ENCIT2012-008 LES SOLUTION OF A METHANOL JET DIFFUSION FLAME - PDF
Greice da Silva Lorenzzetti Andreis, Álvaro Luiz de Bortoli, UFRGS, Brazil
Abstract: The methanol has favorable combustion properties that include lower emissions of particulates and nitrogen oxides. Therefore, this work presents a model for the solution of methanol jet diffusion flames for low Mach number. The model is based on the solution of the Lagrangian flamelet equations for the chemistry and on the mixture fraction for the flow. The governing equations are discretized using the second-order space finite difference method, using LES (Large-Eddy Simulation) with the Smagorinsky model for the turbulent viscosity. Numerical tests are carried out for methanol diffusion flames, and the results compare favorably with data from the literature.
Keywords:diffusion flames; methanol; flamelet; LES.
Presentation Schedule: Wednesday, 14:20-14:40. Session: CEE1-1. Presenter: Greice da Silva Lorenzzetti Andreis.
ENCIT2012-026 THEORETICAL CONSIDERATIONS ABOUT THE STEADY STATE COMBUSTION OF WOOD CHAR IN A BUBBLING FLUIDIZED BED REACTOR - PDF
Carlos Pinho, Universidade do Porto, Portugal
Abstract: A theoretical study on the performance of steady state bubbling fluidized bed burners is presented using a simple mathematical model. The proposed model has pedagogical and practical advantages due to its simplicity. The calculations whose results are plotted in several graphics were carried out based on data obtained in laboratory scale experiments. The experiments carried out with wood chars and the model allows a thorough evaluation of physical and chemical phenomena taking place inside the reactor, as well as a fast approach to the pre-design phase, before going towards more complex and time consuming numerical modeling. In the first part of the paper the steady state modeling is compared with the combustion of successive batches of char particles. Afterwards, the performance of a 1 m diameter bed operating from 700 to 800 ºC is shown.
Keywords:Biomass; Wood char; Fluidized bed; Combustion; Modeling.
Presentation Schedule: Wednesday, 15:00-15:20. Session: CEE1-1. Presenter: Carlos Pinho.
ENCIT2012-098 SPRAY CONE ANGLES OF A DUAL CENTRIFUGAL INJECTOR - PDF
Roger Apaza Vásquez, Fernando de Souza Costa, INPE, Brazil
Abstract: A dual pressure swirl injector is characterized by two independent concentric chambers which can provide independent rotational levels to a single liquid or two different liquids. This paper compares theoretical and experimental results concerning the spray cone angles formed by injection of ethanol and biodiesel through a dual pressure swirl injector. Data are obtained for injection of a single biofuel through the primary and secondary chambers and for injection of ethanol in the primary chamber and biodiesel through the secondary chamber of the injector. Experimental data are obtained using photographic techniques and are analyzed by an image processing software developed in Matlab language.
Keywords:dual pressure swirl injector; ethanol; biodiesel; spray cone angle.
Presentation Schedule: Wednesday, 16:40-17:00. Session: CEE1-1. Presenter: Fernando de Souza Costa.
ENCIT2012-144 A REACTOR NETWORK MODEL FOR PREDICTING NOX EMISSIONS IN AN INDUSTRIAL BURNER - PDF
Amir Roberto de Toni Junior, Thamy Cristina Hayashi, Paulo Smith Schneider, UFRGS, Brazil
Abstract: A chemical reactor network (CRN) is developed and applied to the modeling of a natural gas burner. The CRN development is based on experimental and CFD simulation results of the BERL 300 kW test. The CRN element arrangement, reactor volumes and flow splits are adjusted based on the best agreement with characteristic temperatures of the reactive flow, aiming to reproduce the experimental NOx emissions data. A sensitivity analysis and a parametric study of the CRN are carried out to evaluate its sensitivity to the flow splits adjustments and its ability to predict emission with air preheat and turndown operation. The NOx emissions predicted by CRN are in good agreement until 110ºC preheating and for a turndown ratio of 1,33.
Keywords:chemical reactor network; NOx emissions; BERL 300 kW.
Presentation Schedule: Wednesday, 16:00-16:20. Session: CEE1-1. Presenter: Amir Roberto De Toni Junior.
ENCIT2012-225 GASIFICATION OF BRAZILIAN BIOMASS AND SOLID FOSSIL FUELS: A COMPARATIVE STUDY OF FLUE GAS QUALITY FROM THE GIBBS FREE ENERGY MINIMIZATION APPROACH - PDF
Jhon Jairo Ramirez-Behainne, UTFPR, Brazil
Luiz Guilherme Santos, UFABC, Brazil
Abstract: This work shows a comparative study about the flue gas quality obtained from the gasification process of several biomass and solid fossil fuels by using the Gibbs free energy minimization approach. A mathematical algorithm was implanted in order to simulate the equilibrium composition of carbon monoxide, methane and hydrogen in the flue gas when Brazilian sugarcane bagasse, sawdust, rice husk, coal and oil shale are gasified. The model was applied aiming to determine the effects of the gasification equivalence ratio, fuel moisture, and reaction temperature on the volumetric composition of the flue gas and its higher heating value. Results of simulation for gasification equivalence ratios varying between 0.25 and 0.45, fuel moisture moving in the range of 10 to 30\%, and temperature changing from 700 to 900ºC suggest that there is no significant difference for flue gas quality obtained from several biomass, but between renewable and fossil fuels. On the other hand, the behavior of the flue gas main components in relation to the analyzed factors was as expected when compared with data obtained from previous works. Results also indicated that the non-equilibrium model adopted can be useful for using in preliminary design of gasifiers.
Keywords:Gasification; Thermochemical equilibrium; Biomass; Coal.
Presentation Schedule: Wednesday, 15:40-16:00. Session: CEE1-1. Presenter: Jhon Jairo Ramirez-Behainne.
ENCIT2012-078 COMBUSTION MODELING OF A COMPRESSION IGNITION ENGINE - PDF
Fellipe Tavares Barreto, Wilson Luciano de Souza, UFS, Brazil
Abstract: Since the nineteenth century the internal combustion engines have had its development linked to thermodynamic models that describe its works. The research progress has increased the computational tools utilization which reduces costs and work time against the purely experimental methods. That last one has required, during the last decades, high investments and large return terms. Despite that the comprehension and control of a thermal engines operation are extremely complex due the large diversity of phenomena inherent to many scientific fields such chemistry, fluid mechanics and heat and mass transfer, mechanical vibrations. Under the gaze of that context, this paper describes the development of a mathematics-computational model which was accomplished on the ambiance Simulink, of Matlab. It is able to represent and evaluate the combustion in a compression ignition engine (Diesel). The modeling is zero-dimensional, established based on the first law of thermodynamics, considering the combustion chamber as a closed system where the crank angle is the only independent variable. The thermodynamic variables such pressure and temperature are considered as uniform in whole cylinder volume, at each crank shaft position. The rate of burned combustible and the heat-transfer to the combustion chamber walls are established according to sub-models empirically obtained. The modeling in Simulink consists in the elaboration of a subsystems library in which each subsystem represents an engine component, a theoretical model or a calculator block. The logical and operational link among the subsystems makes up the proposed modeling. The performance of a CI engine whose model is John Deere TF 4039 was evaluated and its results were compared in relation to the theoretical prediction from the literature. Test bench data acquired were exploited in order to validate the mathematics-computational model capability in represent the reality.
Keywords:Numerical Simulation; Diesel Engines; Ignition Compression; Combustion; Simulink.
Presentation Schedule: Thursday, 12:00-12:20. Session: CEE1-2. Presenter: Wilson Luciano de Souza.
ENCIT2012-143 EVALUATING INDIRECT INJECTION DIESEL ENGINE PERFORMANCE FUELED WITH PALM OIL - PDF
Ricardo da Silva Pereira, Manoel Fernandes Martins Nogueira, Maria Emilia de Lima Tostes, UFPA, Brazil
Abstract: Previous works has demonstrated the feasibility of palm oil application as fuel for compression engines as well as others vegetable oils. Such oils can be used without chemical transformations requiring only be filtered and neutralized, both simple processes, and they have high heating values similar to diesel oil. Problems already identified are related with its high viscosity at room temperature and requirement for larger residence time than diesel fuel to complete its combustion reaction. The first problem has been solved with oil pre-heating before high pressure injection pump inlet and there are available systems to perform this task. To the second problem (longer residence time) all proposed approach to solve it rely on keep high temperature in the combustion chamber and accelerate the chemical kinetics in such way that the engine available time for combustion is bigger than the fuel required residence time. It implies that the engine can operate with vegetable oils only at high loads, being replaced by diesel oils at medium and low loads. This problem has been report on all experiments using direct injection compressed engines. Indirect combustion engines have a pre-combustion chamber that is kept always at high temperature independent of the shaft load. Therefore it is supposed that such engines are able to operate with vegetable oils for their full range of operating load. This work tested an indirect injection engine assembled as part of a 20 kVA generator set, (genset) and the results compared with those of direct injection engine. Palm Oil was used as fuel and the genset received instrumentation to measure the fuel temperature and flow rate at engine inlet, elude gas temperature at exit of combustion chamber, electric power produced and gas emitted composition (CO and NOx,). Similar data was obtained for the genset operating with diesel oil for comparison. In order to quantify the inlet amount of energy the diesel oil and palm oil were submitted to test to quantify their high heating value and ultimate analysis. Results showed that indirect injection engine operating with palm oil have an increasing on specific consumption fuel as well as CO and NOx concentration and small drop on eluded gases temperature, compared with direct injection engine consuming palm oil for the same load percentage.
Keywords:palm oil; compression engine; indirect injection; direct injection.
Presentation Schedule: Thursday, 11:40-12:00. Session: CEE1-2. Presenter: Ricardo Pereira.
ENCIT2012-160 SENSITIVE ANALYSIS OF A COAL COMBUSTION MODEL ON A DROP TUBE FURNACE - PDF
Leonardo Zimmer, Fernando Marcelo Pereira, Paulo Smith Schneider, UFRGS, Brazil
Abstract: In the present work one-dimensional model coal combustion on a Drop Tube Furnace (DTF) is developed. The modeling is developed from literature, and the discrete equations that characterize the flow, heat transfer and coal combustion reactions are programmed in FORTRAN 90 language. The results are compared with a reference model and experimental data, and showed good agreement. A sensitivity study is performed to understand the behavior of coal combustion due to changes of some working parameters of the DTF. The sensitivity analysis showed the versatility of the model and thereby the experiment. From the variation of the oxygen concentration, operating temperature and input flow rates a range of results can be obtained. Using the model presented here together with experimental results leads to a detailed study of the kinetic parameters of coal combustion.
Keywords:Drop Tube Furnace; coal combustion; kinetic parameters; numerical model.
Presentation Schedule: Thursday, 11:00-11:20. Session: CEE1-2. Presenter: Leonardo Zimmer.
ENCIT2012-104 REDUCED MECHANISM FOR COMBUSTION OF HYDROGEN AND METHANE WITH NITROGEN CHEMISTRY - PDF
Pedro Azevedo, LNEG, Portugal
Carlos Pinho, Universidade do Porto, Portugal
Isabel Cabrita, LNEG, Portugal
Abstract: A reduced chemical kinetic reaction mechanism that could be used in CFD software was developed to describe the formation of nitrogen oxides and their subsequent destruction in hydrogen and/or hydrocarbon flames with or without seeding of nitrogen compounds. The research work presented here will describe the numerical work done with the application "Chemkin" in order to verify the reduced mechanism agreement to known detailed mechanisms. These mechanisms were validated through comparisons between computational data from a variety of different sources. In addition, numerical experiments were carried out to examine features of methane combustion in which the detailed mechanisms can be used to compare their response. The proposed reduced mechanism yields good agreement with the studied detailed mechanisms, mainly in the species produced from the hydrocarbon oxidation process. Regarding the produced nitrogen species, POA reduced mechanism showed the same tendencies as the detailed mechanisms but there is a need for a better agreement regarding the quantities.
Keywords:Combustion; Reduced mechanism; hydrocarbons; NOx; chemkin.
Presentation Schedule: Thursday, 11:20-11:40. Session: CEE1-2. Presenter: Carlos Pinho.
ENCIT2012-111 CHARACTERIZATION OF A BLURRY INJECTOR FOR BURNING BIOFUELS IN A COMPACT FLAMELESS COMBUSTION CHAMBER - PDF
Claudia Gonçalves Azevedo, Fernando de Souza Costa, José Carlos Andrade, INPE, Brazil
Abstract: In recent years there has been a great interest in the use of biofuels in order to reduce the environmental impact of combustion processes and replacement of fossil fuels. New combustion technologies are also under development, aiming to reduce costs, increase operating efficiency and reduce pollutants emissions. This work describes the spray characteristics of hydrous ethanol and B100 soy biodiesel in a blurry injector for applications in a flameless compact combustion chamber. The experimental results are obtained over a range of liquid and air flow rates, air-to-liquid mass flow ratios (ALR) and injection pressures. The main parameters that have been selected in the experimental characterization are average drop diameter, drop size distribution and discharge coefficient.
Keywords:Blurry injector; Biofuels; Soy Biodiese; Drop Size; Hydrous Ethanol.
Presentation Schedule: Thursday, 12:20-12:40. Session: CEE1-2. Presenter: Fernando de Souza Costa.
ENCIT2012-139 TECHNIQUE TO QUANTIFY TAR CONTENT IN ELUDED GAS AND PERFORMANCE OF A DOWNDRAFT BIOMASS GASIFIER - PDF
Bruno Almeida Pinheiro do Couto, Ellen Lilian Matos de Brito, Manoel Fernandes Martins Nogueira, Danielle Regina da Silva Guerra, UFPA, Brazil
Abstract: One promising sources for renewable energy is vegetable biomass. A more efficient process and also able to wider solid biomass applications is its conversion from solid to gas phase through a gasification process. The bottleneck for such technology is the high tar and solid particle concentratios in the gasifiers eluded gas. These two species are toxic, carcinogenic and have potential to deteriorate mechanical equipments, reducing their useful lifetime, increasing maintenance frequency and finally defining the gasifier quality. Based upon it, this paper presents a performance study of an open-top and fixed bed downdraft gasifier using açai seed (biomass fuel) applying a locally developed sampling equipment which is able to separate and quantify tar, soot and non condensable gases concentration and evaluate gasifier thermal and carbon conversion efficiency. Results obtained show that açai seed has 16.795 MJ/kg of Higher Heating Value, lower than the average value for biomasses. Furthermore, the locally developed sampling line was able to quantify soot, tar and non-condensable gases concentration and allowing the low heating value calculation in dry basis as 2.266 MJ/kg.
Keywords:Biomass Gasification; Açai Seed; Tar Measurement; Performance.
Presentation Schedule: Wednesday, 14:40-15:00. Session: CEE1-1. Presenter: Bruno Almeida Pinheiro do Couto.
ENCIT2012-249 DATA ACQUISITION SYSTEM AND LOAD CONTROL SYSTEM FOR DIESEL POWER GENERATOR TESTING - PDF
Marco Aurélio Mendes Justino, Osmano Souza Valente, Eduardo Chaves Moreira dos Santos, Márcio José da Silva, José Ricardo Sodré, PUC-Minas, Brazil
Abstract: This work describes a data acquisition system developed for diesel power generator fuel consumption testing. The data acquisition system was developed using LabView software. The software and hardware that are integral part of the system are detailed. The main input and output data of the system are described. Typical results produced by the system are presented for tests carried out in a 50 kW diesel power generator.
Keywords:data acquisition; control system; Diesel Engines; Power Generation.
Presentation Schedule: Wednesday, 16:20-16:40. Session: CEE1-1. Presenter: Eduardo Chaves Moreira dos Santos.
ENCIT2012-073 EXPERIMENTAL ANALYSIS OF LOW-RANK COAL COMBUSTION UNDER AIR AND OXY-FUEL CONDITIONS - PDF
Adriano Roberto Carotenuto, UFRGS, Brazil
Rodrigo Corrêa da Silva, BTU, Germany
René Lúcio Rech, Paulo Smith Schneider, Nilson Romeu Marcílio, UFRGS, Brazil
Hans Joachim Krautz, BTU, Germany
Abstract: An experimental study is performed in a laboratory facility, designed to investigate the combustion process under turbulent and swirling flows and covering a temperature range similar to those found in existing furnaces. The global kinetic parameters are determined with the aid of gas-potentiometric analysis by using oxide-ion conducting solid electrolytes. The complete samples burn-out sieved to a size range of 1.250-2.000 mm is evaluated under air-firing and oxy-fired conditions (21\% O2 and 79\% CO2 in vol.). Oxygen concentrations curves for the combustion process are plotted for both oxidant environments. Tests are performed for 3 levels of gas temperature, keeping the same O2 concentration at the feeding stream. Results show higher fuel reactivity under oxy-fuel than air-fired conditions. The influence of the swirling flow within the cyclone reactor on the results is commented.
Keywords:Oxy-fuel combustion; lignite coal; effective reaction rate constant; gasification reaction.
Presentation Schedule: Wednesday, 15:20-15:40. Session: CEE1-1. Presenter: Adriano Roberto Carotenuto.