Research Of Reducing Energy Consumption Of Air Conditioning Chilled Water System

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.