Papers by Valdecir Dalpasquale
Operational behavior of an ear corn seed dryer = Comportamento operacional de um secador de sementes de milho em espigas
This work aimed to analyze the operational behavior of a fixedbedear corn dryer in commercial sca... more This work aimed to analyze the operational behavior of a fixedbedear corn dryer in commercial scale. It was carried out by controlling the variables involved in the process, such as: ambient and drying air conditions, airflow, product temperature, and fuel consumption (corncobs). Data were collected at the high season of harvesting, following the operational procedures adopted by the owner. The whole process indicated that the dryer operates in the recommended levels of temperature, an average of 41.7oC.The highest product temperature during drying process was 42.0oC. The total drying time (over 100 hours) is too high for commercial drying. Exhausting drying consumed more than 85% of the total drying time, and it is only effective when moisture contents are above 18%. Fuel consumption in effective drying varied from 295 kg to 365 kg of corncobs (fuel source) per point of moisture removed, which means more than 16,000 kJ/kg. Objetivou se, neste trabalho, analisar o comportamento oper...
Modelo matemático para simulaç ão de resfriamento de produtos agrícolas em fluxos contracorrentes
RESUMO. O resfriamento de produtos agr í colas secos em altas temperaturas, apesar de t é cnica e... more RESUMO. O resfriamento de produtos agr í colas secos em altas temperaturas, apesar de t é cnica e economicamente vantajoso, tem sido relegado a segundo plano porque nã o se tem conduzido experimentos a respeito. A razã o desses n ã o terem sido conduzidos foi devido à aus ê ncia de modelo de simulaç ã o capaz de viabilizar sua utilizaç ã o em fluxos contracorrentes, uma vez que a simulaç ã o matem á tica permite a obten ç ã o de resultados em curto per í odo de tempo e com poucos investimentos financeiros. O modelo de simulaç ã o de secagem em fluxos contracorrentes da MSU, o modelo mais completo atualmente dispon í vel, tem solu ç ã o de natureza logar í tmica positiva, o que dificulta sua obtenç ã o. Nova demonstraç ã o daquele modelo resultou em outro com soluç ã o de natureza logar í tmica negativa, o que lhe garante convergê ncia para o resultado. Apó s otimizaç ã o desse novo modelo em cada sistema de secagem onde for utilizado, torna-se poss í vel dimensionar nã o apenas resf...
The objective of this work was to evaluate the current losses of drying and processing of corn in... more The objective of this work was to evaluate the current losses of drying and processing of corn in a unit of reception. The case study consisted of evaluation of machines and equipments, as well as the evaluation of operational procedures adopted by the unit. The methodology was based on determination of the dryer and cleaning machines operational parameters. The results evidenced drying non uniformity and corn losses due to overdrying. It was also observed that corn cleaning increased mechanical damages and consequent breakage of the product, instead of just cleaning it. The average losses due to overdrying were of 1.21 % points and the broken material represented losses in the order of 1.12 % points.
Drying of soybeans in continuous-flow dryers and fixed-bed drying systems /
Thesis (Ph. D.)--Michigan State University. Dept. of Agricultural Engineering, 1981. Includes bib... more Thesis (Ph. D.)--Michigan State University. Dept. of Agricultural Engineering, 1981. Includes bibliographical references (leaves 146-154).
Drying simulation model of agricultural products with constant air enthalpy
Engenharia Agrícola
Mathematical drying simulation of agricultural products reached its highest point in the decades ... more Mathematical drying simulation of agricultural products reached its highest point in the decades of 1960 and 1970, with prominence for MSU and Thompson's models. However, none of them used the constant enthalpy condition of drying air during the process, being limited to checking if the relative humidity of the air did not exceed 100%. Studies conducted in the State University of Maringá allowed to conclude that energy and mass balances of a drying process are included when using the same air enthalpy in such process. The absolute humidity of the air is adjusted as a function of the removed humidity of the product. With that new absolute humidity of the air and with the constant enthalpy, the new temperature of the drying air is evaluated in the exit of the layer and, with those two psychrometric properties, the relative humidity of the air. If it reaches the saturated condition, the drying process is stopped at that time and position. The results obtained by simulation were che...
The objective of this work was to evaluate the mechanical damages in grains of five commercial co... more The objective of this work was to evaluate the mechanical damages in grains of five commercial corn hybrids due to harvest humidity. The work was conducted in Astorga - PR, during the autumn/winter harvest of 2007 and the summer harvest of 2007/2008. The harvests occurred in five distinguished periods (7.20, 7.27, 8.03, 8.10 and 8.17.2007 in the autumn/fall harvest and 3.15, 3.22, 3.31, 4.07 and 4.22.2008 in the summer harvest) and also in five replications, being the grain samples underwent to moisture content determination at an oven heated to 103 ± 1 ºC for 72 h in the laboratory. After that, the mechanical damage (cracked grain, torn grain and broken grain) was evaluated with a diaphanoscope and a magnifying glass of increase of 10x, and the corn grain samples were willing in a completely randomized design. The data were submitted to analyses of variance and regression. It was observed that the occurrence of endosperm scratched and the fragmented corn grains increased, while, th...
Fixed-bed drying simulation with constant enthalpy, using the improved Michigan State University model
Acta Scientiarum. Technology, 2012
ABSTRACT Drying of agricultural products at high temperatures can be simulated by mathematical mo... more ABSTRACT Drying of agricultural products at high temperatures can be simulated by mathematical models, which intend to describe the drying process close to commercial patterns. They are based on simultaneous heat and mass transfer between the product that is losing moisture, and the air that is supplying energy to the process. All models use these balances, never allowing values of relative humidity of the air to be greater than 100%. However, it has not been common to evaluate air enthalpy, which should not have significant variation during the entire process, accepted as adiabatic. In this work, a mathematical model is proposed for fixed-bed corn (Zea mays L.) drying simulation, according to the Michigan State University (MSU) model. In the numerical solution, the enthalpy of the drying air was maintained constant as a quantitative physical indicator for correction of the heat and mass exchange in each step of the process, in order to obtain more real evaluations in all drying stages, and in the results for final moisture of the grain. As a result, greater space and time intervals for the simulation were possible. The simulation was validated by comparisons with literature results.
The experiment was carried out to evaluate the time for harvesting seeds of three hybrids of corn... more The experiment was carried out to evaluate the time for harvesting seeds of three hybrids of corn (Zea mays L.) at their best physiological quality and the use of the milk line as an indicator of the physiological seed maturity. Single hybrids CD 1723 and CD 5501 and double hybrid OC 705 seeds were collected for 59 days, every four
Acta Scientiarum. Agronomy, 2005
Danos mecânicos em grãos de híbridos comerciais de milho em função da umidade de colheita
Semina: Ciências Agrárias, 2011
Acta Scientiarum. Agronomy, 2006
This work aimed to analyze the operational behavior of a fixedbed ear corn dryer in commercial sc... more This work aimed to analyze the operational behavior of a fixedbed ear corn dryer in commercial scale. It was carried out by controlling the variables involved in the process, such as: ambient and drying air conditions, airflow, product temperature, and fuel consumption (corncobs). Data were collected at the high season of harvesting, following the operational procedures adopted by the owner. The whole process indicated that the dryer operates in the recommended levels of temperature, an average of 41.7 o C.The highest product temperature during drying process was 42.0 o C. The total drying time (over 100 hours) is too high for commercial drying. Exhausting drying consumed more than 85% of the total drying time, and it is only effective when moisture contents are above 18%. Fuel consumption in effective drying varied from 295 kg to 365 kg of corncobs (fuel source) per point of moisture removed, which means more than 16,000 kJ/kg.
International Journal of Food Science & Technology, 2011
This study was conducted to identify and assess the critical control points (CCPs) in groundnut-b... more This study was conducted to identify and assess the critical control points (CCPs) in groundnut-based food production in southern Brazil in order to reduce or eliminate aflatoxin contamination. This methodology has been suggested by the Food and Agriculture Organization (FAO) of the United Nations. Reception of prime matter, groundnut storage, roasting and thermal treatment were the main CCPs identified. Critical factors were the determination of aflatoxin, moisture content and water activity (A w ) during groundnut reception and storage, control of temperature, roasting time and thermal treatment in the groundnut-based food manufacturing. The critical limit for moisture was 8.2% and 0.6 was established for A w . In Brazil, the limit for aflatoxins B 1 , B 2 , G 1 and G 2 has been established at 20 ppb. Temperatures of 180°C ⁄ 1 h and 80°C ⁄ 40 min were established for roasting and thermal treatment stages of groundnut-based food, respectively.
Acta Scientiarum. …, 2008
Photoacoustic spectroscopy and thermal relaxation method to evaluate corn moisture content
Journal de Physique IV (Proceedings), 2005
In this study, samples of popcorn with different degrees of moisture were analyzed. The optical a... more In this study, samples of popcorn with different degrees of moisture were analyzed. The optical absorption bands at the mid infrared were measured using photoacoustic spectroscopy and were correlated to the sample moisture. The results were in agreement with moisture data determined by the well known reference method, the Karl Fischer. In addition, the thermal relaxation method was used to determine the sample specific heat as a function of the moisture content. The results were also in agreement with the two mentioned methods.
Brazilian Archives of Biology and Technology, 2005
The experiment was carried out to evaluate the time for harvesting seeds of three hybrids of corn... more The experiment was carried out to evaluate the time for harvesting seeds of three hybrids of corn (Zea mays L.) at their best physiological quality and the use of the milk line as an indicator of the physiological seed maturity. Single hybrids CD 1723 and CD 5501 and double hybrid OC 705 seeds were collected for 59 days, every four days, starting 23 days after female flowering. Seed dry weight, moisture content, germination, vigour (cold and accelerated aging tests), black layer formation and seed milk line development were analysed. The harvesting time started 47 days after female flowering with high physiological quality of the seeds identified by a joint analysis of those seven characteristics of them. The milk line at stage 4 proved to be the best indicator of the time to harvest corn seeds for maximum physiological quality, because different stages of milk line development in corn seeds could be easily identified in the filed without any special equipment.
Applied Mathematics and Computation, 2008
In this work, numeric simulation of fixed-bed corn drying (Zea mays L.) is conducted, using the M... more In this work, numeric simulation of fixed-bed corn drying (Zea mays L.) is conducted, using the MSU drying model. It uses explicit methods of finite differences in its solution, which demands conditions of stability for the values of space intervals (Δx) and time increment (Δt). In this work, the following conditions are proposed: backward finite differences in the space and in the time dimensions, which is a stable numeric procedure.
Neste trabalho, entende-se como grãos todos os produtos agrícolas, apesar de não ser a denominaçã... more Neste trabalho, entende-se como grãos todos os produtos agrícolas, apesar de não ser a denominação correta para soja e feijão, dentre outros. Os principais grãos são o arroz, o milho e o trigo. A secagem de grãos pode ser definida de modos distintos, de acordo com o enfoque que se deseja dar. Nos estudos mais teóricos, a ênfase recai sobre os mecanismos de transporte de energia e matéria. Assim, a secagem pode ser definida como um processo em que há trocas simultâneas de calor e massa entre o ar do ambiente de secagem e os grãos. Nos casos gerais, entretanto, define-se secagem como a operação unitária responsável pela redução do teor de umidade de certo produto até um nível considerado seguro para o armazenamento. Entende-se como seguro o nível de umidade abaixo do qual a atividade respiratória dos grãos e legumes é reduzida, e o ataque de insetos e fungos é dificultado. Esse nível varia para os diferentes tipos de produtos agrícolas, mas, para as condições brasileiras e grãos e legumes mais comuns, compreende uma faixa entre 10% e 14% de umidade, expressa em base úmida.
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Papers by Valdecir Dalpasquale