Microreactors for biodiesel synthesis: design, fabrication, and characterization

The present work describes microreactors for biodiesel continuous synthesis that have been designed, fabricated, characterized, and aimed at achieving a reproducible microfluidic device to compose a modular portable biodiesel production demonstration unit. A straightforward method is presented for the microfabrication and sealing of the microfluidic device that performs the role of a microreactor for biodiesel synthesis, built on a brass metal base and sealed with either a metal cover or a glass cover for easy microscopic observation of two-phase flow patterns. The microfluidic device contains a Υ-junction squared microchannel architecture with width and depth of 400 µm. Microchannels were engraved using a micromilling technique and sealed either by welding, with tin as an additional material, in the case of the all metal device, or by using an epoxy glue, which served as an adhesive to seal a metal−glass device. The quality of the metal-on-metal seal was examined using microscopic analysis of multiple cross sections of the device, whereas the quality of the metal-on-glass seal was analyzed via direct visual inspection of flows within the device using an optical microscope to verify the existence or absence of leaks. An experimental setup was then built to carry out biodiesel synthesis in the metal−metal microreactor, using soybean oil of food grade, absolute ethanol, and sodium hydroxide, NaOH, as a catalyst for the reaction. For a molar ratio ethanol/oil 20:1, a quantity of NaOH catalyst of 1.0 wt.% at a controlled temperature of 47.5°C, it was possible to achieve a yield of fatty acids ethyl esters of 87.2% with 98% of triglyceride converted, for a residence time of 10 min. The experimental analysis confirms the applicability potential of the designed microreactor in the synthesis proposed.Indisponível

Experiments and Simulations of Laminar Forced Convection With Water–Alumina Nanofluids in Circular Tubes

This work reports fundamental experimental-theoretical research related to heat transfer enhancement in laminar channel flow with nanofluids, which are essentially modifications of the base fluid with the dispersion of metal oxide nanoparticles. The nanofluids were synthesized by a two-step approach, using a dispersant and an ultrasound probe or a ball mill for alumina nanoparticles dispersion within the aqueous media. The theoretical work involves the proposition of an extension of the thermally developing flow model that accounts for the temperature variation of all the thermophysical properties, including viscosity and the consequent variation of the velocity profiles along the thermal entry region. The simulation was performed by making use of mixed symbolic-numerical computation on the Mathematica 7.0 platform and a hybrid numerical-analytical methodology (generalized integral transform technique, GITT) in accurately handling the governing partial differential equations for the heat and fluid flow problem formulation with temperature dependency in the thermophysical properties. Experimental work was also undertaken based on a thermohydraulic circuit built for this purpose, and sample results are presented to verify the proposed model. The aim is to confirm that both the constant properties and temperature-dependent properties models, besides available correlations previously established for ordinary fluids, provide adequate prediction of the heat transfer enhancement observed in laminar forced convection with such nanofluids and within the experimented Reynolds number range.Indisponível

Trends in Nanotechnology Patents Applied to the Health Sector

Authors thank to CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) for access to the Derwent database, available at the CAPES Journal Portal (http://www.periodicos.capes.gov.br/).Submitted by Anderson Silva ([email protected]) on 2013-04-12T17:59:53Z No. of bitstreams: 1 Trends in Nanotechnology Patents Applied to the Health Sector.pdf: 270085 bytes, checksum: 23e22426f946fac982649c5fe06832e1 (MD5)Approved for entry into archive by Gentil Jeorgina([email protected]) on 2013-04-15T12:28:09Z (GMT) No. of bitstreams: 1 Trends in Nanotechnology Patents Applied to the Health Sector.pdf: 270085 bytes, checksum: 23e22426f946fac982649c5fe06832e1 (MD5)Made available in DSpace on 2013-04-15T18:07:37Z (GMT). No. of bitstreams: 1 Trends in Nanotechnology Patents Applied to the Health Sector.pdf: 270085 bytes, checksum: 23e22426f946fac982649c5fe06832e1 (MD5) Previous issue date: 2012Instituto Nacional de Propriedade Industrial. Rio de Janeiro, RJ, Brasil; Universidade Federal do Rio de Janeiro. Escola de Química. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto de Comunicação e Informação Científica e Tecnológica em Saúde. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto de Comunicação e Informação Científica e Tecnológica em Saúde. Rio de Janeiro, RJ, Brasil.Instituto Nacional de Propriedade Industrial. Rio de Janeiro, RJ, Brasil; Universidade Federal do Rio de Janeiro. Escola de Química. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio de Janeiro. Escola de Química. Rio de Janeiro, RJ, Brasil.he aim of the article is to present a method for identifying trends in patent applications for nanotechnology applied to the health sector around the world, based on the International Patent Classification. This classification divides the sector into: dental care, drugs, diagnostic kits, and medical apparatus & medical care. The Derwent database was mined for patent documents using nanotechnology terms associated with the IPC subclasses from the health subsectors. The number of patents was found to be rising, led by the United States, particularly universities and R centers. In the dental care subsector, nanotechnology was found to be used in composite material for manufacturing dental appliances. In drugs, the focus is on the use of nanoparticulate compositions comprising agents that are useful for a variety of diseases. In diagnostic kits, nanostructures have been patented that are capable of detecting target analytes. Meanwhile, in medical apparatus & medical care, patent applications have been made for nanocapsules and/or nanocomposite materials inserted in devices and guide catheters. A study was also made of patents in Brazil, where the same assignees and the same country (United States) as in the survey of global patents were found to be the leading patent applicants / holder