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    Convection and radiation combined surface heat transfer coefficient in baking ovens
    (Elsevier Sci Ltd, 2009) Sakin, Melike; Kaymak-Ertekin, Figen; Ilicali, Coskan
    The combined surface heat transfer coefficient is a determining parameter of convective baking process time and efficiency, as well as the resulting food product quality. By this study, the combined surface heat transfer coefficient term was determined at the convective oven temperature range of 70-220 degrees C, with fan (turbo) and without fan (static oven) applications. The methods of "Lumped Capacity" and "Time-Temperature Matching" were used. Both methods utilize the time-temperature data at a fixed position of a definite material, during unsteady state heating up period inside the convective oven. The increase in oven temperature and the fan application in the oven derived higher calculated values of surface heat transfer coefficients. Good agreement was observed between both methods and the literature values. The given methods are applicable to other oven types and heating modes. (C) 2009 Elsevier Ltd. All rights reserved.
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    Convection and radiation combined surface heat transfer coefficient in baking ovens
    (Elsevier Sci Ltd, 2009) Sakin, Melike; Kaymak-Ertekin, Figen; Ilicali, Coskan
    The combined surface heat transfer coefficient is a determining parameter of convective baking process time and efficiency, as well as the resulting food product quality. By this study, the combined surface heat transfer coefficient term was determined at the convective oven temperature range of 70-220 degrees C, with fan (turbo) and without fan (static oven) applications. The methods of "Lumped Capacity" and "Time-Temperature Matching" were used. Both methods utilize the time-temperature data at a fixed position of a definite material, during unsteady state heating up period inside the convective oven. The increase in oven temperature and the fan application in the oven derived higher calculated values of surface heat transfer coefficients. Good agreement was observed between both methods and the literature values. The given methods are applicable to other oven types and heating modes. (C) 2009 Elsevier Ltd. All rights reserved.
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    Freezing time prediction for partially dried papaya puree with infinite cylinder geometry
    (Elsevier Sci Ltd, 2010) Ilicali, Coskan; Icier, Filiz
    Dehydrofreezing which is the drying of foods to intermediate moisture content and subsequent freezing has the advantages of lowering the transportation costs due to reduced weight and improved texture. The available empirical equations for freezing time prediction and the experimental data on thermo-physical properties are for fresh produce. Some of these empirical equations were used to predict the freezing times of papaya puree infinite cylinders with initial moisture contents similar to 52% to similar to 91%. The accuracies of these methods to predict the freezing times for final center temperatures of -10 degrees C and -18 degrees C were discussed. The most accurate methods for fresh and partially dries papaya puree were suggested. (C) 2010 Elsevier Ltd. All rights reserved.
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    Modeling the moisture transfer during baking of white cake
    (Elsevier Sci Ltd, 2007) Sakin, Melike; Kaymak-Ertekin, Figen; Ilicali, Coskan
    Moisture transfer characteristics of cake batter during baking in a convective oven were investigated. The moisture content profiles of a thin layer of cake batter were experimentally determined, through baking at the oven temperatures of 50, 80, 100, 140 and 160 degrees C. The experimental oven temperatures were selected in order to cover the possible batter temperatures attained by the cake during a complete baking process. The data were analyzed analytically to calculate the effective moisture diffusivity. The analytical solution used the method of slope of drying curves, and the moisture diffusivity was related to the temperature and the average moisture content of cake batter. The temperature dependency of the moisture diffusivity followed an Arrhemus type equation. The moisture diffusivity increased with decreasing moisture content exponentially at I 00 140, and 160 degrees C, whereas it could be well constant at 50 and 80 degrees C oven temperatures. This was attributed to the difference in structure of product during baking at different temperatures. The overall non-linear regression of the results defined the effective moisture diffusivity as a function of both average moisture content and temperature of cake batter. For validating the predicted moisture diffasivity values and equations, the baking process was simulated by a numerical method using implicit finite difference technique. The drying curves from numerical solution, which used the predicted moisture diffusivities as input variables, were compared to the experimental drying curves and a very good agreement was achieved. (c) 2006 Elsevier Ltd. All rights reserved.
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    Modified Dincer and Dost Method for Predicting the Mass Transfer Coefficients in Solids
    (Walter De Gruyter Gmbh, 2016) Ilicali, Coskan; Icier, Filiz
    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.
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    Prediction of Mass-Average and Surface Temperatures, and the Temperature Profiles At the Completion of Freezing For Shapes Involving One-Dimensional Heat Transfer
    (Wiley-Blackwell, 1992) Ilicali, Coskan; Engez, Semih Tevfik; Cetin, Metin
    A model for predicting the temperature profiles of simple-shaped foodstuffs at the end of freezing was developed. It was shown that with appropriate selection of effective thermal diffusivity and initial temperature data, the standard solution of the unidimensional unsteady state heat conduction equation can be used in predicting the average and surface temperatures of infinite slabs at the end of freezing operation. For the calculation of average and surface temperatures in infinite cylinders and spheres, unsteady state solutions were corrected by an empirical factor that was derived from temperature profiles predicted by an accurate finite difference scheme. The temperature profiles calculated from the proposed model were compared with the predicted results obtained from a numerical model. Mean absolute errors between the predictions of the proposed model and the numerical model were 0.54C and 0.46C for average and surface temperatures, respectively.
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    Simultaneous heat and mass transfer simulation applied to convective oven cup cake baking
    (Elsevier Sci Ltd, 2007) Sakin, Melike; Kaymak-Ertekin, Figen; Ilicali, Coskan
    The convective oven cake baking process was investigated by experimental and numerical methods as a simultaneous heat and mass transfer process. A mathematical model was established representing cake baking in finite cylinder geometry. The heat and mass transfer mechanisms were defined by Fourier's and Fick's second laws, respectively. The implicit alternating direction finite difference technique was used for the numerical solution of the representative model, where the initial and boundary conditions were defined in accordance with the nature of the cake baking process. The numerical solution of the model simulated the process, and predicted temperature and moisture profiles within the baking cake batter as output, considering the volume increase. Prior to the utilization of the developed model in predicting the temperature and moisture profiles for cup cake baking, the results of the numerical model were compared with analytical results involving only heat or mass transfer with constant thermophysical properties. Excellent agreement was observed. The simulated results for cup cake baking agreed generally well with the experimental temperature and moisture profiles recorded during a complete cake baking process. (c) 2007 Elsevier Ltd. All rights reserved.