Gonçalo Medeiros - Academia.edu (original) (raw)
Papers by Gonçalo Medeiros
Dissertação apresentada para obtenção do grau de Doutor em Engenharia Química, na Faculdade de En... more Dissertação apresentada para obtenção do grau de Doutor em Engenharia Química, na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Prof. Doutor Alberto Manuel Carneiro Seren
Computer and Information Science Applications in Bioprocess Engineering, 1996
Warm air drying of peas was studied to assess the effect of drying conditions on some relevant ph... more Warm air drying of peas was studied to assess the effect of drying conditions on some relevant physical properties of the product. Experimental drying data was well correlated by a previously described model where an implicit variation of moisture diffusivity during the dehydration is considered. Using that model, the experimental data could be reproduced within 6.1%. Drying conditions have influenced shrinkage of the product, as expressed by apparent density, and moisture diffusivity but not sorption isotherm.
Journal of Food Engineering, 1994
Warm air drying of peas was studied to assess the effect of drying conditions on some relevant ph... more Warm air drying of peas was studied to assess the effect of drying conditions on some relevant physical properties of the product. Experimental drying data was well correlated by a previously described model where an implicit variation of moisture d@sivity during the dehydration is considered. Using that model, the experimental data could be reproduced within 6.1%. Drying conditions have influenced shrinkage of the product, as expressed by apparent density, and moisture di#usivity but not sorption isotherm. Variation of moisture di@sivity during the process was calculated using the method of slopes. The results were shown to be consistent with assumptions included in the drying model considered. NOTATION % Water activity cP Specific heat @J/kg per%) C Parameter for GAB equation (eqn (2)) C,-C, Parameters for Lozano equation (eqn (1)) D Effective diffusivity of water in solids (m*/s) Fo Fourier number (= Dt/R2) h Surface heat transfer coefficient (W/m* per "C) H, Absolute humidity of air (kg/kg dry basis (db)) k Parameter for GAB equation (eqn (2)) K Thermal conductivity of solid (W/m per"(Z)
Journal of Food Engineering, 1990
A simplified mathematical model based on basic physical and transport properties, such as mass an... more A simplified mathematical model based on basic physical and transport properties, such as mass and heat difisivities, is proposed for the prediction of the behaviour offoods during drying. The model takes into account the effect of moisture-solid interaction at the drying surface by means of any sorption equation available and the change in solid density due to shrinking. Fourier's and Fick's laws describe the transfer of heat and mass in the solid. At the surface, mass and heat balances together with the chosen sorption equation are used to represent the vaporization of water. Temperature and moisture-content profiles are obtained by integration of the resulting set of partial differential equations, an implicit-finitedifferences algorithm being used. The model, which predicted experimental results for the drying of apple slices and carrot cubes to within I.1 % of the moisture content and 12% of the drying rate, can therefore be used for the determination of drying profiles. NOTATION 2 Water activity External surface area of the solid (m') ci Empirical parameters for eqn (13), i = 1 to 4 cP Heat capacity of the solid, at constant pressure (kcal/kg "C) D Moisture-effective diffusivity within the solid (m2/s) E" Latent heat of vaporization of water (kcal/kg) h Air-solid heat-transfer coefficient (kcal/m2 s 'T) *To whom correspondence should be addressed.
Dissertação apresentada para obtenção do grau de Doutor em Engenharia Química, na Faculdade de En... more Dissertação apresentada para obtenção do grau de Doutor em Engenharia Química, na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Prof. Doutor Alberto Manuel Carneiro Seren
Computer and Information Science Applications in Bioprocess Engineering, 1996
Warm air drying of peas was studied to assess the effect of drying conditions on some relevant ph... more Warm air drying of peas was studied to assess the effect of drying conditions on some relevant physical properties of the product. Experimental drying data was well correlated by a previously described model where an implicit variation of moisture diffusivity during the dehydration is considered. Using that model, the experimental data could be reproduced within 6.1%. Drying conditions have influenced shrinkage of the product, as expressed by apparent density, and moisture diffusivity but not sorption isotherm.
Journal of Food Engineering, 1994
Warm air drying of peas was studied to assess the effect of drying conditions on some relevant ph... more Warm air drying of peas was studied to assess the effect of drying conditions on some relevant physical properties of the product. Experimental drying data was well correlated by a previously described model where an implicit variation of moisture d@sivity during the dehydration is considered. Using that model, the experimental data could be reproduced within 6.1%. Drying conditions have influenced shrinkage of the product, as expressed by apparent density, and moisture di#usivity but not sorption isotherm. Variation of moisture di@sivity during the process was calculated using the method of slopes. The results were shown to be consistent with assumptions included in the drying model considered. NOTATION % Water activity cP Specific heat @J/kg per%) C Parameter for GAB equation (eqn (2)) C,-C, Parameters for Lozano equation (eqn (1)) D Effective diffusivity of water in solids (m*/s) Fo Fourier number (= Dt/R2) h Surface heat transfer coefficient (W/m* per "C) H, Absolute humidity of air (kg/kg dry basis (db)) k Parameter for GAB equation (eqn (2)) K Thermal conductivity of solid (W/m per"(Z)
Journal of Food Engineering, 1990
A simplified mathematical model based on basic physical and transport properties, such as mass an... more A simplified mathematical model based on basic physical and transport properties, such as mass and heat difisivities, is proposed for the prediction of the behaviour offoods during drying. The model takes into account the effect of moisture-solid interaction at the drying surface by means of any sorption equation available and the change in solid density due to shrinking. Fourier's and Fick's laws describe the transfer of heat and mass in the solid. At the surface, mass and heat balances together with the chosen sorption equation are used to represent the vaporization of water. Temperature and moisture-content profiles are obtained by integration of the resulting set of partial differential equations, an implicit-finitedifferences algorithm being used. The model, which predicted experimental results for the drying of apple slices and carrot cubes to within I.1 % of the moisture content and 12% of the drying rate, can therefore be used for the determination of drying profiles. NOTATION 2 Water activity External surface area of the solid (m') ci Empirical parameters for eqn (13), i = 1 to 4 cP Heat capacity of the solid, at constant pressure (kcal/kg "C) D Moisture-effective diffusivity within the solid (m2/s) E" Latent heat of vaporization of water (kcal/kg) h Air-solid heat-transfer coefficient (kcal/m2 s 'T) *To whom correspondence should be addressed.