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Publications (10 of 43) Show all publications
Jakubowicz, I., Vega, A., Sällström, J. H. & Yarahmadi, N. (2025). Pipeopsy: A Novel Method for Status Assessment of District Heating Pipes in Operation. Journal of Pipeline Systems Engineering and Practice, 16(1), Article ID 04024061.
Open this publication in new window or tab >>Pipeopsy: A Novel Method for Status Assessment of District Heating Pipes in Operation
2025 (English)In: Journal of Pipeline Systems Engineering and Practice, ISSN 1949-1190, Vol. 16, no 1, article id 04024061Article in journal (Refereed) Published
Abstract [en]

This study presents a novel status assessment method for district heating (DH) pipelines in operation, which we call "Pipeopsy"(a biopsy for pipes). The method evaluates adhesion strength between the service pipe and polyurethane (PUR) insulation, which is a crucial property for the durability of DH pipes and the extent of degradation of PUR foam closest to the service pipe. This method is based on three parts: (1) measuring adhesion strength and taking samples of the foam, (2) analyzing the foam in a laboratory using Fourier-transform infrared (FTIR) spectroscopy, and (3) restoring pipeline by replacing the foam and sealing the casing by welding polyethylene plugs in the holes. Temperature dependence and measurement accuracy of the shear strength test method have also been examined, as well as correlation with the standard axial shear strength test method. The shear strength of the aged pipes shows no temperature dependence, while the quotient between the value produced with the plug method and axial method is 3.1. Compared with the standard test methods, the advantages of Pipeopsy involve small cost, less damage to pipes, and the use of simple mobile tools for taking samples and performing measurements. Importantly, testing can be performed without shutting down the operation of DH pipelines. Furthermore, the method provides not only the information on adhesion strength but also information on the extent of chemical degradation in PUR. This combination of information provides a more detailed picture of the status of pipes and can be used to make a prediction about the remaining lifetime. Pipeopsy produces many results in a short time, and better statistics, which provide a solid basis for decision-makers focused on the maintenance of DH pipes or for applying artificial intelligence. 

Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2025
Keywords
Shear strength; District heating pipelines; Heating pipes; Infrared: spectroscopy; Novel methods; Pipe insulation; Polyurethane insulation; Shear strength tests; Status assessment; Temperature dependence; Test method; Fourier transform infrared spectroscopy
National Category
Civil Engineering
Identifiers
urn:nbn:se:ri:diva-76329 (URN)10.1061/JPSEA2.PSENG-1689 (DOI)2-s2.0-85211931437 (Scopus ID)
Note

This work was financed directly by Energiforsk, the SwedishEnergy Agency. RISE and Swedish energy companies (VattenfallAB, Öresundskraft AB, Göteborg Energi AB, Jönköping EnergiAB, E. ON Energilösningar AB, Kraftringen AB, Gävle EnergiAB) contributed with in-kind work and gave access to field mea-surement test sites in their networks. Powerpipe Systems AB con-tributed with in-kind work and produced test pipe

Available from: 2024-12-27 Created: 2024-12-27 Last updated: 2024-12-27Bibliographically approved
Jakubowicz, I. & Yarahmadi, N. (2024). Review and Assessment of Existing and Future Techniques for Traceability with Particular Focus on Applicability to ABS Plastics. Polymers, 16(10), Article ID 1343.
Open this publication in new window or tab >>Review and Assessment of Existing and Future Techniques for Traceability with Particular Focus on Applicability to ABS Plastics
2024 (English)In: Polymers, E-ISSN 2073-4360, Vol. 16, no 10, article id 1343Article in journal (Refereed) Published
Abstract [en]

It is generally recognized that the use of physical and digital information-based solutions for tracking plastic materials along a value chain can favour the transition to a circular economy and help to overcome obstacles. In the near future, traceability and information exchange between all actors in the value chain of the plastics industry will be crucial to establishing more effective recycling systems. Recycling plastics is a complex process that is particularly complicated in the case of acrylonitrile butadiene styrene (ABS) plastic because of its versatility and use in many applications. This literature study is part of a larger EU-funded project with the acronym ABSolEU (Paving the way for an ABS recycling revolution in the EU). One of its goals is to propose a suitable traceability system for ABS products through physical marking with a digital connection to a suitable data-management system to facilitate the circular use of ABS. The aim of this paper is therefore to review and assess the current and future techniques for traceability with a particular focus on their use for ABS plastics as a basis for this proposal. The scientific literature and initiatives are discussed within three technological areas, viz., labelling and traceability systems currently in use, digital data sharing systems and physical marking. The first section includes some examples of systems used commonly today. For data sharing, three digital technologies are discussed, viz., Digital Product Passports, blockchain solutions and certification systems, which identify a product through information that is attached to it and store, share and analyse data throughout the product’s life cycle. Finally, several different methods for physical marking are described and evaluated, including different labels on a product’s surface and the addition of a specific material to a polymer matrix that can be identified at any point in time with the use of a special light source or device. The conclusion from this study is that the most promising data management technology for the near future is blockchain technology, which could be shared by all ABS products. Regarding physical marking, producers must evaluate different options for individual products, using the most appropriate and economical technology for each specific product. It is also important to evaluate what information should be attached to a specific product to meet the needs of all actors in the value chain.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI), 2024
Keywords
ABS resins; Elastomers; Information management; Life cycle; Plastic recycling; Plastics; Styrene; Acrylonitrile butadiene styrene plastic; Acrylonitrile-butadiene-styrene; Block-chain; Circular economy; Digital information; Physical information; Physical marking; Traceability; Traceability systems; Value chains; Light sources
National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-73582 (URN)10.3390/polym16101343 (DOI)2-s2.0-85194271148 (Scopus ID)
Note

Funding: European Commission, grant no. 101058636.

Available from: 2024-06-13 Created: 2024-06-13 Last updated: 2024-06-13Bibliographically approved
Jakubowicz, I., Enebro, J. & Yarahmadi, N. (2021). Challenges in the search for nanoplastics in the environment—A critical review from the polymer science perspective. Polymer testing, 93, Article ID 106953.
Open this publication in new window or tab >>Challenges in the search for nanoplastics in the environment—A critical review from the polymer science perspective
2021 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 93, article id 106953Article in journal (Refereed) Published
Abstract [en]

Nanoplastics (NPs), which we define in this paper as solid plastic particles with the size <1 μm, unintentionally produced from the degradation and fragmentation of larger plastic objects are probably the least known area of plastic litter but are suspected to pose the greatest risk to the environment. However, no NPs have been detected in natural environments to date. This review attempts to provide a critical overview from the polymer science perspective of the relevant scientific literature, which could facilitate finding secondary NPs in natural environments. The information on secondary NPs has been scarce due to the big challenges in sampling, separation, and detection of these nanoscale particles. This review highlights the most important challenges and obstacles and discusses the mechanisms of generation of secondary NPs. It provides also a critical overview on modern instrumentation, newly developed workflows, promising techniques for sampling and sample preparation, and detection methods including spectroscopies (Raman and FT-IR), microscopies (SEM and TEM) and mass spectrometry (GC–MS and ToF–SIMS). We conclude that finding NPs in natural environments is plausible yet uncertain, which drives towards the development of a methodology for collection, separation and identification of NPs in environmental matrices along with a thorough evaluation of the process of formation of secondary NPs, their fate and effects on living organisms and the environment. To find nanoplastics in natural environments it is important to know the process of their formation, their fate, and experimental constraints.

Place, publisher, year, edition, pages
Elsevier Ltd, 2021
Keywords
Analytical methods, Detection, Environmental degradation, Nanoplastics, Sampling, Biology, Detection methods, Environmental matrixes, Modern instrumentation, Nanoscale particles, Natural environments, Sample preparation, Scientific literature, Separation and identification, Mass spectrometry
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-50929 (URN)10.1016/j.polymertesting.2020.106953 (DOI)2-s2.0-85096197728 (Scopus ID)
Note

Funding details: Naturvårdsverket; Funding details: Naturvårdsverket, NV-06511-19; Funding text 1: The authors are grateful to the Swedish Environmental Protection Agency (Naturvårdsverket) , grant ID NV-06511-19 for financial support.

Available from: 2020-12-02 Created: 2020-12-02 Last updated: 2023-05-26Bibliographically approved
Vega, A., Yarahmadi, N. & Jakubowicz, I. (2021). Cyclic axial loads and thermal ageing of district heating pipes. Paper presented at 17th International Symposium on District Heating and Cooling, Nottingham Trent University, DHC2021, 6–9 September 2021, Nottingham, United Kingdom. Energy Reports, 7, 105-109
Open this publication in new window or tab >>Cyclic axial loads and thermal ageing of district heating pipes
2021 (English)In: Energy Reports, E-ISSN 2352-4847, Vol. 7, p. 105-109Article in journal (Refereed) Published
Abstract [en]

Thermal ageing at elevated temperatures is the standard method to determine the service life of pre-insulated district heating pipes nowadays. However, DH pipes are also subjected to axial movements which can affect the adhesion strength between the polyurethane foam and the service pipe. This contact surface is usually exposed to the highest temperatures. In this project, DH pipes were aged at elevated temperatures and at the same time cyclic axial loads were applied. Two DH pipes were only exposed to thermal ageing at 130 and 140 °C, while two other similar pipes were also exposed to cyclic axial loads. The adhesion strength was evaluated as the function of ageing time using the RISE plug method. Any changes in the chemical structure of the PUR samples were also observed using Fourier transform infrared spectroscopy. Comparing the results in this investigation, we found that the degradation of the mechanically loaded pipes was significantly faster than the degradation observed in non-loaded pipes at the same ageing temperatures. The FTIR study revealed that cyclic mechanical loads accelerated the chemical degradation of the PUR foam during thermal ageing. This study shows how important it is to consider all influencing factors in accelerated ageing. The methods presented here should be considered as an alternative to thermal ageing at high temperatures because the combination of mechanical and thermal loads reproduces better the real operating conditions. It is even of bigger interest when energy from different sources will be connected to the fourth generation of DH networks, which can cause more temperature fluctuations.

Keywords
Polyurethane, Foam, District heating, Mechanical stress, Thermal ageing
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-58165 (URN)10.1016/j.egyr.2021.09.033 (DOI)
Conference
17th International Symposium on District Heating and Cooling, Nottingham Trent University, DHC2021, 6–9 September 2021, Nottingham, United Kingdom
Available from: 2022-01-14 Created: 2022-01-14 Last updated: 2023-05-26Bibliographically approved
Banushi, G., Vega, A., Weidlich, I., Yarahmadi, N., Kim, J., Jakubowicz, I. & Sällström, J. H. (2021). Durability of District Heating Pipelines Exposed to Thermal Aging and Cyclic Operational Loads. Journal of Pipeline Systems Engineering and Practice, 12(1), Article ID 04020067.
Open this publication in new window or tab >>Durability of District Heating Pipelines Exposed to Thermal Aging and Cyclic Operational Loads
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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.

Available from: 2021-01-19 Created: 2021-01-19 Last updated: 2023-05-26Bibliographically approved
Vega, A., Yarahmadi, N. & Jakubowicz, I. (2020). Determining the useful life of district heating pipes: Correlation between natural and accelerated ageing. Polymer degradation and stability, 175, Article ID 109117.
Open this publication in new window or tab >>Determining the useful life of district heating pipes: Correlation between natural and accelerated ageing
2020 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 175, article id 109117Article in journal (Refereed) Published
Abstract [en]

District heating (DH) systems constitute a smart and environmentally friendly solution for energy distribution in the heat sector in Europe. This technique is still expanding but already faces some issues such as status assessment of the current DH networks and the development of new generation networks for low-temperature DH. Therefore, it is essential to understand the ageing behaviour of pipes under operating conditions and to find the relevant parameters that control the degradation processes. Many factors affect the deterioration of DH pipes, especially the polyurethane foam, which makes it very complex to find a reliable prediction model. Models based on a linear Arrhenius relationship using results from high ageing temperatures seem to be incorrect. For this study, 10 pipes that have been in service for many years in Sweden and Norway were evaluated. The aim was to study the impact of natural ageing on the mechanical adhesion and chemical structure of the polyurethane foam, which affects the pipe's performance. A test method developed at the Research Institutes of Sweden (RISE), called RISE plug method, was used to study the mechanical adhesion strength. In addition, Fourier transform infrared spectroscopy was used to observe any change in the chemical structure. The results were compared with previous analyses of DH pipes exposed to accelerated ageing. This information helps to provide a better comprehension of the deterioration of the current generation of pre-insulated DH pipes and to improve the accelerated ageing methods used nowadays to predict the technical lifetime of DH pipes. Our results suggest that the lifetime of DH pipes has been underestimated when using artificial ageing at relatively high temperatures. The data collected from naturally aged pipes gave confirmatory information about their physical status compared with our laboratory tests. This study also suggests that infrared analyses could be used as an early indication of the degradation of the polyurethane foam at the interface with a steel pipe. 

Place, publisher, year, edition, pages
Elsevier Ltd, 2020
Keywords
Accelerated ageing, Adhesion strength, Degradation, District heating pipes, Lifetime prediction, Natural ageing, Polyurethane foam, Adhesion, Bond strength (materials), Deterioration, Forecasting, Fourier transform infrared spectroscopy, Polyurethanes, Rigid foamed plastics, Structure (composition), Temperature, Arrhenius relationship, District heating system, Natural and accelerated ageing, New Generation networks, District heating
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-44447 (URN)10.1016/j.polymdegradstab.2020.109117 (DOI)2-s2.0-85081137520 (Scopus ID)
Note

Funding details: Energimyndigheten; Funding details: Vattenfall;

Funding text 1: The authors would like to thank Powerpipe Systems AB, Göteborg Energi, Hafslund Varme AS, Jönköping Energi AB, Vattenfall AB, Borås Energi och Miljö AB, Tekniska Verken i Linköping AB, Kraftringen Energi AB, Energimyndigheten, Energiföretagen Sverige and Swedenergy AB for valuable discussions, manufacturing of pipes and economic support.

Available from: 2020-03-17 Created: 2020-03-17 Last updated: 2023-05-26Bibliographically approved
Vega, A., Yarahmadi, N., Sällström, J. & Jakubowicz, I. (2020). Effects of cyclic mechanical loads and thermal ageing on district heating pipes. Polymer degradation and stability, 182, Article ID 109385.
Open this publication in new window or tab >>Effects of cyclic mechanical loads and thermal ageing on district heating pipes
2020 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 182, article id 109385Article in journal (Refereed) Published
Abstract [en]

The lifetime of pre-insulated district heating pipes is commonly evaluated by thermal ageing at elevated temperatures and is calculated using the Arrhenius equation. In this investigation, the effects of a repetitive shear stress during thermal ageing of pipes were studied. The degradation of polyurethane foam, especially at the interface with a steel pipe was evaluated from measurements of the adhesion strength and of alterations in the chemical structure of polyurethane by Fourier transform infrared spectroscopy. The main conclusion was that the thermal degradation of mechanically stressed district heating pipes was significantly faster than that of non-loaded pipes aged at the same temperature. It was also shown that the faster degradation of the mechanically loaded pipes is mainly due not to fatigue but to accelerated chemical degradation of the polyurethane foam. The results suggest that this methodology should be considered as an accelerated test method in order to avoid overestimation of the lifetime of district heating pipes and to show better ageing characteristics of mechanically stressed pipes, especially those intended for use in the fourth generation district heating networks 

Place, publisher, year, edition, pages
Elsevier Ltd, 2020
Keywords
Adhesion strength, Degradation, District heating pipes, Lifetime prediction, Mechanical stress, Polyurethane foam, Shear strength, Thermal ageing, Fourier transform infrared spectroscopy, Polyurethanes, Rigid foamed plastics, Shear flow, Shear stress, Testing, Thermal aging, Thermal fatigue, Accelerated test methods, Arrhenius equation, Chemical degradation, Cyclic mechanical load, District heating networks, Elevated temperature, Fourth generation, District heating
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-49464 (URN)10.1016/j.polymdegradstab.2020.109385 (DOI)2-s2.0-85092232291 (Scopus ID)
Note

Funding text 1: The investigation 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) [10] .; Funding text 2: The authors thank IEA-DHC Annex XII for financial support, Powerpipe Systems AB, for manufacturing the pipes, and Prof. Ingo Weidlich and Dr. Gersena Banushi, HCU HafenCity University for valuable discussions.

Available from: 2020-10-21 Created: 2020-10-21 Last updated: 2023-05-26Bibliographically approved
Forsgren, L., Noyan, E., Vega, A., Yarahmadi, N. & Boldizar, A. (2020). The thermo-oxidative durability of polyethylene reinforced with wood-based fibres. Polymer degradation and stability, 181, Article ID 109374.
Open this publication in new window or tab >>The thermo-oxidative durability of polyethylene reinforced with wood-based fibres
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2020 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 181, article id 109374Article in journal (Refereed) Published
Abstract [en]

Aiming at better understanding the ageing behaviour of cellulose composites, the accelerated thermo-oxidative ageing of polyethylene reinforced with two types of wood-based cellulose fibres was studied. Materials were prepared by extrusion mixing of either un-stabilized or stabilized polyethylene reinforced with 5 and 20 vol % cellulose content. The materials were extruded into strips and then aged at 90°C in circulating air. The effect of accelerated ageing up to 31 days was assessed by oxidation induction time and mechanical properties in tension. The results indicated that the added cellulose fibres did not increase the degradation of the composites during this ageing. Reinforcement with 20 % cellulose fibre having a 28 % lignin content together with 0.005 % Irganox 1010 antioxidant resulted in a remarkable improvement in the resistance against accelerated thermo-oxidation, compared to the pure polyethylene with added antioxidant. The findings of increased lifetime of LDPE by addition of wood-based reinforcement is of great interest, since the durability aspect is crucial to understand and predict before usage in commercial applications and especially as structural composites.

Place, publisher, year, edition, pages
Elsevier Ltd, 2020
Keywords
Accelerated ageing, Extrusion, Thermo-oxidation, Thermomechanical properties, Wood-based cellulose composites, Aliphatic compounds, Antioxidants, Cellulose, Durability, Polyethylenes, Tensile strength, Textile fibers, Thermooxidation, Wood, Cellulose composites, Cellulose content, Commercial applications, Oxidation induction time, Pure polyethylenes, Structural composites, Thermo-oxidative ageing, Reinforcement
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-49468 (URN)10.1016/j.polymdegradstab.2020.109374 (DOI)2-s2.0-85091628290 (Scopus ID)
Note

Funding text 1: The authors thank the Swedish Research Council Formas and Chalmers University of Technology for financial support. The Swedish Research Institute (RISE) is acknowledged for assistance with the ageing and testing equipment. The authors also thank Stora Enso for the supply of thermomechanical pulp as well as Södra Skogsägarna for the analysis of the cellulosic tissue. Axel Martinsson at the department of chemistry and chemical engineering is gratefully acknowledged for assistance in analysing the carbohydrate content of both cellulosic tissue and TMP. Dr J. A. Bristow is gratefully acknowledged for the linguistic revision of the manuscript.

Available from: 2020-10-20 Created: 2020-10-20 Last updated: 2023-05-26Bibliographically approved
Yarahmadi, N. (2019). Sustainable management of plastic waste from hospitals: Final report of the project.
Open this publication in new window or tab >>Sustainable management of plastic waste from hospitals: Final report of the project
2019 (English)Report (Other academic)
Abstract [en]

This project has been performed within the strategic research program RE:Source, with funding from the Swedish Energy Agency and participating partners. We would like to send a warm thank to all participants for their dedication and commitment during the project. Without their contributions the success of this project would not have been possible.

The big interest the project received nationally and in other Nordic countries shows the importance of the area, and we are looking forward to following up and expand this work further as a national, Scandinavian and/or European project in the future

Publisher
p. 45
Series
IVL ; C391
Keywords
recycling, plastic waste, hospital, pre-treatment
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-53463 (URN)
Note

RE:SOURCE Project number: 42528-1

Available from: 2021-06-03 Created: 2021-06-03 Last updated: 2023-05-26Bibliographically approved
Vega, A., Yarahmadi, N. & Jakubowicz, I. (2018). Determination of the long-term performance of district heating pipes through accelerated ageing. Polymer degradation and stability, 153, 15-22
Open this publication in new window or tab >>Determination of the long-term performance of district heating pipes through accelerated ageing
2018 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 153, p. 15-22Article in journal (Refereed) Published
Abstract [en]

The lifetime of pre-insulated district heating pipes (DHPs) is commonly evaluated using the method described in the normative European Standard EN 253. This lifetime is normally calculated using an Arrhenius equation, which makes use of test results from accelerated ageing tests at elevated temperatures. In this investigation, long-term accelerated ageing tests of DHPs at elevated temperatures were carried out. The ageing behaviour, especially at the interface between steel pipe and polyurethane (PUR) foam, showed several routes of degradation. It is clearly demonstrated using measurements of shear strength, thermal conductivity and alterations of chemical structure by Fourier Transform Infrared spectroscopy that the results of accelerated ageing at 170 and 150 °C significantly diverge from those obtained from the ageing test at 130 °C. It is therefore concluded that accelerated ageing at commonly used high temperatures does not create an acceleration of degradation processes at the steel/PUR interface relevant for the DHP application, but rather a significant alteration in mechanism. This finding is of crucial importance for the use of EN 253 and the development of future methods for lifetime prediction of DHPs.

Keywords
Accelerated ageing, Degradation, District heating pipe, Lifetime prediction, Polyurethane foam, Shear strength, Thermal conductivity, District heating, Fourier transform infrared spectroscopy, Polyurethanes, Testing, Accelerated ageing tests, Arrhenius equation, Degradation process, Elevated temperature, Long term performance
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-34304 (URN)10.1016/j.polymdegradstab.2018.04.003 (DOI)2-s2.0-85045381494 (Scopus ID)
Note

 Funding details: Energimyndigheten; Funding details: BASF;

Available from: 2018-08-06 Created: 2018-08-06 Last updated: 2023-05-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5579-2947

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