Modelling and Simulation of the Fifth-Generation District Heating and Cooling Abugabbara, Marwan 2021 Document Version: Publisher's PDF, also known as Version of record Link to publication Citation for published version (APA): Abugabbara, M. (2021). Modelling and Simulation of the Fifth-Generation District Heating and Cooling. Division of Building Services, LTH, Lund University. 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LUND UNIVERSITY PO Box 117 221 00 Lund +46 46-222 00 00 Download date: 09. Oct. 2021 MARWAN ABUGABBARA MARWAN AN ECOLABEL 3041 0903 NORDIC SW Modelling and Simulation the of Fifth-Generation District Heating and Cooling Modelling and Simulation of ryck, Lund 2021 the Fifth-Generation District Printed by Media-T Heating and Cooling MARWAN ABUGABBARA FACULTY OF ENGINEERING | LUND UNIVERSITY Heating setpoint Cooling setpoint District Weather warm pipe Balancing unit Building1 Building2 Building3 District Flow junction Reference cold pipe pressure HX HP CH Department of Building and Environmental Technology District warm pipe Faculty of Engineering District cold pipe Lund University 415144 ISBN 978-91-85415-14-4 ISRN LUTVDG/TVIT-21/1004-SE(138) 2021 789185 ISSN 1652-6783 9 Modelling and Simulation of the Fifth- Generation District Heating and Cooling Marwan Abugabbara LICENTIATE DISSERTATION by due permission of the Faculty of Engineering, Lund University, Sweden. To be defended at lecture hall V:C, building V-huset, John Ericssons väg 1, Lund on 11 June 2021 at 13:00. Faculty opponent Peter Sorknæs Associate Professor, Department of Planning Aalborg University, Denmark Organization Document name LUND UNIVERSITY LICENTIATE DISSERTATION Faculty of Engineering Date of issue 2021-05-11 Department of Building and Environmental Technology Division of Building Services Author Sponsoring organizations See acknowledgments Marwan Abugabbara section Title and subtitle Modelling and Simulation of the Fifth-Generation District Heating and Cooling Abstract District heating and cooling are efficient systems for distributing heat and cold in urban areas. They are a key solution for planning future urban energy-efficient systems due to their high potential for integrating renewable energy sources. The systems also play an important role in community resilience, which makes them a multidisciplinary research topic. The continuous development of these systems has now reached the fifth-generation whereby end-customers can benefit from the intrinsic synergies this generation offers. A typical Fifth-Generation District Heating and Cooling (5GDHC) system consists of connected buildings that together have simultaneous heating and cooling demands. Local heat pumps and chillers in decentralised substations modulate the low network temperature to the desired building supply temperatures. The demands are potentially balanced by the means of recovering local waste heat from chillers, while also utilising heat pumps to provide direct cooling. The heat carrier fluid in the distribution pipes can therefore flow in either direction in the so-called bidirectional low-temperature network. A balancing unit is incorporated to compensate for network energy imbalances. The exchange of energy flows is realised at different stages within the individual building and across connected buildings. Numerous factors influence the quantity and quality of the exchanged energy flows. Demand profiles in each building, the efficiency of building energy systems, and control logics of system components are some examples of these factors. Investigating this generation using traditional computational tools developed using imperative programming languages is no longer suitable due to system complexity, size variability, and changes adopted in different use cases. Modelica is a free open-source equation-based object-oriented language used for the modelling and simulation of multi-domain physical systems. Models are described by differential-algebraic and discrete equations. The mathematical relations between model variables are encapsulated inside an icon that represents the model. Different component models interface variables through standardised interfaces and connection lines. Large complex systems are composed by the visual assembly of components in a Lego-like approach. Models developed in Modelica can be easily inherited for rapid virtual prototyping and/or edited to adopt changes in the model use. This dissertation has a fourfold objective. Firstly, it demonstrates the development of a simulation model for an installed 5GDHC system located in Lund, Sweden. Secondly, it characterises the components that constitute a 5GDHC system. Thirdly, it unravels the exchange of energy flows at different system levels and describes, in a logical progression, the modelling of 5GDHC with Modelica. Fourthly, it presents ethical risk analyses of the different role-combinations that may arise in 5GDHC business models. The developed model is used in performing annual simulations and to evaluate the system performance under two different substation design cases. The results indicate that adding a direct cooling heat exchanger in each substation can reduce the electric energy consumption at both substation and system levels by about 10 and 7 %, respectively. Moreover, the annual waste heat to ambient air can be decreased by about 17 %. The dissertation fosters an ethical discourse that engages the public and all who take part in the multidisciplinary research on 5GDHC to guarantee safe operation and appropriate services. Future research will build on the models presented in this dissertation to investigate different network temperature and pressure control strategies, in addition to adopting several design concepts for balancing units and thermal energy storage systems. Key words Waste heat recovery; Heat pumps; 5GDHC; Modelica; Ethical risk analyses ISRN LUTVDG/TVIT-21/1004-SE(138) Language English ISSN 1652-6783 ISBN 978-91-85415-14-4 (printed) ISBN 978-91-85415-15-1 (e-published) Recipient’s notes Number of pages 138 Price Security classification I, the undersigned, being the copyright owner of the abstract of the above-mentioned dissertation, hereby grant to all reference sources permission to publish and disseminate the abstract of the above-mentioned dissertation. Signature Date 2021-05-11 Modelling and Simulation of the Fifth- Generation District Heating and Cooling Marwan Abugabbara Cover illustration by Marwan Abugabbara © copyright pp 1-78 Marwan Abugabbara Paper 1 © The Authors (Open access) Paper 2 © The Authors (Open access) Paper 3 © The Authors (Submitted manuscript) Lund University, Faculty of Engineering Department of Building and Environmental Technology Division of Building Services SE-221 00 Lund Sweden ISBN 978-91-85415-14-4 (printed) ISBN 978-91-85415-15-1 (e-published) ISRN LUTVDG/TVIT-21/1004-SE(138) ISSN 1652-6783 Printed in Sweden by Media-Tryck, Lund University Lund 2021 To my mother, Maisa Farrag (1954 – 2013) To my father, Y’akoub Abujbara (1946 – 1999) “The psyche is the greatest of all cosmic wonders and the sine qua non of the world as an object. […] Swamped by the knowledge of external objects, the subject of all knowledge has been temporarily eclipsed to the point of seeming non-existence.” – Carl Jung, The Spirit of Psychology Acknowledgments Acknowledgments A research project is a fruitful collaboration between many individuals and organisations. I would like to take this opportunity to acknowledge the impact the following individuals and organisations have had on this research. Institutional The work behind this research was carried out at the Division of Building Services, Department of Building and Environmental Technology, Faculty of Engineering, Lund University. I would like to begin by thanking my supervisors for their involvement during the past two years. To my main supervisor Dennis Johansson for making my research environment conducive to concentrated and productive work. I have learned a great deal from Dennis about the management and coordination of research projects by observing his work methods. To my assistant supervisor Saqib Javed for providing me with invaluable feedback that has greatly influenced my academic development. Saqib gives multiple rounds of critical feedback on every single written word, which is an incredible asset for any PhD student at the beginning of their academic career. To my assistant supervisor Hans Bagge for the comments and advice especially on the writing about engineering ethics. I would like to extend my thanks to my colleague Jonas Lindhe for kindly sharing the spreadsheet