Projeto, construção e análise de eficiência térmica de um sistema de aquecimento solar de água de baixo custo

We studied the feasibility of using a system of Solar Water Heating (SAS) with low cost, for three configurations. In configurations I and II have the collector grid absorber composed of six PVC tubes placed in parallel on the tile cement. In configuration II, the PVC tubes were transparent cover made of plastic bottles. Configuration III uses a collector composed of 12 black HDPE pipes, supported on four cement tiles 2.44 m x 0.50 m, two by two overlapping and interspersed with a filling of glass wool, comprising an area exposed to the global radiation incident of 2.44 m2, with the top two tiles painted matte black. In this configuration, the HDPE pipes replace conventional PVC pipes painted black. The total cost of SAS for configuration III, the most economical, was around $ 150.00. For the configurations tested the system of operation was thermosyphon collector. The study showed that the proposed systems have good thermal efficiency, are easy to install and handle and have low cost compared to conventional.

Análise de viabilidade técnica de utilização da Fibra de bananeira com resina sintética em Compósitos

This paper aims to present the feasibility of using a composite using discarded material from the cultivation of banana tree (pseudostem), which is fibrillated together with synthetic resin replacing glass fiber to be used in structural elements that do not demand large mechanical stress such as reservoirs, troughs, domes, sewage pipes etc.. For this, there were studies about the mechanical properties of a composite made with polyester resin and fiber of banana tree (Musa sp, musac), in which the splints were removed from the pseudostem, being made fibrillation by hand, with the aid of a brush steel, followed by natural drying. After treatment for cleaning and removal of wax, the fiber was cut into pieces of approximately 60 mm to 100 mm, for, together with synthetic resin, make cards of a features fiber composite with random orientation relative to the weight of the resin. We used three different percentages of fiber (3%, 6% and 9%), in order to make a comparative study between them and what would be the one with the best performance. Were manufactured specimens of each material and then subjected to uniaxial tensile tests, three point bending, moisture absorption and thermal characteristics. The results show that, in general, the use of banana tree fiber is feasible simply by an improvement in the production process (machining of the procedure) and greater care in the manufacture of parts

Simulação computacional da interação fluido-estrutura em bombas de cavidades progressivas

The pumping through progressing cavities system has been more and more employed in the petroleum industry. This occurs because of its capacity of elevation of highly viscous oils or fluids with great concentration of sand or other solid particles. A Progressing Cavity Pump (PCP) consists, basically, of a rotor - a metallic device similar to an eccentric screw, and a stator - a steel tube internally covered by a double helix, which may be rigid or deformable/elastomeric. In general, it is submitted to a combination of well pressure with the pressure generated by the pumping process itself. In elastomeric PCPs, this combined effort compresses the stator and generates, or enlarges, the clearance existing between the rotor and the stator, thus reducing the closing effect between their cavities. Such opening of the sealing region produces what is known as fluid slip or slippage, reducing the efficiency of the PCP pumping system. Therefore, this research aims to develop a transient three-dimensional computational model that, based on single-lobe PCP kinematics, is able to simulate the fluid-structure interaction that occurs in the interior of metallic and elastomeric PCPs. The main goal is to evaluate the dynamic characteristics of PCP s efficiency based on detailed and instantaneous information of velocity, pressure and deformation fields in their interior. To reach these goals (development and use of the model), it was also necessary the development of a methodology for generation of dynamic, mobile and deformable, computational meshes representing fluid and structural regions of a PCP. This additional intermediary step has been characterized as the biggest challenge for the elaboration and running of the computational model due to the complex kinematic and critical geometry of this type of pump (different helix angles between rotor and stator as well as large length scale aspect ratios). The processes of dynamic generation of meshes and of simultaneous evaluation of the deformations suffered by the elastomer are fulfilled through subroutines written in Fortan 90 language that dynamically interact with the CFX/ANSYS fluid dynamic software. Since a structural elastic linear model is employed to evaluate elastomer deformations, it is not necessary to use any CAE package for structural analysis. However, an initial proposal for dynamic simulation using hyperelastic models through ANSYS software is also presented in this research. Validation of the results produced with the present methodology (mesh generation, flow simulation in metallic PCPs and simulation of fluid-structure interaction in elastomeric PCPs) is obtained through comparison with experimental results reported by the literature. It is expected that the development and application of such a computational model may provide better details of the dynamics of the flow within metallic and elastomeric PCPs, so that better control systems may be implemented in the artificial elevation area by PCP

Painéis-sanduíche com núcleo de EPS reciclado: metodologia de execução e determinação de propriedades termofísicas

New materials made from industrial wastes have been studied as an alternative to traditional fabrication processes in building and civil engineering. These materials are produced considering some issues like: cost, efficiency and reduction of nvironmental damage. Specifically in cases of materials destined to dwellings in low latitude regions, like Brazilian Northeast, efficiency is related to mechanical and thermal resistance. Thus, when thermal insulation and energetic efficiency are aimed, it s important to increase thermal resistance without depletion of mechanical properties. This research was conducted on a construction element made of two plates of cement mortar, interspersed with a plate of recycled expanded polystyrene (EPS). This component, widely known as sandwich-panel, is commonly manufactured with commercial EPS whose substitution was proposed in this study. For this purpose it was applied a detailed methodology that defines parameters to a rational batching of the elements that constitute the nucleus. Samples of recycled EPS were made in two different values of apparent specific mass (ρ = 65 kg/m³; ρ = 130 kg/m³) and submitted to the Quick-Line 30TM that is a thermophysical properties analyzer. Based on the results of thermal conductivity, thermal capacity and thermal diffusivity obtained, it was possible to assure that recycled EPS has thermal insulation characteristics that qualify it to replace commercial EPS in building and civil engineering industry

Metodologia de análise e diagnóstico de fratura em um componente automotivo sujeito a cargas cíclicas alternadas

The competitiveness of the trade generated by the higher availability of products with lower quality and cost promoted a new reality of industrial production with small clearances. Track deviations at the production are not discarded, uncertainties can statistically occur. The world consumer and the Brazilian one are supported by the consumer protection code, in lawsuits against the products poor quality. An automobile is composed of various systems and thousands of constituent parts, increasing the likelihood of failure. The dynamic and security systems are critical in relation to the consequences of possible failures. The investigation of the failure gives us the possibility of learning and contributing to various improvements. Our main purpose in this work is to develop a systematic, specific methodology by investigating the root cause of the flaw occurred on an axle end of the front suspension of an automobile, and to perform comparative data analyses between the fractured part and the project information. Our research was based on a flaw generated in an automotive suspension system involved in a mechanical judicial cause, resulting in property and personal damages. In the investigations concerning the analysis of mechanical flaws, knowledge on materials engineering plays a crucial role in the process, since it enables applying techniques for characterizing materials, relating the technical attributes required from a respective part with its structure of manufacturing material, thus providing a greater scientific contribution to the work. The specific methodology developed follows its own flowchart. In the early phase, the data in the records and information on the involved ones were collected. The following laboratory analyses were performed: macrography of the fracture, micrography with SEM (Scanning Electron Microscope) of the initial and final fracture, phase analysis with optical microscopy, Brinell hardness and Vickers microhardness analyses, quantitative and qualitative chemical analysis, by using X-ray fluorescence and optical spectroscopy for carbon analysis, qualitative study on the state of tension was done. Field data were also collected. In the analyses data of the values resulting from the fractured stock parts and the design values were compared. After the investigation, one concluded that: the developed methodology systematized the investigation and enabled crossing data, thus minimizing diagnostic error probability, the morphology of the fracture indicates failure by the fatigue mechanism in a geometrically propitious location, a tension hub, the part was subjected to low tensions by the sectional area of the final fracture, the manufacturing material of the fractured part has low ductility, the component fractured in an earlier moment than the one recommended by the manufacturer, the percentages of C, Si, Mn and Cr of the fractured part present values which differ from the design ones, the hardness value of the superior limit of the fractured part is higher than that of the design, and there is no manufacturing uniformity between stock and fractured part. The work will contribute to optimizing the guidance of the actions in a mechanical engineering judicial expertise

Desinfecção solar de água para comunidades de baixa renda

The use of solar energy for water disinfection, and is accessible to disadvantaged communities because of its low cost, has the advantage of using disposable materials such as bottles of polyethylene terephthalate (PET). We present a study that used two methods of disinfection: the methodology proposed by the project Solar Water Disinfection (SODIS), which consisted of water disinfection by solar radiation and temperature and the methodology which the temperature of the water for disinfection. In both, we seek to eliminate microorganisms that cause serious diseases such as dysentery, typhoid, cholera, etc. Water samples were collected in the community of Bass, where the population has low income and the incidence of waterborne diseases is high. The experiments were divided into two stages. In step 1 we studied the feasibility of disinfection and in step 2 the feasibility of the pilot plant to obtain adequate levels of disinfection temperatures desired. The results showed the efficiency of the disinfection process, reaching an average of 80 to 100% death of microorganisms, but regrowth was observed in some samples. Finally on the good results of stage 1, is designed and built and tested in an experimental pilot plant, which has shown to be feasible to promote water disinfection through the use of solar energy. The water after treatment is in accordance with the limits established by Brazilian legislation for clean water, maintaining a positive performance for the disinfection and acceptable levels of bacterial regrowth

Composito de poliuretano de mamona e residuo industrial para isolacao termica e absorcao sonora

This work proposes the development of an innovative material made from a vegetable polyurethane matrix and load of industrial waste, from retread tires, for thermal insulation and environmental comfort. Experimental procedures are presented, as well as the results of the thermal and acoustic performance of this composite material, made from an expansive foam derived from the castor seed oil and fiber of scrap tires. The residue was treated superficially with sodium hydroxide, to eliminate contaminants, and characterized macroscopically and microscopically. Samples were produced with addition of residues at levels of 5%, 10%, 15% and 20% by weight, for determination of thermal properties: conductivity, heat capacity and thermal diffusivity, sound absortion index and density. The results were compared to commercially available thermal insulation and sound absorbing products. According to the analysis of results, it was concluded that the developed composite presents characteristics that qualify it as a thermal insulation with superior performance, compared to commercial available insulation, and sound absorption capacity greater than the castor oil polyurethane s, without addition of the residue

Avaliação do processo industrial da cerâmica vermelha na região do Seridó - RN

Particularly in Braziland in Rio Grande do Norte, companies manufacturing red ceramic, play an important role as agents of development to study the region Seridó- RN, specific place for carrying out the research. It is observed in this region a concentration of red ceramic industries of small size, which, despite its importance in the ceramic, they are unable to enjoy or use the new forms of administrative management and technological advances designed and offered by universities, centers of research and projects of governments, remained almost entirely outside the progress and modernization, technological and administrative. These companies still have outdated technology, and management processes, providing quality problems and standardization of end products. Upon these conditions are the companies going through crisis and struggling to survive alone and without assistance. The region of Seridó-RN, lets make a detailed case study of red ceramic companies in the region proposed from the existing theoretical and actual lifting of the condition of the product manufacturing red ceramic, allowing through this overview of the implementation of collect samples of raw materials, allowing the study of each ceramic industry that contributed to the participation of the research, which was determined parameters such as: analysis of the physical, chemical and technological properties of raw materials, characterization of the processes used, raising the technological resources considering equipment, machinery, supplies, raw materials and facilities available and its organization by type of products from companies involved in this study. The methodology consists of the following steps: collection of raw material, crushing and screening, characterization of raw materials (liquid limit, chemical analysis, mineralogical analysis, differential thermal analysis, sieve analysis), mixing, forming, cutting, drying and burning of ceramic bodies and bodies of evidence. The results showed that it was clay with distinct characteristics with respect to plasticity. With respect to the different compositions of mixtures of ceramic masses, we conclude that the ceramic properties showed a direct proportionality with increasing fraction of the clay not plastic. However, the compositions of the masses studied proved to be the most appropriate for the types of simulated clay for use in ceramics. Adopted in the ceramic processing made it possible to obtain products the resulted in consistent properties, and in some cases even exceeding the requirements of technical studies and standard-Brazilian clays to obtain ceramic products such as tiles, bricks and tiles to floor. Based on the discussions from the results obtained in the various processing steps of this work, one can draw conclusions according to the physico-chemical and mineralogical properties of raw materials, the properties of ceramic products burned and analysis. This work may be used by other researchers, private companies and governmental organizations, undergraduate students and graduate, can develop studies and future research to: develop projects to modify the furnaces; mapping projects develop and rationalize the exploitation of raw materials ;promoting reforestation and forest management; develop reduction projects and recovery of waste; develop training projects in manpower sector, and develop security projects, improving the conditions of work in the area pottery

Mecanismos de desgaste, história térmica e ciclo de vida de componentes de um motor de combustão interna de aeromodelo

We developed an assay methodology that considered the temperature variation and the scanning electron microscopy as a method to quantify and characterize respectively the consumption evolution in three 46 LA machines, with internal combustion and two-stroke engines, 7.64 cm3 cylinder capacity, 23.0 millimeters diameter and 18.4 millimeters course, RPM service from 2.000 to 16.000 rpm, 1.2 HP power, and 272 grams weight. The investigated engines components were: (1) head of the engine (Al-Si alloy), (2) piston (Al-Si alloy) and (3) piston pin (AISI 52100 steel). The assays were carried out on a desktop; engines 1 and 2 were assayed with no load, whereas in two assays of engine 3 we added a fan with wind speed that varied from 8.10 m/s to 11.92 m/s, in order to identify and compare the engine dynamic behavior as related to the engines assayed with no load. The temperatures of the engine s surface and surroundings were measured by two type K thermopairs connected to the assay device and registered in a microcomputer with data recording and parameters control and monitoring software, throughout the assays. The consumed surface of the components was analyzed by scanning electron microscopy (SEM) and microanalysis-EDS. The study was complemented with shape deformation and mass measurement assays. The temperature variation was associated with the oxides morphology and the consumption mechanisms were discussed based on the relation between the thermal mechanical effects and the responses of the materials characterization

Obtenção e caracterização de farinha de frutas e vegetais através do uso de um sistema de secagem solar de baixo custo

In this work a solar drying system for food dehydration was developed. It is a direct exposition drying apparatus that uses solar energy to heat the circulating air. First, the construction and assembly of this apparatus was described, in which was used scrap wraps of used tires for thermal insulation, allowing the reuse of solid waste, being an ecologically correct recycling option. After, the results obtained in experiments for cashew drying showed the thermal and economical feasibility of the proposed solar drying system, focusing on the process of flour production and in its chemical characterization. It was also demonstrated the social importance of this production for socially excluded people, since the value added to this fruit, in relation to its in nature form, may represent an option for job and income generation. The main features of the proposed dryer are its low cost and its easy fabrication and assembly process. After cashew drying, the obtained product was processed into flour by using a knife mill and it was added crushed rapadura to reduce the rancid taste caused by tannin

Construção e analise de desempenho de um sistema de aquecimento solar de água utilizando placa de policarbonato como superfície absorvedora

It was studied a system for heating water to be used to obtain water for bathing at home, the absorbing surface of the collector is formed by one plate of polycarbonate. The polycarbonate plate has 6 mm thick, 1.050 mm wide and 1.500 mm long with an area equal to 1,575 m². The plate was attached by its edges parallel to PVC tubes of 32 mm. The system worked under the thermo-siphon and was tested for two configurations: plate absorber with and without isolation of EPS of 30 mm thick on the bottom surface in order to minimize heat losses from the bottom. The tank's thermal heating system is alternative and low cost, since it was constructed from a polyethylene reservoir for water storage, with a volume of 200 liters. Will present data on the thermal efficiency, heat loss, water temperature of thermal reservoir at the end of the process simulation and baths. Will be demonstrated the feasibility of thermal, economic and material pickup proposed for the intended purpose.

Análise preditiva a partir da caracterização das emissões gasosas e do óleo lubrificante em frotas com motorização a diesel

This work was motivated by the importance of conducting a study of vehicle emissions in captive fleets with diesel engine, coupled with the predictive maintenance plan. This type of maintenance includes techniques designed to meet the growing market demand to reduce maintenance costs by increasing the reliability of diagnoses, which has increased interest in automated predictive maintenance on diesel engines, preventing problems that might evolve into routine turn into serious situations, solved only with complex and costly repairs, the Reliability Centered Maintenance, will be the methodology that will make our goal is reached, beyond maintaining the vehicles regulated as fuel consumption and emissions. To Therefore, technical improvements were estimated capable of penetrating the automotive market and give the inshore fleet emission rates of opacity of the vehicles, being directly related to the conditions of the lubricating oil thus contributing to reducing maintenance costs by contributing significantly to emissions of pollutants and an improvement in the air in large cities. This criterion was adopted and implemented, em 241 buses and produced a diagnosis of possible failures by the correlation between the characterization of used lubricating oils and the analysis of opacity, with the objective of the aid the detection and solution of failures for the maintenance of sub-systems according to design criteria, and for this to be a deductive methodology to determine potential causes of failures, has been automated to implement a predictive maintenance system for this purpose was used in our study a mobile unit equipped with a opacimeter and a kit for collection and analysis of lubricating oil and the construction of the network diagnostics, we used a computer program in Microsoft Office Access 2007 platform tool is indispensable for creating a database data, this method is being used and successfully implemented in seven (7) bus companies from the city of Natal (RN) Brazil

Desenvolvimento de um protótipo para alimentação de pós para aspersão térmica em tocha de plasma

The nanometric powders have special features that usually result in new properties, originating applications or expanding them in various fields of knowledge. Because having a high area/volume ratio, phenomena such as superficial strength of adsorption becomes greater than the weight of the powder which makes more difficult its handling. The high power of agglomeration of these powders requires study and development of equipments to enable its management into the plasma torch. The objective of this work is to develop a powder feeder which can solve the mainly problems about insertion of powder into the thermal spray developed in the laboratory of plasmas, which are carried out with plasma torch arc not transferred (plasma spray). Therefore, it was made a aluminum s powder feeder and tests were performed to verify their operation and determine its rate of deposition by spraying powders of niobium pentoxide (Nb2O5) and titanium dioxide (TiO2) with particle sizes less than 250 mesh (<0.063 mm). We used masses of 0.5 g - 1.0 g and 1.5 g of each powder in tests lasting 15 seconds - 20 to 25 seconds for each mass. The tests were performed in two ways: at atmospheric pressure using argon gas with a flow of 9 l / min as carrier gas and through a Venturi pipe also using argon gas with a flow of 9 l / min as carrier gas and with a flow of 20 l/min as the feed gas passing through the Venturi pipe. The powder feeder developed in this paper is very easy to be handling and building, resulting in feeding rate of 0.25 cm3/min - 1.37 cm3/min. The TiO2 showed higher feeding rates than the Nb2O5 in all tests, and the best rates were obtained with tests using mass 1.5 g and time of 15 seconds, reaching feeding rate of 1.37 cm3/min. The flow of feed had low interference in feeding rate during the tests

Desempenho mecânico de compósitos híbridos de fibras naturais e poliéster não saturado

With the objective to promote sustainable development, the fibres found in nature in abundance, which are biodegradable, of low cost in comparison to synthetic fibres are being used in the manufacture of composites. The mechanical behavior of the curauá and pineapple leaf fibre (PALF) composites in different proportions, 25% x 75% (P1), 50% x 50% (P2) e 75% x 25% (P3) were respectively studied, being initially treated with a 2% aqueous solution of sodium hydroxide. Mechanical analyses indicated that with respect to studies of traction, for the combination of P1 and P3, better results of 22.17 MPa and 16.98 MPa, were obtained respectively, which are higher than that of the combination P2. The results of the same pattern were obtained for analysis of bending resistance where P1 is 1.21% and P3 represents 0.96%. In the case of resistance to bending, best results were obtained for the combination P1 at 49.07 MPa. However, when Young's modulus values were calculated, the values were different to the pattern of the results of other tests, where the combination P2 with the value of 4.06 GPa is greater than the other combinations. This shows that the PALF had a greater influence in relation to curauá fibre. The analysis of the results generally shows that in combinations of two vegetable fibers of cellulosic origin, the fiber which shows higher percentage (75%) is the best option than to the composition of 50%/50%. In the meantime, according to the results obtained in this study, in the case where the application should withstand bending loads, the better composition would be 50%/50%

Análise da magnetohidrodinâmica com transferência de calor em canais de placas paralelas via transformação integral

The main goal of the present work is related to the dynamics of the steady state, incompressible, laminar flow with heat transfer, of an electrically conducting and Newtonian fluid inside a flat parallel-plate channel under the action of an external and uniform magnetic field. For solution of the governing equations, written in the parabolic boundary layer and stream-function formulation, it was employed the hybrid, numericalanalytical, approach known as Generalized Integral Transform Technique (GITT). The flow is sustained by a pressure gradient and the magnetic field is applied in the direction normal to the flow and is assumed that normal magnetic field is kept uniform, remaining larger than any other fields generated in other directions. In order to evaluate the influence of the applied magnetic field on both entrance regions, thermal and hydrodynamic, for this forced convection problem, as well as for validating purposes of the adopted solution methodology, two kinds of channel entry conditions for the velocity field were used: an uniform and an non-MHD parabolic profile. On the other hand, for the thermal problem only an uniform temperature profile at the channel inlet was employed as boundary condition. Along the channel wall, plates are maintained at constant temperature, either equal to or different from each other. Results for the velocity and temperature fields as well as for the main related potentials are produced and compared, for validation purposes, to results reported on literature as function of the main dimensionless governing parameters as Reynolds and Hartman numbers, for typical situations. Finally, in order to illustrate the consistency of the integral transform method, convergence analyses are also effectuated and presented