title: Thin layer drying kinetics of by-products from olive oil processing.
abstract: The thin-layer behavior of by-products from olive oil production was determined in a solar dryer in passive and active operation modes for a temperature range of 20-50 °C. The increase in the air temperature reduced the drying time of olive pomace, sludge and olive mill wastewater. Moisture ratio was analyzed to obtain effective diffusivity values, varying in the oil mill by-products from 9.136 × 10(-11) to 1.406 × 10(-9) m(2)/s in forced convection (m(a) = 0.22 kg/s), and from 9.296 × 10(-11) to 6.277 × 10(-10) m(2)/s in natural convection (m(a) = 0.042 kg/s). Diffusivity values at each temperature were obtained using the Fick's diffusion model and, regardless of the convection, they increased with the air temperature. The temperature dependence on the effective diffusivity was determined by an Arrhenius type relationship. The activation energies were found to be 38.64 kJ/mol, 30.44 kJ/mol and 47.64 kJ/mol for the olive pomace, the sludge and the olive mill wastewater in active mode, respectively, and 91.35 kJ/mol, 14.04 kJ/mol and 77.15 kJ/mol in natural mode, in that order.
authors.affiliation: Department of Mechanical, Energetic, and Materials Engineering, Industrial Engineering School, University of Extremadura, Avenue Elvas s/n, 06006, Badajoz, Spain; E-Mails:  tmiranda@unex.es  (T.M.);  jiarranz@unex.es  (J.I.A.);  cvrojas@unex.es  (C.V.R.).
authors.forename: Irene
authors.initials: I
authors.lastname: Montero
authors.forename: Teresa
authors.initials: T
authors.lastname: Miranda
authors.forename: Jose Ignacio
authors.initials: JI
authors.lastname: Arranz
authors.forename: Carmen Victoria
authors.initials: CV
authors.lastname: Rojas
mesh_terms: D003890:Desiccation; D004058:Diffusion; D005511:Food Handling / Q000379:methods*; D008962:Models, Theoretical; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000032:analysis
chemical_list: D000069463:Olive Oil; D010938:Plant Oils; D014867:Water