Valdiney Cambuy Siqueira

Modelagem matemática para a secagem de clones de café (Coffea canephora Pierre) em terreiro de concreto

The objective of this work was to obtain and evaluate the drying curves for the coffee berry species Coffea Canephora , and to fit different mathematical models into the experimental data of four clones. Coffee berries from the following clones were used: Cpafro 194, Cpafro 193, Cpafro 167 and Cpafro 180, harvested at moisture contents of 1.20; 1.32; 1.51 and 1.46 (decimal d.b.), respectively. The drying continued in a concrete yard until the moisture content of 0.10 (decimal d.b.) was achieved. Ten mathematical models cited in literature were fitted to the experimental data in order to represent the drying process. According to the results and based on the statistical parameters, it can be concluded that the Page model represents well the drying of four coffee berry clones; for the clone Cpafro180, the Verna and other models were also satisfactory in describing the phenomenon. The drying time in concrete yard for coffee berry clones Cpafro 194, Cpafro 193, Cpafro 167 and Cpafro 180, up to the moisture content of 0.10 (decimal d.b.) was 117.5 hours and the diffusion coefficient was 4.50 x 10 -11 ; 5.17 x 10 -11 ; 5.08 x 10 -11 and 5.50 x 10 -11 m 2 s -1 , for analyzed clones, respectively.

Drying kinetics of jatropha seeds

Given the necessity of developing jatropha cultivation equipment, this work adjusted different mathematical models to experimental data obtained from the drying of jatropha seeds submitted to different drying conditions and selected the best model to describe the drying process. The experiment was carried out at the Federal Institute of Goias - Rio Verde Campus. Seeds with initial moisture content of approximately 0.50 (kg water/kg dry matter) were dried in a forced air-ventilated oven, at temperatures of 45, 60, 75, 90 and 105°C to moisture content of 0.10 ± 0.005 (kg water/kg dry matter). The experimental data were adjusted to 11 mathematical models to represent the drying process of agricultural products. The models were compared using the coefficient of determination , chi-square test, relative mean error , estimated mean error and residual distribution. It was found that the increase in the air temperature caused a reduction in the drying time of seeds. The models Midilli and Two Terms were suitable to represent the drying process of Jatropha seeds and between them the use of the Midili model is recommended due to its greater simplicity .

MODELAGEM MATEMÁTICA E DIFUSIVIDADE EFETIVA DAS SEMENTES DE PINHÃO MANSO (Jatropha curcas L.) DURANTE A SECAGEM

The aim of this study was to adjust different mathematical models to experimental data for jatropha seed drying (Jatropha curcas L.) and determine the effective diffusion coefficient and obtain the activation energy for the temperature range used. Jatropha seeds harvested with moisture content of 0.67 (decimal d.b.) and dried in a natural environment to reduce and homogenize the moisture content for 0.30 (decimal d.b.). Jatropha drying was performed in experimental drier maintained at controlled temperatures of 30; 40; 50; 60 or 70 ± 1 oC and relative humidity of 55.98; 41.44; 35.35; 26.21 and 13.37 ± 3%, respectively. Experimental data were fitted to eleven mathematical models used to represent the process of drying of agricultural products. It was concluded that among the models tested, Page and Henderson and Modified Pabis presented the best fitting to experimental data, and the Page model selected for describing the drying curves from jatropha because of their simplicity; the effective diffusion coefficient increases with increasing temperature, with magnitudes between 3.93x10-10 and 9.19x10-10 m2 s-1 for the temperature range 30-70 oC, respectively. The activation energy for liquid diffusion during jatropha drying was 15.781 kJ mol-1.

Forma e tamanho dos frutos de pinhão-manso durante a secagem em cinco condições de ar

dry matter). The roundness, sphericity, volume, surface area, projected area and surface-volume ratio were determined during drying. It is concluded that the reduction of the moisture content and the drying conditions alter the shape and reduce the size of the fruit of Jatropha, being possible to adjust a single equation to the experimental data of volume and surface area of the fruit of Jatropha during drying at different temperatures.

Cinética da secagem de clones de café (Coffea canephora Pierre) em terreiro de chão batido

The objective of this work was to study the drying kinetics of four coffee berry clones Coffea canephora species dried in ground pavement and to fit different mathematical models to different experimental data selecting the one that best represents the phenomenon. Have been used coffee berry of clones: Cpafro 194, Cpafro 193, Cpafro 167 and Cpafro 180, harvested at moisture content of 1.20; 1.32; 1.51 e 1.46 (decimal d.b.), respectively. The drying continued in ground pavement until achieved the moisture content of 0.13 (decimal d.b.). Ten mathematical models cited in the literature were fitted to the experimental data in order to represent the drying process. Based on the statistical parameters it can be concluded that the Verma, Dois Termos and Aproximacao da Difusao models represent well the drying of four coffee berry clones, and beyond these for the clone Cpafro 167, the Thompson, Page, Newton, Logaritmico, Henderson e Pabis and Exponencial de Dois Termos models also shown in satisfactory description of the phenomenon; the drying time in ground pavement of coffee berry clones Cpafro 194, Cpafro 193, Cpafro 167 and Cpafro 180, until the moisture content of 0.13 (decimal d.b.) was 189.5 hours.

Modelagem matemática para a secagem de clones de café ( Coffea canephora Pierre) em terreiro de concreto - DOI: 10.4025/actasciagron.v31i2.588

The objective of this work was to obtain and evaluate the drying curves for the coffee berry species Coffea Canephora , and to fit different mathematical models into the experimental data of four clones. Coffee berries from the following clones were used: Cpafro 194, Cpafro 193, Cpafro 167 and Cpafro 180, harvested at moisture contents of 1.20; 1.32; 1.51 and 1.46 (decimal d.b.), respectively. The drying continued in a concrete yard until the moisture content of 0.10 (decimal d.b.) was achieved. Ten mathematical models cited in literature were fitted to the experimental data in order to represent the drying process. According to the results and based on the statistical parameters, it can be concluded that the Page model represents well the drying of four coffee berry clones; for the clone Cpafro180, the Verna and other models were also satisfactory in describing the phenomenon. The drying time in concrete yard for coffee berry clones Cpafro 194, Cpafro 193, Cpafro 167 and Cpafro 180, up to the moisture content of 0.10 (decimal d.b.) was 117.5 hours and the diffusion coefficient was 4.50 x 10 -11 ; 5.17 x 10 -11 ; 5.08 x 10 -11 and 5.50 x 10 -11 m 2 s -1 , for analyzed clones, respectively.

Qualidade do café conilon submetido à secagem em terreiro híbrido e de concreto

Avaliar a qualidade do cafe conilon (Coffea Canephora Pierre) depois da secagem em terreiro hibrido e de concreto, processado por via seca para as condicoes climaticas do Estado de Rondonia, foi o principal objetivo deste trabalho. O cafe foi colhido, manualmente, pelo sistema de derrica no pano, com teor de agua de aproximadamente 50% (b.u.), separado por diferenca de massa especifica em tres grupos: cerejas, boia e cafe mistura. Posteriormente, cada um dos grupos foi dividido em dois lotes e submetidos a secagem em terreiro hibrido e terreiro de concreto. A analise sensorial foi realizada pela degustacao por especialista e a qualidade quimica do produto foi avaliada por meio das analises da acidez titulavel, solidos soluveis totais e condutividade eletrica. Conclui-se que o tempo necessario para que os cafes boia, mistura e cereja atingissem o teor de agua de 9,5 ± 0,5 (%b.u.) foi de 168 horas no terreiro de concreto e no terreiro hibrido foi de 48, 54 e 60 horas, respectivamente. O cafe submetido a secagem em terreiro de concreto obteve melhor qualidade em comparacao ao cafe secado em terreiro hibrido, decorrente da taxa de remocao de agua mais lenta, em media 3,1 vezes menor que no terreiro hibrido, e em funcao das condicoes climaticas favoraveis a secagem em terreiro de concreto.

Shape and size of jatropha beans (Jatropha curcas L.) during drying at different temperatures

This study was carried out to study the physical properties of the jatropha beans over the drying under six air conditions, based on measurements of roundness, sphericity, volume, superficial area, projected area and surface/ volume ratio. Jatropha beans with moisture content around 0.61 (decimal d.b.) were subjected to thin-layer drying in oven with forced-air circulation under six temperature conditions (36, 45, 60, 75, 90 and 105 °C) and relative humidity of 31.7; 19.6; 9.4; 4.8; 2.6 and 1.5% respectively , until reaching the moisture content of 0.1 1 ± 0.006 (decimal d. b.). The results showed that the necessary time for jatropha beans to reach the moisture content of 0.11 ± 0.006 (decimal d.b.) were 1.5; 2.25; 3.0; 4.75; 6.75 and 12.0 h for the drying temperatures of 105, 90, 75, 60, 45 and 36 °C, respectively; and the reduction in the moisture content as well as the drying conditions promoted changes in the shape and reduced the size of the jatropha beans.