1. Institute of Thermal Science and Power Systems, Zhejiang University, Hangzhou 310027, China 2. Ningbo Wanli Pipeline Limited Company, Ningbo 315800, China
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.
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.
Fig.4Average 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.1Temperature 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.2Characteristics of temperature and pressure along heating network
Fig.5Average 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.3Steam parameters under three different working conditions in test section 1-2
Fig.6Heat 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.4Characteristic 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.5Steam flow resistance loss of test section 1, 2 in working condition 1
Fig.7Composition 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.6Pipe flow loss characteristics of heating network
[1]
张林 “十三五”时期北京城市供热展望[J]. 区域供热, 2016, 35 (6): 128- 130 ZHANG Lin Prospects of urban heating in Beijing during the "13th Five-Year Plan"[J]. District Heating, 2016, 35 (6): 128- 130
[2]
赵星海, 魏春明, 辛国华 浙江供热现状及蒸汽供热距离的研究[J]. 能源研究与信息, 2008, 24 (3): 148- 151 ZHAO Xing-hai, WEI Chun-ming, XIN Guo-hua Present situation of heat supply in Zhejiang and study on steam heat supply distance[J]. Energy Research and Information, 2008, 24 (3): 148- 151
doi: 10.3969/j.issn.1008-8857.2008.03.005
[3]
魏明浩 大型、长距离输送供热管网的技术探讨[J]. 区域供热, 2017, 36 (3): 100- 103 WEI Ming-hao Technical discussion on large-scale and long-distance transportation heating network[J]. District Heating, 2017, 36 (3): 100- 103
[4]
ERTÜRK M Optimum insulation thicknesses of pipes with respect to different insulation materials, fuels and climate zones in Turkey[J]. Energy, 2016, 113 (20): 991- 1003
[5]
DAŞDEMIR A, URAL T, ERTÜRK M, et al Optimal economic thickness of pipe insulation considering different pipe materials for HVAC pipe applications[J]. Applied Thermal Engineering, 2017, 121 (13): 242- 254
[6]
BALO F, SUA L S Techno-economic optimization model for “sustainable” insulation material developed for energy efficiency[J]. International Journal of Applied Ceramic Technology, 2017, 15 (3): 792- 814
[7]
刘承婷. 蒸汽管道保温材料与保温结构优化研究[D]. 大庆: 东北石油大学, 2013. LIU Cheng-ting. Optimization of insulation material and structure in steam pipeline[D]. Daqing: Northeast Petroleum University, 2013.
[8]
吴佳富. 供热管网保温材料及结构研究与评价[D]. 南京: 南京师范大学, 2019. WU Jia-fu. Research and evaluation of insulation materials and structure of heating pipe network[D]. Nanjing: Nanjing Normal University, 2019.
[9]
KAYNAKLI O Economic thermal insulation thickness for pipes and ducts: a review study[J]. Renewable and Sustainable Energy Reviews, 2014, 30 (2): 184- 194
[10]
王振华. 管廊供热管道保温材料及其厚度的研究[D]. 太原: 太原理工大学, 2018. WANG Zhen-hua. Study on thermal insulation materials and thickness of heating pipeline in pipe gallery[D]. Taiyuan: Taiyuan University of Technology, 2018.
[11]
BAŞOĞUL Y, KEÇEBAŞ A Economic and environmental impacts of insulation in district heating pipelines[J]. Energy, 2011, 36 (10): 6156- 6164
doi: 10.1016/j.energy.2011.07.049
[12]
张增刚. 蒸汽管网水力热力耦合计算理论及应用研究[D]. 北京: 中国石油大学, 2008. ZHANG Zeng-gang. Research on coupling hydraulic and thermal calculation for steam pipe network theory and its application[D]. Beijing: China University of Petroleum, 2008.
[13]
TALER D, KACZMARSKI K A numerical model of steam pipeline[J]. Procedia Engineering, 2016, 157 (1): 158- 162
WANG H, ZHU T A novel model for steam transportation considering drainage loss in pipeline networks[J]. Applied Energy, 2017, 188 (4): 178- 189
[17]
KRUCZEK T Determination of annual heat losses from heat and steam pipeline networks and economic analysis of their thermomodernisation[J]. Energy, 2013, 62 (23): 120- 131
[18]
黄以明. 集中供热管网优化设计[D]. 西安: 西安理工大学, 2007. HUANG Yi-ming. Optimal design of the central heat supply network[D]. Xi'an: Xi'an University of Technology, 2007.
[19]
ZHONG W, FENG H, WANG X, et al Online hydraulic calculation and operation optimization of industrial steam heating networks considering heat dissipation in pipes[J]. Energy, 2015, 87 (13): 566- 577
[20]
杨世铭, 陶文铨. 传热学[M]. 4版. 北京: 高等教育出版社, 2006: 787.
[21]
吴青, 许振宇, 李金琦, 等 架空热力管线管托散热修正系数研究[J]. 节能技术, 2011, 29 (6): 498- 501 WU Qing, XU Zhen-yu, LI Jin-qi, et al The study on correction coefficient of heat loss of pipe bracket on the overhead thermal pipeline[J]. Energy-Saving Technology, 2011, 29 (6): 498- 501
doi: 10.3969/j.issn.1002-6339.2011.06.005
[22]
叶婷, 田文, 王汝恒, 等 站间输油管道内部受力简化模型[J]. 西南科技大学学报, 2016, 31 (1): 35- 39 YE Ting, TIAN Wen, WANG Ru-heng, et al Internal stress simplified model of pipelines between the stations[J]. Journal of Southwest University of Science and Technology, 2016, 31 (1): 35- 39
doi: 10.3969/j.issn.1671-8755.2016.01.008
