Simulation And Control Analysis Of The Central Air Conditioning Water System In A Large Commercial Building

In the actual operation of the central air-conditioning system of large commercial buildings,many problems are often caused due to the large cooling area and high cooling load.For example,the equipment selection is too large,the equipment unit is improperly controlled,and the pipe network is too complicated,which leads to hydraulic imbalance.These problems not only lead to higher energy consumption during operation,and increase in equipment maintenance costs in the later period,but also easily reduce the cooling effect of end users.In order to achieve the country’s sustainable development,sound and fast development goals,on the one hand,it is necessary to "expand domestic demand and upgrade consumption",and on the other hand,it is necessary to achieve the goal of "carbon peak by 2030 and carbon neutral by 2060".In this context,energy-saving optimization and transformation of large-scale commercial buildings is particularly important.This dissertation takes the central air-conditioning chilled water system of a large commercial building in Wuhan as the research object,and conducts research on the important and difficult points such as hydraulic imbalance and refrigeration unit group control that are prone to large-scale chilled water network.Analysis,software modeling,and comparative result analysis,to specifically solve the corresponding problems of the project.In view of the static hydraulic imbalance caused by the complicated main network and the large distribution range of different branches,the static flow balance valve is used to adjust the resistance coefficient of different branches,which fundamentally solves the problem of unbalanced resistance;for different zoning purposes For the problem of large cooling load fluctuations in different periods,the dynamic balance valve is used to adjust the pipeline resistance in real time to meet the cooling load needs of end users;at the same time,in order to improve the operating efficiency of the equipment on the mechanical room side and enhance the stability of the equipment and water supply,The water pump adopts a variable frequency for constant pressure controlling,and an optimized control strategy for circulating control of the refrigeration unit.After completing the simulation platform construction and parameter calibration,simulations are carried out for different situations.The results show that under steady-state conditions,the static flow balance valve can significantly improve the steady state of hydraulic imbalance;under transient conditions,the dynamic balance valve can ensure that the terminal water supply meets the requirements.The frequency conversion for constant pressure controling of the water pump have also achieved preeminent effects.The pressure difference between the supply and return water of the sub-catchment is maintained within the set value,and the energy consumption of the water pump is reduced by more than 35%compared with the power frequency operation.The start and stop of the refrigeration unit are also adjusted,which greatly improves the operational stability and avoids the problem of too frequent state change of the unit.