【作者】 黄啸；

【导师】 陆茵；

【作者基本信息】 宁波大学 ， 水产品加工及贮藏工程， 2011， 硕士

【摘要】 中空纤维膜无泡供氧是指液相内无肉眼可见气泡的供氧方式,其传氧模式是将加压空气或纯氧连续通入中空纤维膜的管腔内,水在管外流动,在膜两侧氧分压差的推动下,管腔内的氧透过膜壁上的微孔扩散进入管外的水中。疏水性中空纤维膜组件膜壁上有大量孔径在10-1μm数量级的孔道,与水接触时由于材料的疏水性和毛细管效应,水不会进入这些微孔,而另一侧的气体则可以充斥于微孔中,在微孔末端与水接触并进行传递,由于其单位体积中有大量微孔,在作为无泡供氧器时水气的接触面积特别大,气液传质效果好,与传统的泡式供氧相比,这种新颖的膜式无泡供氧具有传氧效率高、无泡沫产生,具有滤菌作用,动力消耗低等优点,因此水体的无泡供氧方式可用以解决水产品活体长途、高密度运输过程中的水体缺氧问题。本文首先将中空纤维膜无泡供氧这种新型的水体充氧技术的实际充氧效率与密封供氧和鼓风供氧两种传统水体充氧技术的实际充氧效率进行对比。结果表明膜式无泡供氧能在最短的时间内实现较好的充氧效果,充氧能力明显优于另外两种充氧方式,证明了膜式无泡供氧的高效性。在此基础上利用中空纤维膜组件作为膜接触器,以纯氧为气源对水体进行无泡充氧实验,建立了一个新的传质模型,结果表明总的传质系数随供气压力的增加而增加;水流速度对中空纤维膜供氧传质效果的影响与传统的流速对传质系数的影响规律有所不同,随着流速的增大,氧的传质系数存在一个先增加、再减小、而后再增加的变化,因此在用膜接触器进行液体充氧时需要选择合适的流体速率,以达到最佳传质效果,从传质理论上实验证明膜式无泡供氧技术的科学性。最后利用膜式无泡供氧技术,首次将该充氧方式应用到水产品活体运输领域,针对水产品活体长时间运输水体充氧效果不佳影响其存活率及目前时兴的活物礼品市场,设计了一种礼品装水产品活体运输箱,并进行水产品活体的模拟运输,水产品的存活率均达到95%以上,取得了理想运输结果,证明了膜式无泡供氧技术的实用性。更多还原

【Abstract】 Bubbleless aeration using hollow fiber membrane contactor is a novel aeration method without visible bubbles. With the flowing of pressure air or pure oxygen in the lumen-side and water in the shell-side in a opposite direction, oxygen can diffuse into the water through the membrane micropores because of the oxygen pressure difference. There is a large amount of pores which size is around 10-1μm in the hydrophobic hollow fiber membrane. In the shell-side, due to the hydrophobicity of the material and capillary effect, water cannot permeate into the lumen-side of the membrane. While in the other side, gas filling in micropores can transfer into water in high efficiency since the relatively large contact area between gas phase and liquid phase, the hollow fiber membrane contactor shows a good performance of gas mass transfer. Compared to the traditional bubble aeration, the bubbleless aeration has obvious advantages, such as high efficiency of oxygen transfer, no bubble, filtering bacteria and low power consumption. Consequently, this novel aeration method can be used to solve the hypoxic water problems during the long distance and high density transportation of living aquatic products.Firstly, the oxygen transfer efficiency of bubbleless aeration using hollow fiber membrane contactor is compared to that of sealed bag aeration and air blast aeration. The results show that bubbleless aeration represents a good oxygenation capacity. It can significantly increase the dissolved oxygen in a short period of time. It fully proves the high efficiency of bubbleless aeration in water oxygenation.Secondly, the hollow fiber membrane module is used as a contactor, and the air supply is pure oxygen. Bubbeless aeration experiment has been done and a novel mass transfer model of the process is established. The result shows that with the pressure increased, the oxygen mass transfer coefficient increases. In other way, the oxygen mass transfer coefficient increases dramatically, and then decreases dramatically, finally increases gradually when the water flow velocity increase. This is differ from traditional rule. Consequently, it’s demanded to choose a appropriate liquid flux to achieve the optimum result when hollow fiber membrane bubbeless aeration utilized. It fully proves the scientificity of bubbleless aeration from the theory of mass transfer.Lastly, in this paper, the novel aeration method is firstly applied in the field of living aquatic products transportation. Aimed at tackling survival rate of living aquatic products in long distance transportation affected by dissolved oxygen and currently fashionable living creature gift market, a gift packed transporting apparatus is designed. The experiment of high density transportation of living aquatic products shows that the survival rate is above 95%. Consequently, this apparatus is effective in high density transportation of living aquatic products. It fully proves the practical applications of bubbleless aeration.更多还原