This research was conducted to study heat transfer in Japanese pears based on their exact geometry as measured by a 3D laser scanner. Some of the thermal properties of three cultivars of Japanese pear (Pyrus pyrifolia) were measured, boundary conditions were defined and heat transfer modeling was conducted using COMSOL Multiphysics 4.2a software based on the finite element method. The thermal conductivity of each examined cultivar was estimated from the model and found to be 0.66 ± 0.01, 0.56 ± 0.09 and 0.58 ± 0.06 W/m•K for Kosui, Niitaka and Oushu, respectively, which are acceptable comparing to other fruits. The thermal diffusivity of the cultivars was also calculated and was in the range of 1.37 × 10 −7 to 1.76 × 10 −7 m 2 /s. Low RMSE values of the model results compared to experimental data were observed. The model was validated with data obtained from a thermal camera and the results showed that the model is successful in predicting the temperature profile inside the fruit at any time.
This research was conducted to study gas transfer in three cultivars of Japanese pear based on their actual geometry obtained from a 3D Laser Scanner. Gas diffusivity and skin resistance to gas diffusion found to be dependent on the cultivar. Gas diffusivity for ethane was found to be 8.10 1.2, 3.67 0.11 and 5.97 0.42 (10 8 m 2 s 1) for Kosui, Niitaka and Oushuu, respectively. Niitaka was found to have the highest skin resistance due to a noticeably lower number of lenticels on the skin. As expected gas diffusivity increased with increasing of temperature while skin resistance decreased. It was found that the diffusivity of CO2 is much lower than O2. The model was validated by conducting experiments to measure the internal concentration at different points of the fruit and comparing them with model results. The model was shown to be successful in predicting the internal gas concentrations.
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