Study On Energy Analysis And Control Of Variable Flow System

The proportion of buildings'energy consumption in society is always high, and the energy consumption of air condition is about 40% of the buildings', so the energy-saving of air-condition system has significance for Energy-saving and Emission reduction. As one main department of air condition, water system has been a hot topic studied by experts and scholars.Variable flow system could adjust the volume by air condition load, it reduce the energy consumption of chillers and pumps, can save energy obviously. Comparing with Constant Flow system, Variable flow system is more complicated. For realizing energy-saving better, it need study the operating characteristics and control features. This thesis gives one research on variable flow system with the variable secondary flow system of one residence community in Hefei.This thesis analyses the control strategy of secondary variable flow system and the thermal feature of chiller, network and table cooler. It analyses the performance of pump and network running together. The secondary frequency conversion pump is important for controlling and energy-saving. It should choose the pump with sheer performance curve when two or more pumps are parallel connection. When the system adopts start/stop control, the volume of control point should be as small as possible; the network's impedance is added accordingly but not too much. Compared with the constant pressure control, Minimum resistance control's efficiency of energy-saving is better and performs more obviously at low load ratio.It proposed the concept of Total Hydraulic Balancing. A system designed well should consider the Co-ordination of each part besides the reasonableness of one part itself. If the total hydraulic balancing is not good, the effect of comfort and energy-saving would be worse. For realizing total hydraulic balancing, it could think about it from three fields.