Urban Heating System Of The Secondary Network Modeling And Dynamic Analysis

The central heating in northern China is developing very rapidly in recent years.Whether the heating area,radius,length of heating pipelines networks,or heating form had changed greatly.In order to improve the heating quality better,during the heating period,adjusted according to the needs of users of the thermal heat,which can not only meet the consumer needs of individual users on the temperature,but also can save the energy consumption,reduce pollutant emissions.However,the load regulation of heating system has been a difficult problem in the operation and management of heating pipe network.When the demand of hot users have changed,if the improper operation of regulation,not only caused a hydraulic loss,heating quality can't be improved,but also maybe lead to a further thermal imbalance.Therefore,it is very important to set up a simulation model of the hydraulic and thermal system of the central heating pipes networks.In this paper,based on mathematical graph theory and Kirchhoffs law,establish a hydraulic calculation model of the heating pipe network and simulate calculation of the various distribution pipe flow.Based on the calculated pipe flow,the heat dissipation and temperature variation of the length of each pipe section can be analyzed.For not easy to obtain building resistance parameters,is by the method of data to identify buildings as a "black box" model processing,fitting out the corresponding relations between pressure and flow rate.According to the energy conservation equation,grasp the main influence factors of room temperature,ignoring secondary factors,simplified heat user model,the buildings as a whole,does not consider building local differences.The dynamic model of the radiator,the peripheral protective structure and the indoor temperature is established.The influence of solar radiation and wind speed on the heat dissipation of exterior envelope is considered.The secondary network which is a residential area in Dongying,Shandong province,hydraulic calculation simulation model is established.Under different working conditions,simulate the flow distribution of each section and Analysis of the buried pipeline heat loss under different environmental temperature and temperature hysteresis response section in the OpenModelica.Using Modelica language program to simulate outdoor temperature,water temperature,water flow under the change of indoor temperature changes with the time.The model has been running in Dongying combined heat and power supply center,the trial operation results show that the hydraulic calculation model has high reliability and practicability,and the thermal inertia of buildings caused by the room temperature change law is basically in accordance with the measured data.