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2021 (English)In: Journal of Pipeline Systems Engineering and Practice, ISSN 1949-1190, Vol. 12, no 1, article id 04020067Article in journal (Refereed) Published
Abstract [en]
Fourth generation district heating networks (4GDH) must be designed for future energy systems, integrating renewable volatile energy sources, with lower operation temperatures, and consequent reduction of heat losses and increased energy efficiency. The lower levels of operating temperature and the greater amount of cyclic loading, influence aging, and the service life of 4GDH pipelines, differently from traditional district heating (DH) networks, and thus require proper investigation of the system response at the cross-sectional level. To evaluate the material durability of 4GDH pipelines, we have analyzed the behavior of the service steel pipe, the insulation foam, and their adhesive interaction, using an innovative analytical and experimental procedure. This paper describes the influence of traditional and future operational loading conditions on the performance of preinsulated bonded single-pipe systems, representing the majority of currently operating DH pipelines. The performed fatigue analysis of the steel service pipe showed that the lifetime of 4GDH pipelines is expected to increase because of the lower operating temperature, and the low impact of thermal loading volatility in the network, compared to conventional DH. The accelerated aging tests of DN 50/160 pipes demonstrated that the combined effect of cyclic mechanical loading and thermal aging accelerates the rate of chemical degradation of the PUR foam, leading to a faster deterioration of the mechanical adhesion strength. The shear strength tests of naturally aged DH pipes revealed that, besides the initial pipe system characteristics and aging period, the residual shear strength of the polyurethane (PUR) foam depends on the temperature history, decreasing with the level of operating temperature and amount of fluctuation. The obtained results give a better understanding of the performance of traditional and 4GDH pipelines in operation that need to be appropriately considered in the engineering design standards of DH networks toward a more sustainable and energy-efficient infrastructure.
Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2021
Keywords
Accumulated damage, Foam aging, Fourth generation district heating system, Pipeline durability, Shear tests, 4G mobile communication systems, Adhesives, Deterioration, District heating, Durability, Energy efficiency, Systems engineering, Temperature, Thermal aging, Thermal fatigue, Accelerated aging test, Cyclic mechanical loading, District heating networks, Experimental procedure, Operating temperature, Operation temperature, Residual shear strength, Shear strength tests, Pipelines
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-51889 (URN)10.1061/(ASCE)PS.1949-1204.0000521 (DOI)2-s2.0-85096038490 (Scopus ID)
Note
Funding text 1: The work presented herein is part of the research project “Effects of loads on asset management of the 4th generation district heating networks” funded by the International Energy Agency Technology Collaboration Programme on District Heating and Cooling including Combined Heat and Power (IEA DHC), that is greatly acknowledged. The authors would like to thank Prof. Thorsten Urbaneck from the Department of Mechanical Engineering at the Chemnitz University of Technology, and Mr. Thomas Göschel from inetz GmbH, for providing helpful guidance and information on the collected temperature data from 4GDH. Thanks are extended to Powerpipe Systems AB, Gothenburg Energy, Hafslund Varme AS, Jönköping Energy AB, Vattenfall AB, for the valuable discussions, manufacturing of pipes and support ideas. Moreover, the authors would like acknowledge the colleagues at RISE, especially Mr. Anders Persson for helping on experimental set up. Thanks are extended to Mr. Eun Sick Kang from the Pipeteckorea Co. Ltd., for the cooperation in the axial shear strength test of naturally aged pipes in Korea.
2021-01-192021-01-192023-05-26Bibliographically approved