Non-equilibrium thermodynamic analysis of double diffusive, nanofluid forced convection in microreactors with radiation effects

This paper presents a theoretical investigation of the second law performance of double diffusive forced convection in microreactors with the inclusion of nanofluid and radiation effects. The investigated microreactors consist of a single microchannel, fully filled by a porous medium. The transport of heat and mass are analysed by including the thick walls and a first order, catalytic chemical reaction on the internal surfaces of the microchannel. Two sets of thermal boundary conditions are considered on the external surfaces of the microchannel; (1) constant temperature and (2) constant heat flux boundary condition on the lower wall and convective boundary condition on the upper wall. The local thermal non-equilibrium approach is taken to thermally analyse the porous section of the system. The mass dispersion equation is coupled with the transport of heat in the nanofluid flow through consideration of Soret effect. The problem is analytically solved and illustrations of the temperature fields, Nusselt number, total entropy generation rate and performance evaluation criterion (PEC) are provided. It is shown that the radiation effect tends to modify the thermal behaviour within the porous section of the system. The radiation parameter also reduces the overall temperature of the system. It is further demonstrated that, expectedly, the nanoparticles reduce the temperature of the system and increase the Nusselt number. The total entropy generation rate and consequently PEC shows a strong relation with radiation parameter and volumetric concentration of nanoparticles

Effects of nanofluid and radiative heat transfer on the double-diffusive forced convection in microreactors

Understanding transport phenomena in microreactors remains challenging owing to the peculiar transfer features of microstructure devices and their interactions with chemistry. This paper, therefore, theoretically investigates heat and mass transfer in microreactors consisting of porous microchannels with thick walls, typical of real microreactors. To analyse the porous section of the microchannel, the local thermal non-equilibrium model of thermal transport in porous media is employed. A first-order, catalytic chemical reaction is implemented on the internal walls of the microchannel to establish the mass transfer boundary conditions. The effects of thermal radiation and nanofluid flow within the microreactor are then included within the governing equations. Further, the species concentration fields are coupled with that of the nanofluid temperature through considering the Soret effect. A semi-analytical methodology is used to tackle the resultant mathematical model with two different thermal boundary conditions. Temperature and species concentration fields as well as Nusselt number for the hot wall are reported versus various parameters such as porosity, radiation parameter and volumetric concentration of nanoparticles. The results show that radiative heat transfer imparts noticeable effects upon the temperature fields and consequently Nusselt number of the system. Importantly, it is observed that the radiation effects can lead to the development of a bifurcation in the nanofluid and porous solid phases and significantly influence the concentration field. This highlights the importance of including thermal radiation in thermochemical simulations of microreactors

Two-dimensional heat and mass transfer and thermodynamic analyses of porous microreactors with Soret and thermal radiation effects: An analytical approach

Transport of heat and mass and the thermodynamics of porous microreactors with thermal diffusion and radiation effects are investigated analytically. The examined configuration includes an axisymmetric, thick-wall microchannel with an iso-flux thermal boundary condition imposed on the external surfaces. The microchannel is filled with porous materials and accommodates a zeroth order homogenous chemical reaction. Internal radiative heat transfer is modelled in addition to heat convection and conduction, while the local thermal non-equilibrium approach is taken within the porous section of the system. The transport of species is coupled with that of heat via the inclusion of thermodiffusion or Soret effect. Two-dimensional heat and mass transfer differential equations are solved analytically. The results are subsequently used to predict the thermodynamic irreversibilities inside the reactor and a thorough analysis of local and total entropy generation rates is performed. Also, the changes in Nusselt number, calculated on the internal walls of the microreactor, versus various parameters are reported. It is shown that the radiation effects can impact the temperature of the solid phase of the porous medium and lead to alteration of Nusselt number. It is further observed that the transfer of mass is the main source of irreversibility in the system. The findings are of particular use for the design and analysis of the microreactors with homogenous chemical reactions and can be also used for the validation of computational models

Fatty acid production by four strains of Mucor hiemalis grown in plant oil and soluble carbohydrates

Four Mucor hiemalis strains (M1, M2, M3 and M4), isolated from soil at a depth of 0 - 15 cm in the Juréia- Itatins Ecology Station (JIES), in the state of São Paulo, Brazil and were evaluated for the production of-linolenic (GLA) and other unsaturated fatty acids. Five growth variables (temperature, pH, carbon source, nitrogen source, and vegetable oils) were studied. Liquid media containing 2% vegetable oil (palm oil, canola oil, soybean oil, sesame oil, or sunflower oil) or 2% carbohydrate (fructose, galactose, glycerol, glucose, lactose, maltose, sucrose, sorbitol or xylose) and 1% yeast extract as a nitrogen source were used. The greatest biomass production was observed with M3 and M4 strains in palm oil (91.5 g l-1) and sunflower oil (68.3 g l-1) media, respectively. Strain M4 produced greater quantities of polyunsaturated acids in medium containing glucose. The GLA production in the M4 biomass was 1,132.2 mg l-1 in glucose medium. Plant oils were inhibitors of fatty acid production by these strains

VITIMIZAÇÃO DE ESTUDANTES UNIVERSITÁRIOS EM SUA MOBILIDADE URBANA EM RIO CLARO, SÃO PAULO

Este artigo apresenta alguns resultados de uma pesquisa realizada com estudantes da UNESP, Campus de Rio Claro, para avaliar alguns fatores relacionados à sua vitimização na mobilidade urbana, com foco na vitimização sexual das mulheres em meios de transporte público. Neste estudo foram analisadas as inter-relações entre características pessoais, influências socioculturais e condições de infraestrutura de ambientes relacionados a transporte urbano. A pesquisa foi realizada no primeiro semestre de 2018, quando foram coletados 462 questionários com respostas válidas. O perfil dos participantes se constituiu de 46,6% do sexo feminino e 42,6% do sexo masculino, sendo 69,7% de brancos e 19,5% de não-brancos (por auto declaração). Estudantes que declararam pertencer ao grupo LGBT+ representam 19,8% do total de respondentes. Os estudantes da UNESP usam 6 diferentes modais de transporte: bicicleta, carro, motocicleta, táxi, transporte por aplicativo e ônibus. Os grupos de estudantes mais vulneráveis foram identificados como LGBT+ com 31,7% de vítimas, mulheres com 26,5% de vítimas e não-brancos com 21,4% de vítimas

Alterações do estado mental e da psicomotricidade em usuários

The use of drugs has been related to serious psychopathological disorders. The aim of this study consisted of evaluating mental and psychomotor disturbances in chronic cocaine addicts. Subjects were chemical dependent, male and female, from 13 to 49 years old (average 26.6 years), attending on psychiatry service. The methods consisted of detailed clinical history, Brief Psychiatric Rating Scale, Hamilton Rating Scale for Depression, and Hospital Anxiety and Depression Scale. There was significant correlation (pO uso crônico de drogas tem sido associado a distúrbios psicopatológicos graves. O objetivo deste estudo consistiu em avaliar alterações mentais e da psicomotricidade em usuários crônicos de cocaína. Foram estudados 50 sujeitos dependentes químicos, de ambos os sexos, com idade entre 13 e 49 anos (média: 26,6 anos), encaminhados para atendimento psiquiátrico. Os métodos utilizados consistiram em anamnese detalhada, Escala Psiquiátrica Breve, Escala de Depressão de Hamilton e Escala Hospitalar de Ansiedade e Depressão. Houve correlação significativa (

Biodegradation and toxicity of waste from anaerobic fermentation of stillage

Several studies have been carried out to produce biofuels by anaerobic digestion of stillage from ethanol fermentation. This type of process, known as ABE Fermentation, generates by-products such as acetone, butanol and ethanol. This fermentation can use pure or mixed cultures of anaerobic bacteria, mainly of the genus Clostridium. In this context, there is the need for deeper studies for proper disposal of the residue resulting from Anaerobic Fermentation of ethanolic stillage, hereinafter referred to as AF stillage (stillage from Anaerobic Fermentation), obtained after this fermentation. Thus, the aim of this study was to evaluate the biodegradation and toxicity of stillage from Anaerobic Fermentation. The biodegradation of AF stillage in soil samples in the presence and absence of commercial inoculum was evaluated using a respirometric method described by Bartha & Pramer, according to the standard NBR 14283 (ABNT, 1999). The production of CO2 was evaluated for 57 days. Additionally, quantification of microorganisms was carried out at the beginning and end of the experiment. Toxicity tests were performed with the microcrustacean Daphnia similis using raw AF stillage and leachate from the respirometry test, according to the standard NBR 12713 (ABNT, 2009). The results of the respirometry test showed that, after 13 days of incubation, the biodegradation efficiency of all samples was above 30%. Using the Friedman statistical test, results showed that adding the inoculum caused no statistically significant difference in the biodegradation of AF stillage. The acute toxicity tests were performed on raw AF stillage and on the leachates showed that toxicity was removed after biodegradation in soil at all concentrations used. Thus, discharge of AF stillage into soil is an alternative viable disposal.16371863187