bluuebunny/crossref_metadata_2025 huggingface dataset:
STATORS USE INFLUENCE ON THE PERFORMANCE OF A SAVONIUS WIND ROTOR USING COMPUTATIONAL FLUID DYNAMICS
Authors: Akwa J. V. , Petry A. P.
Published: October 2018

This paper aims at verifying the influence of using five kinds of stators in the averaged moment and power coefficients of a Savonius wind rotor using computational fluid dynamics (CFD). The analyzed stators have cylindrical shape with two and three openings, one and four deflector blades and walls shaped like a wings. The equations of continuity, Reynolds Averaged Navier-Stokes – RANS and the Eddy Viscosity Model k-ω SST, in its Low-Reynolds approaches, with hybrid near wall treatment; are numerically solved using the commercial software Star-CCM+, based on Finite Volume Method, resulting in the fields of pressure and velocity of the flow and the forces acting on the rotor buckets. The moment and power coefficients are achieved through integration of forces coming from the effects of pressure and viscosity of the wind on the buckets device. The influence of the stators use in the moment and power coefficients is checked by changing the geometry of the device for each simulations series, keeping the Reynolds number based on rotor diameter equal to 433,500. The obtained values for averaged moment and power coefficients indicate that for each type of stator used, there was maximum performance for a given tip speed ratio of rotor. Improvement in performance over the operation without stator was obtained only to the operations using stator with four deflector blades and to the stator with cylindrical shape with three openings. The improvement percentage in performance obtained for the best condition (use of four deflector blades at tip speed ratio equal to 1) is 12% compared to the performance of the rotor operating without stator.
EDITORIAL
Authors: Bianchi Marcus V. A.
Published: October 2018

The search for sustainable energy solutions has accelerated significantly in recent years driven by concerns caused by supply limitations, such as Peak Oil (or Gas, Coal, and Uranium), and by climate change.  Many communities and industries are now facing the prospect of increased energy costs, potential energy supply disruptions, and carbon emission limits.  Recently, the scientific academies of 13 countries1 (including Brazil) issued a joint statement calling on world leaders to increase energy efficiency, promote a shift to less-polluting energy sources, and intensify research into new energy technologies that produce no emissions.  Also recently, a coalition of 16 of the world’s biggest cities (São Paulo is one of them), under a plan developed by the William J. Clinton Foundation2, pledged investments of billions of dollars to cut building energy use and releases of heat-trapping gases linked to global warming.The field of thermal sciences plays a critical role in managing these challenges.  In a recent initiative, the National Science Foundation3 invited a number of thermal science researchers to identify frontier challenges and associated opportunities in five areas, one of which was sustainable energy technologies (the remaining were biological systems and biotechnology, security, information technology, and nanotechnology).  While a final report was not yet published when this editorial was written, the passionate discussions pointed to action in research and education from academic institutions, government, and industry.  Some of the topics discussed include fuel cells, seawater agriculture, biomass, sustainability metrics, carbon sequestration, and broad education of non-technical individuals on thermal sciences.The research findings published in Engenharia Térmica in the past have shown significant progress in areas related to energy, particularly oil and renewables.  We are confident we will continue to receive articles’ submissions that help enable sustainable energy solutions in the near future.
PRESSURE DROP IN A SPOUTED BED OF CORK STOPPERS
Authors: Magalhães A. , Pinho C.
Published: October 2018

The spouted bed is a particular type of fluidized bed which is well suited forthe handling of large size particles like cork stoppers. It is commonly usedfor the drying of granulates and the present work is the first part of a studyconcerning the drying of cork stoppers in a laboratory scale spouted bed reactor. The study considers two stoppers size, one the port wine stopper and another small size stopper. The choice of these smaller sizes was imposed by the small dimensions of the reactor. In this preliminary set of experiments the fluid-dynamics regime of the particular two phase flow was characterized. For different experimental situations covering several air flows and temperatures typical of cork drying operations the evolution of pressure drop was evaluated and a correlation for the minimum spouting velocity was obtained.
FUNCTIONS, FUNCTIONING AND OPTIMIZED POSITIONING OF PRESSURE CONTROL VALVES IN OIL-HYDRAULIC CIRCUITS
Authors: Reis M. N. E. , Tavares S. G. , Soares C. B. , Soares J. A. , Antunes R. H. R. , Fossa C. H. L. , Monteiro P. R.
Published: October 2018

The pressure control valves can perform different functions in the hydraulic systems, such as: establish maximum pressure, reduce pressure in some circuit lines, and establish sequence movements, among other functions. The main operation of these valves consists of providing a balance between pressure and the force load on a spring. Most of these valves can be positioned in many different levels, between totally open and totally closed, depending on the flow and on the pressure differential. The pressure control valves are usually named according to their primary functions, e.g., lock wire valve, sequence valve, safety valve, etc. and, their basic function is limit or to determine the pressure of the hydraulic system for the attainment of a certain function of the equipment in motion. They are also classified by the type of connections, by the size and by the selected pressure band. Instead of relief and security, discharge, counterbalance, sequence, reducing and shock suppressor valves represent the pressure control devices. In this paper, oil-hydraulic circuits are suggested for practical lessons of Hydraulic and Pneumatic Commands where they regulate valves of pressure, by acting in the following situations: limiting the maximum pressure of the system, determining a level of pressure, determining two different levels of pressure, determining at the same time two distinct levels of pressure, unloading the pump. The functions of these devices will be discussed and analyzed as an attempt to improve their position in the circuit.
EVALUATION OF THE THERMAL COMFORT IN CONTACT WITH CERAMIC TILES
Authors: Effting C. , Güths S. , Alarcon O. E.
Published: October 2018

In places where people are bare feet, the thermal sensation of cold or hot depends on the environmental conditions and material properties including its microstructure and crustiness surface. The uncomforting can be characterized by heated floor surfaces in external environments which are exposed to sun radiation (swimming polls areas) or by cold floor surfaces in internal environments (bed rooms, path rooms). The property named thermal effusivity which defines the interface temperature when two semiinfinite solids are putted in perfect contact. The introduction of the crustiness surface on the ceramic tiles interferes in the contact temperature and also it can be a strategy to obtain ceramic tiles more comfortable. Materials with low conductivities and densities can be obtained by porous inclusion are due particularly to the processing conditions usually employed. However, the presence of pores generally involves low mechanical strength. This work has the objective to evaluate the thermal comfort of ceramics floor obtained by incorporation of refractory raw materials (residue of the polishing of the porcelanato) in industrial atomized ceramic powder, through the thermal and mechanical properties. The theoretical and experimental results show that the porosity and crustiness surface increases; there is sensitive improvement in the comfort by contact.
APPLICATION OF THE MONTE CARLO METHOD IN THE SOLUTION OF RADIATION HEAT TRANSFER IN PARTICIPATING MEDIA
Authors: Maurente A. , Bayer P. O. , França F. H. R.
Published: October 2018

The temperatures of the gases produced in combustion processes are very high so thermal radiation constitutes an important heat transfer mechanism in industrial furnaces. Most furnaces can be modeled as gray enclosures containing non-gray gases. The radiation heat transfer can be obtained with the aid of the weighted-sum-of-gray-gases model, determining the zonal exchange areas for each of the gray gases considered in the sum. For some enclosures with simple geometries, there are correlations to obtain the direct exchange-areas which can be used to determine the total exchange areas. However, for enclosures with complex geometries, determining the direct exchange areas can become a difficult task. In this case, the use of the Monte Carlo method is advantageous, for it allows one to approach geometric complexities without additional complications. Therefore, the method was applied to compute total exchange areas in enclosures containing participating media. Two cases were considered: cylindrical enclosures and enclosures that have generic geometries formed from cube combinations. The results presented a good agreement with solutions available in the literature.
MODELING AND SIMULATION OF INDUSTRIAL FCC RISERS
Authors: Souza J. A. , Vargas J. V. C. , Von Meien O. F. , Martignoni W. P.
Published: October 2018

Risers are considered vital parts in Fluidized Catalytic Cracking (FCC) conversion units. It is inside the riser reactor that the heavy hydrocarbon molecules are cracked into lighter petroleum fractions such as liquified Petroleum gas (LPG) and gasoline. The FCC process is considered a key process in the world petroleum industry, since it is the main responsible for the profitable conversion of heavy gasoil into commercial valuable products. This work presents a simplified transient model to predict the response of a FCC riser reactor, i.e., the fluid flow, temperature and concentrations of the mixture components throughout the riser and at the exit. A bi-dimensional fluid flow field combined with a 6 lumps kinetic model and two energy equations are used to model the gasoil mixture flow and the cracking process inside the riser reactor. The numerical results are in good agreement with experimental data, as a result, the model can be utilized for design, and optimization of FCC units. The simulation herein presented shows the applicability of the proposed method for the numerical simulation and control of industrial riser’s units.
INVERSE ANALYSIS APPLIED TO AN ILLUMINATION DESIGN
Authors: Schneider P. S. , França F. H. R.
Published: October 2018

This work investigates the application of the  inverse analysis to an illumination design of a three-dimensional rectangular enclosure. The problem consists of finding the luminous fluxes on the light source elements, located on the top of the enclosure, that satisfies a prescribed uniform luminous flux on the design surface, located on the bottom surface. The solution assumes that all the surfaces emit and reflect diffusely, and that the hemispheric spectral emissivities are wavelength independent in the visible region of the spectrum. The inverse analysis is described by a system of linear equations that is expected to be ill-conditioned since it involves the solution of a Fredholm integral equation of the first kind. To tackle the ill-conditioned system of equations, the TSVD (Truncated Singular Value Decomposition) regularization method is applied. In addition to presenting a methodology to solve for the luminous exchanges in a enclosure, starting from a thermal radiation energy balance, this work considers two design cases: one in which the light source elements cover the entire top surface; and one in which a reduced number of light sources are considered, a more practical solution. In both cases, the proposed inverse design is capable of providing a solution that satisfies the prescribed luminous flux on the design surface within average and maximum errors less than 1.0 % and 5.0 %, respectively.
BETTER SELL BAGASSE THAN SURPLUS ELECTRICITY?
Authors: Jaguaribe E. F. , Lobo P. C. , De Souza W. L. , Rocha R. M. , Nascimento E. T.
Published: October 2018

Over the past decade, electricity consumption in Brazil grew faster than generation capacity. This situation obliged an urgent return to investment in the sector, and revitalization of the restructuring in the national electricity sector. In these circumstances, the use of renewable energy sources, such the biomass, became an option for decentralized electricity generation. Sugar cane bagasse is one of the most important biomasss residues for electricity generation. The present publication analyses an investment made in the expansion of the energy cogeneration system in an industry that produces sugar and alcohol, from sugar cane, considering the seasonal bagasse price, energy generation costs and a 10 year period. With the new cogeneration system the factory became self-sufficient in energy, with a saleable surplus of 21,240 MWh, at an average power of 4,000 kW. However, an economic analysis indicated that the best option would have been to maintain the original system and sell surplus bagasse at R$ 26.00/t.
THE ASSIMPTOTICAL SOLUTION FOR THE STUDY OF THE TRANSITION OF A GAS-LIQUID FLOW FROM COUNTER-CURRENT TO CO-CURRENT
Authors: Biage M. , Campos J. C. C.
Published: October 2018

The transition of a flow of a liquid film from counter-current to co-current to a gas flow is known as the flooding phenomenon. In this paper is shown a quite criterions mathematical formulation in the form to identify with success the flooding point. One applies thus the conservation equations for a bi-dimensional and isothermical flow. Using the theorem of the PI of Vashy-Buckingham one makes a dimensional analysis in order to obtain parameters that make it possible to establish an asymptotic analysis for the a-dimensional equations and reduce a set of PDEs to a unique PDE for the thickness of the liquid film. This PDE will be decomposed in an equation for the permanent problem and another referring to the transient. It will be developed only the non–linear permanent equation applying the spectral method of collocation of Chebychev for its discretization. One intends in this paper to stress the physical interpretation of the equations for the thickness of the liquid film obtained through the asymptotic expansion and describe the characteristics of the used numeric method (spectral technique). The results are compared to others found in the literature proving that the spectral method of collocation is a very powerful technique for the solving of this kind of problem.
ANAEROBIC DIGESTION AS CENTRE OF DAIRY LIVESTOCK AND AGRICULTURE INTEGRATION: BASIS FOR MEDIUM-SCALE CDM PROJECTS DEVELOPMENT
Authors: Fiorelli F. A. S. , Diaz G. O.
Published: October 2018

Dairy producers should improve their activity with modern production techniques/technologies to meet the requirements of a stricter consumer market. In this sense, crop and livestock systems integration represents an interesting alternative for using the dairy farm available resources. This paper analyses the use of anaerobic digestion as basis for supplying energy, fertilizers and feed needs of a farming unit, by means of digestion products usage: biogas, which can be used in energy conversion systems to provide the required energy for processing/conservation equipment for milk and other farming products; and effluent, that can be used as a replacement for chemical fertilizers and for aquatic plants/fish feeding. Fossil fuels replacement by biogas can be classified as a Clean Development Mechanism (CDM) project, and economic resources obtained by carbon credits commercialisation may support the required production modernisation. The paper analyses the anaerobic digestion process, evaluating biogas in medium-scale dairy farms, as well as the quantification of carbon credits generated by introducing proper manure and culture remains management.
HYDROCRACKING OF FISCHER-TROPSCH PRODUCTS
Authors: Teles U. M. , Fernandes Fabiano A. N.
Published: October 2018

The hydrocracking behavior the product of a Fischer-Tropsch synthesis consisting of a C4–C30 mixture of paraffins and olefins on a platinum/amorphous silica–alumina catalyst has been analyzed and optimized. The influence of temperature on the selectiveness of the hydrocracking has been investigated. Time and temperature optimization was performed in order to obtain the best operating conditions for the enhancement of gasoline and diesel cuts.
ACOUSTIC CAVITIES DESIGN PROCEDURES
Authors: Santana Jr. A. , Silva M. S. , Lacava P. T. , Góes L. C. S.
Published: October 2018

Combustion instability is recognized as one of the major problems frequently faced by engineers during the development of either liquid or solid propellant rocket engines. The performance of the engine can be highly affected by these high frequencies instabilities, possibly leading the rocket to an explosion. The main goal while studying combustion chambers instability, either by means of baffles or acoustic absorbers, is to achieve the stability needed using the simplest possible manner. This paper has the purpose of studying combustion chambers instabilities, as well as the design of acoustic absorbers capable of reducing their eigenfrequencies. Damping systems act on the chamber eigenfrequency, which has to be, therefore, previously known.
ANALYSIS OF WALL SHAPE IN INDOOR AIR CIRCULATION BY THE FINITE ELEMENT METHOD
Authors: Drach P. R. C. , Karam F. J.
Published: October 2018

The use of computational models in built environments comes from the need to deal with situations as close as possible to the reality and also to study functional spaces that could be able to provide, for example, thermal comfort. In this work we analyze some cases of indoor air circulation in built environments through a mixed stabilized finite element method, applied to the Navier-Stokes equations in velocity and pressure variables. The implemented numerical method ensures stability for the internal constraint imposed by the velocity field, and accommodates moderate to large advective effects. The obtained internal wind field allows the choice of wall shapes that increase or not the ventilation and can alter its distribution, allowing in this way a better adequacy of the built environment for the climate needs and its objectives.
EFFECT OF REYNOLDS NUMBER ON THE SUCTION INFLUENCE ON THE TURBULENT BOUNDARY LAYER STRUCTURES
Authors: Oyewola M. O.
Published: October 2018

The effect of Reynolds number on the influence of suction on the turbulentboundary layer structures has been quantified through the measurements ofthird- and fourth-order turbulence statistics for several suction rates and streamwise locations downstream of the suction strip. Third- and fourthorderturbulence statistics are more sensitive to a change in boundary condition than second-order moments. The data of the third-order turbulent statistics reveal an alteration in the turbulent transport as a result of the manipulation of the organised motion by suction. The alteration is increased as the suction rate is increased but reduces as the Reynolds number is increased. The results support that, relative to no suction case, Reynolds number modulates the behaviour of higher-order turbulent statistics without changing the actual mechanism of suction on the boundary layer. In general, it is proposed that Reynolds number effect on suction influence in a turbulent boundary layer is universal for the large-scale quantities. This argument is supported by the behaviour of root mean square fluctuating spanwise vorticity.
ABOUT THE EXACT SOLUTION IN TWO PHASE-STEFAN PROBLEM
Authors: Boucíguez A. C. , Lozano R. F. , Lara M. A.
Published: October 2018

Two cases of the two - phase Stefan problem in a semi - infinite slab are presented here: one has heat flux boundary condition proportional to t−½ and the other has constant temperature boundary condition. In these two cases the exact solution exists, the relationship between the two boundary conditions is presented here, and the equivalence between the two problems is shown.
A PENDULUM-BASED MODEL FOR FLUID STRUCTURE INTERACTION ANALYSES
Authors: Martins D. A. M. , Silveira-Neto A. , Steffen Jr V.
Published: October 2018

In the present contribution a pendulum-based model is used to represent fluid-structure interactions. For this purpose, a theoretical and experimentalanalysis of the dynamic behavior of a viscously damped spherical non rotational single-degree-of-freedom pendulum was performed. The dampingprocess is characterized according to two different regimes: in the first, it can be seen as a viscous low Reynolds’ number flow and, in the second, it can be considered as a viscously damped system. The pendulum was tested experimentally in a large reservoir containing a Newtonian fluid for validation purposes and good agreement was found between numerical and experimental results.
MODELING OF THE KINETIC OF SALICYLIC ACID ADSORPTION IN POLYMERIC AND ACTIVATED CHARCOAL ADSORBENTS
Authors: Câmara L. D. T. , Silva Neto A. J.
Published: October 2018

The understanding of adsorption mechanisms of compounds utilized in many medications and prescription drugs represents an important step for the development of different separation processes of such substances. The adsorption kinetic study of such chemical compounds through the application of new models permits a better comprehension of the involved mechanisms, leading to the estimation of important parameters that will be incorporated in the equipment design. In this work a kinetic model of irreversible adsorption is implemented, which is dependent on both solute and site concentrations. It showed to be very effective correlating the simulated results with the adsorption experiments of salicylic acid through three adsorbents in different temperature conditions. The application of an inverse problem approach, with the minimization of the squared residues cost function, was successful in determining the kinetic parameters. The increase in the kinetic constants obtained with the temperature increase was followed by a reduction in the adsorption capacity of the adsorbents. Thermodynamic parameters were also estimated, leading to the comprehension about the equilibrium states of the adsorption systems considered.
EDITORIAL
Authors: Vargas J. V. C.
Published: October 2018

Petroleum will continue to play a key role in the world energetic matrix for long, in spite of the pessimistic predictions about the near shortage of the existing reserves. The offshore exploration technology in deep sea water has challenged such predictions. The recent discovery of oil in the pre-salt layer in the southern Brazilian sea coast is one of those events. The so called pre-salt layer consists of a region that develops along 800 kilometers between the Brazilian states of Espírito Santo and Santa Catarina, below the bottom of the sea, and encompasses three sedimentary basins (Espírito Santo, Campos and Santos). The oil found in this area is at depths that exceed 7 thousand meters, below a thick salt layer that geologists think that had the property of preserving oil quality. However, the oil found in deep sea water usually is heavy oil, and difficult to be refined, requiring refining advanced technologies of fluidized catalytic cracking unities (FCCU). Hence, there will be a demand for the construction and optimization of those unities in larger scale, requiring effective mathematical models and even new technologies. For example, currently Brazil is energetically independent, but exports heavy oil and imports light oil, due to the lack of the necessary number of FCCU’s for the efficient refining of heavy oil. Therefore, it is considered that the theoretical, numerical and experimental study of heavy oil refining technologies emerges as a promising line of research to be considered by thermal engineering scientists.
FUZZY LOGIC CONTROL APPLIED TO A PHOTOVOLTAIC SYSTEM CONNECTED TO CITY NETWORK FOR RESIDENTIAL USE
Authors: Lamas W. Q. , Tani H. M. , Reis L. O. M. , Ribeiro A. C.
Published: October 2018

A simplified topology using power electronics and fuzzy logic control techniques for developing a photovoltaic generation system, at a low cost, to be used in residential systems, connected to the local distribution grid is herein proposed. A technique for determining maximum power points on photovoltaic panels, in order to transfer the powerful generated to the load, is studied, so to impart a minimum energy loss in the whole system. In the fuzzy logic controller development the relevant functions to the input and output photovoltaic system variables and the rules to be used in this controller is established and obtained from other photovoltaic systems, adapted to the system. Simulation results are obtained always focusing maximum power search by a fuzzy logic controller, through intelligent changes into control variables that will carry the work cycle of increasing converter and the inverter bridge. It is shown that while exists solar radiation variation and low voltage available on photovoltaic module, the increasing converter will supply necessary voltage to the inverter bridge operation.
SIMULATION AND EXPERIMENTAL EVALUATION OF AN INNOVATIVE ROTARY COMPRESSOR WITH VARIABLE SPEED DISPLACERS
Authors: Kopelowicz H. J. , Barreto A. R. , Moutella F. L. C. , Arêas H. T. , Parise J. A. R. , Siqueira C. E. R.
Published: October 2018

This paper describes preliminary studies of a new rotary compressor with variable speed displacers. Two displacers rotate concentrically, in an annular space, at variable and phased angular velocities, thus creating two variable-volume compression spaces between them. The displacers are individually driven by two concentric shafts. An innovative driving mechanism imposes phased variable angular speeds to the shafts and, consequently, to the displacers, thus providing a volume variation in the gas compression spaces. The driving mechanism also offers a convenient way of capacity control, from zero to 100%, at constant electric motor speed. A mathematical model simulating the performance was developed. A traditional simulation model for positive displacement compressors was employed, where mass and energy conservation equations, in differential form, were applied to the control volumes (two compression spaces). Uniformly distributed thermodynamic properties of gas, varying with time, were assumed for each control volume. Equations describing the volume variation with time, the gas to cylinder wall heat transfer and gas flow through valve ports and leakage passages were also employed. The resulting mathematical model was a system of ordinary differential equations, the numerical integration of which provides the time-history of pressure and temperature of the gas inside the compression chambers. A prototype was also constructed and tested. First performance results are presented, showing the compressor behaviour under different operational conditions.
DEVELOPMENT OF AN AIR HEATING AND HUMIDIFYING SYSTEM FOR MECHANICAL VENTILATION OF INTENSIVE CARE UNIT PATIENTS
Authors: Ferreira E. L. , Vargas J. V. C. , Campos M. C. , Dias F. G. , Ordonez J. C. , Brioschi M. L. , Botelho E. F.
Published: October 2018

The mechanical ventilators, also named artificial ventilators, are devices used in Intensive Care Units (ICU) for clinically critical patients. The equipment provides artificial breathing for the patient, creating favorable conditions for the patient recovery. It works as a system that is connected to the electric grid and two other networks, one supplies compressed air and the other supplies pure oxygen. Inside the equipment the gases are mixed, and then warmed up and humidified to be finally delivered to the patient. The existing system for treatment of the mixture is not effective, since it delivers the breathing air to the patient out of the normal physiology recommended range, i.e., temperature ~32-34°C and relative humidity ~80-95%. The objective of this work was to develop a new air heating and humidifying system for mechanical ventilation. First, it was built an air feeding system, composed by a compressor and an electronically controlled valve to simulate an actual mechanical ventilation system in the laboratory. A device for conditioning the air (temperature and humidity) was conceived and built for treating the air feeding system output air. The results of the laboratory measurements show that the developed equipment was capable of making the breathing air to reach the recommended ranges by the normal physiology.
A FERRITE POTENTIAL INFLUENCE ON HEAT TRANSFER CONDITIONS IN INDUSTRIAL MOLD DURING THE CONTINUOUS CASTING OF STEELS
Authors: Karlinski V. , Fogazzi W. , De Souza B. V. , Ferreira C. R. F. , Dos Santos C. A. , Spim J. A.
Published: October 2018

This paper aims to apply a solidification mathematical model to the process of the continuous casting of steel. Heat transfer coefficients in the mold were determined by the inverse method and they are related with both macrostructure conditions and carbon equivalents of carbon steels from peritectic reactions. Both structure characterization and ferrite potential were established by solidification parameters and chemical composition after casting. Samples were cut at different positions of the metal/mold interface, whereas the selected sections were polished and etched with a reagent for the metallographic examination. The image processing system was used to analyze as-cast structure for every selected position. It was observed that during casting, numerical predictions about metal/mold heat transfer coefficients along the mold are in accordance with type-A and B steels ferrite potential, due to both its sticking and depression tendency.
COMPUTATIONAL MODELING OF A REGULAR WAVE TANK
Authors: Gomes M. N. , Olinto C. R. , Rocha L. A. O. , Souza J. A. , Isoldi L. A.
Published: October 2018

This paper presents two different numerical methodologies to generate regular gravity waves in a wave tank. We performed numerical simulations of wave generation through the FLUENT® package, using the Volume of Fluid (VOF) multiphase model to reproduce the wave propagation in the tank. Thus it was possible to analyze two methods for generating regular waves that could be used in future work, especially in the study of devices of energy conversion from ocean waves into electrical energy.
A NUMERICAL STUDY OF THE INFLUENCE OF TEMPERATURE FLUCTUATIONS IN THE THERMAL RADIATION FIELD
Authors: Dos Santos E. D. , Galarça M. M. , Mossi A. C. , Petry A. P. , França F. H. R.
Published: October 2018

The present paper performs a numerical study of the influence of fluctuations on the temperature field over the thermal radiation field with the purpose to simulate the effect of Turbulence-Radiation Interactions (TRI). To evaluate the behavior of the divergence of the radiant heat flux for a flame in a cylindrical cavity, four temperature profiles are imposed: an average temperature profile and other three with 10%, 20% and 30% of turbulence intensity. The radiative transfer equation is solved using the discrete ordinates method (DOM) and the participating medium is treated as a gray gas. The results demonstrate that the fluctuations of temperature profiles increase significantly the mean divergence of the radiant heat flux in comparison with the average temperature profile, reaching to approximately 20% for the profile with 30% of turbulence intensity.
POROUS MEDIA MICROSTRUCTURE RECONSTRUCTION USING PIXEL-BASED AND OBJECT-BASED SIMULATED ANNEALING – COMPARISON WITH OTHER RECONSTRUCTION METHODS
Authors: Diógenes A. N. , Dos Santos L. O. E. , Fernandes C. P. , Moreira A. C. , Apolloni C. R.
Published: October 2018

In this contribution the issue of the stochastic reconstruction of particulatemedia from 2D photomicrographic images is addressed with particular reference to pore space connectivity. The reconstruction of porous bodies in 2D or 3D space was achieved by using simulated annealing techniques. Two methods were proposed to reconstruct a well connected pore space. The first, named PSA (Pixel-based Simulated Annealing), a pixel-movement based, three constraints were found to be necessary for  the successful reconstruction of well connected pore space: the two-pointcorrelation function, the d3-4 distance transform distribution and the  linealpath function for the pore phase. The second, named OSA (Object-based Simulated Annealing), only constrains the two-point correlation function. Following several researches which tried to reconstruct porous media using pixel-movement based simulated techniques, we propose a new parameter to add a microstructure descriptor, but we also propose a new technique, based in moving the microstructure grains (spheres) instead of the pixels. Both methods were applied to reconstruct reservoir rocks microstructures, and the 2D and 3D results were compared with microstructures reconstructed by truncated Gaussian methods. The PSA resulted in microstructures characterized by poor pore space connectivity, and by artificial patterns, while the OSA reconstructed microstructures with good pore space connectivity. These results indicate that the OSA method can reconstruct better microstructures than the present methods.
REUSE OF WASTEWATER FROM POLYESTER FIBRES DYEING PROCESS BY THERMAL FIXATION WITH DYE ACID BASE: CASE STUDY IN A BRAZILIAN AUTO PARTS FACILITY
Authors: Lamas W. Q. , Fujisawa R. S.
Published: October 2018

This work aims to test biodegradable chemicals into treatment of textile waste water from an auto parts facility with goal of reuse of water treated in dyeing process of lace used in safety belts. It presents a method that suits the treatment of waste water with local environmental regulations and allows the reuse of water through the adoption of actions that replace the conventional physical-chemical treatment by biodegradable products, which naturally extend the possibility of reuse beyond the process and increase the quality of water for reuse in that one, allowing satisfy the requirements of product quality demanded by the market. This work proposes substitution of some chemicals by biodegradable products and comparison to previous results obtained with current treatment for the same conditions preestablished. Also the ultra-filtration method had evaluated and its results were compared to traditional process and to new proposal. According to results obtained, replacement of traditional chemicals by biodegradable products is technical and economical viable and attends to the waste water reuse policy proposed.
THE TEMPERATURE RESPONSE OF COMPACT TUBULAR MICROALGAE PHOTOBIOREACTORS
Authors: Ribeiro R. L. L. , Mariano A. B. , Dilay E. , Souza J. A. , Ordonez J. C. , Vargas J. V. C.
Published: October 2018

A mathematical and computational modeling of a photobioreactor for the determination of the transient temperature behavior in compact tubular microalgae photobioreactors is presented. The model combines theoretical concepts of thermodynamics with classical theoretical and empirical correlations of Fluid Mechanics and Heat Transfer. The physical domain is discretized with the Volume Element Model (VEM) through which the physical system (reactor pipes) is divided into lumped volumes, such that only one time dependent ordinary differential equation, ODE, results for temperature, based on the first law of thermodynamics. The energetic interactions between the volumes are established through heat transfer empirical correlations for convection, conduction and radiation. Within this context, the main goal of this study is to present a numerical methodology to calculate the mixture (algae + water + nutrients) temperature inside the compact photobioreactor. A pilot plant is under construction, in the Center of Research and Development for Self-Sustainable Energy (NPDEAS), located at UFPR, and the experimental data obtained from this research unit will be used to validate the present numerical solution. Temperature is one of the most important parameters to be controlled in microalgae growth. Microalgae that are cultivated outside their growth temperature range may have a low growth rate or die. For this reason a numerical simulation of the system based on the operating conditions and environmental factors is desirable, in order to predict the transient algae growth temperature distribution along the reactor pipes. The VEM creates an “artificial” spatial dependence in the system or process under analysis by dividing the space (physical domain) into smaller sub domains, namely Volume Elements (VE). Each VE interacts with its neighbors by exchanging energy and/or mass. Thus, each VE is treated as a control volume from classical thermodynamics, i.e., with uniform properties and exchanging mass and energy with its neighbors. The problem is then formulated with the energy equation applied to the fluid VE and to the wall VE. These equations form a system of time dependent ODE’s, which are not dependent on space, therefore eliminating the need for the solution of a system of partial differential equations, PDE’s, depend on time and space, as is the case of traditional numerical methods (e.g., finite element, finite volume and finite differences). The resulting ODE’s were solved using a fourth order Runge-Kutta method with adaptive time step.
EXPERIMENTAL STUDY OF A CAPACITIVE TOMOGRAPHY SYSTEM FOR MULTIPHASE FLOW
Authors: Moura L. F. M. , Cenedese E. , Azevedo Filho A. C.
Published: October 2018

This paper presents the experimental development of a capacitive tomography system applied to the study of multiphase flows. A capacitance sensor with eight electrodes and a capacitance measurement transducer were constructed. The two-phase flow void fraction was obtained through an electric-mechanical measurement system. The reconstruction of the image of several two-phase flows was obtained using the linear back projection method. Numerical simulation of the capacitance values between electrode pairs wereperformed, through the method of finite elements, in order to obtain the sensibility maps. This experimental procedure showed the influence of several parameters on the quality of the reconstructed images. The quality of the reconstructed images for air-water and water-oil flows, for different void fractions, demonstrated the validity of the tomography system developed.
NUMERICAL STUDY OF A CAPACITIVE TOMOGRAPHY SYSTEM FOR MULTIPHASE FLOW
Authors: Moura L. F. M. , Cenedese E. , Azevedo Filho A. C.
Published: October 2018

This paper presents the development of a capacitive tomography system applied to the study of multiphase flows. A numerical analysis, through the finite elements method, was performed to obtain data for the optimization ofthe geometry of the capacitance sensor. The image reconstruction of several flow patterns was obtained through the method of linear back projection, allowing the verification of the influence of several parameters upon the quality of the images, making its application easier in an experimental procedure. Several numerical simulations were performed for air-water flow, for the stratified and annular patterns. A resource of cut-off level, which depends of previous knowledge of the liquid fraction, was implemented in a way to improve the quality of the reconstructed images. The results obtained for several values of void fraction and for different patterns of flow, demonstrate the validity of the developed tomographic system.
APPLICATION OF GALERKIN FINITE ELEMENT METHOD IN THE SOLUTION OF 3D DIFFUSION IN SOLIDS
Authors: Romão E. C. , De Campos M. D. , Martins J. A. , De Moura L. F. M.
Published: October 2018

This paper presents the numerical solution by the Galerkin Finite Element Method, on the three-dimensional Laplace and Helmholtz equations, which represent the heat diffusion in solids. For the two applications proposed, the analytical solutions found in the literature review were used in comparison with the numerical solution. The results analysis was made based on the the L2 Norm (average error throughout the domain) and L¥ Norm (maximum error in the entire domain). The two application results, one of the Laplace equation and the Helmholtz equation, are presented and discussed in order to to test the efficiency of the method.
SOLAR SOFTWARE APPLIED TO DESIGN A PHOTOVOLTAIC SYSTEM TO SUPPLY THE ENERGY DEMAND OF AN ITALIAN SCHOOL
Authors: Laranci P. , Silveira J. L. , Lamas W. Q.
Published: October 2018

This paper has as objective to describe the use of SOLAR 1.1 software todesign a system for supplying a part of the electric demand of a schoolsituated in Umbertide, comparing the use o SOLAR 1.1 to real results of asystem implanted yet. This software version helps also to conduce theeconomic analysis for grid connected or standalone photovoltaic systemsfor the choice of convenient values of investment rate and annuity factorand it calculates the payback period of investment in the photovoltaic plant.
EDITORIAL
Authors: Vargas J. V. C.
Published: October 2018

I would like to direct the attention of the reader to the matter of sustainable progress and development. The first world nations, having started the industrial revolution, have experienced an evolution process longer than the other nations in the globe. Hence, as a rule of thumb, their enterprises have considered a sustainability view. However, the other nations, aiming at their own industrial development and reducing the gap with respect to the more developed countries, normally neglect that aspect, generating a chaotic development of unforeseen consequences, such as India, China, and Brazil itself. A quite illustrative example is the overwhelming global advance of the electronics industry in the past 30 years. Brazilians produce more than 300 tons of electronic residues annually. Unfortunately, the country does not have appropriate places for the disposal of that equipment. The chemical composition of those residues is very diverse. If those plastics and metals are disposed incorrectly in nature, they have the potential to contaminate the soil, the water, and the entire environment. In the first world, there is a established industry for reselling the used electronics that has not been established in Brazil, perhaps due to a cultural issue, then, this turns the country into one of the greatest generators of electronic residues in the world. The used electronic boards are sold as scrap metals and plastics at a low price to Europe for reprocessing and the rest is simply buried, since they contain brome based plastics that are not suitable for recycling with currently available technologies. There are several possible routes for searching a solution to the problem, such as mechanical, chemical, and energetic plastics recycling, and for the metals pyrometallurgy, hydrometallurgy, mechanical processing and electrometallurgy. However, all such routes require scientific research and development in which certainly the area of thermal engineering is a major component.
AN EXERGY COST ANALYSIS OF A COGENERATION PLANT
Authors: Gonçalves L. P. , Arrieta F. R. P.
Published: October 2018

The exergy analysis, including the calculation of the unit exergetic cost of all flows of the cogeneration plant, was the main purpose of the thermoeconomic analysis of the STAG (STeam And Gas) combined cycle CHP (Combined Heat and Power) plant. The combined cycle cogeneration plant is composed of a GE10 gas turbine (11250 kW) coupled with a HRSG (Heat Recovery Steam Generator) and a condensing extraction steam turbine. The GateCycleTM Software was used for the modeling and simulation of the combined cycle CHP plant thermal scheme, and calculation of the thermodynamic properties of each flow (Mass Flow, Pressure, Temperature, Enthalpy). The entropy values for water and steam were obtained from the Steam Tab software while the entropy and exergy of the exhaust gases were calculated as instructed by. For the calculation of the unit exergetic cost was used the neguentropy and Structural Theory of Thermoeconomic. The GateCycleTM calculations results were exported to an Excel sheet to carry out the exergy analysis and the unit exergetic cost calculations with the thermoeconomic model that was created for matrix inversion solution. Several simulations were performed varying separately five important parameters: the Steam turbine exhaust pressure, the evaporator pinch point temperature, the steam turbine inlet temperature, Rankine cycle operating pressure and the stack gas temperature to determine their impact in the recovery cycle heat exchangers transfer area, power generation and unit exergetic cost.
LIQUID METAL FLOW CONTROL BY DC ELECTROMAGNETIC PUMPS
Authors: Borges E. M. , Braz Filho F. A. , Guimarães L. N. F.
Published: October 2018

The cooling system of high-density thermal power requires fluids of high thermal conductivity, such as liquid metals. Electromagnetic pumps can be used to liquid metal fluid flow control in cooling circuits. The operation of electromagnetic pumps used to flow control is based on Lorentz force. This force can be achieved by magnetic field and electric current interaction, controlled by external independent power supplies. This work presents the electromagnetic pump operational principles, the IEAv development scheme and the BEMC-1 simulation code. The theoretical results of BEMC-1simulation are compared to electromagnetic pump operation experimental data, validating the BEMC-1 code. This code is used to evaluate the DC electromagnetic pump performance applied to Mercury flow control and others liquid metal such as Sodium, Lead and Bismuth, used in nuclear fast reactors.
EXPERIMENTAL METHOD FOR SPRAY VELOCITY FIELD PREDICTION MODEL IN PRESSURE SWILL ATOMIZERS
Authors: Souza E. J. J. , Ponte M. J. J. S.
Published: October 2018

Pressure swill atomizers are widely used in engineering as an effective device for vaporization and liquid mass transfer in physical or chemical processes. Among many applications those atomizers are used in modern fuel injection systems for spark engines. An even fuel and air mixture may increase the overall engine performance by higher efficiency and low flue gas emissions. In applied atomization, one of the most important characteristics is the spray velocity field prediction. Droplet sizing models are also important, but they are relatively popular on books and papers. By the other hand spray velocity field prediction and profile is relatively rare. This work focus on the prediction of the velocity field of pressure swirl atomize by means of an experimental approach and applied statistics. For the spray measurements this study used a non-intrusive, quantitative method by Laser Doppler Interpherometry (LDI) for the spray velocity field and droplet sizing. Also four models for the film thickness calculation at atomizer discharge are compared considering their statistical significance.
GALERKIN FINITE ELEMENT METHOD AND FINITE DIFFERENCE METHOD FOR SOLVING CONVECTIVE NON-LINEAR EQUATION
Authors: Romão E. C. , De Campos M. D. , De Moura L. F. M.
Published: October 2018

The fast progress has been observed in the development of numerical and analytical techniques for solving convection-diffusion and fluid mechanics problems. Here, a numerical approach, based in Galerkin Finite Element Method with Finite Difference Method is presented for the solution of a class of non-linear transient convection-diffusion problems. Using the analytical solutions and the L2 and L∞ error norms, some applications is carried and valuated with the literature.