【作者】 董晓丽；

【导师】 赵敬德；

【作者基本信息】 东华大学 ， 热能工程， 2012， 硕士

【摘要】 20世纪90年代以来,为了加快我国的经济发展步伐,我国采取了许多方法来刺激经济的发展。但是随着经济的快速增长,能源供应不足成为制约中国国民经济发展的瓶颈。在面临如此巨大的能源挑战问题,通过降低空调冷冻水系统输送能耗来实现节能显得很有意义。冷冻水大温差技术作为一项很有潜力的节能技术,受到人们的关注。冷冻水大温差是一项通过提高冷冻水的供回水温差、减少冷冻水流量来降低空调冷冻水泵输送能耗的节能技术。本文就冷冻水大温差系统进行了以下几个方面的研究：空调系统采用大温差冷冻水大温差系统对冷水机组蒸发温度、压缩机的单位制冷剂耗功及冷水机组COP的影响的研究；以风机盘管作为末端装置,就冷冻水大温差系统对风机盘管性能的影响进行了研究；冷冻水大温差与变流量系统结合,采用变频调速水泵代替常规水泵,研究部分负荷下,变频调速水泵的瞬时功率；利用静态经济分析方法,建立冷冻水大温差变流量系统的优化模型。以上的研究主要得出以下几个结论：对于冷水机组而言降低供水温度,使得冷水机组蒸发温度下降,冷水机组效率下降；建立了压缩机单位制冷剂耗功与冷冻水供水温差及供水温度之间的关系式；冷冻水大温差系统对风机盘管的潜热影响最大,并得到对于风机盘管而言,最佳供回水温差与供水温度之间的一一对应的关系；针对冷水机组和风机盘管这两部分,初步得到了系统最优供回水温度的取值范围。供水温度在5.43℃以上,回水温度在12-13℃左右。本文不仅定性的研究了空调冷冻水大温差系统对冷水机组、风机盘管、冷冻水泵的影响,还对系统进行了优化,为其在实际工程中的应用提供理论根据,也为今后进一步的研究提出了问题和方向。此外,本文还提出用微胶囊悬浮液来代替水做为载冷剂,来降低空调冷冻水的输送能耗。并进一步对微胶囊悬浮液进行了研究。微胶囊浆液是由包裹相变材料的微胶囊颗粒与载流体组成,是·一种新型的融储热与传热于一体的潜热型功能热流体,它能够提供较大的相变潜热,从而增大微胶囊浆液的有效比热容,降低空调冷冻水输送能耗。本文在该微胶囊浆液国内外已有的研究工作基础上,运用理论分析计算的方法研究了微胶囊浆液对冷水机组和空调末端(风机盘管)的影响,并定量的计算出其影响程度。具体的工作如下：概述了微胶囊液应用在冷冻水系统中的优势,对近几年国内外众多学者所做的相关文献进行了介绍总结。介绍了微胶囊浆液中相变材料的选取方法,微胶囊浆液的进出制冷机的温度的制定方法。介绍了微胶囊浆液的物性参数的具体的计算方法,引入了微胶囊浆液的有效比热。并根据相似原理,分析得到微胶囊浆液的对流换热系数与相同温度下水的对流传热系数的比。通过对微胶囊浆液的分析研究,结果表明：当C14/C16以16：25的质量比混合作为相变材料时,微胶囊浆液进口温度为11℃、出口温度为7℃为宜。微胶囊浆液的质量分数不宜太大,应低于17.7%。质量分数取0.1时,微胶囊浆液的有效比热容是水的2.1,Nusselt数是水的0.7倍,对流换热系数减少了近35%左右。制冷量相等时,采用微胶囊作为载冷剂时,蒸发器的蒸发温度降到3.8℃。微胶囊浆液对空调末端风机盘管面积的影响程度不大更多还原

【Abstract】 Since the1990s, in order to speed up the pace of economic development, our country adopted many ways to stimulate the development of the economy. But with the rapid economic growth, the energy supply constraints become the bottleneck of the national economy development. Facing such a great energy challenges, it seems very meaningful to study how to reducing energy consumption of air conditioning chilled water system. As a potential energy-saving technology, the technology of chilled water with large temperature difference raises concerns of the public.Chilled water temperature difference is an energy-saving technology to reduce transport energy consumption of air conditioning chilled water pump by raising supply and return temperature and reducing the flow of chilled water.In this paper, we made some research on the system of chilled water with large temperature difference from the following aspects:the effect of the use of the system of chilled water with large temperature difference in the air conditioning system on the evaporation temperature of the chillers, the power consumption with unit refrigerant of the compressor, the COP of the chillers; the effect of the system of chilled water with large temperature difference on the fan coils, which are the main terminal devices; the research of instantaneous power of the variable-frequence pump under partial load, with the premise of the combination of the system of chilled water with large temperature difference and the system of variable flow, and the variable-frequence pump instead of conventional water pump; the construction of the model of the system of variable flow with chilled water under large temperature difference, using the method of static economy analysis.The conclusions show as follows:for the chillers, as the temperature of water supply decreased, the evaporation temperature reduced, and the efficiency of the chillers decreased; the establishment of the correlations of the power consumption with unit refrigerant of the compressor and the temperature difference and the temperature of water supply; the effect of the latent heat of the system of the chilled water with large temperature difference on the fan coil is the greatest, and for the fan coil, the reasonable temperature difference between the water supply and the return water and the supply water was one to one relationship; for the chillers and the fan coil, we preliminary got the best range of the temperature of the supply water and that of the return water, and the temperature of the supply water is above5.43, the temperature of the return water is in12-13.In this paper, we not only qualitatively studied the effect of the system of the chilled water with large temperature difference on the chillers, fan coils, and the chilled water pump, but also we made an optimization on the system, which provided the theory basis for its application in engineering, and put forward some questions and direction for the further research.In addition,the opinion that using microencapsulated suspension liquid instead of water as a coolant can reduce the energy consumption of air conditioning chilled water.The microencapsulated suspensions were studied. Microencapsulated phase change material suspension consisted of the microencapsulated particles of phase change material and the carrier fluid is a new kind of functionally latent thermal fluid, which can storage and transfer energy. Through supplying larger latent heat of phase change to increase the effective heat capacity of microencapsulated phase change material slurry and decrease the transportation energy consumption of air-condition cooling water.In this paper, on the basis of the existing research work of microencapsulated phase change material slurry(MPCS) at home and abroad and using the theoretical analysis and calculation methods to study the impact of MPCS to chillers and air-condition end(fan coil), and quantitatively calculates its degree of influence. Specific work is as follows:Made an overview of the advantage of the application of the MPCS in the chilled water system, and summarizes the literature of many scholars ant home and abroad in recent years.Introduced the selection about phase change materials and the methods of fixing the inlet and outlet chillers temperature.Introduced the specific calculating method of the MPCS’physical parameters and raises the effective specific heat of MPCS. Based on similar principles, analyzed the ratio of the convective heat transfer coefficient between the MPCS and water at the same temperature. By analyzing of MPCS, the results show that:when C14/C16at quality ratio of16:25mixed as the phase change material, the better inlet temperature of MPCS is11℃, and the better outlet temperature is7℃. The mass fraction of the MPCS should not be too large and should be less than17.7%. When mass fraction of the MPCS is0.1, the effective specific heat is2.1times of water and Nu is0.7times of water, the convection heat transfer coefficient decreas nearly35%. When cooling capacity is the same, using MPCS as the refrigerant evaporator the evaporation temperature is dropped to3.8℃, but the impact to the area of the fan coil is litter.更多还原