Modelo matemático para otimização dos custos de um sistema híbrido eólico-solar : aplicação no bombeamento de petróleo

This work purposes the application of a methodology to optimize the implantation cost of an wind-solar hybrid system for oil pumping. The developed model is estimated the implantation cost of system through Multiple Linear Regression technique, on the basis of the previous knowledge of variables: necessary capacity of storage, total daily energy demand, wind power, module power and module number. These variables are gotten by means of sizing. The considered model not only can be applied to the oil pumping, but also for any other purposes of electric energy generation for conversion of solar, wind or solar-wind energy, that demand short powers. Parametric statistical T-student tests had been used to detect the significant difference in the average of total cost to being considered the diameter of the wind, F by Snedecor in the variance analysis to test if the coefficients of the considered model are significantly different of zero and test not-parametric statistical by Friedman, toverify if there is difference in the system cost, by being considered the photovoltaic module powers. In decision of hypothesis tests was considered a 5%-significant level. The configurations module powers showed significant differences in total cost of investment by considering an electrical motor of 3 HP. The configurations module powers showed significant differences in total cost of investment by considering an electrical motor of 5 HP only to wind speed of 4m/s and 6 m/s in wind of 3 m, 4m and 5 m of diameter. There was not significant difference in costs to diameters of winds of 3 m and 4m. The mathematical model and the computational program may be used to others applications which require electrical between 2.250 W and 3.750 W. A computational program was developed to assist the study of several configurations that optimizes the implantation cost of an wind-solar system through considered mathematical model

Viabilidade do uso de secadores solar de convecção natural e forçada para a secagem do coco Licuri

Licuri is a palm tree from the semiarid regions of Bahia State, Brazil. It is an important source of food and feed in that region, since their nuts are commonly eaten by humans and used as maize substitute for poultry feeding. The aim of this dissertation is to study the feasibility for use of natural convection solar dryers and forced being compared with the traditional drying outdoors for drying coconut licuri Syagrus coronate. The study led to the construction of two prototype solar dryer for carrying out experiments proving: model Solar Drying System Direct Exposure to Natural Convection built with wood, has a drying chamber with direct cover transparent glass laminates 4 mm, using techniques for proper isolation of the drying chamber. The two prototypes were comparatively analyzed for performance and drying efficiency with traditional extractive use by the community. Were evaluated the variables: time and drying rates and quality of the final samples of coconut licuri. The fruits were harvested and brought the town of Ouricuri, in the city of Caldeirão Grande, BA for the experiments comparing the three methods of drying was used a standard load of 4.0 kg The quantitative analysis for the result of the drying rate was found in 74% yield and 44% for natural and forced convection respectively compared with the traditional drying. These drying rates represent variation 3-5 times lower. Drying using forced convection licuri showed better quality, was found in a reddish pulp, representing the quantities that were kept of the nutrient beta carotene, and not notice the flavor change from the previous system, the final cost of construction of this system were higher . The prototypes built competitive advantage and had testified fully to resolve the technical difficulties previously encountered in the production of products made of coconut licuri. Allowing add value and increase their potential use for the fruit extractive communities of semi-arid region of Bahia

Sistema de secagem solar para frutos tropicais e modelagem da secagem de banana em um secador de coluna estática

In this study were projected, built and tested an electric solar dryer consisting of a solar collector, a drying chamber, an exhaust fan and a fan to promote forced hot air convection. Banana drying experiments were also carried out in a static column dryer to model the drying and to obtain parameters that can be used as a first approximation in the modeling of an electric solar dryer, depending on the similarity of the experimental conditions between the two drying systems. From the banana drying experiments conducted in the static column dryer, we obtained food weight data as a function of aqueous concentration and temperature. Simplified mathematical models of the banana drying were made, based on Fick s and Fourier s second equations, which were tested with the experimental data. We determined and/or modeled parameters such as banana moisture content, density, thin layer drying curves, equilibrium moisture content, molecular diffusivity of the water in banana DAB, external mass transfer coefficient kM, specific heat Cp, thermal conductivity k, latent heat of water evaporation in the food Lfood, time to heat food, and minimum energy and power required to heat the food and evaporate the water. When we considered the shrinkage of radius R of a banana, the calculated values of DAB and kM generally better represent the phenomenon of water diffusion in a solid. The latent heat of water evaporation in the food Lfood calculated by modeling is higher than the latent heat of pure water evaporation Lwater. The values calculated for DAB and KM that best represent the drying were obtained with the analytical model of the present paper. These values had good agreement with those assessed with a numeric model described in the literature, in which convective boundary condition and food shrinkage are considered. Using parameters such as Cp, DAB, k, kM and Lfood, one can elaborate the preliminary dryer project and calculate the economy using only solar energy rather than using solar energy along with electrical energy