| Summary: | 碩士 === 國立屏東科技大學 === 機械工程系 === 90 === In this research, the cooling process of carrot, radish, potato, Indian jujube, night-blooming gereus, guava, and wax-apple was studied. This thesis develops a simple but very effective method which combines the center-line-fixed-temperature method and the flow field simulation program PHOENICS to predict thermal conductivity (κ) and thermal diffusivity (α) of fruits and vegetables. A measuring system was also designed to test the developed method. The cooling curves of various specimens were established by measuring samples'' center temperatures using thermocouple and temperature recorder during the cooling process. The cooling curves from both experiment and simulation were compared with each other. Experimental parameters for heat transfer and boundary conditions of fruit and vegetable were fed to the flow field simulation program, and solved the heat conduction equation. The results showed that the differences of both aforementioned methods were minute, and the trend of cooling curves were corresponding consistent. Therefore this developed model can be utilized in predicting temperature distribution for fruit and vegetable during cooling or cold storage.
Also in this study, wax-apple produced the freshness of in Ping-Tong were also studied for its low temperature, high humidity storage. The results indicated that low temperature contributed to the improvement of shelf-life, color change, and texture, comparing with room temperature storage. It proved that 12℃ would not cause the chill injury, and showed be useful in preserving the quality for fruits and vegetables.
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