Propriedades físicas, aerodinâmicas e térmicas de frutos de café conilon (Coffea canephora)

• Ano de defesa: 2012
• Autor(a) principal: Treto, Pedro Casanova
• Orientador(a): Correa, Paulo César
• Banca de defesa: Moura, Waldênia de Melo , Donzeles, Sergio Mauricio Lopes , Rosa, Henrique Marcio Pereira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Engenharia Agrícola
• Departamento: Construções rurais e ambiência; Energia na agricultura; Mecanização agrícola; Processamento de produ
• País: BR
• Palavras-chave em Português: Coffea canephora; Armazenamento
• Palavras-chave em Inglês: Coffea canephora; Storage
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/743

Coffee is considered one of the most important agricultural products in Brazil, by revenue generated of exports and industrialization, as the number of direct and indirect jobs associated with their agribusiness. The species of greatest importance in the international economic market are Coffea arabica (Arabica coffee) and Coffea canephora (robusta). Considering the limited research in the drying process and to obtain data that can be used in systems development processes during harvest and postharvest, the present study aimed to evaluate the influence of water content on physical, aerodynamic and thermal properties of coffe fruits (Coffea canephora). It was used coffee cherries (Coffea canephora), clones 83 and 74 of the clonal variety EMCAPA 8141 and clones 31 and 32 of the clonal variety EMCAPA 8131, coming from an experimental farm of EPAMIG in the municipality Leopoldina, Minas Gerais. Subsequently the different batches of coffee were dried in an oven with forced ventilation with air temperature of approximately 60 ±3 °C until different levels of water content. During drying, for each moisture content obtained, samples were homogenized and forwarded to the determination of their properties, always in triplicate. For the four clones were determined true and bulk density, porosity, shape, size and shrinkage in each maturation stage, besides adjusting the models available in the literature. It was also studied the influence of water content on the aerodynamic properties during the drying process. The process was studied by techniques of Computational Fluid Dynamics using the k-ε turbulence model. It was also determined the thermal properties (specific heat, thermal conductivity and diffusivity) for coffee cherries from Coffea canephora species, clone 32 of clonal variety EMCAPA 8131. When studying the behavior of each clone was determined that the projected area, surface area, volume and porosity increase with increasing moisture content for all clones, while the bulk and true densities increased with increasing moisture content of coffee cherries to a maximum and then decreases. The shape of the conilon coffee cherries is influenced during the drying process, promoting the decrease of sphericity and roundness values with reduced moisturer content. The shrinkage showed a nonlinear behavior with decreasing reducing the moisture content of the conilon coffee cherries. The models adapted Bala & Woods, Correa and polynomial adjusted to the experimental values to estimate the shrinkage of conilon coffee cherries depending on the moisture content represented satisfactorily the phenomenon studied, with the model of the polynomial better fit in all cases. By increasing the moisture content, the terminal velocity increased non-linearly in all conilon coffee clones and maturation stages studied. It was determined the experimentally drag coefficient in a horizontal wind tunnel of each clone. The drag coefficient showed a non-linear behavior as a function of the Reynolds number, but decreased by increasing the Reynolds number. The numerical model used represented the process properly with differences between the experimental and numerical drag coefficient less than 5 %. It was possible to determine the distribution of pressures and velocities by numerical simulation finding that the aspect ratio has a minimum influence on them, which means that it is possible to use the same aspect ratio for all clones. It was determined that the thermal properties of the conilon coffee cherries are dependent on the moisture content. The specific heat and thermal conductivity of conilon coffee cherries increased with increasing moisture content, whereas the thermal diffusivity decreasing with increasing moisture content. It carried out the identity test by identifying the combination and physical property represented by a common model.