Research On Energy-saving Operation Management Of Central Air-Conditioning System In Public Buildings

Many countries have taken a number of energy-saving measures, and issued a variety of standards and norms to promote the implementation of building energy conservation Since the building energy saving ideas initiated by the oil crisis in 1970's. Energy-saving of air-conditioning system, which is a major focus of building energy efficiency, should be focused mainly on control and operation management.When put into operation after design and construction, energy consumption of central air-conditioning system is mainly influenced by operation management. In fact, as the terminal link of energy-saving of the system, it plays an important part. Taking ChangSha as a representative of the hot summer and cold winter zone, based on the investigation and detection of specific data, this paper analyzed the impacts of different control and operation management methods of central air-conditioning system on energy consumption and indoor comfort, and found that automatic control, frequency conversion equipment, in accordance with resetting the chilled water temperature with changing load and optimization control of start-stop unit were energy-saving measures of central air-conditioning system to achieve the economic operation and management.With the development of variable frequency technology, big temperature difference technology has also been promoted and applied, especially for chilled water system, it has been applied to many projects and have achieved a good example of the energy saving effect. However, with a number of limits, the big temperature difference for cooling water system application has been controversial, and in view of this situation, this paper, from the visual angle of economical technology, established mathematic models, and on the basis of the models, by optimization calculation which aimed at the minimum sum of the annual depreciation cost and operation cost, this paper educed the relationship between the cooling water temperature, temperature difference and the price of electricity. The results indicated that the optimum cooling water temperature difference is about 10℃untill electricity price goes to 21$/kWh which suggested that the cooling water big temperature difference has a wide foreground; the optimum cooling water temperature is between 31~33℃.It should be noticed that when the life of cooling tower and pumps goes longer, for example 20 years, and the value of Cat and U are 100$/(m3/h) and 121$/W, the optimum cooling water temperature difference is about 10℃untill electricity price goes to 9$/kWh. This article is also aimed at cooling water management detail. In the perspective the effect of concentration multiple on cooling water salt concentration, through analysis and calculation, the results showed that the greater the concentration, the bigger the cooling water salt concentration goes. CaCO3, as the most harmful and most common scale of the water system, its solubility is taken as a calculation basis, and results showed that to prevent scaling, the concentration multiple should be controlled in the range of 3 to 4.