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浙江大学学报(工学版)
Journal of ZheJiang University (Engineering Science)  2021, Vol. 55 Issue (6): 1135-1141    DOI: 10.3785/j.issn.1008-973X.2021.06.014
    
Experimental study on characteristics of thermal and pipeline loss of steam heating pipeline network
Jian-fa ZHAO1(),Long-biao QIAO1,Hai-liang YANG2,Liang ZHANG1,*(),Zi-tao YU1
1. Institute of Thermal Science and Power Systems, Zhejiang University, Hangzhou 310027, China
2. Ningbo Wanli Pipeline Limited Company, Ningbo 315800, China
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Abstract  

The characteristics of steam heat network in actual operation were tested using enthalpy drop method and surface heat flow method. Heat loss characteristics and composition characteristics of the heating network were analyzed. Results showed that operating conditions and steam state greatly influenced on the accuracy of enthalpy drop method in evaluating heat loss of steam heating pipe. The actual heat rate of heat supply network was 135.66 W/m2, of which the heat rate of pipeline insulation was 67.67 W/m2, accounting for about 49.88%. The steam flow resistance loss accounted for 14.98%, and the local heat loss of supports, elbows and traps accounted for 35.14%. The condensation loss coefficient of the heat supply network was defined based on the relationship between actual pipe loss and condensation loss of the heat supply network. Heat loss model was constructed based on heat loss of the heat supply network combined with actual measurement data. The condensation loss coefficient of the heat supply network was 0.16.

Key words： heat loss      steam heating network      insulation pipe      enthalpy drop method      pipeline loss     
Received: 29 August 2020      Published: 30 July 2021
CLC:  TK 315  
Fund:  浙江省科协“育才工程”资助项目（2018YCGC009）
Corresponding Authors: Liang ZHANG     E-mail: 21927035@zju.edu.cn;jackway@zju.edu.cn
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Jian-fa ZHAO
Long-biao QIAO
Hai-liang YANG
Liang ZHANG
Zi-tao YU
Cite this article:

Jian-fa ZHAO,Long-biao QIAO,Hai-liang YANG,Liang ZHANG,Zi-tao YU. Experimental study on characteristics of thermal and pipeline loss of steam heating pipeline network. Journal of ZheJiang University (Engineering Science), 2021, 55(6): 1135-1141.

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https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2021.06.014     OR     https://www.zjujournals.com/eng/Y2021/V55/I6/1135


蒸汽热网热力损失与管损特性实验研究

采用焓降法和表面热流法，分别对实际运行的蒸汽热网特性进行现场测试，分析得到热网散热损失特性和组成特征. 结果表明，运行工况和蒸汽状态对焓降法在评估供热管道散热损失中的准确性具有重要的影响. 所测热网的实际散热热流密度达到135.66 W/m2，其中管道保温散热为67.67 W/m2，约占49.88%；蒸汽流动阻力损失占14.98%，支架、弯头、疏水器等局部散热占35.14%. 基于实际管损与热网冷凝散热损失的关系，定义热网冷凝损失系数. 建立基于热网散热损失的管损模型，结合实际测量数据，得到该热网的冷凝损失系数为0.16.


关键词： 热力损失,  蒸汽热网,  保温管道,  焓降法,  管损 
Fig.1 Measuring point distribution along pipeline
Fig.2 Sketch of enthalpy drop method
Fig.3 Sketch of surface heat loss method
Fig.4 Average steam temperature along heating network
测试段 Δt /(℃·km?1) Δtst /(℃·km?1)
测点1至2的测试段 8.59 8.88
测点2至3的测试段 6.77 7.00
测点3至4的测试段 2.35 2.43
测点4至5的测试段 1.57 1.62
测点5至6的测试段 ?0.18 ?0.18
Tab.1 Temperature drop characteristics along heating network
测点 tn /℃ pn /MPa tsa /℃ Δto /℃
1 254.64 1.28 194.42 60.22
2 243.47 1.26 193.74 49.72
3 210.96 1.20 191.66 19.30
4 193.58 1.11 188.39 5.19
5 183.65 0.98 183.31 0.34
6 184.40 1.03 185.32 ?0.92
Tab.2 Characteristics of temperature and pressure along heating network
Fig.5 Average heat loss of pipeline calculated by enthalpy drop method
工况 qm /(t·h?1) tn /℃ pn /MPa Δto /℃
工况1 49.62 267.17 1.34 70.76
工况2 44.33 261.46 1.32 65.70
工况3 61.06 235.29 1.18 44.34
Tab.3 Steam parameters under three different working conditions in test section 1-2
Fig.6 Heat loss characteristic in test section 1-2 under different working conditions
ta /℃ v /(m·s?1) $q_{\rm{s}}^{'} $ /(W·m?2) $q_{\rm{s}}^{''} $ /(W·m?2) qs /(W·m?2)
16.39 0.08 72.14 63.20 67.67
Tab.4 Characteristic of heat loss from pipe insulation
${\xi ^{'}} $ $q_{\rm{f}}^{'} $ /(W·m?2) ${\xi ^{''}} $ $q_{\rm{f}}^{''} $/(W·m?2) qf /(W·m?2)
0.015 14.55 15 5.77 20.32
Tab.5 Steam flow resistance loss of test section 1, 2 in working condition 1
Fig.7 Composition characteristics of insulated pipes heat loss
工况 $\Delta q_{{m} }^{'}$ /(t·h?1) $\Delta q_{{m} }^{''}$ /(t·h?1) Δqm /(t·h?1) δ /% ε
工况1 2.66 9.82 12.48 5.15 0.21
工况2 1.38 11.14 12.52 2.67 0.11
工况3 1.97 10.75 12.71 3.81 0.16
平均值 2.00 10.57 12.57 3.88 0.16
Tab.6 Pipe flow loss characteristics of heating network
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