Suchergebnisse

A primeira década do terceiro milênio trouxe mudanças inimagináveis para a sociedade humana, principalmente como conseqüência do impressionante crescimento da velocidade e qualidade da comunicação em todas as áreas. Os avanços científicos que resultaram da interação mais efetiva entre grupos de pesquisadores em localidades distantes do globo são cada vez mais evidentes. No entanto, a mesma taxa de progresso não tem sido observada em outros desafios científicos importantes, tais como a interdisciplinaridade na pesquisa. Ainda é difícil para os cientistas em áreas diferentes interagir e trocar informação na busca de novas descobertas e soluções para problemas existentes por longa data que envolvem várias disciplinas. Exceções são centros científicos que são criados por iniciativa privada ou governamental com objetivos bem especificados, mas a humanidade tem o potencial de realizar muito mais do que isso. Uma maneira possível de lidar com e mudar essa realidade seria um esforço dos autores de cada área de produzirem artigos sobre problemas abertos atuais em seus respectivos campos que necessitem de conhecimento de outras áreas para serem resolvidos. Nesse sentido, a engenharia térmica poderia tomar a iniciativa nessa direção, uma vez que está presente em praticamente todos os sistemas físicos, a começar pelo conceito e uso da energia. Conseqüentemente, Engenharia Térmica sugere aos autores a produção de artigos que formulem problemas de natureza altamente interdisciplinar que apresentem resultados até mesmo preliminares e estabeleçam desafios ainda a serem vencidos através do trabalho conjunto de cientistas de áreas diferentes. The first decade of the third millennium has brought unimaginable changes to the human society, mainly as a result of the astonishing increase of communication speed and quality in all areas. The scientific advances that resulted from the more effective interaction among groups of researchers in distant locations of the globe are increasingly more evident. However, the same progress rate has not been observed in other important scientific challenges, such as research interdisciplinarity. It is still difficult for scientists in different areas to interact and exchange information in the search of new discoveries and solutions to long existing problems that involve several disciplines. Exceptions are scientific centers that are created by governmental or private initiative with well specified goals, but mankind has the potential to accomplish much more than that. One possible way to cope with and change that reality would be an effort by authors of each area to produce articles on current open problems in their respective fields that need knowledge from other areas to be solved. In that sense, thermal engineering could take the lead in that direction, since it is present in practically all physical systems, starting from the concept and use of energy. Therefore, Engenharia Termica suggests to authors the production of articles that formulate problems of highly interdisciplinary nature that present even preliminary results and state the challenges still to be overcome through the joint work of scientists from different areas.

Fossil fuels are currently recognized as unsustainable because of depleting supplies and the contribution of these fuels to the accumulation of carbon dioxide in the environment. Therefore, renewable, carbon neutral, alternative fuels are necessary for environmental and economic sustainability. Several countries have been considering the use of alternative fuels derived from agriculture. In that context, ethanol derived from sugar-cane and/or corn crops, and biodiesel derived from oil crops are potential renewable and carbon neutral alternatives to fossil fuels. Unfortunately, fuel from crops, waste and animal fat cannot realistically satisfy even a small fraction of the existing global demand for fuels. In Brazil, the government has been subsiding ethanol from sugar-cane crops for more than 30 years, and together with research investment on oil off-shore exploration, the initiative made possible for the country, at least for the moment, to become energy self sufficient, but due to oil supplies depletion, that scenery will change in the near future. Another limiting factor is cost. For example, the economic aspect of biodiesel production limits its development and large-scale use. Biodiesel usually costs almost twice the price per liter of conventional diesel fuel, currently in the US.Apart from economic aspects, it is clear that biofuel production technology needs to be improved to meet global fuel demand rate. One possible direction is the use of microalgae, that appear to be the only source of renewable biodiesel that is capable of meeting the diesel fuel global demand. Like plants, microalgae use sunlight to produce oils but they do so more efficiently than crop plants. Oil productivity of many microalgae greatly exceeds the oil productivity of the best producing oil crops.Approaches for making microalgal biodiesel economically competitive therefore need to be developed.The mission of Engenharia Térmica is to document the scientific progress in areas related to energy, particularly oil and renewables. We are confident we will continue to receive articles' submissions that help enable sustainable energy solutions in the near future.

The ever growing demand of energy generation and distribution has been one of the concerns of governments and the focus of research institutions. Likewise, how to supply the energy demands necessary for the development of nations having the lowest environmental impact possible has also been studied. Biofuels have been pointed out as an alternative for that energy challenge, since their use reduce the carbon footprint of industries and vehicles. Biofuels can be obtained from microalgae with the advantage of not competing for space with corn, sugar cane or other crops for food industry. Even though attractive, the biofuel production from microalgae presents some challenges, as for example the separation process required to obtain microalgae biomass. The culture is very diluted and the dewatering must be efficient, low cost and cause no damage to the cell. With the intent to address this issue, the herein paper presents a study of an alternative way to increase flocculation efficiency according to the temperature of the culture with the potential to improve the filtration efficiency in a continuous process. An increasing in the flocculation temperature from 20°C to 60°C increased the flocculation efficiency from 97.79% to 98.64%, using ferric chloride as a flocculant agent.