Projeto de trocador de calor para uma máquina de aquecimento de vidro para laminação

The object of this study is a glass heating machine for rolling process, designed in 2006 and which is manufactured regularly. By customer request it is intended to increase the production capacity of this machine. However, initial tests have shown that the existing heat exchanger cannot supply the necessary thermal energy demand. A study of the thermal characteristics of the equipment was performed in order to obtain the required information to study alternatives for expanding its capacity taking into account space limitations and the need to rationalize costs, avoiding unnecessary oversizing

Conforto térmico de edificações: análise crítica das tecnologias existentes

The rising in greenhouse gases emission as consequence of industrial expansion especially in developing countries is appointed as one of those reasons responsible for global warming. High-level temperatures are set as responsible for low productivity and high levels of discomfort. With the increase of worldwide energy demand, due to the population growth, this work aims to be an introductory text revising the current ventilation (mechanical and natural) and refrigeration technologies as well as low energy cooling techniques and architectural alternatives that seeks offering good ventilation and ideal buildings temperatures, making them sustainable. In addition, the text deals with the measurement instruments used to evaluate the parameters defined by international and national standards. At last, a case of study applies few concepts and technologies described in the text, introducing the results achieved, the limitations and suggestions to future works

Prediction equations to estimate the demand of energy and crude protein for maintenance, gain and egg production for laying Japanese quails

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The limits of human development and the use of energy and natural resources

The development of nations is an unquestionable requirement. A lot of challenges concerning health, education and economy are present. A discussion on these development models has occupied the minds of decision makers in recent years. When energy supply and demand is considered, the situation becomes critical and the crucial question is: how to improve the quality of life of developing countries based on available models of development that are related to the life style of developed countries, for which the necessary use and waste of energy are present? How much energy is essential to humanity for not so as to endangering the survival conditions of future generations? the human development index (HDI) establishes the relationship among energy use, economic growth and social growth. Here it can be seen that 75% of the world population has a significant energy consumption potential. This is a strong reason to consider that the sustainable development concepts on energy policies are strategic to the future of the planet. This paper deals with the importance of seeking alternative development models for human development balance, natural resources conservation and environment through rational energy use concepts. (c) 2004 Elsevier Ltd. All rights reserved.

Power flow for primary distribution networks considering uncertainty in demand and user connection

This paper presents a method for calculating the power flow in distribution networks considering uncertainties in the distribution system. Active and reactive power are used as uncertain variables and probabilistically modeled through probability distribution functions. Uncertainty about the connection of the users with the different feeders is also considered. A Monte Carlo simulation is used to generate the possible load scenarios of the users. The results of the power flow considering uncertainty are the mean values and standard deviations of the variables of interest (voltages in all nodes, active and reactive power flows, etc.), giving the user valuable information about how the network will behave under uncertainty rather than the traditional fixed values at one point in time. The method is tested using real data from a primary feeder system, and results are presented considering uncertainty in demand and also in the connection. To demonstrate the usefulness of the approach, the results are then used in a probabilistic risk analysis to identify potential problems of undervoltage in distribution systems. (C) 2012 Elsevier Ltd. All rights reserved.

Vibration energy harvesting using piezoelectric transducer and non-controlled rectifiers circuits

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Energy balance optimization of sugarcane crop residual biomass

This work presents a mathematical model for helping mills choose sugarcane varieties for planting. It maximizes crop residual biomass energy balance by considering the difference between generated and consumed energy in the process of transferring this biomass from the field to the processing center; it takes into account enterprise demand restrictions and cane planting area. For this full zero-one linear programming techniques were proposed. The model is viable for choosing sugarcane varieties that would benefit sugarcane production and industrial systems, by reducing crop residue and increasing final energy production. (c) 2006 Published by Elsevier Ltd.

Development and energy balance of sugarcane in the norte fluminense, Brazil

The growing concern for renewable and cleaner energy sources has increased the demand for biofuels, pointing out the ethanol from sugarcane. The aim of this study was quantify the partition of energy balance components and monitor the physiological development indexes of the sugarcane, relating them to water availability conditions of climate and soil in Campos dos Goytacazes, Norte Fluminense, Brazil. To this end, a micrometeorological station was settled in an area of 13 ha in commercial cultivation. The culture was regularly monitored at 85, 102, 128, 149, 174, 194, 215, 235, 255 and 280 days after cutting (DAC). The variations in water availability directly influenced the rates of crop growth and energy balance. Under the conditions studied most of the available energy (53%) was consumed by the latent heat flux.

Reliability assessment of energy limited systems using sequential montecarlo simulation

This paper explains why the reliability assessment of energy limited systems requires more detailed models for primary generating resources availability, internal and external generating dispatch and customer demand than the ones commonly used for large power systems and presents a methodology based on the full sequential Montecarlo simulation technique with AC power flow for their long term reliability assessment which can properly include these detailed models. By means of a real example, it is shown how the simplified modeling traditionally used for large power systems leads to pessimistic predictions if it is applied to an energy limited system and also that it cannot predict all the load point adequacy problems. © 2006 IEEE.

A statistical analysis of loss factor to determine the energy losses

Given that the total amount of losses in a distribution system is known, with a reliable methodology for the technical loss calculation, the non-technical losses can be obtained by subtraction. A usual method of calculation technical losses in the electric utilities uses two important factors: load factor and the loss factor. The load factor is usually obtained with energy and demand measurements, whereas, to compute the loss factor it is necessary the learning of demand and energy loss, which are not, in general, prone of direct measurements. In this work, a statistical analysis of this relationship using the curves of a sampling of consumers in a specific company is presented. These curves will be summarized in different bands of coefficient k. Then, it will be possible determine where each group of consumer has its major concentration of points. ©2008 IEEE.

The need of subsidy for the implementation of photovoltaic solar energy as supporting of decentralized electrical power generation in Brazil

The growing demand for electrical power and the limited capital invested to provide this power is forcing countries like Brazil to search for new alternatives for electrical power generation. The purpose of this paper is to present a technical and economic study on a 15 kW solar plant installed in an isolated community, highlighting the importance of the need for financial subsidy from the government. It evaluates the importance of parameters such as the annual interest rate, specific investment, the marginal cost of expanding the electrical power supply and the government subsidy on amortization time of capital invested. © 2012 Elsevier Ltd All rights reserved.

Analysis of hybrid waste-to-energy for medium-sized cities

Urban centers have a huge demand for electricity and the growing problem of the solid waste management generated by their population, a relevant social and administrative problem. The correct disposal of the municipal solid waste (MSW) generated in cities is one of the most complex engineering problems that involves logistics, safety, environmental and energetic aspects for its adequate management. Due to a national policy of solid wastes recently promulgated, Brazilian cities are evaluating the technical and economic feasibility of incinerating the non-recyclable waste. São José dos Campos, a São Paulo State industrialized city, is considering the composting of organic waste for biogas production and mass incineration of non-recyclable waste. This paper presents a waste-to-energy system based on the integration of gas turbines to a MSW incinerator for producing thermal and electric energy as an alternative solution for the solid waste disposal in São José dos Campos, SP. A technical and economic feasibility study for the hybrid combined cycle plant is presented and revealed to be attractive when carbon credit and waste tax are included in the project income. © 2013 Elsevier Ltd.

Modeling of hydraulic and energy efficiency indicators for water supply systems

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Energy recovery from agro-industrial wastewaters through biohydrogen production: kinetic evaluation and technological feasibility

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Volt-VAR multiobjective optimization to peak-load relief and energy efficiency in distribution networks

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)