Construction And Experimental Research Of Double-Layer Radiant Heating And Cooling Air-Conditioning System With Phase Change Energy-Storage

Independent humidity control air-conditioning is very important for energy-saving, which is widely used in building and other industrial fields. Compared with traditional air-conditioning, radiant heat exchanging system (typical independent humidity control air-conditioning) is more energy-saving, quiet and healthful. The most common radiant heat exchanging system is the radiant floor heating system, which can only work in winter and will be idle in summer. As a result, the maintenance consumption of the system will be improved and people need an additional refrigeration device to only work in summer, which will improve the cost and waste more building space. In order to improve the economy and reliability of the radiant floor heating system, a new air-conditioning with two energy-storage layers is proposed in this paper, which can realize both cooling and heating. This paper was focused on several key issues, including energy-storage and energy-release performance of the new system, effect of system structure on system performance and optimization of the new system under both two modes. The detailed results are shown as follows:Firstly, energy consumption of radiant floor heating system was analyzed and the application of radiant floor heating system with phase change material was researched. Furthermore, the disadvantage of the system was studied and a new double-layer radiant heating and cooling floor with phase change material was proposed. The high-efficiency electric driven heat pump was used as the energy source of the new floor and a new double-layer radiant heating and cooling air-conditioning system with phase change material was proposed. The new system can realize peak shifting and valley filling to reduce electric network pressure. What's more, the experimental system of the double-layer radiant heating and cooling floor with phase change material was built, which established the base of the heating and cooling experiment.Secondly, two experimental boxes were established. The cold energy storage layer is upper than thermal energy storage layer in box A, and the thermal energy storage layer is upper than cold energy storage layer in box B. The heating experiment of two different boxes was researched under three different operational conditions. The results show that the new system can meet the heating need of users. The significance of improvement of supplied water temperature is to reduce the time of thermal energy storage process of the system, which can reduce the energy loss in the energy storage process. Under the heating mode, the two-layer system in experimental box B has better thermal storage efficiency than that in experimental box A, and the temperature in experimental box B is higher than that in box A in the end of thermal energy storage process. In the heat release process of the system, the stability of air temperature in box A is better than that in box B, and the air temperature has a highest value in both two boxes. In the heat release process of the system, the floor temperature of box A improves with the running of the system, while the floor temperature of box B decreases with the running of the system, and the floor temperature of box B is higher than that of box A.Thirdly, the cooling experiment of two different boxes was researched under a typical operational condition. The results show that the new system can meet the cooling need of users. In the working process of the system, the air temperature is low as the air is closed to floor, where the temperature difference is higher than others. The cold energy storage ability of the cold energy storage material is closed in the two boxes. In the cold energy storage process, the levelling layer temperature changes later than thermal energy storage material. The stored cold energy in box A is more than that in box B. The heat transfer performance of box B is better than that of box A under the premise of considering the two modes. On the other hand, compared with box A, box B has better thermal comfort and no condensation.Finally, the heat transfer model of the double-layer radiant floor heating and cooling system with phase change material was established. The results show that the system can meet the need of users under both two modes. In the thermal energy storage process of the system, the layer temperature is high in centre layer and low in layers of both sides. When the supplied water temperature is 42?, the thermal energy storage ability of the thermal energy storage material is used completely. In the cold energy storage process of the system, the layer temperature is low in centre layer and high in layers of both sides. When the supplied water temperature is 16?, the cold energy storage ability of the cold energy storage material is used best. Under both cooling and heating modes, the temperature difference between condensing temperature and evaporation temperature of the heat pump in the double-layer radiant heating and cooling air-conditioning system with phase change material which uses electric driven heat pump as the energy source is lower than that of traditional heat pump. By this way, the coefficient of performance of the heat pump can be increased and the economy of the double-layer radiant heating and cooling air-conditioning system with phase change material can also be improved.