Simulação numérica da distribuição de temperatura de café armazenado em ambiente resfriado e natural

Abstract

The storage of agricultural products is of great importance in maintaining product quality between harvest and commercialization. For coffee, quality losses can strongly influence its market value, which makes storage one of the main stages in the entire production chain. The use of numerical and computational techniques, such as the finite element method (FEM) and the computational fluid dynamics (CFD), allows the analysis and simulation of systems that involve, among others, heat transfer, as is the case in grain storage. A computational model based on these techniques that satisfactorily represents a real system can be used to test and analyze decision alternatives, without the need for real experimentation. In this work, we study the storage of mocha coffee using computational techniques, a demand that came from the private sector. Coffee was stored for 6 months in a cool environment, with the objetive of keeping the beans between 15 and 18ºC, and in a natural environment. For the comparison between initial and final samples of the product after storage, water content, apparent specific mass, colorimetry, specific heat, thermal conductivity, thermal diffusivity and sensory analysis were determined. It was found that the water content and specific heat were the only properties where significant changes happened. Through sensory analysis, it was observed that both systems maintained the quality of the coffee used equally. A computational model was developed to simulate the heat transfer process for both types of storage. By comparing the results of the simulations with those observed experimentally for the temperature distribution during storage, a general average relative error of 2.34% was obtained for the natural environment and 5.74% for the cooled environment.