The present study was developed with the objective of evaluating, in a technical and economic way, the behavioral change between the preventive strategies of an air condensing turbine (Model: H3800S), applied in an industrial chemical plant that produces fertilizers, sulfuric acid and installed in Brazil, city of Araxá / MG. The industry has a recovery boiler, generating an overheated steam at a temperature of 400 ° C, and a pressure of 4.3 MPa, which is directed to a steam turbine coupled to an electric generator, thus constituting a turbogenerator group (GTG ) with 11.50 MWe electric power generation capacity (Wele). The generated Wele was made available to be consumed by an industry and represents 22.45% of the total consumption, if it is operating at nominal capacity. The generation capacity of this GTG in the period between preventive maintenance is influenced by the internal losses that occur in the turbine and the steam in an environment of three sources: friction between moving doors, fluid leaks and friction in labyrinth seals of steam. The operation of the steam turbine reduced the generation capacity and, consequently, negatively impacted the cost of an installation of this unit, due to the capacity of production of greater amount of electric energy (Eele), made available by the concessionaire that serves a region of installation industry. The only thing is minimized when a steam turbine is used in this GTG undergoes periodic preventive maintenance in order to reconstitute or replace the worn or damaged components.

The development of new technologies and the improvement of the efficiency of the refrigeration systems becomes important in a scenario in which the climatic conditions of the planet is worrisome. The use of CO2 in transcritical refrigeration cycles represents an alternative to the problem of global warming. In this context, this work carried out a thermoeconomic analysis of a subcritical cycle and a transcritical cycle, both containing CO2. The mathematical models for such analysis of both cycles were developed in the EES (Engineering Equation Solver) software. A multiobjective optimization method was used to find the point of best efficiency and cost of both cycles. Analyzing the optimum points for some ambient temperatures, the exergy efficiency and the cost of the subcritical cycle operating with R404A in the high temperature region are on average 15.2% and 17.9% higher than the transcritical cycle, that is, the transcritical cycle has lower total cost. The subcritical cycle operating with R1234yf in the high temperature region has, on average, COP 6.23% higher and cost 3.1% lower than the subcritical cycle operating with R404A. The results show that in deciding which of the cycles is best for a given ambient temperature range, one must always take into account the relationship between cost and efficiency. Replacing the R404A subcritical cycle with the R1234yf in addition to reducing the GWP from 3800 to 6 increases the COP and decreases the total cost of the system.

The present work is composed by a comparative thermoeconomic analysis between two refrigeration systems: Vapor Compression Cascade Refrigeration System (SRCCV) and Integrated Refrigeration System by Absorption and Vapor Compression (SIRACV). The thermoeconomic analysis compares the systems under energy, exergic, economic and environmental aspects. The development of mathematical models for each of the systems is performed through the EES (Engineering Equation Solver) program. The optimized functions are exergy destruction and total cost rate (sum of cost rates for investment, operation, maintenance and carbon credits) by minimizing these functions. The optimization method used is the weighted sum of the objectives, which consists in transforming the multiobjective problem into a mono-objective problem by assigning weights for each objective, this can be achieved by assigning different weights for each goal, then a new function that represents the linear relationship between all the objectives is found. In present case the two objective functions are exergy destruction and total cost rate. In multiobjective optimization, the process of choosing among optimized solutions involves the definition of an equilibrium point, also called the ideal point. In order to achieve a real solution of the minimum values of the described functions simultaneously one must determine which is the smallest distance from the ideal point to the curve that defines the optimized solutions.

Drying is one of the earliest known unit operations. Currently, it is mainly applied in the food industry, in addition to several processes, such as in ceramic enterprises. Through vaporization, this process removes liquid content, usually water, from a solid material. One way of protecting the product to be dried, reducing its drying time and increasing efficiency is the use of dryers, which can be of several models. Solar dryers, which are integrated, distributed or mixed, stand out due to the use of an abundant and renewable source of energy. In the case of the mixed, the solar radiation affects both the collector, where the air is heated and routed to the drying chamber, as well as in the chamber itself. In order to increase drying efficiency in the mixed dryers, the air from the collector can be brought into the drying chamber at a temperature higher than that normally achievable. Thus, the presence of obstacles in the collector can increase the air path, causing it to become warmer. The objective of this work was to compare the energy and exergetic efficiencies of a mixed active solar dryer with traditional flat plate and flat plate with baffles, determining the drying curves. The products used for drying were ceramic bricks, which remained for 12 hours in a container before each experiment. A test was performed with baits and two without, due to the cloudiness on one of the days. The non-baffled tests had mean exergetic efficiencies higher than those with baffles in (0.52±0.10)% and (0.22±0.12)%, and the baffle tests showed the other average efficiencies greater, surpassing the experiments without (5.84±1.87)% and (9.08±2.05)%, drying (5.40±1.40)% and (7.34±1.53)% and in the latent exergetics in (0.24±0.05)% and (0.49±0.05)%. The final moisture content of the baffle assay was lower (0.33±0.01)% and (1.91±0.01)% in the wet basis and (0.39±0.01)% and (2.32±0.01)% on dry basis than on non-baffles. Thus, the insertion of baffles in the dryer collector plate made its performance superior to that of traditional flat plate equipment.

The present study aims to evaluate the performance of heat transfer during convective boiling in micro/nanostructured microchannels by surface coating techniques, chemical and micro/nanoelectromechanical processes. This study has investigative and computational bias. The methodology adopted consisted in carrying out a bibliographical research on the general context of the microchannel area and convective boiling. After that, several manufacturing techniques were analyzed to obtain nanostructured surfaces in microchannels. Three methods were categorized for this purpose: surface coatings using special materials, chemical processes and micro/nanoelectromechanical systems. Subsequently, 22 research works on the state of the art for micro/nanostructured microchannels were selected. Then, five correlations were chosen, based on normal microchannels available in the literature of the last 12 years. These correlations were then compared through a database with 873 experimental points from studies with the working fluids R134a and water in normal and micro/nanostructured microchannels. As a result, one of these correlations had a wide range of adjustment to the database (100%), for bands of adjustment to the experimental data of ±10%, ±20% and ±30%, also considering the database for micro/nanostructured microchannels. Finally, it was suggested the experimental investigation of nanostructures influence by varying parameters associated with them, such as a shape factor. In addition, another suggestion was to obtain correlations for convective boiling in micro/nanostructured microchannels using genetic optimization algorithms.

The increasing energy demand has been a subject constantly discussed. The increase in energy production capacity and the implementation of new energy sources try to get around this problem. However, these measures alone will not be enough to support the growing demand. Increasing the energy efficiency of mechanisms and processes presents itself as an ally of fundamental importance for the continuity of global energy supply and development of society. The compressors are equipment that have wide applicability both in the industrial sector and at home and are responsible for high energy consumption. This work aims to study an alternative valveless compressor, object of a patent of invention, which is presented as an alternative to improve the energy efficiency of conventional reciprocals. Its unique mechanism is responsible for opening and closing the valve system with a focus on reducing load losses during the suction and discharge phases. In order to evaluate the improvement caused by this mechanism, it was mathematically simulated a one-dimensional model in the non-valved compressor's MATLAB software and the numerical results obtained were compared as the mathematical model of an automatic compressor with automatic valves described in Volf's (2017) master's work. The comparative analysis showed an increase in the isentropic efficiency of approximately 12.4% and an increase in the volumetric efficiency of approximately 3.3%. A parametric analysis made it possible to identify the area of the suction and discharge window section, equal to 6.00 cm², as the optimized value to obtain the highest isentropic and volumetric efficiency values when compared to the initially proposed model.

The present work consisted in an analysis and thermoeconomic optimization of an ITES (Ice Thermal Energy Storage) system to attend air conditioning systems where the Four E methodology was applied (energy, exergy efficiency analysis, economic and environmental analysis of the storage). A mathematical model of the system was developed and a case study was applied to the set of buildings that make up the headquarters of the Attorney General's Office - PGR in Brasília / DF. The optimized functions were total exergetic efficiency (maximized) and total cost rate (minimized)  through the Nelder-Mead Simplex method. Then, the set of solutions obtained from the optimized functions were plotted in a Pareto from where the optimal point of greatest total exergy efficiency and lowest total cost rate of the ITES system was selected. For the selection of the optimal point, the techniques TOPSIS - Technique for Order of Preference by Similarity to Ideal Solution and LINMAP - Linear Programing Technique for Multidimensional Analysis of Preference were used. Finally, this system was compared to a system operating in a conventional way, without thermoaccumulation and from the point of view of horo-seasonal blue and Green modalities from which it was possible to obtain the time of return of the investment and the feasibility of the implementation of the system ITES. The results showed that the system with thermoaccumulation presented an exergetic efficiency of 61.72% while for the conventional system the exergética efficiency obtained was 59.65%. The TOPSIS Decision Making Technique was selected for annual savings of approximately 427,000 US$/years for an exergistic efficiency difference of only 1.16%. The results also showed that the ITES system operating with green rates provided electricity savings of around 11% per year compared to the operation of the conventional system, thus leaving to emit about 88.94 tons of CO₂ annually. The payback periods obtained for the operation of the ITES system in the horo-seasonal blue and green modalities were 6.53 years and 3.34 years respectively. In this way the work contributed to a critical analysis from the thermoeconomic and environmental point of view, pointing out the feasibility of the ITES system for air conditioning plants.

The main goal of this study is to evaluate the technical and economic feasibility of a hybrid system, composed by a photovoltaic generator and a battery, which must provide energy to a typical house of Belo Horizonte/MG during the consumption peak time. Extensive literature reviews of energy storage systems, mainly batteries, and of silicon-based photovoltaic modules are made to characterize them and to show their technological evolution over the last years. Four specific cases are selected and analyzed in detail, from the achievement of an extensive and complete database. The sizing of the photovoltaic generator, the inverter and the battery capacity (based on its Depth of Discharge) are made for each case. Then, the dimensioned hybrid systems are simulated in SAM (System Advisor Model), a software provided without costs by NREL (National Renewable Energy Laboratory). The results show technical feasibility for all the cases and economic feasibility for just one of them considering the base scenario adopted in this study, which has no financing or government/power distribution company incentives. Parametric analyses show that economic feasibility can be achieved for all the studied cases if the incentives are equal to 30% of the hybrid system initial costs.

The present work investigates the refrigerant coolant HFO1234yf, under the condition of nanofluid, with addition of SiO2, TiO2 e ZnO particles, in order to estimate the sedimentation velocity, thermal conductivity, dynamic viscosity, density, specific heat and CTC (single phase and biphasic laminar flow), order to compare them with the values found for the pure R-134a. The thermophysical properties were calculated using adjusted correlations for nanorefrigerants, considering fluid in liquid phase and steam, at temperatures of 283K to 323K, nanoparticles of 5nm to 50nm and concentrations of 1% to 6%. With this, it was verified that the properties had a more significant improvement in the nanofluido with concentrations of nanoparticles of 6%, with diameters of 5nm, mainly for HFO1234yf-ZnO. This, however, exceeded the values of the pure R-134a in all properties except for the thermal conductivity and the CTC for single-phase laminar flow. Finally, it was concluded that, even with the eminent sedimentation of the nanoparticles, the increase of the nanoparticles showed to be an alternative in terms of performance for refrigeration systems, due to the improvement of thermo-physical properties of the nanofluids.

The increasing of vehicle unities around the world demands higher fuel consumption and consequently increase at vehicles exhaust gas pollutants emissions which represents 19% of total greenhouse effect gas promoters. Researches concerning design of internal combustion engine explore computational and technological devices to simulate the performance of vehicles exhaust gas pollutants emissions. The fierce automotive market requires a high understanding level of such tools to reach shorter times to develop design resolutions. Unidimensional models are recognized as a viable choice for internal combustion engine simulations, reaching deviations of less than 7% in comparison with empirical data. GT-POWER Software is performed to unidimensional simulations of internal combustion engine solving equations of energy conservation, momentum, continuity, heat transfer and combustion. The aim of this research is to purpose an unidimensional model to simulate the performance of a SIGMA 1.6 16V FORD engine to a rotation rate between 1000 and 6000 rpm at a wide open throttle condition. Torque, power, volumetric efficiency, specific fuel consumption rate and specific emissions rates for CO, CO2, THC and NOx are presented to the subject engine operating with commercial gasoline (E25). Final analysis presents deviations of less than 5% concerning torque, power and effective mean pressure, 4% for specific fuel consumption rate and finally 3% about volumetric efficiency.

In order to increase efficiency and competitiveness of parabolic trough collector solar systems and reduce production costs of the so-called clean energy, the next generations of solar systems must focus on increasing its operation temperatures. Since thermal oil, the conventional heat transfer fluid of these systems, is chemically unstable at temperatures above 400 °C a way to achieve better thermodynamic efficiency levels is investigate new heat transfer fluids witch allow system operation at higher temperatures compared to those usually adopted. The use of molten salts as heat transfer fluids in parabolic trough solar concentrators is a promising concept, offering a path to make the energetic efficiency associated to solar power plants comparable to those associated to conventional Rankine cycles, since molten salts are considered chemically stable up to 600 °C. In view of this and other benefits offered by the use of this heat transfer fluid, a three-dimensional computational mathematical model was developed in order to simulate the behavior of a parabolic trough solar field based on the Finite Element Method for the evaluation of molten salt exit temperature from the horizontal receivers of parabolic trough solar concentrators in comparison to that of the thermal oil if both operate as heat transfer fluids under the very same conditions. The mathematical model of the system was validated using data from the demo solar field "Usina Solar" owned by the Centro Federal de Tecnologia de Minas Gerais. Based on the results of this investigation, it is concluded that it is possible to adopt molten salt as heat transfer fluid of a parabolic trough solar power generation plant in order to increase its thermodynamic efficiency, making it comparable to the efficiency of Rankine cycles powered by fossil fuels or charcoal. For this purpose, a larger area of the solar energy absorber is required due to the high density of the molten salts compared to other synthetic oils.

The drying is one of the oldest operations of conservation of foods used by the man and it can be defined as the removal of moisture content of the product through the application of a heat source. In general the heated air is responsible to remove the moisture content of the product and take it away. It is an operation of transfer of heat and mass in transient regime that causes a reduction of volume of the product and in general alters their sensory aspects. The drying is present in several areas, besides being one of the main stages of the products improvement in the agroindustry. The cocoa is very popular in all the world and in Brazil it has a prominent role being the sixth biggest producer of the world with production aroud of 260,000 t/ano. The high  initial moisture content of the cocoa, between 50 % and 60 %, and the low moisture content after the drying, around 10 %, have guided the choice of the cocoa. This work has an aim  of  compare the performance of an active solar drier (type cabin) with an electric drier in the cocoa drying through drying tests with measurement of the parameters involved in the process and perform an energetic and exergética analyze in both driers. Also the factor of sensitive heat was calculated for each drier. The drying time in the electric drier was 18 hours for a 4 kg of cocoa, while in the solar drier were about 8 hours for 1.5 kg of cocoa. Both driers were able to carry out the drying of the cocoa with success. The electric drier had a bigger average thermal efficiency (60%) than the solar drier (31%). The efficiency of drying of the electric drier was bigger than the solar drier, 8.3 %, against 4.8 %. In the electric drier the moisture content in final wet base was (9.30 ± 0.49) % while in  the solar drier this value was (12.00 ± 0.97) %. Both driers reached exergetic efficiency above 90% with low exergetic destruction.

Computational fluid dynamics simulation tools are widely used in cutting-edge industry for evaluation and characterization of phenomena involving equipment and processes in areas such as automotive, aerospace and shipbuilding. However, the a/pplication of such tools in the industry and research areas related to the conversion and use of solar energy has been very little explored. This paper applied the finite volume method for evaluating performance of a flat plate solar collector. The analysis is based on a three dimensional model of a collector with seven risers and double glass cover. The construction characteristics of the simulated collector were defined from an optimization model created by the research group responsible for the R & D 438 Cemig / ANEEL, which incorporates this work. It was later made a prototype model by a specialized company according to the criteria established by the working group. After manufacturing the collector was tested in a laboratory accredited by INMETRO for certification of solar collectors, generating experimental data used to validate the computational model proposed in this work. The main points analyzed were the thermal efficiency for different operating conditions, the flow profile in the risers and the characteristics of the natural convection observed in the layers of air between the absorbing plate and glass covers. The results obtained from the model are in good agreement with the experimental data of outlet temperature with corresponding thermal efficiency and maximum absolute deviation of 6.8%. Also the flow profile in the absorber tubes presented a behavior consistent with numerical and experimental evaluation studies found in the literature.

This study aimed to improve a mathematical model, first developed by Domanski (1989) using FORTRAN language, able to predict the performance of a finned tube heat exchanger trough the tube-by-tube method. To the proposed model were incorporated louvered fins and vortex generator fins, the R134a and R1234yf refrigerant, the pressure drop of air to flow between the fins and to update the correlations used to calculate the convection coefficient of tubes and fins. Additionally it was incorporated to mathematical model the calculation generated entropy during operation of the equipment. The new model was validated by comparison with experimental and numerical results, present in the literature. A minimization of the number of entropy generation was made according evaporator’s six parameters: type of fins and the distance between them, the distance between the tube rows and the diameter of them, type of coolant and the internal surface of the tubes. The results showed that the factors that most influence the entropy generation were the distance between the fins, the distance between the tube rows and the type of coolant, Besides that the largest share of irreversibility is associated with the flow of air between the fins. The combination that presented the lowest entropy generation number was: split fin with the distance of 2,23 mm between them, tubes with diameter of 11 mm and micro-finned surface, distance between tube rows of 40 mm and operating with R22.

Solar energy has significantly spread in the whole world. One of its main uses is to produce heat and electricity for residential areas, business and industries. The world´s increasing consumption of energy, together with the reduction of non-renewable natural resources, has led to a new demand of adaptable technological solutions that can allow cogeneration such as the PV/T. This research work focuses on PV/T and it was born from a project demand of P&D GT 498 by CEMIG. The project was named “Desenvolvimento de Solução PV/T  para Aumento de Eficiência de Usinas Solares” (Development of PV/T solutions to increase solar power plant’s efficiency). The theoretical knowledge of this research work provided the base to design such prototypes through the assessment of the thermal and electrical performance of the installment of photovoltaic modules on tube-sheet collectors and serpentine collectors. The research work seeks to elaborate numerical models for tube-sheet collectors and serpentine collectors described by Duffie and Beckman (2006). The models were implemented on the software Engineering Equation Solver-EES, provided by the Federal Center for Technological Education from Minas Gerais CEFET MG (Centro Federal de Educação Tecnológica de Minas Gerais – CEFET MG). Analyzes were performed with water’s temperature raging of 25°C to 70°C, irradiation of 800 W/m² and wind speed of 1 m/s. The flat plate solar collector reached efficiencies of 54,7% and 4% by the firt and second law of thermodynamics respectively. The serpentine collectors reached efficiencies of 58,1% and 4,3 % by the first and second law of thermodynamics respectively. The Tube-sheet PVT with two covers offered global efficiencies (electrical + thermal) of 50% and 16,4% respectively. On the other rand the Tube-sheet PVT with one cover offered 40,2% and 15,6 % of global efficiencies by the firt and second law of thermodynamics respectively. The Serpentine PVT with two covers offered global efficiencies of 52,5% and 16,8% respectively. On the other rand the Serpentine PVT with one covers offered 43% and 15,8 % of global efficiencys by the firt and second law of thermodynamics respectively. It was possible to check that to the others constant boundary condition, the incrising of irradiance generates increasing on thermal efficiencies of first and second law, but reduces the electrical efficiencies. The electrical and thermal efficiency can be increased simultaneously with the water’s temperature reduction on PVTs input. Which indicates that the use of PVT is strongly linked with the application desired either production heat or electricity, with the PVT’s with one convers more efficients on electricity production.

Fierce global competition and the need for more efficient and sustainable production systems require from the companies continuous optimization of theirs production processes. Improvements of industrial equipment, processes and analytical methods are directly linked to the pursuit of reducing energy waste. In this sense, cogeneration is an alternative to energy recovery available in industrial processes. Considering the importance of a cogeneration system in the environmental, economic and energy context of an industrial plant, is proposed in this work a methodology that analyzes the energy performance of cogeneration power plant. The analysis considers the overall equipment effectiveness (OEE) that measures the performance from the perspective of total productive maintenance, the energy utilization factor that is based on the first law of thermodynamics and the availability utilization factor that is based on the second law of thermodynamics. It was used information from a cogeneration power plant which operates in a Rankine cycle inside a large steel company located in the state of Minas Gerais. The power plant of this study can produce steam and electricity using as primary fuel the waste gases from the steel production process, supplemented with fuel oil. It was observed that the overall equipment effectiveness (OEE) reached 73.0%, the energy utilization factor was 32.7% and the availability utilization factor was 24.3% during the analyzed period. It was also observed that the OEE indicator was more promising than the other two for use in a cogeneration power plant. The results show the importance of the maintenance process to improve the cogeneration system efficiencies and its contribution to the sustainability of the production process.

Environmental policies and energy from every continent, motivated by the dependence on oil and the air pollution include initiatives to promote transport systems based on alternative fuel vehicles. In this context and in the Brazilian scenario, this thesis aims to make a comparative analysis of current and usual vehicles with internal combustion engine and electric vehicles. Among several alternative fuel vehicles opted for the electric vehicle by this technological option being produced on a large scale in the world market. For such a comparison was necessary to create a methodology, called Strategic Life Cycle Assessment, AECV, so that the results were based on technical merit, considering all impacts, besides being careful in light of the economy and sustainable manner. It was concluded that unquestionably AECV is a methodology capable of analyzing and comparing the global impacts of new technologies and that among the analyzed vehicle internal combustion own most relevant environmental impacts when compared to the electric vehicle.

This study presents an evaluation of the thermodynamic behavior of a prototype mixed active solar dryer. To perform the evaluation of energy and exergy flow of air through the solar dryer, the drying tests with samples of the phosphate rock concentrate were performed. The prototype was built with wood structure of low weight, high mechanical strength with galvanized steel and glass cover for passage of solar radiation. The monitoring of the parameters of the drying air was conducted through sensors and equipment installed at points of entry and exit from the solar dryer. Measurements around the dryer were performed to assess the environmental and climatic conditions where the dryer was installed. To determine the temperature of the absorber plate a model was tested using data measured in the solar dryer. In conjunction with testing of solar drying tests for evaluation of the initial and final samples of the phosphate rock concentrate humidity, using the electric oven were conducted. With data collected charts of the main parameters in order to evaluate the performance of the air flow, measured at the entrance, inside and on the output of solar dryer has been developed. To perform the tests with two lots of samples of phosphate rock concentrate were used. At first unable to find the thermal efficiency of the solar dryer. The result of the instantaneous thermal efficiency of the dryer ranged from 9.7% to 31.3%. The thermal efficiency of drying ranged from 2.2% to 3.1% between the three test days. The irreversibility presented a behavior proportional to solar radiation and Exergy efficiency had values ranging from 9.7% to 34.7%. Thus the behavior of energy efficiency and exergy efficiency showed a similar behavior.

Residential refrigerators, popularly known as fridges and freezers, are responsible for about 8% of the electricity consumed in Brazil. Therefore, any measure that allows reducing the consumption of these devices is important for creating a more sustainable economy. The manufacturers of these refrigerators continuously invest in research aiming to make their equipment more efficient from an energy point of view and more competitive. In this context, there are numerous studies and activities designed to increase the energy efficiency of household refrigeration systems, using different investigations strategies. However, very few studies have been conducted to verify the impact of dust accumulation on coil condensers with natural air circulation over it lifecycle which may cause loss of thermal efficiency, with consequent increase in electricity consumption. This research allowed determining experimentally the energy consumption of a typical residential refrigerator with approximate twenty years old, considering accumulation of dust on the condenser. Additionally, the same refrigerator was subjected to tests checking the power consumption without accumulation of dust. To realize the experiment was obtained a chamber with controllable weather, courtesy of Campinas University, which enabled perform the tests under ideal conditions, keeping the environment temperature external to the fridge around 32 ° C , with a limit range of less than 1 °C. The test methodology was based on national standards, and the chamber and the refrigerator were instrumented for temperature measurements at different points. The chamber temperature was controlled using a temperature controller, PID type, and an air heating system consisted of electrical resistances, whereas the cooling system consisted of a air conditioner adapted. The electrical power of compressor was monitored using an active power transducer. All analog signals measured were sent to an acquisition data system for further processing and analysis. The fridge with accumulation of dust showed an increase in energy consumption of about 10% compared to the same equipment without dust, all done in controlled conditions in laboratory.

This work evaluates the applicability of a new methodology of test for characterization of concentrating cylindrical parabolic solar collectors through the conduction of experimental investigation in the solar installation of CEFET-MG/CEMIG named Solar Plant, which is located at the dependences of the Campus II of CEFET-MG. The method allows the determination of the useful collector heat flux, the thermal and optical collector efficiencies, beyond other important parameters, such as, the Incident Angle Modifier (IAM) and the effective collector thermal capacitance. The Quasi Dynamic Method consist basically of a non linear function that correlates the collector useful heat flux with different independent variables representative of the different energy gains or losses of the collector. In this work were performed five experimental tests under different conditions of solar radiation, temperature and mass flow rate of the working fluid entering the collector, with different incident angles for the solar beam radiation. The collector parameters were obtained after a detailed statistical evaluation of the collected data through a statistic model recommended by the European Standard, named ―Multivariable Linear Regression MRL. The terms referent to the IAM of the beam and diffuse radiation were treated separately, which allowed obtaining the value of constant "𝑏0" of the IAM for the collectors. Further, it was possible to determine the coefficients of first order referent to the thermal collector losses, as well as, the specific thermal effective collector capacitance. The tests performed showed a maximum thermal collector efficiency, corresponding the thermal losses "zero" (close to the optical efficiency) equal to 42,7 % and other thermal efficiencies for different thermal losses comparable to the values obtained by Borges (2012) during tests performed using the Quasi Static Method. Additionally, the method allowed the determination of the specific thermal effective collector capacitance that was equal to 6057 J.m-2.K-1. Finally the Quasi Dynamic Method showed to be satisfactory and potentially strong to evaluate, in a simple and efficient way, concentrating solar collectors of the type cylinder parabolic used in concentrating solar plants.

In Brazil, the sugarcane sector has drawn much attention in the last years due to its great potential of energy cogeneration. The bagasse from sugar cane is used as fuel in boilers to produce steam that drives generator turbine and produces electricity. However, bagasse still has approximately 50% moisture on a wet basis (wb). This bagasse with high moisture content has low combustion efficiency and requires a higher consumption for steam production. Thus, the bagasse must undergo a process of dehydration. The used dryers were: an electric dryer and a solar dryer. In order to compare the energy efficiency of dryers in the bagasse drying, were performed seven experimental drying tests, four in the electric dryer and three in the solar dryer. The test for determining the initial moisture content of bagasse showed moisture content of approximately 60,58%. In the case electric dryer, the temperature setting at 70°C and a speed of 7,1m/s resulted in increased removal of moisture bagasse. In the case of energy efficiency of electric dryer, the temperature setting at 60°C and a speed of 4,3m/s showed more efficient. With the solar dryer, the best condition moisture removal and energy efficiency occurred in the test with the highest values of incident solar radiation. From the results in the seven experimental tests, it was found that the temperature had most influential parameter in convective drying of bagasse and the flow velocity of the drying air had was the great impact on the power consumption of the dryers. In the energy evaluation of the dryers were calculated the energy consumption indicators of the electric dryer and of the solar dryer, respectively: drying efficiency 16,4% and 1,22%, thermal efficiency 60,8% and 15,1% and specific consumption of energy 14,4 MJ/kg and 200,9 MJ/kg. The results showed that the electric dryer was the equipment bigger energy efficiency in the drying of bagasse cane sugar.

A prototype solar collector photovoltaic / thermal type (PVT) was constructed to simultaneously generate electricity and thermal energy for heating water for domestic purposes. The thermal collector is formed from a stainless steel plate absorber consists of internal channels through which water circulated through natural circulation. On the upper side of the absorber plate, an electric circuit formed by photovoltaic cells polycrystalline silicon has been installed. The system of water heating collector consisted of a thermal reservoir, which allowed the storage of hot water with natural stratification, simulating collectors residential use found in the market. Several temperature sensors were installed in the collector and the thermal reservoir to determine the energy stored in them. A pattern of daily hot water consumption was implemented with withdrawal of hot water in selected time. The system was evaluated experimentally on four consecutive days to evaluate the daily performance of the PVT collector through energy audits conducted in the solar collector and the heat reservoir. The thermal, electrical and overall efficiencies were determined PVT collector aiming to raise the advantages of simultaneous generation of electricity and heat systems compared to conventional thermal electricity generation and not simultaneously, using separate components. The prototype was first subjected to characterization tests to survey the characteristic curves “I versus V" conditions with and without cooling to determine the parameters of the PV panel. According to the test results, the average thermal efficiency of the collector was 59 % and the mean electrical efficiency of 11%. After the analysis of the test results was a study of the technical and economic feasibility of the collector.

This paper aims to present the literature correlations involving heat exchangers air cooled with an analysis of the thermo-hydraulic performance of the air side. A literature search was conducted by the thermo-hydraulic performance as the surface made by comparisons to improve the design of heat exchangers. The surfaces were smooth compared, ventilated and corrugated. Correlations were derived from theoretical and experimental results which have incorporated the effects of geometrical parameters on performance of the thermo-hydraulic coils in order to determine the heat transfer and pressure drop. Some geometrical parameters were analyzed for each type of surface such as the pitch of the fins and the number of rows of tubes. For each surface analyzed by means of the correlations, a result was obtained, some being similar to those surveyed and not others.

This work investigated and evaluated the influence of construction parameters on energy consumption in office buildings located in the Santa Iphigenia in Belo Horizonte - MG, city area where is located a large number of commercial buildings. This work reached a methodological procedure applied to the study, which achieved the goals set, and for this we used a methodology based on the survey design characteristics, the pattern of occupation and use of equipment that defined a predominant type. This methodology has provided conditions in computer simulations to evaluate the influence of design characteristics of these changes in energy consumption. The changes consisted predominantly of the type in the percentage of windows, installation of movies in the window panes, types of lighting and HVAC system. The increase in the percentage of non-installation of windows and the glass films did not imply a large impact on consumption of the building and are responsible for increases of 2.63 and 3.21% respectively in the consumption of the building. However, the choice of lamps and air conditioning led to an increase of 18.5 and 18.4% respectively decreases in consumption of the building when using incandescent light bulbs and appliances like split. The simple payback analysis proved satisfactory and rapid exchange of the incandescent bulbs with fluorescent ones, as for air conditioning the time of return on investment was much higher. These simulations allowed us to identify the influence of construction parameters on energy consumption in office buildings in order to verify an improved energy performance.

The search for new sources of energy becomes imperative in the midst of the accelerated civilization development. In this scenario it is possible to detect a lot of countries seeking the diversification of its energy matrix in order to achieve growing demand. It is evident that electricity is at present the main energy supply essential and strategic for economic and social development of the contemporary society. However, the primary sources used for electricity generation in most countries are hydrocarbons (oil and coal), considered as non-renewable energy sources, providers of greenhouse gases (GHGs), and responsible for global warming and climate changes that the world is witnessing nowadays. The generation of electricity through the wind is one of the main alternatives to replace non-renewable sources, due to its low environmental impact, reduced deployment time and high availability of areas for wind farms. However, a critical aspect of this kind of power generation is its low production efficiency. Although on favorable conditions such as annual winds basis and a persistent work from the operators in order to increase the availability of wind turbines installed in wind farms, these ones still shows, in general, a poor production performance. The present work demonstrates a study performed in a wind farm in northeastern Brazil, where global production efficiency was measured according to OEE (Overall Equipment Efficiency) parameter developed by TPM (Total Productive Maintenance), risk studies using FMEA (Failure Modes and Effects Analysis) technique that allows to identify the critical failure modes present in system responsible for plenty of the low production efficiency and by reliability studies using RCM methodology (Reability Centered Maintenance), whose objective is increased reliability of the turbines constituent systems of the wind farm. Through the use of these methodologies it was possible to define a master plan for maintenance which is able to increase the operational efficiency of the wind farm.

This dissertation Consist in set up the parameters of heat transfer and pressure drop to compact heat exchangers of the coil type for thermo systems. With the purpose of optimize designs, for a reduction of energy wear. For this, Will be bulding a experimental apparatus with focus of produce experimental dates. This experimental apparatus is based in the Ashare 33 norm. The Calibration analysis will purpose, such as the error analysis. The gives will compared with the literature, to validate the test.

This work consists on the determination of the constant of time and thermal efficiency of the concentrating collectors of the solar thermal installation located at CEFET-MG, Campus II. The first phase of the work consisted of a deep bibliographic review to raise international standards, technical reports divulgated by international laboratories, technical articles, master and doctoral dissertations thesis covering topics referent to the tests of concentrating collectors of the type cylinder parabolic, also named through concentrating collectors. The second phase consisted of the adaptation of the existing solar installation with the insertion of new equipment and instruments in order to be possible to perform the tests over controlled conditions. The third phase consisted of the elaboration of the methods and procedures necessaries to conduct the tests of constant of time and thermal efficiency of the collector considering different temperatures of the working fluid at the inlet of the collector. A platform was constructed at the highest point of the testing area where it was installed a tracking system compound by three radiometers used by instantaneous measurements of the global in the horizontal plane, direct normal and diffuse in the horizontal plane radiations. Another small platform was set at the structure of the collectors allowing the measurement of solar radiation in the aperture plane of the collectors. Instruments for measuring of the volume flow rate and temperatures of the working fluid at inlet though the collector were utilized to determination of the useful energy. All the measurements were performed instantaneously in periods of time close to the solar noon in order to obtain solar radiation levels inside the limits established by the standards. The tests of constant of time revealed values lower than one minute, which shows this type of collector respond promptly to changes of the solar radiation. The tests of thermal efficiency revealed values lower than those obtained by commercial solar plants, being that the main cause can be attributed to the degradation of the material of the reflector superficies of the collectors due to the long time of the installation.

The development of the health sector in Brazil is directly link to the problem of waste management from the health facilities. Despite of the controversies over the real danger of these waste and their impacts on the environmental and human health, most scientists suggest the necessary management of hospital wastes (HW). Segregation of such waste should take place at the point of production and it can generate substantial savings. The context of this paper proposes the technique of incineration inventory of hospital waste and considers this technology that best meets the assumptions of reducing the environmental liabilities of the hospital waste with the opportunity to use energy. For the preparation of the inventory, data were collected from Company A located in the metropolitan region of Belo Horizonte, identifying thus the energy potential of waste through the methodology of Life Cycle Assessment, established in the Brazilian Standard ISO 14040. The electricity provided by the system after the burning of waste for thermal recovery was estimated considering the First Law of Thermodynamics, that the results show an estimated heat of reaction of 8.71 MWh/t of incinerated HW. Whereas about 17% of the thermal energy available is converted into electrical energy potential and, in general, the HW process incinerators small loads compared to municipal solid waste incinerators, the generation of electric power is presented as a procedure with low viability economy. Therefore, other alternatives of energy use should be considered for the Company, as well as for small incinerators HW, such as steam generation and preheating of the waste, which require lower costs and ensure better use of available heat during the process.

Strategies for energy efficiency in industrial applications involve interfaces for maintainability, energy economy and environmental sustainability. Traditionally, thermal insulation is the most practical mechanism for steam pipe’s energy efficiency. However, life cycle analysis presented thermal insulation residues as a still unsolved problem. So, many vegetal fibers as thermal insulation are proposal, while reflexive insulation researches are underdeveloped, especially for industrial applications. On the other hand, thermal coatings nanotechnology has been successfully developed as an alternative for conventional insulation. Before this context, energy efficiency of reflexive systems with thermal coatings as steam pipe’s thermal insulation is investigated. Reflexive insulation provides thermal radiation heat transfer reduction through low emissivity and high reflectivity materials associates with air cavities. Factorial design methods are used for investigated factors principal effects and its interactions within heat transfer process in reflexive systems associate with thin films with ceramic micro-spheres or hollow glass particles. The results suggest reflexive insulation as a promising alternative technology, with considerable application particularities for each nanotechnology coatings.

The solid waste from the waste water treatment plant of a steel wire pickling process, after dewatering in a filter press, remains with 70% of moisture content. To avoid soil and groundwater contamination by its polluting capacity, the solid must be handled, stored and disposed, avoiding anyway the contact with the soil. The environmental correct dispositions practiced for this kind of waste are controled landfill or the cement furnace coprocessment. The costs for these dispositions are significantly high, and can be decreased by thermal drying, decreasig its weigh and volume. Preliminary studies have demonstrated that using artificial dryers (that use electric energy or fossil fuel to heat the air) is economicaly unfeasible for this aplication. This study made analysis of this solid waste drying, varying the drying temperature, the weigh, surface area and geometry of samples. It suplies important information for the search of a technical and economical feasable alternative to the drying operation of the solid waste and presents an amount of basic conditions to be used in solid waste drying projects. The solar energy use offers low operational costs and environment advantages, even though by the renewable aspect of this kind of energy, as by no stuff gas emission.

A solar installation named “CEFET-MG Solar Plant” is installed inside the CEFET-MG campus, being currently the unique installation of this type in the country. This installation is constituent by concentrated collectors of the type parabolic cylinder with linear focus. This work has as principal objective, through experimental tests in laboratory, define the thermal loss of the heat element used in the solar field collectors through the study of the absorbent surface temperature influence, the speed of the wind and the environment air temperature on the global coefficient of absorbent heat transference. This work allows finding opportunities for the advance of existing solar installation, beyond helping to improve news installations in this type of systems.