Perda de pressão estática em uma coluna de grãos de quinoa

Abstract

RESUMOObjetivou-se, neste trabalho, avaliar os efeitos do fluxo de ar sobre a queda da pressão estática em massa granular de quinoa, cultivar Real, com diferentes teores de impurezas; ajustar os modelos matemáticos aos dados experimentais obtidos e selecionar o modelo que melhor represente o fenômeno. Inicialmente, o produto estava isento de impurezas e com teor de água de 17% base seco. Foram feitas adições de impurezas nos percentuais de 1, 2, 3, 4 e 5. Utilizando-se um equipamento devidamente projetado e construído e fluxos de ar variando de 0,1 a 0,4 m 3 s -1 m -2 , foram determinadas as pressões estáticas da quinoa limpa e com impurezas. Os dados experimentais de perda de carga foram ajustados às equações comumente utilizadas para descrever o fenômeno. Os resultados permitiram concluir que: a) a pressão estática em uma coluna com grãos de quinoa aumenta com o incremento de fluxo de ar; b) O aumento do nível de impureza provocou redução da queda de pressão estática; c) As equações que melhor representam os dados experimentais da queda de pressão no interior do leito com grãos de quinoa, sem e com impurezas, foram as equações de Shedd e de Guimarães, respectivamente. Palavras-chave:Chenopodium quinoa Willdenow, fluxo de ar, impurezas, resistência ao fluxo de ar Loss of static pressure in a column of quinoa grains ABSTRACT The aim of this study was to evaluate the effects of air flow on the drop in static pressure in granular masses of the quinoa cultivar Real, with different levels of impurity and adjust the mathematical models to the obtained experimental data selecting those that best represent the phenomenon. The product was initially free of impurities and with moisture content of 17% on dry weight basis. To check the influence of impurities on resistance to air flow, additions of these impurities were made at 1, 2, 3, 4, and 5%. Using a piece of equipment duly designed and built and air flows ranging from 0.1 to 0.4 m 3 s -1 m -2 , the static pressures of clean quinoa and quinoa with impurities were determined. The equations commonly used to describe the phenomenon were adjusted to the experimental data of pressure drop. The results permit to conclude that: a) static pressure in a column with quinoa grains increases with the increase in air flow; b) increase in the level of impurity lead to a reduction in the static pressure drop; c) the equations that best represent the experimental data of pressure drop inside the bed with quinoa grains, with and without impurities, were the Shedd and Guimarães equations, respectively.

Variation of static pressure in a crambe (Crambe abyssinica Hochst) grains column

“…The increase in the static pressure of the gradient with the highest airflows is noted. These results corroborate those obtained in other experiments, such as quinoa (Gratão et al, 2013), peanut pods (Figueiredo et al, 2012), macadamia nut (Biaggioni et al, 2005), canola (Santos et al, 1999), white (Lukaszuk et al, 2008), grains, and cereals in general (ASAE, 2011).…”

“…The results corroborate research with other agricultural products such as canola (Andrade et al, 2001), quinoa (Gratão et al, 2013), and chickpeas (Shahbazi, 2011).…”

“…The results corroborate research with other agricultural products such as quinoa (Gratão et al, 2013), chickpeas (Shahbazi, 2011), and pistachio (Kashaninejad and Tabil, The Figure 5 shows the pressure loss in the function of air flux density with different grains in comparison to the crambe. It can be seen from Figure 5 that the static pressure exerted by crambe is greater than that of other grains like soy, corn, and coffee, and approximates to the resistance offered by small grains such as barley and oats; this fact is due to the size and shape of the crambe grains with characteristics that are very similar to these small grains (ASAE, 2011).…”

Static Pressure Drop in Layers of Castor Bean Grains

“…The increased content of coarse impurities reduces the bulk density and increases the porosity of castor bean grains, as impurities occupy the void space in the product mass. Similar results were obtained by Gratão et al (2013) and Botelho et al (2019) working with quinoa beans and soybeans and husk rice, respectively.…”

Experimental dryer design for agricultural products

“…(5) Table 4 shows the value of the drop in pressure calculated for wheat considering some layer thickness values and air flow density recommended for drying agricultural products in stationary dryers (DALPASQUALE et al, 1991). When studying the resistance to the passage of air through a mass of quinoa grains as a function of the grain layer depth, impurity content and increase of air flow, GRATÃO et al (2013) found that the static pressure increases linearly with increasing the grain layer depth; also, for the same product layer depth the static pressure increases with the increase of air flow. In addition, the authors reported that other researchers studying different agricultural products have also observed similar behavior, thus reinforcing the behavior of the information presented in Table 4, which were the basis to select the appropriate fan for the experimental dryer.…”