Coskan Ilicali

Methods for the freezing time of ellipses

A modified equivalent cylinder diameter is proposed for predicting the freezing times of two-dimensional irregular objects. The proposed equivalent diameter was used in predicting the freezing times of ellipses. The predictions using the equivalent diameter was compared with the predictions of a finite difference numerical model and with the predictions of the previously proposed models. The equivalent diameter approach agreed with the numerical data up to 10%. The accuracy of the previously proposed models depended on the centre temperature at the end of freezing.

Laminar flow of power law fluid foods in concentric annuli

Abstract The flow of power law fluids for isothermal, laminar flow in concentric annuli was investigated experimentally and numerically. Similar to the results of Russel & Christiansen (1974, Indust. Engng Chem. Process Des. Develop. 13 , 391–398) it was observed that plots of the natural logarithm of a reduced shear stress at the outer wall of the annulus vs the natural logarithm of a reduced pseudo-shear rate were identical to those for tube flow. However, in contrast to the findings of Russel & Christiansen (1974), the y intercepts and the slopes of these plots were found to be equal to In K′ and n, respectively. Frederickson & Birds (1958, Indust. Engng Chem. 50 , 347–352) solution was found to be in perfect aggreement with the numerical solution in every case. The Hanks & Larsen (1979, Indust. Engng Chem. Fundamentals, 18 , 33–35) equation also agreed very well with the numerical solution. The Russel & Christiansen (1974, Indust. Engng Chem. Process Des. Develop., 13 , 391–398) method gave an absolute mean error of 3.6% against the numerical results for pressure drop.

Modified Dincer and Dost Method for Predicting the Mass Transfer Coefficients in Solids

Abstract The analytical model developed by Dincer and Dost [3] for the estimation of diffusivities and mass transfer coefficients has been reviewed, and the equations used for the evaluation of the mass transfer coefficients have been corrected. The corrected equations have been used for the calculation of mass transfer coefficients from literature data. It was observed that the corrected diffusivities showed significant differences from the previously calculated values. The use of the modified equations in future drying calculations will lead to more realistic mass transfer coefficient values.