Research On Energy Saving Of Central Air-conditioning Circulating Water System

Building energy saving is one of the problems concerned by the whole world, and it is also one of the important policies during the "Fifteen Five-Year Plan". Energy consumption of air-conditioner is one of the important components of building energy consumption. Therefore, air-conditioner energy saving is also one of the important researching subjects. Air-conditioning system includes air system and water system. Energy consumption of water system accounts for a large ratio in the whole air-conditioning system. Thus researching of energy saving of water system of air-conditioner is significant.Water transport equipment of air-conditioning system is pump. Energy consumptions during transportation include: loss of cooling capacity and flow resistance loss during transportation. For piping system which transport cooling capacity, the energy which overcomes flow resistance transfers into heat and results in loss of cooling capacity.Besides heat preservation of the water pipeline, the following things should be done to reduce energy consumption of the pump:1) Try to reduce the resistance of valves and filtersValve is the main component in regulating resistance characteristics of the pipeline. The resistance of valve will increase the delivery lift and electricity consumption of the pump, so regulating resistance by valve should be avoided as much as possible.2) Set suitable water flow rate Flow rate is proportional to electricity consumption of the pump. Flow rate of the air-conditioning system is determined by cooling load and heating load, and temperature difference of supply water and return water. The larger the temperature difference of supply water and return water and the smaller the flow rate, the smaller of electricity consumption of the pump will be.3) Enhancing pump efficiencyPump efficiency refers to the utilization degree of shaft power of prime mover by fluid. The efficiency varies from zero to maximum with different operating states. Under the same output power, if the efficiency decreases, the energy consumption of the pump will increase. Therefore, suitable pumps should be selected for the design of air-conditioning system to make them operating under optimum states.Firstly, energy saving analysis of qualitative regulation: and quantitative regulation of water system is made in the dissertation. Secondly, feasibility of pump energy saving in water system of air-conditioner is analyzed, and determination method of high efficiency section for the operation of several frequency conversion pumps is provided. Finally, a chilled water system model is analyzed in detail. Efficiency control mode based on the measuring of pump flow is proposed to ensure the pump operating in high efficiency area.