caa a22 4500 463163184 CHVBK 20180406164754.0 cr unu---uuuuu 170326e20070101xx s 000 0 eng 10.1007/s11242-006-9023-1 doi (NATIONALLICENCE)springer-10.1007/s11242-006-9023-1 Pabis Stanisław Polish Society of Agricultural Engineering, ul. Polna 54/17, 00-644, Warszawa, Poland aut Theoretical models of vegetable drying by convection [Elektronische Daten] [Stanisław Pabis] The results of experiments are often used to model empirical phenomena. However, the term model is applied in various meanings. A model is usually treated as an abstract formal structure that can replace a material system considered as original, in respect to the aim of modeling. Certain formal structures may be treated as theoretical models of empirical phenomena. On the other hand, a material system can also be referred to as a model of an abstract system, e.g., a set of equations or a hypothesis. Such a material system, if it is a distinct empirical interpretation of the language of a given theory, is then called a real model. Both kinds of models are applied in drying technology, but the second one is more inventive. The mathematical structures are treated as empirical formulae or as theoretical models properly derived from true or legitimated promises of a given theory. The advantages of some mathematical theoretical models of drying processes versus empirical formulae are discussed. The creation of new mathematical theoretical models of convection drying kinetics of some shrinking solids is presented and analyzed. One of the above models was also hypothetically suggested for modeling the drying of cut vegetables in a fluidized-bed. Despite its initial acceptance due to peer empirical justification on cut carrots and celery, it still requires further theoretical analysis. Other models indicated here are theoretical models of vegetable drying in a tunnel drier. These models are created by deduction from laws of heat and mass transfer theory and its basic equations. Springer Science+Business Media, B.V., 2007 Drying nationallicence Vegetables nationallicence Mathematical models nationallicence Theory nationallicence Hypotheses nationallicence A ( M ) : Surface area of product with water content M < M 0 (m2) nationallicence A 0 : Initial surface area of dried product (m2) nationallicence K : Drying coefficient (min−1) nationallicence L : Latent heat of water vaporisation at product surface temperature (kJ kg−1) nationallicence M 0 : Initial average water content of product (kg kg−1) nationallicence M d : Dry matter of product (g) nationallicence M e : Equilibrium water content (kg kg−1) nationallicence M ( τ ) : Water content (kg kg−1) nationallicence N : Exponent in Eq. 11 nationallicence P 0 : Mass of wet (M=M 0) product (kg) nationallicence P d : Mass of dry (M=0) product (kg) nationallicence V 0 : Initial volume (M=M 0) of dried product (m3) nationallicence V d : Volume of dry (M=0) product (m) nationallicence V ( M ) : Volume of product with average water content M < M 0 (m3) nationallicence b : Value of shrinkage coefficient if M=0, dimensionless nationallicence k : Varying rate of drying (kg kg−1 min−1) nationallicence k 0 : Constant drying rate (kg kg−1 min−1) nationallicence n : Empirical coefficient nationallicence t : Drying air temperature (°C) nationallicence t A : Surface temperature of dried product (°C) nationallicence α : Heat transfer coefficient (kJ m−2 min−1 K−1) nationallicence ρ o : Initial density of moist product (M=M 0) (kg m−3) nationallicence ρ d : Density of dry product (M=0) (kg m−3) nationallicence τ : Drying time (min) nationallicence Transport in Porous Media Kluwer Academic Publishers 66/1-2(2007-01-01), 77-87 0169-3913 66:1-2<77 2007 66 11242 https://doi.org/10.1007/s11242-006-9023-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11242-006-9023-1 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Pabis Stanisław Polish Society of Agricultural Engineering, ul. Polna 54/17, 00-644, Warszawa, Poland aut NATIONALLICENCE 773 0- Transport in Porous Media Kluwer Academic Publishers 66/1-2(2007-01-01), 77-87 0169-3913 66:1-2<77 2007 66 11242 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer