Heat Transfer in Steaming of Rice Cake
Date Issued
2010
Date
2010
Author(s)
Wu, Shang-Tse
Abstract
Steaming is a common process in food processing, and many studies pointed out that the high convection heat transfer coefficient in steaming. However, in real processing, the steam quality had a significant effect on reducing the heating efficiency. Therefore, the purpose of this study was concentrated on estimating the convection heat transfer coefficient by steaming of rice cake. Mass transfer was less significant in steaming of rice cake for the mass difference was only 2.3 % after steaming process. In addition, the mass transfer of water barely affects the convection heat transfer. The phenomena reduced the complexity in estimating the convection heat transfer coefficient. In the study, COMSOL Multiphysics was applied to simulate the steaming of rice cake with the measured food properties as well as the convection heat transfer coefficient which was estimated by the lumped mass method and heat flux method. The estimated convection heat transfer coefficient was 800~5800 W/m2 K in lumped mass method; and was 50~480 W/m2 K in heat flux method. The results showed that the lumped mass method had the greater estimation in heat transfer coefficient than heat flux method by comparing the results between the simulation and experiment data. In the experiment of rice flours solution, the DSC result indicated that the gelatinization enthalpy appears at the range of 65 ~ 90 ℃. To simulate this phenomenon to predict the gelatinization enthalpy, different specific heat referred to DSC result was modified in COMSOL Multiphysics calculation. The model was successfully constructed with relative error 7.6 % between the experiment and simulation, so the increment of specific heat on predicting gelatinization enthalpy is valid.
Subjects
Steaming process
convection heat transfer coefficient
gelatinization
Type
thesis
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