Singh J P, Ghaly A E
Department of Process Engineering and Applied Science, Dalhousie University, Halifax, Nova Scotia, Canada.
Appl Biochem Biotechnol. 2007 Jul;142(1):1-16. doi: 10.1007/s12010-007-0004-9.
An ultraviolet (UV) coil reactor was designed and used for the online sterilization of cheese whey. Its microbial destruction efficiency was compared to that of the conventionally used UV reactor. Both reactors have the same geometry (840 ml volume and 17 mm gap size) and were tested at 11 flow rates of 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, and 70 ml/min. The results obtained from this study showed that despite of its high turbidity, cheese whey could be sterilized using UV radiation if the proper reactor design and flow rate are used. The performances of the UV reactors were governed by the flow rate and the hydraulics of flow inside the reactor. The flow was laminar in both the reactors, as the Reynolds number was in the range of 1.39-20.10. The phenomenon of Dean Flow was observed in the coil reactor and the Dean number was in the range of 1.09-15.41. Dean vortices resulted in higher microbial destruction efficiency in the coil reactor in a shorter retention time. The rate of microbial destruction was found to be exponential in the conventional reactor and polynomial in the coil reactor. Increasing the flow rate from 5 ml/min to 70 ml/min decreased the microbial destruction efficiency of the conventional reactor from 99.40 to 31.58%, while the microbial destruction efficiency in the coil reactor increased from 60.77% at the flow rate of 5 ml/min to 99.98% at the flow rate of 30 ml/min and then decreased with further increases in flow rate reaching 46.2% at the flow rate of 70 ml/min. The maximum effluent temperatures in the conventional and coil reactors were 45.8 and 46.1 degrees C, respectively. Fouling in the coil reactor was significantly less compared to the conventional reactor. The extent of fouling was influenced by flow rate and reactor's hydraulics.
设计了一种紫外线（UV）盘管反应器并用于奶酪乳清的在线杀菌。将其微生物破坏效率与传统使用的紫外线反应器进行了比较。两种反应器具有相同的几何形状（体积840毫升，间隙尺寸17毫米），并在5、10、15、20、25、30、35、40、50、60和70毫升/分钟这11种流速下进行了测试。本研究获得的结果表明，尽管奶酪乳清浊度高，但如果使用合适的反应器设计和流速，仍可利用紫外线辐射进行杀菌。紫外线反应器的性能受流速和反应器内部的水流动力学控制。两个反应器中的水流均为层流，因为雷诺数在1.39 - 20.10范围内。在盘管反应器中观察到了迪恩流现象，迪恩数在1.09 - 15.41范围内。迪恩涡旋在较短的停留时间内使盘管反应器中的微生物破坏效率更高。发现传统反应器中微生物破坏速率呈指数关系，而盘管反应器中呈多项式关系。流速从5毫升/分钟增加到70毫升/分钟时，传统反应器的微生物破坏效率从99.40%降至31.58%，而盘管反应器中的微生物破坏效率从5毫升/分钟流速下的60.77%增加到30毫升/分钟流速下的99.98%，然后随着流速进一步增加而降低，在70毫升/分钟流速下达到46.2%。传统反应器和盘管反应器中的最高出水温度分别为45.8摄氏度和46.1摄氏度。与传统反应器相比，盘管反应器中的结垢明显更少。结垢程度受流速和反应器水流动力学的影响。
