屋顶纸盒灌装机包装材料灭菌模拟模型

Simulation model for the packaging material sterilization of gable-top carton filling machine

为保证屋顶纸盒无菌灌装机中包装材料无菌性,该研究采用质量分数为2%过氧化氢溶液雾化气溶胶对纸盒内表面进行灭菌,并基于纸盒灭菌过程建立数值模型并进行工艺优化。分析空气助力喷嘴雾化系统原理,结合计算流体力学(Computational Fluid Dynamics,CFD)与欧拉-拉格朗日(Euler-Lagrange)模型设置雾化连续相与分散相,得到不同雾化时间及雾化空气压力条件下溶液液滴直径、喷雾形状;通过实际条件下雾化形状对比,验证得到建立模型模拟结果与实际条件间误差较小(<15%),模型具有可靠性。在此基础上,建立纸盒灭菌过程数值模型,结合空气助力喷嘴雾化模拟与包装材料壁面液膜模型,分析250、500、1 000m L规格屋顶纸盒灭菌灭菌剂气溶胶覆盖均匀性。250m L纸盒存在底面过度灭菌、溶液覆盖残留量大,而1 000 mL纸盒存在底面灭菌不足、溶液接触量小等问题。通过调整喷雾高度、雾化空气压力等喷嘴雾化参数,优化纸盒灭菌工艺。250m L纸盒增加喷雾高度至50mm,1 000m L纸盒增加空气压力至200 kPa可使溶液分布均匀,改善灭菌效果,为屋顶纸盒灌装机包装材料过氧化氢气溶胶灭菌参数设置提供依据。

Packaging materials can be widely used to protect food products from contamination while in storage. In this study,the sterilization process was simulated and optimized using hydrogen peroxide(HO) solution atomized aerosol on the inner surface of a gable-top carton. The efficacy of hydrogen peroxide solution was evaluated with the different size boxes in the sterilization process. The process, principle, and influencing factors of solution atomization were analyzed using the sterilization process of hydrogen peroxide in the packaging materials of the roof box packaging machine. Finally, the optimal scheme was provided for uniform sterilization. The Euler-Lagrange model was selected to simulate the atomization process of an air-assisted nozzle. A comparison was also made to clarify the effects of atomization times and air pressure on the atomization quality. Specifically, the Droplet Sauter average diameter decreased, whereas, the atomization distance increased with the increase of atomization time. There was an increase in the spray distance, angle, and range, with the increase in air pressure. As such, a more uniform liquid atomization was achieved during this time. The different simulation conditions were compared with the actual spray debugging, in order to observe the spray shape. At the same time, the spray angle, and spray distance were measured under different conditions. It was found that the errors between the measured and the simulated values were within 15%, indicating the excellent performance of the simulation. The air-assisted spray model was then applied to the sterilization process, combined with the structural simulation of gable-top cartons with different specifications. There was a significant effect of carton specifications on the distribution of atomized droplets, especially in the bottom position.Specifically, the low height of the 250 m L carton led to a large number of droplets gathering on the bottom surface of the carton. There was a more outstanding increase in the spray height, and the atomized solution escape. By contrast, the solution aggregation of the bottom surface was reduced for the more uniform distribution of the side solution. Therefore, the optimal spray height was achieved for uniform and safe sterilization, indicating the higher concentration of HOresidues on the bottom surface. In 1 000 mL cartons, almost no droplets were attached to the bottom end and bottom surface, due to the higher height than that of the rest. In this case, the distribution of the liquid film was more uniform, whereas, the higher thickness was obtained to increase the atomizing air pressure. Therefore, the optimal air pressure was recommended to appropriately increase for better sterilization. More importantly, there was insufficient bottom of the carton sterilization. The numerical model of hydrogen peroxide sol sterilization can be expected to combine with different process parameters, thereby to output the simulation for higher sterilization efficiency. At the same time, the process parameters were optimized for the different cartons.The finding can also provide a strong reference for the process design of aerosol sterilization on the packaging materials,particularly diversified size roof carton filling machine in the future.