Sensoriamento óptico quase-distribuído aplicado ao monitoramento de trocadores de calor de usinas hidrelétricas

This work aims to develop optical sensors for temperature monitoring in hydroelectric power plant heat exchangers. The proposed sensors are based on the Fiber Bragg Gratings technology. First of all, a prototype with three sensors inscribed in a same fiber was developed. This fiber was then fixed to a conventional Pt100 sensor rod and inserted in a thermowell. The ensemble was then calibrated in a workbench, presenting a maximum combined uncertainty of 2,06 °C. The sensor was installed in one of the heat exchangers of the Salto Osório’s hydroelectric power plant. This power plant is situated in the Iguaçu river, at the Paraná state. Despite the satisfactory results, the sensor was improved to a second version. In this, fifteen optical Bragg sensors were inscribed in a same fiber. The fixation with a conventional sensor was no longer necessary, because the first version results comproved the efficiency and response time in comparison to a conventional sensor. For this reason, it was decided to position the fiber inside a stainless steel rod, due to his low thermal expansion coefficient and high corrosion immunity. The utilization of fifteen fiber Bragg gratings aims to improve the sensor spatial resolution. Therefore, measurements every ten centimeters with respect to the heat exchanger’s height are possible. This provides the generation of a thermal map of the heat exchanger’s surface, which can be used for determination of possible points of obstruction in the hydraulic circuit of the heat exchanger. The heat exchanger’s obstruction in hydroelectric power plants usually occur by bio-fouling, and has direct influence in the generator’s cooling system efficiency. The obtained results have demonstrated the feasibility in application of the optical sensors technology in hydroelectric power plants.

Proposta de uma matriz de decisão em energia hidrelétrica com o uso do método multicritério, para formulação de políticas públicas no estado do Paraná

Brazil is internationally acknowledged for its renewable sources, most notably, hydroelectric power plant projects which correspond to 65% of electricity production supply to the National Interconnected System. The main question behind this research is: what are the weights and the relative importance of the variables which have influence on the decision making process for the expansion of hydroelectric generation projects in Parana? The main objective is to propose a multi-criteria decision procedure, in association with water sources options that take into consideration the weight and relative importance of the alternatives having influence on the decision by enterprises in the generation of electricity in the state of Paraná. As far as the approach to the problem is concerned, this research can be classified as having mixed methodologies, applying Content Analysis, Delphi technique and the Analytic Hierarchy Process. Following Delphi methodology, a group of 21 was selected for data collection, all of those linked to Paranaense hydroelectricity market. And the main result was the construction of a decision tree in which it was possible to identify the importance and relative weight of the elements associated with the four dimensions of energy. In environmental dimension, the highest relative weight was placed on the loading capacity of Parana system; the economic dimension, the amortization of investment; in social dimension, the generation of direct work places and in institutional dimension, the availability of suitable sources of financing. Policy makers and business managers make their decisions based on specific criteria related to the organization segment, market information, economic and political behavior among other indicators that guide them in dealing with the typical tradeoffs of projects in hydropower area. The results obtained in the decision tree show that the economic bias is still the main factor in making investment decisions. However, environmental impacts on the State loading capacity, income generation, providing opportunities for direct as well as indirect jobs. And at an institutional level, the absence of funding sources show that the perception of experts is focused on other issues beyond the logic behind development per se. The order of priority of variables in this study indicates that in the current environment of uncertainty in the Brazilian economy as many variables must be analyzed and compared in order to optimize the scarce resources available to expand local development in relation to Paranaense water matrix.

Estudo numérico do impacto das emissões veiculares e fixas da cidade de Manaus nas concentrações de poluentes atmosféricos da região amazônica

The main aim of this study was to evaluate the impact of the urban pollution plume from the city of Manaus by emissions from mobile and stationary sources in the atmospheric pollutants concentrations of the Amazon region, by using The Weather Research and Forecasting with Chemistry (WRF-Chem) model. The air pollutants analyzed were CO, NOx, SO2, O3, PM2.5, PM10 and VOCs. The model simulations have been configured with a grid spacing of 3 km, with 190 x and 136 y grid points in horizontal spacing, centered in the city of Manaus during the period of 17 and 18 of March 2014. The anthropogenic emissions inventories have gathered from mobile sources that were estimated the emissions of light and heavy-duty vehicles classes. In addition, the stationary sources have considered the thermal power plants by the type of energy sources used in the region as well as the emissions from the refinery located in Manaus. Various scenarios have been defined with numerical experiments that considered only emissions by biogenic, mobile and stationary sources, and replacement fuel from thermal power plant, along with a future scenario consisting with twice as much anthropogenic emissions. A qualitative assessment of simulation with base scenario has also been carried out, which represents the conditions of the region in its current state, where several statistical methods were used in order to compare the results of air pollutants and meteorological fields with observed ground-based data located in various points in the study grid. The qualitative analysis showed that the model represents satisfactorily the variables analyzed from the point of view of the adopted parameters. Regarding the simulations, defined from the base scenarios, the numerical experiments indicate relevant results such as: it was found that the stationary sources scenario, where the thermal power plants are predominant, resulted in the highest concentrations, for all air pollutants evaluated, except for carbon monoxide when compared to the vehicle emissions scenario; The replacement of the energy matrix of current thermal power plants for natural gas have showed significant reductions in pollutants analyzed, for instance, 63% reductions of NOx in the contribution of average concentration in the study grid; A significant increase in the concentrations of chemical species was observed in a futuristic scenario, reaching up to a 81% increase in peak concentrations of SO2 in the study area. The spatial distributions of the scenarios have showed that the air pollution plume from Manaus is predominantly west and southwest, where it can reach hundreds of kilometers to areas dominated by original soil covering.