Navegando por CNPq "CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA::TECNOLOGIA QUIMICA"

Agora exibindo 1 - 3 de 3

Acesso aberto (Open Access)
Análise da convecção natural no escoamento laminar em cavidades parcialmente preenchidas com meios porosos utilizando transformadas integrais
(Universidade Federal do Pará, 2016-04-15) QUARESMA, Sil Franciley dos Santos; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
A numerical study is performed to analyze the natural convection in a vertical rectangular enclosure that is partially filled with a porous medium, by the Generalized Integral Transform Technique (GITT). The first studies concerning flow transient in a channel partially filled with porous medium without the effect of natural convection in order to understand the technical solution or problems with interfaces. Two different formulations were studied: the two-domain approach and the single-domain approach. Subsequently a numerical study is performed to analyze the steady-state thermal natural convection fluid flow and heat transfer in a vertical rectangular enclosure that is partially filled with a porous medium. The flow is modeled using the Brinkman- Forchheimer extended Darcy and energy conservation equation was used to predict the heat transfer. The mathematical description of the problem is based on a one-domain formulation of the conservation equations. Finally it carried out the study of double diffusive natural convection, also nominated thermosolutal natural convection in partially porous enclosures. The validity of the so-called one-domain approach used in this case compared to existing results in the literature. A particular class of problems dealing with thermal and double diffusive natural convection mechanisms in partially porous enclosures is presented, and it is shown that this configuration exhibits specific features in terms of the heat and mass transfer characteristics.
Acesso aberto (Open Access)
Avaliação do teor de espilatol no ciclo de cultura de duas cultivares de Aemella oleracea (L.) R. K. Jansen em extratos obtidos por entração supercritica
(Universidade Federal do Pará, 2018-12-10) SILVA, Ana Paula de Souza e; FERREIRA, Gracialda Costa; http://lattes.cnpq.br/4250668524181387; CARVALHO JÚNIOR, Raul Nunes de; http://lattes.cnpq.br/5544305606838748; https://orcid.org/0000-0002-4433-6580
Acmella oleracea (L.) R. K. Jansen is a species native to South America, popularly known as jambu, and has been consumed for many years as an ornamental, medicinal, and food plant. To obtain espilantol, the main bioactive compound of this species, various extraction techniques have been used in order to obtain the isolated substance, since it is not commercially available. Among the techniques, supercritical carbon dioxide extraction stands out as it showed high selectivity for espilantol, with yields above 50%, resulting in a purity above 90% of the isolated compound. The objective of this work was to evaluate the influence of rainfall and harvest time on the yield of spilanthol with supercritical CO2 in two cultivars of Acmella oleracea (L.) R. K. Jansen flowers, as well as to evaluate their pharmacological effect. For this purpose, the following procedures were performed: raw material characterization; optimization of the process variables (flow and time); obtaining of extracts by supercritical extraction; determining of the process cost on an analytical scale; determination of the total phenolic compounds concentration in the extracts by Folin-Ciocalteu method; spilanthol content quantification in the extracts by gas chromatography coupled to mass spectrometry, and evaluation of its antinociceptive in vivo activity. The main results were: the mineral analysis indicated high levels of iron, calcium, zinc, and magnesium; the process optimization resulted in a CO2 use decrease from 955,8g to 477,9g, and reduced extraction costs from R$ 20.47 to R$ 11.45. The higher espilantol content was 29.22%, while the highest phenolic content was 43.04%. The flowers of both Acmella oleracea cultivars were considered good sources of iron, calcium, zinc, and magnesium. The highest values of extract yield, spilanthol content and total phenolic compounds were obtained in the rainy season and in the shortest harvest times. Between the two cultivars evaluated, no significant statistical differences were found.
Acesso aberto (Open Access)
Recobrimento de sementes de linhaça (Linum usitatissimum L.) com suspensão biopolimérica em leito de jorro
(Universidade Federal do Pará, 2016-12-14) SANTANA, Elza Brandão; FARIA, Lênio José Guerreiro de; http://lattes.cnpq.br/7428609361678173; COSTA, Cristiane Maria Leal; http://lattes.cnpq.br/0581730621014796
It was studied application of starch in natura come from manioc starch (Manihot esculenta Crantz) in obtaining a biopolymer suspension in the coating of linseed (Linum usitatissimum L.), using as coating equipment a conventional spouted bed. We analyzed the physical and chemical characteristics of cassava starch and seeds, as well as the physiological characteristics of the seeds in natura and covered. Tests were carried out to obtain the biopolymer suspension including preliminary immersion coating tests, to evaluate the acceptance of the seed structure by the polymer matrix, based on physical data (angle of repose). For the execution of the coating process, tests were performed to define the coating operation, which included adjustments in the operating system from the study of fluid dynamics to the pumping of the suspension to make it possible to define the conditions of operation of the spouted bed. Fluid dynamics curves were constructed with different charges and atomization pressures, obtaining the fluid dynamic parameters ΔPM, ΔPje, ΔPmj and Umj. From the fluid dynamics results, the operating conditions were determined for a load of 1000 g of seeds, spray pressure of 5 psi, distance of the spray nozzle of 14 cm above the fixed seed bed and air velocity in the range of 1,9 to 1,29Umj. To analyze the coating process used an experimental design type PCCR considering the input variables, air temperature (Tar) and flow rate of the suspension (Qs), and efficiency responses (η), growt of the particle (δ), loss grip (Pad), process evaporation rate (Ėp), germination (G) and germination speed index (GSI). To estimate an optimal point of this operation was applied to define desirability function, wherein the generated optimum for the overall desirability was 0.9630 with the seed bed operating at 51 °C and 12 mL/min, respectively. The obtained results show that the coating process was efficient in relation to the values obtained for the responses and also to maintain the physiological qualities of the seeds. In addition, to open precedents for application in foods since the seeds covered had water activity of 0,34, in front of an initial activity of 0,62 for the seeds in natura.