Study On Optimal Design Of District Energy Base Station And Pipe Network

In the current environment of international energy conservation and emission reduction, regional energy technology has been widely spread and used. District heating and cooling system is a part of the regional energy system, with a combination of distributed energy, thermal power plants, city gas system, garbage power plants and other waste heat utilization as an energy cascade utilization system to greatly achieve energy conservation and emission reduction. The pipe network of transmission and distribution is an important part of the regional energy cooling and heating system, it is about 30% to 40% of total cost of station system and electricity consuming contributes high operating cost, therefore, this pipe network design will greatly determine the expenses and annual operating costs on regional initial investment of the energy heating and cooling systems. Here in this paper, with the example of energy transmission and distribution of the constructions in Shennong area(Zhuzhou City), the pipe network design will be studied through constructing a mathematical model to make it optimized, the main contents and results are in the following several aspects:Firstly, to build a regional energy station and a model of network optimization through theoretical engineering economics will effectively combine the energy conversation and efficiency of regional energy transmission and distribution pipeline system. The objective function of optimizing mathematical model is annual equivalent cost, with the constrained condition of pipe network flow velocity, discrete standard diameter, node flow balance, pipe segment water balance to meet the energy needs of users. By combining the pipeline network system of topological structure, each parameters and mathematical model through graph theory and get the final results through fmincon function of optimization tool box of MATLAB.Secondly, the energy station and pipeline optimization is main studied in three aspects: insulating layer thickness, station action radius, the secondary pump settings. Buried pipe insulation by building on conversion cost optimization objective function, the analysis reveals the relationship of the economic insulation layer thickness of directly buried insulating pipe, the flow temperature and the conductivity of insulation layer material; From the point of pipe temperature rising to construct thermal equilibrium among pump operating energy transmission, heat transfer loss between pipe and soil, fluid temperature rising. Ensuring the energy efficiency rate of refrigeration unit does not fall and with the premise of pipeline temperature rising, to study the affect relationship of station action radius with insulation layer thickness, the system cooling load and flow velocity in the pipe; Calculating the typical design day energy consumption of energy distribution system of inside and outside region of Shennong by not setting and setting secondary pump to compare and analysis the energy efficiency and location advantages.Thirdly, using MATLAB to run the program, taking an example of the energy transmission and distribution network of inside and outside of Shennong area, to get the diameter and insulation layer thickness of the pipe network and round the diameter based on discrete standard, it comes out the fluid flow speed and pipe specific frictional resistance meets the requirements of "national civil engineering design measures- HVAC power Volume". The result analysis is assessed among the power price, payback period for investment and the annual average depreciation rate.