Study On Control Method Of Pressure Difference Of Primary Pump Based On End Demand

As the world’s energy consumption continues to rise,the high energy cost and environmental problems become increasingly prominent.Meanwhile,the energy consumption of air conditioning system accounts for an increasing proportion in the total energy consumption of the society.Therefore,how to reduce the energy consumption of air conditioning system has been a hot issue.In the energy consumption of the air conditioning system,the energy consumption of the freezing water pump and the cooling water pump accounts for about 20% ~ 30%,and the flow rate and head of the water pump are determined according to the design condition.Therefore,it is of great practical significance to reduce the running energy consumption of water pump under partial load by adopting reasonable control method of air conditioning system to meet people’s living demand,so as to improve the running efficiency of air conditioning system,improve the energy utilization efficiency in China,and alleviate the contradiction between energy supply and demand.In this paper,the influence of different pressure differential control on water pump energy consumption is simulated by the variable flow water system of air conditioning.Firstly,the mathematical model of water pump,pipe network,unit and air conditioning terminal is established based on the actual air conditioning system.Then,the simulation platform was established through the mathematical logic relationship of pump head,flow rate and impedance,which made up for the lack of ignoring the hydraulic characteristics of the system by TRNSYS software.At the same time,three typical working conditions are simulated to verify the availability of the model,which lays a foundation for the simulation of pressure difference control strategy.On the basis of the traditional constant pressure difference control strategy,the advantages of the terminal demand combined with the most unfavorable thermodynamic circuit variable pressure difference control over the constant pressure difference,the system load variable pressure difference,the most unfavorable hydraulic loop valve opening variable pressure difference are analyzed.The results show that 28.9% of the system load variable pressure difference valve opening is 100%,which is likely to develop into the most adverse thermal loop to affect people’s comfort.Although the pressure difference of the most adverse hydraulic loop valve is the largest in energy saving,there are also 7% of operating conditions where the valve opening degree reaches 100%,which may not meet the requirements of people’s comfort.The end demand combined with the most adverse thermal loop control except the two design conditions,the valve opening in the best range of 92% to 98%,greatly meet the requirements of comfort and valve energy consumption is small,the pump efficiency can reach 61%,July-august water pump energy consumption than the fixed-frequency pump energy saving 68.75%.