大管径三通局部阻力特性数值模拟及多热源集中供热运行分析

发布时间：2018-01-11 04:28

本文关键词：大管径三通局部阻力特性数值模拟及多热源集中供热运行分析　出处：《天津大学》2016年硕士论文　论文类型：学位论文

【摘要】：多热源联网能够更好地适应大规模区域供热的负荷需求及其变化,同时集中供热有利于更好地采用先进技术实现节能减排。结合产学研项目和实际工程案例,基于工程实践,本工程硕士论文围绕供热系统的节能提效,主要工作包括:1)针对供热管网三通分流处的局部阻力影响系统水力平衡及运行能耗的问题,利用Fluent软件模拟了400mm及以上管径三通内流体流动的速度场和压力场,分别考察了分流比q(0~1)、雷诺数Re(4×104~1×106)、管径比dλ(0.38~1)及管间夹角θ(30°~90°)对三通局部阻力的影响。结果表明:研究范围内,主管与侧支管间局阻系数ζ_(01)以及主管与直支管间局阻系数ζ_(02)均随Re增大而减小,当Re达到4.8×105时,基本不再变化。dλ0.8时,ζ_(01)和ζ_(02)均随q增大而单调递增,而当dλ≥0.8时,局阻系数均与q呈抛物线关系。q一定时,随着d增大,ζ_(01)明显减小,当dλ0.7时,减小趋势明显变缓。流动特征分析发现,随着θ增大,侧支管内漩涡尺寸、速度梯度及流线弯曲程度明显增大,导致ζ_(01)明显增大,直支管内速度梯度略微增大使得ζ_(02)略微增加。2)针对实际供热系统的运行能效,通过对该供热系统的热源、一次网和换热站现场调研,得到2014-2015年供暖季系统的运行数据。依据《供热系统节能改造技术规范》(GB/T50893-2013),计算出系统的单位供热量能耗、单位供热面积能耗、锅炉效率、补水率及水力平衡度,并与上述规范评价标准对比。结果显示,该供热系统单位供热量能耗合格,单位面积能耗超标,其中单位面积耗电量3.36kWh/m~2,标准为2~3kWh/m~2;单位面积耗热量0.404GJ/m~2,标准为0.23~0.35GJ/m~2;单位面积供热负荷43W/m~2,较需求热负荷高10W/m~2;6#锅炉处于大流量小温差低效运行状态。系统补水率超标,为1.28%,超过上述标准规定的0.78%;统计的16个换热站中70%出现了水力失调。3)针对由已建1号热源站和拟建2号热源站构成的实际双热源联合供热系统,基于热源供热负荷动态需求,采用图论方法,分析了热源负荷分配比例对一次网循环水泵电耗的影响。结果表明,需求热负荷率分别为100%,95%,90%时,1号站的最佳负荷分配比例分别为57.6%,42.2%,42.2%,此时水泵电耗分别为1439kW,1247kW,1143kW,较最大水泵电耗分别节能28.3%,33.8%,31.4%;当需求热负荷率为85%时,1号站能够满足供热需求,由1号站单独供热更经济。4)结合文献调研及实际工程案例既有运行的1号热源站、拟建的2号热源站以及已规划的3号热源站组成的多热源联合供热系统的特征的分析,初步构思了多热源供热管网物理实验模型,并初步给出了实验方案。
[Abstract]:Heat supply network can better adapt to load demand and change of large-scale regional heating and central heating, is conducive to better use of advanced technology to realize energy saving and emission reduction. With the combination of the project and the actual project cases, based on the engineering practice, this thesis focuses on energy efficiency of heating system, the main work includes: 1) for local resistance heating three way flow of pipe network hydraulic balance and operation system of energy issues, 400mm diameter and above the using Fluent software to simulate the fluid flow through the three velocity field and pressure field were investigated, the split ratio Q (0~1), Reynolds number Re (4 * 104~1 * 106), D (lambda 0.38~1 diameter ratio) and tube angle (30 degrees ~90) influence on three local resistance. The results show that within the scope of the study, the supervisor and the collateral tube resistance factor (01) and _ zeta charge and the straight pipe between the local resistance coefficients of the zeta _ (02) with the increase of Re Large decreases when the Re reaches 4.8 * 105, basically no change of.D lambda 0.8, zeta zeta _ (01) and _ (02) with Q increases monotonically, while D is larger than 0.8, the local resistance coefficients with Q showed a parabola relationship with a certain.Q, with the increase of D. Zeta _ (01) was significantly reduced when D, lambda 0.7, decreased significantly slowed. The flow characteristics analysis showed that with the increase in theta, lateral branch vortex size, velocity gradient and streamline bending degree increased significantly, resulting _ zeta (01) increased significantly, straight tube velocity gradient increase slightly, _. (02) slightly increased.2) according to the actual operation efficiency of the heating system, the heat source of the heating system, a heat exchanger network and field investigation, running data in 2014-2015 system. On the basis of the heating season "technical specification for energy-saving heating system" (GB/T50893-2013), calculate the unit energy consumption of heating system. The heating unit area energy consumption, boiler efficiency, The replenishment rate and hydraulic balance, and with the standard evaluation criteria comparison. The results showed that the qualified heating system unit heating energy consumption, energy consumption per unit area exceed the standard, the power consumption per unit area is 3.36kWh/m~2, the standard 2~3kWh/m~2 0.404GJ/m~2; heat consumption per unit area, the standard is 0.23~0.35GJ/m~2 43W/m~2; the heating load per unit area, compared with the demand of high heat load 10W/m~2; 6# boiler in large flow and small temperature difference in inefficient operation state. The system replenishment rate is 1.28%, exceed the standard, more than the standard 0.78%; statistics of the 16 heat exchange station in 70% the hydraulic imbalance.3) directed by built No. 1 and No. 2 source station the station made the actual double heat source heat source heating system based on the demand of dynamic load, heat supply, by using the method of graph theory, analysis of the heat load distribution ratio on a net consumption of circulating pump is investigated. Results show that the heat load demand rate For 100%, 95%, 90%, the optimal load distribution ratio of 1 stations were 57.6%, 42.2%, 42.2%, the electricity consumption of water pump are respectively 1439kW, 1247kW, 1143kW, than the maximum pump power consumption were 33.8%, saving 28.3%, 31.4%; when the demand of heat load rate is 85%, the number 1 station can meet heating demand by 1 separate heating station more economical.4) combined with literature research and practical engineering case has run 1 heat source station, the No. 2 station of heat source and the characteristics of multi heat source heating system is composed of the planned 3 source station analysis, preliminary idea of multi heat source heating network physics experiment the model, and gives the experimental program.

【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU995

【相似文献】