Computational Fluid Dynamics Modeling The UV-sterilization Of Fresh Apple Juice In Fluid Film

The content of this research paper was a part of the item - "the study on key technology of high quality fresh apple juice and concentrated cloudy apple juice" in the Tenth-Five-Year Science and Technology Plan of China.Fresh apple juice is becoming more and more popular and have already being an important aspect of apple juice for its' sterling flavor, abundant nutrition and moderate prices. Before the sterilize, the fresh apple juice contains various microorganism, which influence the juice's quality and the shelf life. As a new and effective approach, cold sterilization is geting more and more widely used in the food industry, among these new approaches ultraviolet sterilization receives much recognition, because of its high sterilizing effect, lower investmen, easy to operate, and no empoison after sterilization. This paper mainly based on the speciality that ultraviolet can kill almost all the microorganism and is weak in penetrability, use ultraviolet to sterilize the microorganism contained in the fresh apple juice. The juice was formed in fluid film in order to ensure the sterilization in a high penetrability and get a well sterilizing effect, which keep the natural flavor and nutritional qualities furthest. The paper studies several microorganism's endurance,in addition, the factors of irradiating time, irradiating distance,thickness of fluid film were analized respectively to establish the relationship between the factors and the sterilizing effect and make the boundary condition. In order to predict the effect of ultraviolet precisely, it is necessary to use computational fluid dynamics (CFD) analysis, which can be done with the help of a number of available commercial software. The more the cumulative ultraviolet energy the batter the sterilizing effect according to this theory, the simulation was carried by using CFD-code in different entrance velocity and flow patterns. The simulation display the density contour of active bacteria, predict the contour of velocity and turbulence intensity straightly, which provid theoretical foundation for effective flow pattern and controls parameter of sterilization.The...