【作者】 王虹；

【导师】 何国庚；

【作者基本信息】 华中科技大学 ， 制冷及低温工程， 2013， 博士

【摘要】 冰浆的应用在节能方面存在巨大的潜力，减少了对环境有破坏作用的制冷剂的使用量，而且提高了供冷系统的性能。在能源短缺和环境保护要求日益迫切的当今，发展以冰浆为载冷剂的空调系统和冷却系统有着重要的意义和广阔的应用前景。冰浆的制取的方法有许多，其中过冷水法制冰技术因具有结构简单、换热效率高、冰晶制作效率高等特点，成为目前最受关注的动态制冰方式之一。然而，过冷水法制冰的主要缺陷在于过冷却器内结冰存在随机性，冰堵的发生过于频繁，导致系统制冰的断断续续，降低了系统的效率。论文总结分析了当前国内外有关过冷水动态制冰的研究成果，在分析引起冰堵的各种原因基础之上，首次在过冷水动态制冰中引入纳米氟碳涂层材料，并对纳米氟碳涂层性能对过冷却器壁面的影响进行了研究，表明纳米氟碳涂层材料显著改善了水在壁面上的润湿性，有效延迟了水冻结的时间。分别采用纳米氟碳涂层和扰动装置对过冷却器进行了改进，并在理论分析的基础上进行了一系列的过冷水动态制冰实验研究。涂到固体壁面的氟碳膜的平均厚度仅有9.7纳米，这层极薄的膜使得固体表面呈超疏水性，水在纳米氟碳氟碳涂层表面的接触角可高达163.01°。研究表明具有超疏水性的纳米氟碳涂层表面不但能有效抑制结冰也具有防结垢特性。通过对过冷水动态制冰的实验研究发现，采用纳米氟碳涂层过冷却器制冰时，可在过冷却器出口得到较大的过冷度，过冷状态持续时间较长，推迟了过冷却器冰堵发生的时间，冰浆的制取量增加，系统的制冰效率得到提高。在过冷却器内部增加扰动装置进行制冰时，虽然换热系数可得到提高，但却增加了更利用过冷水结晶的条件，使过冷却器发生冰堵的频率更高。本文还基于最小熵增原理和最小耗散原理，对过冷却器的换热性能进行了综合评价。经分析可知，与无涂层过冷却器相比，纳米氟碳涂层优化了过冷却器的换热状态，冷却器的性能提高，相应地也提高了整个制冰系统的效率，达到了节能的目的。更多还原

【Abstract】 There is a vast potential for the application of ice slurry in the energy saving due toreducing usage of the refrigerant with destruction of environment and improving theperformance of the refrigeration system. At present, the energy becoming less and less andthe requirement of environmental protection is daily increasing urgency. Therefore, as anenvironment-friendly medium of ice thermal storage, ice slurry can improve energyefficiency and reduce building energy consumption thanks to the latent heat of ice crystalsand its good fluidity. Supercooling water is used as a superior method to generate iceslurry for its high efficiency and energy conservation. However, the ice blockage occurredin the supercooling heat exchanger is a prominent problem that reduces the efficiency ofthe ice generation system. In this study, in order to avoid or retard ice blockage, afluorocarbon coating with super-hydrophobicity was applied onto the surface of thesupercooling heat exchanger to continuously make ice slurry without any additive.In this paper, n the basis of summarizing the research fruits of dynamic ice-makingusing supercooled water worldwide, a nano-fluorocarbon coating was first applied inice-making system. The surface characteristics of the nano-fluorocarbon coating wereinvestigated, the results showed that the surface wettability of water was significantlyimproved by this nano-fluorocarbon coating material, and the freezing time was delayedeffectively. A nano-fluorocarbon coating and a disturbing device were respectively usedfor the improvement of the supercooling heat exchanger, and a series experiments werecarried out accordingly.The average thickness of the nano-fluorocarbon coated on the solid surface was only9.7nm. It was the very thin film made the solid surface superhydrophobicity with thecontact angle of163.01°. This film not only has a good property in anti-icing but alsoanti-scale. Compared with the uncoated surface, the process of water freezing on thecoated surface with nano-fluorocarbon was slower which demonstrated that the icing onthe coated surface was restrained in the experiment. The experiments were conducted by the self-established ice-making system, and theexperimental results were analyzed. It was found that the supercooling degree in thecoated supercooling heat exchanger was higher, the supercooling state was longer, and thetime of ice blockage was delayed. Thus, more ice production can be obtained accordinglyand the efficiency of the whole ice-making system was enhanced. Though the heat transfercoefficient was increased using the supercooling heat exchanger with a disturbing device,it was more often blocked in the supercooling heat exchanger due to a more favorablecondition for icing offering by the added disturbing device.In this paper, based on the principles of minium entropy production and miniumentansy dissipation with the experimental data and the results, the heat exchangingperformance supercooling heat exchanger was evaluated comprehensively providing aground-work for the improvement and perfection in ice-making test system. The analyticalresults revealed that, the heat exchanging conditions were optimized in the coatedsupercooling heat exchanger with nano-fluorocarbon coating compared with the uncoatedone, the performance of heat exchanger was increased as well, as a result, the efficiency ofthe whole ice-making system was higher and the purpose of energy saving is also attained.更多还原