供热系统动态热特性研究
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摘要
供热系统动态热特性研究不仅可以优化供热系统运行调节,对于提高新能源供热的安全性、经济性、环保性也具有重要意义。本文利用节点法对供热系统的动态热特性进行研究,在快速且大幅度的热源供水温度变化情况下,利用节点法模拟距离热源不同远近的换热站的供水温度,分析供热管网的动态热特性。结果表明:每个换热站的总温降与距离热源的远近成正比,但是每单位长度的温降与距离热源的远近没有必然关系,主要与热源到换热站的管道流量(直径)和管长有关;同时分析节点法对不同温度变化阶段的模拟精度;节点法在快速且大幅度温度变化下的平均误差和标准差分别为0.46℃和1.18℃;最后通过定义动态响应时间分析流体在管网中的延迟时间,结果显示利用节点法计算得到的动态响应时间相对误差分别为5.8%和5.74%。所以节点法对于管网热动态特性研究的精度可以满足实际工程的需要。
The research on the dynamic thermal characteristics of district heating system can not only optimize the regulation of district heating system, but also have important significance for improving the security, economics and environment of new energy heating. In this paper, the dynamic thermal characteristics of district heating system were analyzed with an emphasis on temperature distribution of the network. Therefore, a modeling approach named node method was applied to simulate the temperature distribution at stages with large and quick temperature change. Moreover, the node method was validated by applying it to a real district heating network at different stages of temperature change and comparing with measurements. Results showed that the supply temperature of each substation was proportional to the distance from the heat source, but its temperature decrease per unit of length was irrelevant with the distance from the heat source. Such temperature decrease needed to consider the impact of the flow and length of pipe synthetically. Also, the comparisons disclose that the average error and standard deviation were 0.46 ℃ and 1.18 ℃, respectively. Finally, by defining the dynamic response time, the delay time of the fluid in the pipe network was analyzed. Results showed that the relative error of the dynamic response time calculated with the node method was 5.8% and 5.74%, respectively. Therefore, the node method was accurate enough to satisfy the requirements of practical engineering in the study of thermal dynamic characteristics of pipe network.
The research on the dynamic thermal characteristics of district heating system can not only optimize the regulation of district heating system, but also have important significance for improving the security, economics and environment of new energy heating. In this paper, the dynamic thermal characteristics of district heating system were analyzed with an emphasis on temperature distribution of the network. Therefore, a modeling approach named node method was applied to simulate the temperature distribution at stages with large and quick temperature change. Moreover, the node method was validated by applying it to a real district heating network at different stages of temperature change and comparing with measurements. Results showed that the supply temperature of each substation was proportional to the distance from the heat source, but its temperature decrease per unit of length was irrelevant with the distance from the heat source. Such temperature decrease needed to consider the impact of the flow and length of pipe synthetically. Also, the comparisons disclose that the average error and standard deviation were 0.46 ℃ and 1.18 ℃, respectively. Finally, by defining the dynamic response time, the delay time of the fluid in the pipe network was analyzed. Results showed that the relative error of the dynamic response time calculated with the node method was 5.8% and 5.74%, respectively. Therefore, the node method was accurate enough to satisfy the requirements of practical engineering in the study of thermal dynamic characteristics of pipe network.
引文
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[2] LI K.Research on thermal condition of hot water heat-supply system [D].Harbin:Harbin Institute of Technology,2011
[3] BENONYSSON A,B HM B,RAVN H F.Operational optimization in a district heating system [J].Energy Conversion & Management,1995,36(5):297-314
[4] LARSEN H V,P LSSON H,B HM B,et al.Aggregated dynamic simulation model of district heating networks [J].Energy Conversion & Management,2002,43(8):995-1019
[5] PINSON P,NIELSEN T S,NIELSEN H A,et al.Temperature prediction at critical points in district heating systems [J].European Journal of Operational Research,2009,194(1):163-176
[6] LI Z,WU W,SHAHIDEHPOUR M,et al.Combined Heat and Power Dispatch Considering Pipeline Energy Storage of District Heating Network [J].IEEE Transactions on Sustainable Energy,2015,7(1):12-22
[7] PALSSON H.Analysis of Numerical Methods for Simulating Temperature Dynamics in District Heating Pipes[C]//proceedings of the International Symposium on District Heating and Cooling Simulation,F,2010
[8] BENONYSSON A.Dynamic modelling and operational optimization of district heating systems [D].Denmark:Technical University of Denmark,1991
[9] 王芃.集中供暖系统动态仿真与优化调节 [D].哈尔滨:哈尔滨工业大学,2006
[10] 李爽.基于室温调节的热水供热管网动态水力和热力工况研究 [D].哈尔滨:哈尔滨工业大学,2011
[11] STEVANOVIC V D,ZIVKOVIC B,PRICA S,et al.Prediction of thermal transients in district heating systems [J].Energy Conversion & Management,2009,50(9):2167-2173
[12] ZHOU S,TIAN M,ZHAO Y,et al.Dynamic modeling of thermal conditions for hot-water district-heating networks [J].Journal of Hydrodynamics,2014,26(4):531-537
[13] ZHAO H.Analysis,modelling and operational optimization of district heating systems [D].Denmark :Technical University of Denmark,1995
[14] GABRIELAITIENE I,B HM B,SUNDEN B.Modelling temperature dynamics of a district heating system in Naestved,Denmark—A case study [J].Energy Conversion & Management,2007,48(48):78-86
[15] LIU X,WU J,JENKINS N,et al.Combined analysis of electricity and heat networks [J].Applied Energy,2016,162:1238-1250
[16] GABRIELAITIENE I.Numerical simulation of a district heating system with emphases on transient temperature behaviour [C]//The 8th International Environment Engineering Conference.Vilniaus:Vilniaus Gedimino Technikos Universitetas,2011:747-745
[17] Pupeikis D ,Arūnas Burlingis,Vytautas ■ Required additional heating power of building during intermitted heating[J].Journal of Civil Engineering and Management,2010,16(1):141-148
[18] KENSBY J,TR SCHEL A,DALENB CK J O.Potential of residential buildings as thermal energy storage in district heating systems-Results from a pilot test [J].Applied Energy,2015,137:773-781
[19] ZHANG L,GUDMUNDSSON O,LI H.Comparison of district heating systems used in China and Denmark [J].Euroheat & Power,2013,10(4):12-19