Innovative method of engineering phase change within a bulk fluid (Energy efficient way of manufacturing ice)

制冷在能源消耗研究中往往被忽视，然而，空调、制冷和制冷是主要的耗能活动。按需产生冷却是低效的。在非高峰时段产生寒冷，并在有需求的时候使用它的想法非常有吸引力。产生恒温冷槽的最简单方法是使用相变材料，这种材料在相变的同时能够吸收大量的热量。最吸引人的相变系统之一是可泵送的泥浆冰。泥浆冰是一种优良的储热介质，本身就是一种环境友好型的蓄热介质。所有商用制冰机都有一个寒冷的表面，允许在其上形成冰，然后通过机械或热力去除冰。为了提高结冰速度，必须增加冷表面的面积或降低其温度。这两者都有经济上的惩罚；大的表面意味着大的昂贵的单元。较低的温度意味着较低的能源效率。该项目是关于在主体流体中(远离固体表面)以连续可靠的方式产生冰。这需要在以下几个方面进行研究：1.过冷环境中的相变。形核位置及其对相变的影响3。混合含有不同量溶质的不同温度的溶剂流4.可混相流体中的传热传质5.在驱动温差较小的情况下优化换热拟议的新制冰技术将有一个盐水冷槽。传统的制冷装置将不断地从冷盐水中带走热量，这将把盐水冷却到例如-15摄氏度，但不会冻结它。然后将冷水(温度为0摄氏度)引入冷盐水中，这会导致一些水冻结。结冰的水量取决于纯水在结冰前与盐水的混合程度。这是一个复杂的现象；我们需要水和盐水之间的高传热，同时需要低传质和非常低的混合。这是一个要求很高的工作领域，因为水和盐水之间的区域界限不清，而且受到混合和扩散的强烈影响。尽管如此，制冰机的性能将取决于两种流体之间的传热与传质的比率(这一比率通常被称为刘易斯数)。这项工作将以实验工作为基础，这些实验工作将提供数据，以帮助理解和制定比例规则。最初的实验工作将首先在一个简单的冷冻容器中进行，以证明在可混溶的流体中而不是在固体界面上产生冰的能力。下一步的实验工作需要更复杂的设备，需要泵送冷却卤水流，并有能力收集白酒中产生的冰。

Refrigeration tends to be overlooked in energy consumption studies, however, air conditioning, cooling and refrigeration are major energy hungry activities. It is inefficient to generate cooling on demand. The idea of generating cold during 'off-peak' periods and using it whenever there is a demand is very attractive. The easiest way of generating a constant temperature cold sink is to use phase change materials which are able to absorb large quantities of heat whilst undergoing phase change. One of the most attractive phase change systems is pumpable slurry ice. Slurry ice is an excellent thermal storage medium which is inherently environmentally friendly. All commercial ice generators have a cold surface on which ice is allowed to form, the ice is then either mechanically or thermally removed. To increase the ice generation rate, the area of the cold surface has to increase or its temperature has to decrease. Both of these have economic penalties; large surfaces mean large expensive units. Lower temperatures imply lower energy efficiencies. This project is about the generation of ice in a continuous reliable manner in the bulk fluid (away from solid surfaces). This requires study in the following:1. Phase change in super cooled environments2. Nucleation sites and their effect on phase change3. Mixing solvent streams of different temperature containing different amount of solutes 4. Heat and mass transfer in miscible fluids5. Optimisation of heat transfer with small driving temperature differencesThe proposed new ice making technique will have a brine cold sink. Heat will continually be removed from the cold brine by a conventional refrigeration unit, this will chill the brine to say -15 oC, but not freeze it. Chilled water (at 0 oC) is then introduced into the cold brine, this results in freezing of some of the water. The amount of water which freezes depend on the degree of mixing of the pure water with the brine before it freezes. This is a complex phenomenon; we require high heat transfer between the water and the brine, whilst needing low mass transfer and very low mixing. This is a demanding field of work as the area between the water and the brine is ill defined and strongly affect by mixing and diffusion. Nonetheless the ice maker's performance will be dependent on the ratio of heat transfer to mass transfer between the two fluids (this is ratio is generally referred to as the Lewis number). The work will be underpinned by experimental work which will provide data to assist in understanding and in developing scaling rules. The initial experimental work will initially be undertaken in a simple chilled container to demonstrate the ability to generate ice within a miscible fluid and not at solid interfaces. The next experimental work requires more sophisticated equipment, with pumped chilled brine streams and the ability to harvest the ice generated within the liquor.