| Summary: | 碩士 === 國立屏東技術學院 === 食品技術研究所 === 85 === AbstractIn this research, the freezing process of potato,
carrot, green soybean, corn, taro, hot dog, ham, codfish,
beefsteak, fried chicken, hamburger meat patty, minced pork
ball, and cuttlefish ball was studied. The freezing curves of
various specimens were established by measuring sample's surface
and center temperatures using thermocouple and temperature
recorder during the freezing process. Thermal properties, such
as specific heat capacity, thermal conductivity and thermal
diffusivity were calculated according to the empirical equations
and the compositions of specimens. Biot number, heat transfer
coefficient, and Nusselt number were calculated under different
wind speeds (Reynolds number), freezing temperatures, and the
thermal properties of experimental specimens. Results indicated
that increase of wind speeds and decrease of freezing
temperatures were helpful for the freezing process.Mathematical
relationships of Nusselt number, Reynolds number, Prandtl
number, Geometry factors (G, a/L, and b/L) were derived from
different experiment conditions. They wereNu=0.0037(Re^0.734)(
Pr^0.333)(G^7.122)((a/L)^1.475)((b/L)^5.501)Nu=0.015(Re^0.693)(
Pr^0.333)(G^3.944)((a/L)^0.509)((b/L)^2.573) and for the tested
vegetable specimens above and below freezing point,
respectively.For the tested meat and fish products above and
below freezing point, they wereNu=0.033(Re^0.563)(Pr^0.333)(
G^-1.377)((a/L)^-0.271)((b/L)^-1.124)Nu=0.948(Re^0.495)(
Pr^0.333)(G^-0.279)((a/L)^-0.494)((b/L)^-0.766) and
respectively. The simulated freezing curves were done by the
computer programs, and heat transfer equations of different
coordinate systems according to sample's geometric
characteristics. Results showed that the simulated and
experimental values were closely similar. Therefore, these
mathematical could be adequately used for predicting the optimal
time for different frozen foods in the freezing process. key
words: Surface heat transfer coefficient, Mathematic models of
heat transfer, Frozen foods.-IV-
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