thus the amount of energy needed to generate steam to disable Natal Ziegler catalysts in the production of linear linear polyethylene was calculated. To initiate this, the combined cycle was proposed and its energy and exergy efficiencies were investigated. Also, by changing the key components such as the ammonia solution composition, the ammonia distillation temperature and the input and output pressures of turbine, a way to achieve the energy needed to generate the steam needed to deactivate the Nitra zigzag catalyst in the production of linear linear polyethylene was developed.

 



Volume 12, Issue 6 (3-2013)
Abstract

This paper investigates suitable approximation for Calculating the thermal radiation flux divergence and effect of errors on performance evaluation of porous radiant burners (PRB).Thus, a single layer and a double layer of buried flame type of the porous radiant burners have been selected and numerically simulated. Due to the significant difference in the temperature of the solid matrix and the fluid passing the burner, the energy equations was considered as a non-local thermal equilibrium. Complete kinetics of methane air was used for combustion modeling. Since the effect of lateral walls should be neglected the problem was solved in 1D to present exact solution of RTE and compares the other approximations. Results show that discrete ordinate as well finite volume approximation of RTE show that eight directional spherical split is the best selection. Lower ordinates have substantial deviation and increasing the number of division enlarges computation cost without any considerable improvement on errors reductions. Furthermore, two flux method and Rosseland approximation are not valid for this kind of modeling.

Volume 13, Issue 10 (1-2014)
Abstract

This paper presents pore scale simulation of turbulent combustion of air/methane mixture in porous media to investigate the effects of multidimensionality and turbulence on the flame within pore scale. A porous medium consisting of a staggered arrangement of square cylinders considered here. Results of turbulent kinetic energy, temperature, flame thickness, flame structure and flame speed are presented and compared at different equivalence ratios. The turbulent kinetic energy increases along the burner because of turbulence created by the solid matrix with a sudden jump at the flame front due to increase of the velocity as a result of thermal expansion. Also, it is shown that at higher equivalence ratios, the effect of turbulence within porous burner is highly significant phenomenon. Due to higher turbulence effects in higher equivalence ratios, the flame thickness increases by increasing the equivalence ratio which is in opposite of the trend observed in laminar flow simulation. Also, it is shown that the dimensionless flame speed and excess temperature is higher at lower equivalence ratios due to lower heat loss to the cold upstream environment of burner. Two dimensional structure of flame in the pores of porous medium is shown in the present study via isotherm lines.

Volume 13, Issue 12 (2-2014)
Abstract

In the present study, the effect of intra-pore turbulence within porous burnershas been investigated on combustion of methane/air mixture in such burners. A model is adapted to the porous structure to models turbulence flow. The GRI 3.0 chemical reaction mechanism is utilized for the combustion of methane/air mixture and radiative part of the solid phase energy equation is obtained using the discrete ordinate method. The numerical results show that the gas temperature obtained from turbulence model stays below the corresponding laminar model temperature all over the combustion region, and the flame thickness becomes wider in turbulence model. Although the CO emission are insensitive to laminar or turbulence model, the burning speed and NO emission predictions are found to be significantly improved when the effects of turbulence are taken into account.

Volume 14, Issue 5 (8-2014)
Abstract

A two dimensional numerical study is presented for steady state performance analysis of a catalytic radiant counter-diffusive burner. In these burners, the gaseous fuel enters from the rear of the burner and passes through the insulation and catalyst layers. The oxygen enters the catalyst layer from the burner surface and opposite to the fuel path. The reaction takes place over the catalyst layer. In this paper, the momentum, energy and species conservation equations in porous and non-porous media are solved using the finite element method in the COMSOL software. The simulations are based on proposed corrections on boundary conditions and combustion rate of methane equation. The simulation results compared with experimental measurements published in the literature for the same geometry and conditions which shows a considerable (10%) improvements. It is shown that diffusion of oxygen through the pad limits the catalytic combustion and controls the fuel conversion in the burner.

Volume 15, Issue 4 (6-2015)
Abstract

Nozzles branching, fuel injection angle and nozzle diameter can affect the mixing process and combustion performance of nozzle-mix burners. In the current work, CFD approach and Taguchi method are employed to investigate the effects of these parameters on the irreversibility of combustion process. Combustion in nozzle-mix burner is first simulated by use of CFD method. The governing equations, including continuity, momentum, energy and chemical reactions are solved numerically by use of FLUENT. Standard k-ε and EDC models are used for modeling turbulence and interaction between chemical reactions and turbulence, respectively. Then, the developed model is experimentally investigated and numerical method is validated. Using the Taguchi method, the effects of each parameters, their priority and optimum values are determined by use of Minitab. A L9(33) orthogonal Taguchi array is used with the analysis aim of minimizing irreversibility. Results show that injection angle, number of branches and nozzle diameter have the most influence on the combustion irreversibility, respectively. The optimum configuration of the nozzle-mix burner is determined to have a 45º injection angle, 4 branches and 4mm nozzle diameter. The corresponding irreversibly to this optimum case is 45.88%.

Volume 16, Issue 1 (3-2016)
Abstract

Conjugate heat transfer is one of the most important aspects of energy conversion and plays an important role in the thermal efficiency and fuel consumption of chambers. In the present work, a two-dimensional model for reacting flow is presented to calculate transport equations of mass, momentum, energy and species. A new solver is developed for the open-source OpenFOAM software. This new solver is able to predict the conjugate heat transfer effects of reactions and transport processes in fluid and heat conduction in solid as well as radiation in surrounding surface. The coupled method is used and the continuity of temperature and heat flux on the fluid and solid interface is applied in order to analyze conjugate heat transfer through boundary conditions. Experimental data of honeycomb burner is used to validate the new solver. Numerical results are in a good agreement with experimental data. The results show that change of fluid inlet condition and geometry dimensions affect the interaction of conjugate heat transfer and location of released heat of combustion. The location of flame is moved toward outlet as the inlet velocity is increased and toward inlet as the equilibrium ratio is increased. Increasing the length and thickness of solid reduces the preheat area as well.

Volume 16, Issue 12 (2-2017)
Abstract

In this paper, experimental comparison between conventional burner and porous burner in domestic purposes as stove, according to Iranian National Standard No. 10325 has been carried out. This comparison between the conventional burner available in the Iranian market and its equivalent porous burner is done. First, flammability of the porous silicon carbide burner was investigated. The results showed that the flame is formed when the equivalence ratio is less than 1, so the best performance equivalence ratio was around 0.7. By changing the distance between the pot and the burner and also changing the pot diameter, it was found that for a pot with 26 cm diameter and burner distance of 1 cm, porous burner efficiency increases to 55%. The comparison between the conventional burner and optimum situation porous burner showed that at the same factors like power, distance between the pot and the burner, the pot diameter, the burner diameter, measuring tools and the same method, porous burner efficiency is 1.5 times more than conventional burner. In conventional burners CO and NOX pollutant are 8-26 and 8 times more than porous burners. Due to higher efficiency and lower emissions, conventional burners can supersede porous burners for domestic purposes.

Volume 17, Issue 12 (2-2018)
Abstract

In the present study, combustion phenomenon and heat transfer in a 3-D rectangular porous radiant burner (PRB) are numerically studied. Methane- air mixture with detailed chemical kinetics is considered to model the combustion process inside the porous matrix. Assuming the non-local thermal equilibrium between solid and gas phases, separate energy equations are considered for two phases. Porous medium is assumed as a gray medium that can absorb, scatter, and emit thermal radiation, where the gas phase is considered to be transparent. The governing equations including gas and porous energy equations, the chemical species transport equation and the radiative transfer equation are simultaneously and numerically solved. Discrete ordinates method is used to solve the radiative transfer equation in order to calculate the radiative term in the solid energy equation. The simulation results include temperature fields for the gas and solid phase, species mass fraction distributions, and radiative heat flux profiles along the burner. Finally, the effect of different parameters such as optical thickness, scattering albedo, excess air ratio (EAR) and porosity on the performance of burner are explored.

Volume 18, Issue 6 (10-2018)
Abstract

In the present research, combustion species detection in methane/air flame is carried out based on Flame Emission Spectroscopy (FES). Experimental investigation is performed on a test rig equipped with measurement devices to get the flame emission of a perforated burner which is one of most popular burners used in condensation boilers. Combustion species H2O*, OH*, CH* and C2* are detected from their chemiluminescence The emission of OH* radical was investigated for different equivalence ratios (Φ) and burner powers showing an intensity peak in the range of Φ between 0.77 to 0.85 that corresponds to the maximum heat release rate. Emission of H2O* was also investigated leading to its maximum at Φ=0.82 which shows the most complete combustion equation for different burner powers. The similar experiment showed that OH*/CH* intensity ratio was independent of burner power as is confirmed by previous researchers. One could infer equivalence ratio from the flame emission. Burner surface temperature was also targeted by an infrared thermometer with the purpose of finding the maximum surface temperature of 415 to 420oC which happened at nearly Φ=0.82 for all burner powers. Finding equivalence ratio of the burner by using its natural emission and improving its efficiency by the method of investigating combustion specifications relating to heat release rate is the basis of this work.

Volume 18, Issue 7 (11-2018)
Abstract

Abstract Thermal radiation plays a key role in the heat transfer between the flame and its surroundings. It is essential to provide a reliable method for measurement of flame radiation in the combustion study. Also, it is challenging to measure the radiation flux from the flame in the chamber due to the effect of the walls. The radiation emitted from the walls and the reflection of the flame radiation from the walls interferes with the measurement of the flame radiation. High temperature or high reflection walls can increase the error in the measurement of flame radiation. In this paper, various parameters affecting the flame radiation have been investigated. These studies are based on the wall incident radiation and the wall radiation heat flux. To calculate the flame radiation, a theoretical method is presented which is compared with the CFD simulation results to confirm its correctness. To simulate the flame SM1 of the University of Sydney, a steady flamelet combustion model has been used with the k-ε modified turbulence model. Due to the low optical thickness of the model, the DO radiation model is used to simulate CFD. The CFD results are in good agreement with theoretical results, and the estimation of flame emission are accurately acceptable. The results show that the flame radiation differs from the wall radiation by more than 25%, when the wall radiation coefficient will be smaller than 0.8 or the wall temperature will be more than 330k.

Volume 19, Issue 5 (5-2019)
Abstract

The combustion system used by the Hoffman furnaces for brick factories has a very low efficiency. In the current paper, the performance of the combustion system of Hoffman furnaces of Kolet Pottery Brick Co has improved, using computational fluid dynamics (CFD) by making changes to the Hoffman furnace torch, including the converging the torch head, inserting the spring in the pipe to create the swirl flow, shortening the nozzle length for the better mixing of the fuel and air, and more. The changes were simulated in each step with the FLUENT simulation software. Based on the theoretical results and simulation, optimized torch was made and a field test was carried out on it in a brick factory and the gases from their combustion were analyzed. As a result of these reforms, the combustion efficiency of the Hoffman furnaces has increased from 27% to 47 %, and consumption of fuel oil has decreased by a third. Also, the CO value of 16854 ppm in the old torch was reduced to 298 ppm in the optimized torch and the NO value ranged from 49 to 18 ppm as a result of optimizations.
 



Volume 21, Issue 7 (7-2021)
Abstract

  In this research, the geometric parameters of a preheated furnace burner in the press line of Esfarayen Industrial Complex have been studied, experimentally and numerically. To improve the combustion process in the burner, three different diameters (10, 20 and 30 mm) are provided for the nozzle diameter and three different lengths (225, 250 and 300 mm) for the mixing length of the burner. Ansys-Fluent software and RNG k-ε turbulence model have been used for the simulation and the modeling results show that the applied method has good accuracy and with a maximum error of 23% higher than the experimental values for temperature. This temperature difference is due to the lack of accurate measurement of inlet air flow and also point measurement of temperature in the burner. In the study of the effect of nozzle diameter, it was observed that by increasing the nozzle diameter from 10 to 30 mm, the maximum temperature inside the burner increased by 6%, which against a slight increase in nitrogen oxides (Nox) pollutants inside the burner, the 30 mm diameter for optimum design is selected among the tested diameters. Also, the results of the study for the effect of mixing length on burner performance have shown that by increasing the length, the amount of heat produced decreases slightly, which due to more favorable stability of NOx pollutants due to more space and complete reaction, length of 300 mm has been chosen for optimal design of burner.

Volume 21, Issue 9 (9-2021)
Abstract

In present study, the stress and strain distributions due to the radiant gradient in some radiant tube burners have been investigated. In the design of the burner, several outlet valves are mounted on the wall of the burner tube and the combustion-produced fluid is discharged by the outlets into the furnace. For this purpose, three cylindrical radiant tubes with the same length, diameter, thickness and material and difference in design of fluid outlets are modeled. To simulate the mechanical behavior of the pipes, after the geometric modeling and considering the pipe material and boundary conditions, ANSYS commercial software has been used. The boundary conditions for numerical solution are extracted from the results of the experimental tests. Due to the average fluid velocity within the radial tube, the fluid flow falls into the turbulent range. In order to obtain the stress-strain diagram of the tested alloy, the Ramberg-Osgood equation is used. Due to the solution of the fluid-solid interaction by ANSYS, the best design is concluded through the Von-Mises stress minimum values. Also, by removing the thermal load from the next load step, the residual stresses generated in the samples are calculated. To illustrate the accuracy of the solution, some specimens of the burner have been made and evaluated to verify the numerical solution.

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