| Because the centralized heat-supply system has the advantages including high heating efficiency,environmental pollution is easy to be disposed centralized,etal,the central heating in China has achieved rapid development in recent years as the country attaches great importance to and support vigorously.But because of the low starting point and starts relatively late,the energy efficiency of central heating system in our country’s is still low.In the face of increasingly severe global energy and environmental problems,energy-saving and efficiently operation of the central heating system become the problem which heating industry must pay attention to in our country.In order to realize the energy saving of heating system under the premise of meet the heat user’ comfort,we need to make the amount of heat supply from heat source is consistent with users’ heat requirement at any time.Therefore,analyze the dynamic thermal conditions of heating system becomes very important.Firstly,the thermal conditions calculation model of centralized heating system is build which is suitable to considering pipe temperature attenuation.The conventional heating network model is improved through adding nodes in the import and export of heat users,the network topology structure is established which is suitable to considering pipe temperature attenuation;thermal characteristics of direct connection heating system and indirect connection heating system are analyzed,and then thermal conditions calculation model of direct connection heating system and indirect connection heating system are build.The temperature attenuation degree calculation model of pipe segment is established based on the dynamic properties of the pipe network,and then using the actual operation data of heating system to verify the model,the results show the validity of the theoretical model.The thermal condition of heating system is analyzed by using the calculation model of thermal condition.The influence of temperature attenuation to the indoor temperature of heat users was studied under different operation modes.The analysis shows that the cooling of the network temperature should be considered in order to reduce the thermal imbalance of the user,and in each stage of heating,the influence of section temperature attenuation on the indoor temperature weakening with the increase of outdoor temperature. |
