Construção e análise de desempenho de um fogão solar à concentração utilizando dois focos para cozimento direto

A model of a solar oven with a reflective surface composed of two mirror segments is presented, constituting a two semi-parabolic surfaces made of fiberglass, applied on a ceramic mold, intended to be used in residential and commercial cooking. The reflective surface of the semi-parable is obtained with the use of multiple plain segments of 2 mm wide mirrors. The semi-parabolic structure has visible movements that are comparable to that of the sun. The technical details of the manufacturing and assembling processes will be presented with an analysis of the viability of thermal, economic, and materials of such prototype. This prototype has important social implications and primordial aspects, which combats the ecological damages caused by the wide-scale use of firewood during cooking. It has been demonstrated that the solar oven has the capacity to cook simultaneous two meals distinct for a family of four

Construção e análise de desempenho de um forno/fogão solar tipo caixa construído a partir de uma sucata de pneu

An alternative box-type solar cooker built starting from the scrap of a tire and a scrap of old office chair is presented, which principles functions are the effect greenhouse and the concentration. The tire served as structure for making of is the baking enclosure where the absorber (roasting pan 20x30cm) of the solar is located, being re-covered for a glass blade for the generation of the greenhouse effect isolated lateral and having deep its and for a composite the plaster base and EPS. Segments of plain mirrors had been placed in the laterals of the oven/cook for the concentration of the radiation and a reflecting parable was introduced in the baking enclosure for the exploitation of the incident reflected radiation inside of the oven/cook. The oven/cook is mobile to allow one better aiming of exactly in relation to the apparent movement of the sun. The thermal economic and of materials viabilities of the stove/cook in study will be demonstrate. The average internal temperature of the absorber was around 152,3°C and the internal temperature around 110°C. Will demonstrate that toits low cost and good thermal performance, represents basic characteristics for the viability of large use of such archetype, mainly for cooking the decreases and averages temperatures. One will reveal that the archetype in study is competitive with the box-type solar cooker conceived in the whole world

Análise de desempenho de um fogão solar construído a partir de sucatas de antena de tv

Given the growing environmental crisis caused by degradation, mainly due to the use of polluting energy sources, increasing the growing use of renewable energies worldwide, with emphasis on solar energy, an abundant supply and available to everyone, which can be harnessed in several ways: electricity generation; dehydration of food; heating, disinfection and distillation and cooking. The latter has as its primary feature the viability of clean, renewable energy for society, combating ecological damage caused by large-scale use of firewood for cooking foods, use in tropical countries with high solar radiation, and has funding NGOs throughout the world with the goal of achieving low-income population. The proposed project consists of a solar cooker for concentration, working from the reflection of sunlight by a hub that they converge to a focal point at the bottom of the pot, getting lots of heat. The solar cooker under study consists of two elliptical reflecting parabolas made from the recycling of scrap TV antenna, having 0.29 m² of surface area for each antenna, which were covered by multiple mirrors of 2 mm thick and mounted on a metal structure, with correction for the mobility of the apparent movement of the sun. This structure was built with the recycling of scrap metal, possessing a relatively low cost compared with other solar cookers, around US$ 50.00. This cost becomes negligible, since that will involve a great benefit to not have fuel costs for each meal, unlike the use of gas or firewood for cooking food. The tests show that the cooker has reached the maximum temperature of 740 ° C, for boiling water in an average time of 28 minutes, cooking various types of foods such as potatoes, rice and pasta in an average time of 45 minutes and still going as a solar oven, making pizza baking and meat. These cooking times do not differ much from the cooking times on a gas stove, it becomes the solar cooker as a good consumer acceptance, and furthermore not to deliver the same gases that can poison the food as with the wood stove. Proves the viability of using the stove to cook or bake in two daily meals for a family, still presenting a position to improve his performance with the addition of new materials, equipment and techniques

Obras complementares: um elo entre a leitura e os conteúdos matemáticos

The Federal Government through its Plans and Programs invests in various policies intended to achieve the main goal of the millennium, provide basic education for all. Among them, we highlight in this paper The National Textbook Program, with emphasis on Complementary Works. These works are presented through different genres, such as poems, poetry, short stories, parables, novels, literature, educational materials etc.. providing a range of possible teaching work. However, little is known about the levels of education of teachers as intended. Based on the discussions and studies in this direction, sparked concerns us in the process of teaching and learning in math classes. This made us pay attention to a possibility of study where reading could be included in this process. In this sense, the present study aims at investigating the potential of conceptual and didactic use of Complementary Works on developing the skills of reading and writing mathematics of the first three years of elementary school, and from there, propose a courseware with guidelines for use of these works by teachers of 1st to 3rd year of elementary school. For this, we outline the issues of reading and understanding of mathematical interests as those of our study. In this sense, the proposal was built from the bibliographic works that address the contributions of reading for learning mathematical content, like Machado (2001), Nacarato (2009); Dantas (2011), Smole and Diniz ( 2001). As a result, we created the Guidance for the use of Complementary Works for Teachers to Teach Mathematics with a view to support the practice of teachers and future teachers who teach mathematics. Supported the use of Complementary Works, especially those distributed in public schools by the National Textbook - PNLD and have mathematical content, this guide is intended to present some of the possible use of this feature in math classes. (Education Observatory - Capes / INEP. Ed. 038-2010. TELL Research Group - UFRN - PPGED / PPGEL / PPGECNM - PROPESQ)