The Study And Program Design On Energy-saving Strategies Of Central Air-conditioning Water System

The energy consumption of air-conditioning system usually accounts for more than 50% of the total amount in buildings. With the development of cold and heat source technology, the energy consumption proportion of regrigerating unit is decreasing while the building becomes more complicated due to the economy and technology blooming, which leads to the appearance of enormous central air-conditioning water systems. However, most water systems are still operating on constant flow state, and vast energy is wasted by water pumps. As one kind of the most effective energy-saving methods, variable flow and temperature adjusting measures in water system are paid more and more attention.Taking the main teaching building of ChongQing University for an example first, the optimal boot-up order of refrigerators were given based on the highest system efficiency and the operating characteristics of the chilled and cooling water systems were understood clearly by actual measurements, which provided some valuable reference for the system operation management.For the chilled water system, the feasibility of variable flow were analyzed by measurements and theories. The advantages and disadvantages were pointed out for the three typical frequency conversion control methods of water pump, and the stability of hydraulic operation condition were also researched on. According to a calculating example, the optimal frequency conversion method of multiple water pumps were given out. Besides, the energy saving rate of 5 most common frequency conversion methods were compared, and the optimal method was recommended by author based on the acture operating characteristics of chilled water system.For the cooling water system, the main controversies were discussed at the beginning of the corresponding chapter, and the feasibility of variable flow were verified by tests. The variable flow influence on unit efficiency were analyzed and applicabilities of different frequency conversion control methods were discussed. The energy saving rate of 6 typical frequency conversion methods were caculated, and the best control method was pointed out. At last, the energy saving effects were tested after the energy saving modification of central air-conditioning system.For the quality adjusting energy-saving measures of water system, the application of river-water source heat pump system was a good method. One design and assessment software was developed, which was also applied in the energy saving and emission reduction assessment for a actual river-water source heat pump system in Chongqing. At last, according to the test results of one system, the energy consumption in the river water intaking process was found to be the most important fator directly influencing on the system COP. Thus, the amount of energy saving by main unit and energy wasting by pumps must be balanced carefully before the system design.