scholarly journals Advancing predictive models for particulate formation in turbulent flames via massively parallel direct numerical simulations

2014 ◽  
Vol 372 (2022) ◽  
pp. 20130324 ◽  
Author(s):  
Fabrizio Bisetti ◽  
Antonio Attili ◽  
Heinz Pitsch
Keyword(s):  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Soot Formation ◽  
Model Development ◽  
Turbulent Flames ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Carbon Abatement ◽  
Physico Chemical ◽  
Combustion Modelling

Combustion of fossil fuels is likely to continue for the near future due to the growing trends in energy consumption worldwide. The increase in efficiency and the reduction of pollutant emissions from combustion devices are pivotal to achieving meaningful levels of carbon abatement as part of the ongoing climate change efforts. Computational fluid dynamics featuring adequate combustion models will play an increasingly important role in the design of more efficient and cleaner industrial burners, internal combustion engines, and combustors for stationary power generation and aircraft propulsion. Today, turbulent combustion modelling is hindered severely by the lack of data that are accurate and sufficiently complete to assess and remedy model deficiencies effectively. In particular, the formation of pollutants is a complex, nonlinear and multi-scale process characterized by the interaction of molecular and turbulent mixing with a multitude of chemical reactions with disparate time scales. The use of direct numerical simulation (DNS) featuring a state of the art description of the underlying chemistry and physical processes has contributed greatly to combustion model development in recent years. In this paper, the analysis of the intricate evolution of soot formation in turbulent flames demonstrates how DNS databases are used to illuminate relevant physico-chemical mechanisms and to identify modelling needs.

Extraction and Determination of Physico-chemical Properties of Oil from Watermelon Seeds (Citrullus lanatus L) to Use in Internal Combustion Engines

2017 ◽  
Vol 68 (11) ◽  
pp. 2676-2681
Author(s):  
Mihaela Gabriela Dumitru ◽  
Dragos Tutunea
Keyword(s):  
Fatty Acid ◽  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Citrullus Lanatus ◽  
Combustion Process ◽  
Chemical Properties ◽  
Physico Chemical ◽  
Mean Diameter ◽  
Geometrical Mean ◽  
Reduction Of Nox

The purpose of this work was to investigate the physicochemical properties of watermelon seeds and oil and to find out if this oil is suitable and compatible with diesel engines. The results showed that the watermelon seeds had the maximum length (9.08 mm), width (5.71mm), thickness (2.0 mm), arithmetic mean diameter (5.59 mm), geometrical mean diameter (4.69 mm), sphericity (51.6%), surface area (69.07), volume 0.17 cm3 and moisture content 5.4%. The oil was liquid at room temperature, with a density and refractive index of 0.945 and 1.4731 respectively acidity value (1.9 mgNaOH/g), free fatty acid (0.95 mgNaOH), iodine value (120 mgI2/100g), saponification value (180 mgKOH/g), antiradical activity (46%), peroxide value (7.5 mEqO2/Kg), induction period (6.2 h), fatty acid: palmitic acid (13.1%), stearic acid (9.5 %), oleic acid (15.2 %) and linoleic acid (61.3%). Straight non food vegetable oils can offer a solution to fossil fuels by a cleaner burning with minimal adaptation of the engine. A single cylinder air cooled diesel engine Ruggerini RY 50 was used to measure emissions of various blends of watermelon oil (WO) and diesel fuel (WO10D90, WO20D80, WO30D70 and WO75D25). The physic-chemical properties of the oil influence the combustion process and emissions leading to the reduction of NOX and the increase in CO, CO2 and HC.

An Experimental Investigation of Soot Formation During Nonpremixed Turbulent Combustion of Hydrocarbon Fuels

2002 ◽  
Author(s):  
Bo Yang ◽  
Umit O. Koylu
Keyword(s):  
Computational Models ◽  
Soot Formation ◽  
Reynolds Numbers ◽  
Turbulent Flames ◽  
Laminar Flames ◽  
Pollutant Emissions ◽  
Laser Scattering ◽  
Gaseous Fuels ◽  
Predicting Performance ◽  
High Reynolds

Although practical combustion devices involve turbulent conditions, crucial soot investigations have generally been based on the data obtained from laminar flames with relatively limited number of studies in the literature on turbulent flames. Motivated by the need for data that can allow proper characterization of soot properties within the fuel-rich regions of turbulent flames, optical experiments were carried out within hydrocarbon-fueled nonpremixed turbulent jet flames. Specifically, two gaseous fuels, ethylene and acetylene, were burned at relatively high Reynolds numbers in air at atmospheric pressure. In-situ diagnostics included laser scattering and extinction techniques to determine the soot field at various axial and radial positions in these flames. The findings are relevant not only to developing advanced computational models for accurate predictions of radiative transfer but also to controlling and predicting performance and pollutant emissions in combustion systems.

Subgrid combustion modelling for large-eddy simulations

2000 ◽  
Vol 1 (2) ◽  
pp. 209-227 ◽  
Author(s):  
S Menon
Keyword(s):  
Turbulent Flows ◽  
Internal Combustion Engines ◽  
Large Scale ◽  
Large Eddy Simulations ◽  
Accurate Prediction ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Small Scale ◽  
Large Eddy ◽  
Combustion Processes

Next-generation gas turbine and internal combustion engines are required to reduce pollutant emissions significantly and also to be fuel efficient. Accurate prediction of pollutant formation requires proper resolution of the spatio-temporal evolution of the unsteady mixing and combustion processes. Since conventional steady state methods are not able to deal with these features, methodology based on large-eddy simulations (LESs) is becoming a viable choice to study unsteady reacting flows. This paper describes a new LES methodology developed recently that has demonstrated a capability to simulate reacting turbulent flows accurately. A key feature of this new approach is the manner in which small-scale turbulent mixing and combustion processes are simulated. This feature allows proper characterization of the effects of both large-scale convection and small-scale mixing on the scalar processes, thereby providing a more accurate prediction of chemical reaction effects. LESs of high Reynolds number premixed flames in the flamelet regime and in the distributed reaction regime are used to describe the ability of the new subgrid combustion model.

Quasidimensional Modeling of Direct Injection Diesel Engine Nitric Oxide, Soot, and Unburned Hydrocarbon Emissions

2005 ◽  
Vol 128 (2) ◽  
pp. 388-396 ◽  
Author(s):  
Dohoy Jung ◽  
Dennis N. Assanis
Keyword(s):  
Nitric Oxide ◽  
Diesel Engine ◽  
Diesel Engines ◽  
Soot Formation ◽  
Direct Injection ◽  
Equation Model ◽  
Design Tool ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Cycle Simulation

In this study we report the development and validation of phenomenological models for predicting direct injection (DI) diesel engine emissions, including nitric oxide (NO), soot, and unburned hydrocarbons (HC), using a full engine cycle simulation. The cycle simulation developed earlier by the authors (D. Jung and D. N. Assanis, 2001, SAE Transactions: Journal of Engines, 2001-01-1246) features a quasidimensional, multizone, spray combustion model to account for transient spray evolution, fuel–air mixing, ignition and combustion. The Zeldovich mechanism is used for predicting NO emissions. Soot formation and oxidation is calculated with a semiempirical, two-rate equation model. Unburned HC emissions models account for three major HC sources in DI diesel engines: (1) leaned-out fuel during the ignition delay, (2) fuel yielded by the sac volume and nozzle hole, and (3) overpenetrated fuel. The emissions models have been validated against experimental data obtained from representative heavy-duty DI diesel engines. It is shown that the models can predict the emissions with reasonable accuracy. Following validation, the usefulness of the cycle simulation as a practical design tool is demonstrated with a case study of the effect of the discharge coefficient of the injector nozzle on pollutant emissions.

Subgrid Modeling of Soot Formation in Non-Premixed Turbulent Flames

2007 ◽  
Author(s):  
H. El-Asrag ◽  
S. Menon
Keyword(s):  
Volume Fraction ◽  
Soot Formation ◽  
Soot Volume Fraction ◽  
Reaction Diffusion ◽  
Mean Free Path ◽  
Current Approach ◽  
Turbulent Flames ◽  
Combustion Model ◽  
Method Of Moment ◽  
Air Jet

A subgrid model for soot dynamics is developed for large-eddy simulation (LES) using the Method of Moment with Interpolative Closure (MOMIC). The soot model is implemented within a subgrid mixing and combustion model so that reaction-diffusion-MOMIC coupling is possible without requiring ad hoc filtering. The combined model includes the entire process, from the initial phase, when the soot nucleus diameter is much smaller than the mean free path, to the final phase, after coagulation and aggregation, where it can be considered in the continuum regime. The soot diffusion and the effect of the thermophoretic forces are included in the model. A relatively detailed but reduced kinetics for ethylene-air is used to simulate an experimentally studied non-premixed ethylene/air jet diffusion flame. In this formulation, acetylene is used as a soot precursor species. The soot volume fraction order of magnitude, the location of its maxima, and the soot particle size distribution are all captured reasonably. Along the centerline, an initial region dominated by nucleation and surface growth is established followed by an oxidation region. A possible initial log-normal distribution followed by a more gaussian distribution downstream the centerline is observed. Limitations of the current approach and possible solution strategies are also discussed.

scholarly journals Empirical soot formation and oxidation model

2009 ◽  
Vol 13 (3) ◽  
pp. 35-46 ◽  
Author(s):  
Karima Boussouara ◽  
Mahfoud Kadja
Keyword(s):  
Internal Combustion Engines ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Internal Combustion ◽  
Combustion Model ◽  
Diesel Combustion ◽  
Combustion Engines ◽  
Particulate Emission ◽  
Cycle Simulation ◽  
Air Mixing

Modelling internal combustion engines can be made following different approaches, depending on the type of problem to be simulated. A diesel combustion model has been developed and implemented in a full cycle simulation of a combustion, model accounts for transient fuel spray evolution, fuel-air mixing, ignition, combustion, and soot pollutant formation. The models of turbulent combustion of diffusion flame, apply to diffusion flames, which one meets in industry, typically in the diesel engines particulate emission represents one of the most deleterious pollutants generated during diesel combustion. Stringent standards on particulate emission along with specific emphasis on size of emitted particulates have resulted in increased interest in fundamental understanding of the mechanisms of soot particulate formation and oxidation in internal combustion engines. A phenomenological numerical model which can predict the particle size distribution of the soot emitted will be very useful in explaining the above observed results and will also be of use to develop better particulate control techniques. A diesel engine chosen for simulation is a version of the Caterpillar 3406. We are interested in employing a standard finite-volume computational fluid dynamics code, KIVA3V-RELEASE2.

Measurement and Simulation of Instantaneous Emissions of a Heavy Truck Diesel Engine During Transients

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Xavier Tauzia ◽  
Pascal Chesse ◽  
Jean-François Hetet ◽  
Nicolas Thouvenel
Keyword(s):  
Steady State ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Limiting Factor ◽  
Zone Model ◽  
Gaseous Emissions ◽  
Combustion Heat

During the last decades, pollutant emissions from internal combustion engines used for transportation have become a major concern. Today, not only steady state emissions but also emissions during transients are regulated and have to be studied in order to be reduced. In this paper, we describe a new methodology developed to measure the instantaneous level of gaseous emissions from a internal combustion engine during transients, using an analyzer initially designed for steady state operation. Moreover, a new phenomenological thermodynamical combustion model is proposed in order to compute emissions during transients. The results of these two methods are compared on various transients. The measurement method seems to give good results (except for hydrocarbon (HC) measurements), as long as the speed and load variations are not too fast. Otherwise, the frequency of the analyzer which was used becomes the limiting factor. The new combustion heat release developed to simulate transients, coupled with an existing two-zone model for emission calculations, leads to satisfactory results for CO2 and O2 concentrations and NOx emissions. The agreement with measurements is good for smooth transients and seems promising for faster dynamics. The initial goal was reached, although some improvements are still necessary concerning HC measurements and the fastest transients. These results could be helpful when trying to reduce the amount of pollutant emissions at the exhaust during transients, directly or with after treatment devices.

scholarly journals Combustion Optimization for Coal Fired Power Plant Boilers Based on Improved Distributed ELM and Distributed PSO

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1036 ◽  
Author(s):  
Xinying Xu ◽  
Qi Chen ◽  
Mifeng Ren ◽  
Lan Cheng ◽  
Jun Xie
Keyword(s):  
Power Plant ◽  
Combustion Process ◽  
Optimization Method ◽  
Combustion Efficiency ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Nox Emissions ◽  
Coupling Characteristics ◽  
Learning Machine ◽  
Combustion Optimization

Increasing the combustion efficiency of power plant boilers and reducing pollutant emissions are important for energy conservation and environmental protection. The power plant boiler combustion process is a complex multi-input/multi-output system, with a high degree of nonlinearity and strong coupling characteristics. It is necessary to optimize the boiler combustion model by means of artificial intelligence methods. However, the traditional intelligent algorithms cannot deal effectively with the massive and high dimensional power station data. In this paper, a distributed combustion optimization method for boilers is proposed. The MapReduce programming framework is used to parallelize the proposed algorithm model and improve its ability to deal with big data. An improved distributed extreme learning machine is used to establish the combustion system model aiming at boiler combustion efficiency and NOx emission. The distributed particle swarm optimization algorithm based on MapReduce is used to optimize the input parameters of boiler combustion model, and weighted coefficient method is used to solve the multi-objective optimization problem (boiler combustion efficiency and NOx emissions). According to the experimental analysis, the results show that the method can optimize the boiler combustion efficiency and NOx emissions by combining different weight coefficients as needed.

scholarly journals Emissions of an agricultural engine using blends of diesel and hydrous ethanol

2019 ◽  
Vol 40 (1) ◽  
pp. 7
Author(s):  
Marcelo Silveira de Farias ◽  
José Fernando Schlosser ◽  
Javier Solis Estrada ◽  
Gismael Francisco Perin ◽  
Alfran Tellechea Martini
Keyword(s):  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Renewable Energy Sources ◽  
Standard Procedure ◽  
Diesel Oil ◽  
K Value ◽  
Operating Modes ◽  
Diesel Cycle ◽  
Reduce Emissions ◽  
Hydrous Ethanol

The growing global demand of energy, the decrease of petroleum reserves and the current of environmental contamination problems, make it imperative to study renewable energy sources for use in internal combustion engines, in order to decrease the dependence on fossil fuels and reduce emissions of pollutant gases. This study aimed to evaluate the emissions of a diesel-cycle engine of an agricultural tractor that uses diesel S500 (B5) mixed with 3, 6, 9, 12 and 15% of hydrous ethanol. It determined emissions of CO2 (ppm), NOx (ppm), and opacity (k value) of gases. A standard procedure was applied considering eight operating modes (M1, M2, M3, M4, M5, M6, M7, and M8) by breaking with an electric dynamometer in a laboratory. The experimental design was completely randomized, with 60 replicates and a 6 x 8 factorial design. Greater opacity and gas emissions were observed when the engine operated with 3% ethanol, while lower emissions occurred with 12 and 15%. With these fuels, the reduction of opacity, CO2, and NOx, in relation to diesel oil, was 24.49 and 26.53%, 4.96 and 5.15%, and 6.59 and 9.70%, respectively. In conclusion, the addition of 12 and 15% ethanol in diesel oil significantly reduces engine emissions.

Sign in / Sign up

Export Citation Format

Share Document