| The heating energy consumption of Northern China accounts for 40% of total urban building energy consumption,which is the largest part of building energy consumption.Finding energy saving potential of heating system is an important way and inevitable choice to reduce building energy consumption.This paper focused on the ubiquity problem of hot water heating system,which included large resistance of heat source and heat transfer,inappropriate of circulating pump,high energy consumption of transmission and distribution system,studied the energy saving technology in order to ensure the heating quality and reduce the energy consumption of heating transmission and distribution system.We used different methods,which included theoretical research,field testing,engineering demonstration and socioeconomic benefit evaluation.We investigated the main reason for the high energy consumption of the hot water heating transmission system,analyzed the energy saving potential of those project,researched on import and export piping,variable frequency regulation and the parallel operation conditions of circulating water pump,the adaptability of limit EHR.The result could provide technical support and engineering demonstration for the energy saving reconstruction project of the heating transmission and distribution system,and provide the basis for the relevant energy saving standards.This paper investigated 15 boiler houses and 34 heating stations of 9 heating enterprises in Northern China,studied the type of hot water heating transmission and distribution system,the parameters of power equipment,operation status of different types heating system,concluded that the main reason of the high energy consumption in transmission and distribution system.In this paper,we also analyzed and estimated the energy saving potential of those hot water heating transmission and distribution system,Which could reach to 20%~70%.Aiming at the study of the distribution system of heating piping transportation,this paper modeled and analyzed the steady flow pattern of diffuser,concluded that,in the same flow rate and inlet diameter,the flow shear stress loss rate change greatly in the first half part of diffuser in same flow and inlet diameter.Compared the shear stress in the same position of straight pipe and diffuser,for example,in the 0.1m position,the shear stress of straight reduced to 4.22 Pa from 6.3Pa in diffuser,loss rate reached to 33.0%;in the 0.4m position,it reduced to1.42 Pa from 4.23 Pa in diffuser,loss rate reached to 6.4%.It showed the necessity of mounting diffuser.At the same time,the tee joint flow state resistance of five different angles in the pipe network system are simulated and analyzed,which included degree 0?30?45?60 and 90,obtained the best angle range of tee joint.According to the problem of the worse pump regulation performance,the energy-saving effect of frequency convertor of circulating pump is simulated,measured and comparative analyzed in this paper,it was showed that the measured value of energy efficiency were concordant with simulation curve.The results,which simulated the operation curve of the same model,different models with multi pump parallel,indicated that the change of total flow with the head,the relationship with pipeline character curve and pump characteristic curve.This paper also compared the detection and determination of EHR in this two standards,"Design Standard for Energy Efficiency of Residential Buildings in Sever Cold and Cold Zones”(JGJ26-2010)and “Energy Efficiency Inspection Standard for Residential Buildings”(JGJ/T 132-2009).According to the measurement and calculation of ten heating transmission and distribution System systems after transforming,we suggested that EHR limit required to reduce 20%,which has been written in a Beijing local standard “Technical specification for evaluation of energy saving in residential buildings”(DB11/T1249-2015).In this paper,the above research results are applied in the reconstruction project,such as Inner Mongolia southwest heating system project,Ruyuan Community heating system project,Shoukaiwenquan Community demonstration project,Inner Mongolia central heating system project.Based on program development,pump and its system selection before and after reform,field Testing,energy saving effect and economic evaluation of project,we concluded that electricity saving of per unit area on primary pipe network and secondary pipe network,energy saving rate and energy consumption of transformation system,savings of standard coal,reduction of carbon emission and so on.All the results provided a reference for the application of energy saving reconstruction technology to the existing hot water heating transmission and distribution system.The actual project showed that the Energy consumption level of primary network in transmission and distribution system was from 1.26~1.32×104 kW/m~2,the second one was from 3.30 to 5.54×104 kW/m~2,electricity-saving per unit area of primary network in every heating season was from 0.77 to 0.81kWh/ m~2,the second one was from 0.95 to 3.34kWh/m~2,which convert to carbon emission,the primary network system was from 0.70 to 0.73kg/ m~2,the second one was from 0.95 to 3.34kg/m~2,the total rate of energy saving was from 40% to 60% after reconstruction. |
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