Research And Appliction Of District Heating System Based On The Loop Expansion

Nowdays, energy resources have tended to be few and few, energy saving exists in our life every where.Central heating is one of the main infrastructures of modern cities, with the development of District Heating System, the network become more and more larger, the energy consumption has to be the half of the building energy consumption.The traditional heating network, that pump were singly set up in heat source, is not energy saving. The regulation valves consume at least 30% energy, which is very wastefull. With the extensive use of inverter technology and development of computer-controlled technology, a variety of pumps scheme appeared. According to present situation and the development trend of heating at home and abroad, this paper presents a new system:District heating system based on the loop expansion.This paper first introduces the basic principles and the basic form of the system, expounds on the structure and operation mode of Hydraulic bleeder which is one of the main equipment in the system. And using FLUENT software to simulate its internal flow conditions, the result shows that the internal pressure of the device is basically the same at run time. This plays an important role for improving the stability of pipe network. Compared the new system with direct connection form, mix water connection form and indirect connection form, and found that Hydraulic divider can replace the heat exchanger sometimes.Then, set up the mathematical model of the heating pipe network using graph theory, getting mathematical representation of the basic correlation matrix and the basic loop matrix. Establish pipe network characteristic equations and proposed a solution method which lay the foundation for the analysis of hydraulic conditions. And study a variety of pump scheme, pointed out the best matching:heat sources pump +heat users pressurized pump.The simulation analysis of hydraulic on conventional heating systems, optimal circulation pumps matching, as well as the new syetem show that the energy consumption of the central heating system based on the loop expansion is the least, energy saving rate is about 59%. The new system has good economy and worths to popularization and application.Though earring out analysis of hydraulic regime of heating network, we can know that the best position of zero pressure point is heat source export; it is nothing to do with the size of the heating netwok and load distribution. On the basis of that, this paper presents design methods and design ideas of the system.Finally, give an example with the new system of zhaoyuan, the actual operating parameters indicate the system can solve the hydraulic imbalance and its effect of saving energy is remarkable, save bout 43% than traditionl method in zhaoyuan.The desing method the paper presents is technically feasible and economically reasonable; and it can obtain huge economic and social benefits in practical engineering as long as design and application rationally.