The objective of this study was to determine the physical properties of Jatropha curcas grains, such as: size, shape, density and porosity, and to determine the terminal velocity, comparing the results with those calculated from mathematical models available in the literature. To perform the experimental analysis, samples with different moisture contents, between 4 and 25% (wb), were selected. To determine the size and shape of the grains, sphericity and roundness characteristics were used, and it was found that both stay approximately constant, despite different moisture content. For specific weight and porosity, results show that the porosity is directly proportional to the moisture content until the point where interaction between the moisture content and volumetric contraction causes the specific weight to increase again, thus decreasing porosity. It was also found that the equation used for calculating the terminal velocity is in agreement with the results obtained experimentally. Furthermore, the results also show that the terminal velocity for the Jatropha grains is directly proportional to its moisture content.
The aim of this paper was to analyze, using computational fluid dynamics (CFD), a heating system in a commercial broiler house. Data were collected in a broiler house located in the western mesoregion of Minas Gerais, Brazil. The data were collected at 10 a.m. on the seventh day of chicks’ life in 16 points inside the house. A tetrahedral mesh was adopted for the simulation, and testing of the mesh yielded a geometry of 485,691 nodes. The proposed model was developed in a permanent state condition to simulate the temperature air inside the broiler house, and all other input variables were considered constant. The applied CFD technique resulted in satisfactory fitting of the air temperature variable along the broiler facility as a function of the input data. The results indicated that the model predicted the environmental conditions inside the broiler house very accurately. The mean error of the CFD model was 1.49%, indicating that the model is effective and therefore that it can be used in other applications. The results showed that the heating system provided favorable thermoneutral conditions for chicks in the biggest part of the broiler house. However, there were some areas with air temperature above and below the thermoneutral zone
The market value of coffee is strongly influenced by loss of quality, which makes storage one of the main steps in the entire production chain. The finite element method (FEM) and computational fluid dynamics (CFD) are numerical and computational techniques that facilitate the simulation of agricultural product storage systems. Computational modeling satisfactorily represents real experimentation, simplifies decision-making, and reduces costs. This study aimed to analyze mocha coffee storage for 6 months in a cooled environment with temperatures between 15 and 18 °C and in a natural environment. The water content, bulk density, specific heat, thermal conductivity, and thermal diffusivity were determined and colorimetry and sensory analysis were applied to compare initial and final samples of the product after storage. It was found that the water content and specific heat were the only properties that presented significant changes. Through sensory analysis, it was observed that the quality of the coffee was the same for both systems. A computational model was developed to simulate the heat transfer process during storage. The comparison of the simulation results with the experimental results for the temperature distribution in the grain mass showed overall mean relative errors of 2.34% for the natural environment and 5.74% for the cooled environment.
A model is a representation of a real system that can be analysed and yield predictions under different operating conditions. The aim of this study was to model a milk cooling tank that cools milk to 4 °C to preserve its quality after milking at the farm. The model was developed and simulated using the software Ansys for finite element analysis. The results from the simulations were compared to experimental data. The model simulated milk cooling in the tank with an error lower than 2%, which is considered acceptable for numerical simulations. In other words, the model satisfactorily represents the real system. Thus, alternatives can be directly tested in the computational model to improve and optimise the milk cooling process and to better use the system without actually implementing them in the real system.
The storage of agricultural products is of great importance in maintaining product quality between harvest and commercialization. The use of numerical and computational techniques, such as the finite element method (FEM) and computational fluid dynamics (CFD), allows the analysis and simulation of systems that involve heat transfer, as is the case of grain storage. A computational model based on these techniques that satisfactorily represents a real system was used to test and to analyze decision alternatives without the need for real experimentation. In this study, we sought to study the behavior of the temperature of a mass of stored mocha coffee beans by using computational techniques, as requested by the private sector. The coffee was stored for 6 months in two types of environments: a cooled environment between 15 and 18 °C by using an air temperature control equipment used for artificial cooling and a natural environment. A computational model was developed to simulate the heat transfer process for both types of storage. In the comparison of the temperature distribution during storage from simulation results and for experimental results, an overall mean relative error of 2.34% was obtained for coffee stored in a natural environment, and that of 5.74% was obtained for coffee stored in a cooled environment.
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