Research On The Optimal Control Of The Air-Conditioning Unit Water System And Procedure Development

According to the survey, our country has about 40 billion square meters existing building area and construction area will increase 2 billion square meters a year. Chinese building energy consumption has exceeded the energy consumption of construction and industry accounts for a third of total energy consumption.40 to 54 percent of Chinese energy is consumed by the air conditioning heating and cooling system in which system energy consumption is 70 percent and pump energy consumption is 25 percent. How to reduce the energy consumption of air conditioning system is the key of building energy saving and emission reduction. Factors affecting the energy consumption of air conditioning system, in addition to product quality, are mainly design and the control strategy. With the development of frequency conversion technology, variable water system has been widely used by designers and its energy saving effect is obvious in practical engineering. Because the control method of variable flow water systems are more complex than the constant flow. The choice of control strategy is likely to reduce the energy saving effect or increase the energy consumption of the system. So the control strategy of variable flow water system has been a hot research field of HVAC.In this paper, in order to the goal that energy consumption minimum of air condition water system. On the basis of the study of characteristic of heat transfer in air handling unit, a control strategy that combined variable water temperature and flow and compiled a control software are proposed in order that this theory can be applied for practical engineering.Firstly, the surface air cooler’s dry and wet condition mathematical model are established and the experimental data provided by the manufacturers are fitted to get heat transfer coefficient and contact coefficient equations. By the theoretical calculation of the established mathematical model, the heat transfer dynamic characteristics are analysed.Secondly, energy consumption calculation models of chiller and chilled water pump which parameters are modified are established. Based on the analysis of energy consumption, an optimized control strategy that made energy consumption minimum are proposed.Finally, a optimal outlet water temperature and flow control software of air conditioning water system based on MATLAB7.0 are compiled and the GUI are developed to modify critical parameter for different types of terminals and the heat and cold sources conveniently in practical engineering in the future.