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The quality of stable environments is crucial for maintaining the health of horses, minimizing air pollution, and potentially utilizing waste for fuel production. This study investigates the physical, chemical, and biological characteristics of dry horse bedding across twenty-four horse-riding clubs in Tehran. The objectives are to gather information on current stable practices and assess the suitability of used bedding for reuse or energy generation. Results revealed that the moisture content of the bedding ranged from 39.63% to 76.92%, leading to high drying costs. Ash content varied between 7.73% and 17.20%, while nitrogen content ranged from 0.78% to 1.77%. Hydrogen content was measured between 7.06% and 9.04%, with carbon content ranging from 14.74% to 24.46%. The particle size distribution showed that 70% to 94% of particles were smaller than 3.15 mm, with 0.5% to 1.5% below 0.075 mm, indicating potential health concerns. The average gross calorific value was 19.0372 MJ/kg. While the pellet samples did not meet specifications for non-industrial use, used horse bedding pellets exhibited greater suitability for industrial applications.
 

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Abstract- Possibilities and limitations of 1D and 3D flow simulations in the vaneless turbocharger turbine of a 1.7 liter SI engine are presented experimentally and numerically. A test setup of the turbocharged engine on dynamometer is prepared to validate the results of numerical modeling. Various performance parameters are measured at 12 different engine speeds and the results of measurement in 3 different engine speeds are presented in this report. The complete form of the volute and rotor vanes is modeled. An extensive study on the number of meshes has been undertaken to ensure the independency to meshes. The modeling of rotating wheel is considered by Multiple Rotating Frames (MRF) technique. Finally, the variations of turbine performance parameters are studied under different pulse frequencies of the engine. The results show that at high engine speeds a 3D unsteady flow simulation is required to get reasonably accurate results. The results presented in current report will be used in simulating three dimensional steady and unsteady compressible flow within the turbine of the turbocharger.

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In most airbag systems, the gaseous mixture that fills up the airbag is produced by the fast combustion of a propellant in a combustion chamber called inflator. Since the process of gas production in the airbag inflator is a high-temperature combustion process, having a right understanding and precise control over the combustion in the airbag inflator has always been a challenge. In this paper, the numerical study of combustion process in a pyrotechnic inflator was carried out based on a Zero-Dimensional Multi Zones model. The parametric study show that the performance of inflator is more affected by the propellant characteristics such as mass, combustion index, and propellant temperature coefficient and is not significantly influenced by hardware elements of inflator. In order to simulate hybrid pyrotechnic inflator, the initial pressure of gas plenum was increased by 25 to 50 times. As a result, the performance both in combustion chamber and in discharge tank decreased. This lower temperature leads to a higher thermal efficiency.

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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.

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Abstract- The comfortability of car passengers, reduction of fuel consumption in order to reduce the emission of CO2, and increasing the efficiency of fuel usage are the main goals of car manufacturers. Therefore the combustions in internal combustion engines must be done at temperatures as high as possible. These high temperatures have negative effects such as impact, rattling status in gearbox, low-pitched sound in gearbox, and vibration of vehicles. These vibrations interfere with the comfortability of passengers. In order to reduce the unwanted vibrations as much as possible there is a need to uniform the radial velocity of the flywheel and the inlet torque to the gearbox. In this study the available methods are reviewed and a new approach is proposed which is the two-mass flywheel. The effects of this new flywheel are carefully investigated. The experimental results are compared with the numerical ones and a very good conformation is observed.

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In the present work, the dynamics of lean (ϕ =0.5) premixed hydrogen/air flames in a micro channel with prescribed wall temperature is studied. The investigation is carried out using the low Mach formulation of Navier-Stokes equations with detailed chemistry and molecular transport for different inflow velocity. Ignition-extinction repetitive, steady symmetry flame and asymmetric flame are observed as the inlet velocity increased. Close to lower flammability limit, ignition-extinction repetitive flame was observed duo to imbalance between chemical time scale and residence time scale. In this regime, the reacting flow is affected by high wall temperature and the extinction occurred by the flow temperature. Upon increasing the inlet velocity, symmetric flame can be observed due to the balance between time scales. It is observed that further increasing the inlet velocity would cause symmetry flame to become unstable because of presence of some perturbations in flow field. Based on the obtained results, it is suggested that the perturbations are created by preferential diffusion of species.

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In the present study, fabrication and performance testing of a flameless catalytic pad has been investigated. The catalyst was prepared with 1g of H2PtCl6.6H2O solved in 0.5 liter solvent contains 50% water and 50% ethanol and sprayed on the alumina - silica fiber mat as the catalyst support. The wet pad was dried and calcined before usage. The performance of the heater was evaluated by design and fabrication of a test stand which was capable of measuring parameters such as temperature at surface and in depth of the catalyst layer, the amount of pollutants such as CO and NOx, flow rate and pressure of the fuel and surface air circulation in front of the pad. In addition, by placing the panel containing the pad in an environmental test chamber, the effect of different climate conditions in five cities of Iran, i.e., Borojerd, Khalkhal, Lavan, Mahshahr and Puladshahr were investigated. Average surface temperature of the pad was measured about 350°C. No NOx was detected and CO emission of the burner was measured up to 5ppm. In Khalkhal conditions with the lowest temperature and humidity, the highest temperature at surface was recorded and the maximum CO emissions in Mahshahr with the highest temperature and humidity was about 3ppm. It was shown that increasing the fuel flow rate increases the surface temperature and CO emissions. It was also shown that an increase of environment temperature and humidity, increases the surface temperature.

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The nitrogen oxide emission is known as a potentially hazardous pollutant in reacting flows. To improve this process, it is of fundamental importance to take into consideration environment protection through reduction of fuel consumption in addition to increasing combustion efficiency. The control of NO emission from the combustion process is an important design criterion in modern gas turbine technology. In the present work a two-dimensional combustion simulation is developed for a model gas turbine combustion chamber. The k−ε turbulence model and the eddy dissipation concept model are applied for flow predictions and reaction rate simulation respectively. The flow field pressure linked equations are solved using the SIMPLE algorithm. In the present work, the thermal and prompt NO formations are estimated and calculated for three different methane, propane and pentane fuels. Also the effects of equivalence ratio and primary aeration on nitrogen oxide emission are considered. Results of numerical simulation show that the nitrogen oxide emission significantly affected by the equivalence ratio for all three type of fuels. Also by applying primary aeration the averaged nitrogen oxide production can be significantly reduced.

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The present numerical study investigates the effect of a bluff body on outer wall temperature of a micro scale combustor. Combustion of lean premixed hydrogen-air mixture is simulated in two dimensional domain utilizing detailed chemistry of Li et al. (13 species with 19 chemical reactions) and different mass diffusivity for each species. The effect of bluff body in combustor is studied in two viewpoints: shape of bluff body and number of bluff bodies. Two shapes of bluff body, square and triangular shapes, are considered to study the combustion efficiency and outer wall temperature. The results indicate that the shape of bluff body does not have important effect on outer wall temperature. However, triangular shape outer wall temperature is slightly more than square shape. Results also show that combustion efficiency of the square bluff body is larger than the triangular one. In second part, the effect of number of bluff bodies (i.e. one, two and four bluff bodies) on the micro scale combustor is examined on combustion characteristics. With increasing the number of bluff bodies, the outer wall temperature increases. This is due to the formation of a uniform temperature field in the micro scale combustor.

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This is a study of the effect of synchronous combustion of gas-gasoil, achieved through the injection of gasoil droplets into natural gas flame, on the flame luminosity and radiative heat transfer. Droplets were injected by a single-hole micro-nozzle with a hole diameter of 100 μm and injection pressure of 9 bars. A photovoltaic cell was used to determine the luminous radiation and the total radiation of flame was measured by a thermopile. Also, the combination of chemiluminescence and IR photography of flame were employed to determine the qualitative distribution of soot particles in flame. The results show that the synchronous combustion of gas-gasoil raises the soot content of flame, leading to an increase of the luminosity and volume reaction of flame 38 and 2.5 times in comparison to the non-injection mode. Also, for the synchronous combustion of gasoil and gas with a mass fraction of 10%, the flame temperature changed only 95˚C, whereas the flame radiation rose as much as 52%. The improvement of flame radiation in synchronous combustion of gas-gasoil is due to the enhancement of flame emissivity coefficient in the IR region of electromagnetic wavelengths. Meanwhile, the injection of gasoil droplets increased the CO and NO pollutants by 4 ppm and 35 ppm in comparison to the non-injection mode; Due to the low mass flow rate of injection, however, the increase does not exceed the allowable limit for outlet pollution.

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Biodiesel is a renewable fuel that can be produced from vegetable or animal oil. The main benefit of using biodiesel is its capacity to lower exhaust emissions compared to diesel fuel. Over the last few years, numerous studies have been performed on biodiesel production and its effect to engine performance and emissions. However, in those studies; no attention has been paid in economic analysis of biodiesel usage in engines. In this investigation, various mixtures of biodiesel and diesel fuel have been tested on a four cylinders turbocharged diesel engine. The combustion reaction was determined by using the experimental data. Then, the mass flow rate of each exhaust emissions was calculated, using combustion reaction. The economic analysis was performed considering social cost of emissions, inlet fuel cost and the cost of engine power loss. Because of low diesel fuel price in Iran, the results were determined by ignoring the inlet fuel cost. The technical analysis was also performed considering the engine performance results. The results showed that the 10% and 15% biodiesel-diesel blends (B10 and B15) were more affordable than diesel fuel. The performance results of engine were also acceptable in these blends. The power loss was slight and the highest thermal efficiency was also observed in these blends. All biodiesel blends were more affordable than diesel in emissions economic analysis

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In this paper the stabilizing of non- premixed turbulent flame with a porous medium is studied experimentally. One of the approaches taken to stabilize the flame in high thermal capacity is the usage of the porous medium on the burner. A non-premixed burner with natural gas fuel is used. The First, tests are carried out for the conventional burner and then for the combined burner with the carbide ceramics porous medium. In the conventional burner effects of fuel and air velocity and equivalence ratio on flame length, flame lift off and the stability limit are discussed. Porous silicon carbide ceramics with pore densities of 10ppi, 20ppi and 30ppi are used in the combined burner. Experiments are done at 5cm, 10cm and 15cm distances of porous medium from the burner. The viewed flames in the combined burner are grouped into four regimes. In conventional burner flame in a rich mixture is formed and flame length raise with increasing equivalence ratio. The results show that make less in pore density of the medium increases the possibility of flame formation in the porous medium. Moreover it is observed the flame is formed in the porous medium in an average equivalence ratio of φ=0.63, which is almost the equivalence ratio which a immersed flame is formed in a premixed porous burne.

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Cement rotary kilns are extensively used to change raw material into clinker. This is a complex process and consists of many different phenomena such as bed material reactions, gas phase turbulent combustion and radiation in a rotary drum, and thermal-mass interactions between them. Using CFD, the two-dimensional numerical simulation of cement rotary kiln was performed in the present study. This model included gaseous fuel combustion, bed material reactions, and radiation heat transfer in the kiln. Using this model and parallel processing network, combustion models (PaSR, EDM and mixture fraction) in the cement kilns are investigated. Due to the high Damkohler number in the cement kiln (0.7<Da<17), selecting the appropriate combustion model is difficult. Among the combustion models that were studied, it was found that the PaSR model is the slowest and mixture fraction model is the fastest model whereas the both models predict physics well. Keywords

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Vortex combustion chamber is the new generation of liquid propellant engines chamber, where with the help of different arrangement of injectors, an inner combustion chamber vortex flow is created. This vortex can extremely help cooling and increasing the amount of propellant components mixing in the combustion chamber so it makes it possible to create a complete combustion in a low- capacity chamber. In this research, a vortex chamber has been designed and manufactured for carrying out cold tests with water as its working fluid, in order to study impact of different parameters, including pressure drop, injector quantity and input angle, chamber diameter and the thickness of the supporting step, on the performance of this type of chambers. The designed chamber, has a great deal of capabilities such as replacement ease, change in pressure drop and injectors’ input angle and studying different supporting step’s thickness to create vortex flow. Since practical investigation of all parameters is not cost-effective, cold test has been conducted for some samples and both simulation and validation have been done for it. The simulation results and chamber performance in the tests could match very well; therefore as a result of simulation assurance, the processes and other parameters in the chamber could be studied. By doing these tests we can move toward design, manufacture and test of the main vortex combustion chamber.

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In-Situ Combustion (ISC) is one of thermal heavy oil recovery methods in which the heat required to displace crude oil is generated by combustion of a small fraction of oil inside the reservoir. Because of presence of several processes such as combustion, phase change and reservoir fluids thermal expansion, in-situ combustion is regarded as a very complicated recovery method. In the present work, aiming acquiring a better understanding of ISC physics, the oil in place volume (expressing in terms of oil saturation) effects on performance of ISC is numerically investigated in 1D. In order to increase the model accuracy, a semianalytical model is used to account for heat loss to overburden and underburden. The numerical results show in reservoirs with high initial oil saturation, the mobilized oil is deposited in region near to production well during first days of ISC operation. Consequently, relative permeability of porous reservoir for gas phase considerably decreases. Moreover, combustion front propagation velocity reduces and the reservoir pressure significantly increases in the region upstream of the combustion front. As a result of the front velocity decrease, oil recovery rate decreases. Furthermore, if the pressure increasing is not considered in designing the air injection system, the air injection rate will be decreased and can lead to combustion front quenching. The results also show ignoring heat loss from the reservoir will lead to incorrect prediction of pore blockage.

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In this paper the coupled lattice Boltzmann model is developed for simulation of multi-step combustion mechanism of a methane jet diffusion flame. The lattice Boltzmann scheme employs the double-distribution-function model, one distribution function for solving flow field and another for temperature and species concentration fields. The density and temperature fields are coupled through low Mach number flow field. The solution parameters such as species properties and rate of chemical reactions adjust in every time step according to temperature and concentration of species variations. Using combustion mechanisms instead of one step fast chemistry reaction and considering effect of temperature and species concentration on solution parameters are the main advantages of the developed model. For validation of the model, a four-step reduced mechanism with six species is used for simulation of combustion in a methane jet diffusion flame configuration. Agreement between the present results and experimental data confirms that this scheme is also an efficient numerical method for more detailed combustion simulations.

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The low temperature combustion (LTC) concept is the groundwork of most recent developments in internal combustion diesel engines in order to match stringent environmental standards and regulations. Although, its basic definition which means reducing the combustion chamber temperature to decrease the emissions sounds easy but practical achievement of LTC strategies which can be feasible in a wide range of loads and speeds has its own difficulties. With attention to different effective parameters in a diesel engine combustion process, various methods have been introduced for the purpose of LTC achievement. Two important types of these methods are based upon early and late injection strategies. In addition to analyzing the both mechanisms, in this paper we are intended to implement two different methods in national light duty diesel engine in order to match EURO VI emission standard. One method named UNIBUS is based upon early injection strategies which is benefited from PPC merits and the other one is Modulated Kinetic (MK) which is based upon late injection strategies. Finally both these methods have been compared and contrasted. The results admit the great potentiality of both methods to make a significant and simultaneous reduction in NOx and Soot emissions.

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Detonation engines are expected to be included in a number of aerospace thrusters in the future. Several types of detonation engines are currently under examination, including the rotating detonation engine. In this work, the feasibility study and design of a laboratory sample RDE which has an annular geometry with diameter of 76 mm has been performed. In this sample, hydrogen and standard air are separately injected into the combustion chamber of detonation engine. The injection of fuel and air flows are in the axial and radial directions, respectively. First, numerical studies are validated comparing the FLUENT results with the experimental ones. Then, the geometry and equivalence ratio of injection mixture are investigated parametrically. Considering the negligible variations of thermodynamics parameters in the radial direction of flow field and to reduce the computational costs, a 2D model is used for numerical simulations. Using three different equivalence ratio, it is found that detonation speed, pressure, and temperature behind detonation front, at the equivalence ratio of 1.2 is more than the equivalence ratio of 0.8. Also maximum detonation speed and pressure behind detonation is taken place in stoichiometric condition. The coefficient 0.5 and 2 are used in order to evaluate the effects of chamber length. Because the chamber outflow is semi-subsonic, chamber length change has a significant effect on the engine performance and flow field. The results point out that increasing the chamber length in low injection pressure and high injection pressure leads to increasing and decreasing the height of detonation front, respectively.

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Recently, tubular flames are considered due to their advantageous in geometry of the flame. The major importance of tubular flame is its uniform temperature distribution. Therefore, it may reduce thermal fluctuations along the combustion chamber. In this paper, a non-premixed tubular flame is simulated numerically under various operational conditions. A solver is developed in openFOAM and numerical results are validated against the experimental measurements. Also, temperature distribution and concentration of major species of the flame in the middle of the burner are investigated and compared using global and DRM22 as chemical kinetics. In addition, stability of the flame in air presence as oxidizer has been studied. Results show that by increasing oxygen mole fraction in oxidizer, the equivalence ratio of the steady tubular flame region decreases and the flame will be established uniformly in equivalence ratio near the extinction limit. If pure oxygen is used as oxidizer, flame temperature will be increase strongly and tubular flame can be stable for equivalence ratio between 0.1 and 0.2. Thereupon carbon dioxide from the flue gases is added to the oxidizer to control the flame temperature changes. Establishment of steady tubular flame in presence of carbon dioxide is simulated too. Results show that by decreasing oxygen mole fraction, the equivalence ratio of the steady tubular flame region increases and the stability zone becomes wider

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Spray combustion is utilized in a number of engineering applications such as energy conversion, military industrial, furance and propulsion devices. Current work focused on the effect of liquid fuel droplet diameter on the efficiency of the combustion chamber and formed emission such as NOx and CO in a two-dimensional axisymmetric combustion chamber. The discrete phase model approach employed for simulating Combustion. The gas phase is simulated using an Eulerian approach; while the droplets are treated with a Lagrangian method. The coupling between the two phases and effect of radiation is considered. The mixture-fraction/probability density function (PDF) equilibrium chemistry model is used to predict the combustion of the vaporized fuel. Also, the conservative equations of mass, momentum and energy in the turbulent flow field were solved in conjunction with the k–ε two equation turbulence model. A numerical simulation was carried out to study the influence of droplet size on the formation and emission of NOx and other contaminants. This effect was investigated under different droplet diameter and type of injection. The following conclusions be drawn: Smaller droplets produce higher NOx emission than the larger ones. Larger droplets produce higher CO than Smaller ones.