Dynamic Modeling And Application Of District Cooling System

With the rapid development of Chinese economy in recent years,the construction of urbanization is accelerating and the development of industrialization is deepening.Great changes have taken place in the scale,range and form of Network cooling.While at this stage to reflect real-time characteristics of cooling system simulation system is lack of interoperability and reusability,and for the use of the dynamic characteristics of the cooling system also stay in considering network delay and attenuation stage,for the development of the energy storage properties of pipe network is less.In this paper,by establishing the simulation model of the pipe fittings and the system of the regional cooling system,the dynamic characteristics of the regional pipe network are analyzed,and the optimization of the operation strategy based on the energy storage characteristics of the pipe network is proposed.The main research contents are as follows:The theoretical models of components in the regional cooling system are analyzed,including pipe model,chiller model,fan coil model and building model.A regional cooling system reflecting the dynamic characteristics of the pipe network is built on Dymola platform based on Modelica language.The correctness of the building model is verified by comparing the load value calculated by the Energy Plus software,and the correctness of the pipe model is verified by comparing the measured pipe data of a middle school in Tianjin.Dynamic characteristic of the regional network can be divided into attenuation,delay and energy storage characteristics.Three characteristics are analyzed in the physical,it is concluded that water temperature,outdoor environment temperature,network flow velocity and pipeline length of these four factors for the pipe network are the main influence factors of dynamic response.The sensitivity of these four factors to three dynamic characteristics of pipe network is analyzed by case test.Based on the primary network cooling system of an industrial park in Huizhou,Guangdong province,the application of dynamic characteristics of pipe network is investigated on the simulation platform of Dymola.Combined with Gen Opt program,the shutdown time and strategy of the cooling system before the end of work are optimized,achieving the effect of saving 21% of daily power consumption.Based on TOU price,the application of heat storage and delay characteristics of the pipe network has achieved the effect of saving 6.8% of daily electricity consumption and reducing8.1% of daily electricity charge.It can be seen that the virtual energy storage effect of the pipe network is an important resource for the refrigeration station to participate in the grid demand response.