Vacuum Precooling Model of Leaf Vegetables

In order to study the variation law of temperature field,water concentration field and water vapor concentration field in the vacuum precooling process of leaf vegetables,Comsol software was used to establish a vacuum precooling model,which included the coupling process of diffusion and heat transfer of porous media and was solved by five parts simultaneously. The reliability of the vacuum precooling model was verified by simulating the ham with simple structure. The applicability of the model to leaf vegetables was further verified. The results showed that Ham surface temperature maximum difference was 3.1 ℃,and center was 4.3℃. The overall temperature trend was the same. The model had reliability. The maximum temperature difference of spinach from leaf vegetables was less than 3 ℃. The temperature variation trend of spinach,cabbage,cabbage and cabbage was consistent with the simulation. The model was suitable for leaf vegetables. The results showed that leaf vein affected the parameter distribution of leaf vegetables. Temperature,water concentration and water vapor concentration were all lower along the veins. It could guide the setting of various parameters of vacuum precooling.