Simulation Model And Optimal Operation Of Central Cooling System Based On Water Storage

The central cooling system has the advantages of high energy utilization rate,environmental protection,convenient management and maintenance,etc.,and is widely used at home and abroad.However,the traditional central cooling system has a large difference in energy consumption between day and night,which leads to problems such as low system energy efficiency,high operating costs,and increased grid burden.In order to alleviate the peak and valley pressure of the power grid,reduce the energy consumption of the system,and make the system run economically,this topic takes a central cooling system based on water storage as the research object,establishes its simulation model,and conducts its operation characteristics and optimal operation.researched.In this paper,3 office buildings and 2 shopping malls in a commercial district in Guangzhou are selected as target users,and a central cooling system is designed.The system mainly consists of chillers,cooling towers,pumps,cold storage tanks,pipe networks,users and auxiliary equipment.composition.Based on the idea of modular modeling,the centralized cooling system is divided into three parts: cooling station,pipe network and users,and modular mathematical modeling is carried out for each part.Using the lumped parameter method,mathematical models such as chiller model,cooling tower model,water pump model,cold storage tank model,pipe network hydraulic calculation and thermal calculation model,and user model are established.The above model is written into a computer program using Fortran language,and the cooling station,pipe network and user modules are established with the help of the IMMS model development platform.Model.Based on the established central cooling system simulation model,the effects of chilled water outlet temperature and outlet flow rate,cooling water inlet temperature and inlet flow rate on the system energy efficiency and power consumption were analyzed.According to the pipe network,the static variation law of the cooling capacity of the chiller,the cooling capacity conveyed by the pipe network,the power consumption of the chiller and the cooling loss under different loads,and the step disturbance of the system load,the chilled water supply temperature and the chilled water supply flow,are analyzed.The dynamic change law of the cooling capacity of the chiller,the cooling capacity transported by the pipe network,the power consumption of the chiller and the temperature of the return water in the cooling station is analyzed,and the time lag of the cooling capacity transport process is analyzed.The thermal conditions of end users,intermediate users and the most end users are analyzed,and the simulation results are analyzed to verify the accuracy of the model.In addition,the optimal operation of the central cooling system was studied,and three operating strategies were formulated,including the independent cooling of the chiller,the optimal cooling of the storage water tank,and the priority cooling of the storage water tank.The results show that the optimal cooling of the water tank and the preferential cooling of the water tank are not obvious in energy saving compared with the single supply of the chiller,but they have better peak shifting and valley filling benefits and economy,and the peak shifting rate is 64.6% and 14.8%.The rate reaches 28.6% and 14.8%.Compared with the cooling water tank priority strategy,the cooling effect and the economy are better.