Downloaded from orbit.dtu.dk on: Oct 04, 2021 The Development of a New District Heating Concept Network Design and Optimization for Integrating Energy Conservation and Renewable Energy Use in Energy Sustainable Communities Dalla Rosa, Alessandro Publication date: 2012 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Dalla Rosa, A. (2012). The Development of a New District Heating Concept: Network Design and Optimization for Integrating Energy Conservation and Renewable Energy Use in Energy Sustainable Communities. Technical University of Denmark. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. 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Network Design and Optimization for Integrating Energy Conservation and Renewable Energy Use in energy Sustainable Communities Section of Building Physics and Services, Department of Civil Engineering, Technical University of Denmark 2800, Kgs. Lyngby, Denmark Printed by DTU-Tryk ___________________________________________________________________ _____________________________________________________________________ Hvad er Sandhed andet end en Leven for en Idée? (What is the Truth if not living for an idea?) Søren Kierkegaard, 1835 “Così è la vita, benché raramente essa venga così descritta: un inserirsi, un derivare a suo vantaggio, un parassitare il cammino in giù dell’energia dalla sua nobile forma solare a quella degradata di calore a bassa temperatura. Su questo cammino all’ingiù, che conduce all’equilibrio e cioè alla morte, la vita disegna un’ansa e ci si annida.” (“Such is life, although rarely it is described in this manner: an inserting itself, a drawing off to its advantage, a parasitizing of the downward course of energy, from its noble solar form to the degraded one of low-temperature heat. In this downward course, which leads to equilibrium and thus death, life draws a bend and nests in it.”) Primo Levi, 1975 “It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects”. William Thomson (Lord Kelvin), 1851 This doctoral thesis is submitted in partial fulfilment of the requirements for the Danish PhD degree. The title of the PhD project is “low-energy buildings and heat supply systems based on renewable energy”. Copenhagen, 2nd April 2012 Alessandro Dalla Rosa _____________________________________________________________________ iii Preface This thesis is based on five scientific articles which were either published (three articles) or accepted for publication (one article) in Institute for Scientific information (ISI) journals or presented at international conferences after a peer-review process (one article). The thesis is subdivided into two separate parts, namely PART I and PART II. The first part is an extended synopsis, which places the study in its scientific context, describes the objectives and assumptions, summarises the main results of the research work and provides the link between the appended scientific articles. The second part is the collection of the scientific articles which the thesis is based upon. v Acknowledgements The research presented in this doctoral thesis was conducted within the Section of Building Physics and Services, Department of Civil Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark, in the period March 2009 – April 2012. I express sincere gratitude to my main supervisor, Professor Svend Svendsen, who not only created the conditions for making this work possible, but also has pointed me in the right direction and supported my decisions throughout my studies. He was always able to find time in his busy schedule for constructive discussions, also outside normal working hours. I am grateful to Associate Professor Jørgen Erik Christensen and Senior Researcher Hongwei Li, who have been my co-supervisors and were decisive to help me solve critical issues during my studies. I acknowledge the staff of the Section of Building Physics and Services and my colleague researchers for their cooperation and assistance. I appreciate having spent time with them, especially during the social events, the “Tuesday and Friday breakfasts”, the “open office” meetings and the annual “Julefrokost” (Christmas lunch). I particularly thank my officemates, in order of appearance David Appelfeld, Lies Vanhoutteghem, Marek Brand and Hakan Tol, who made the atmosphere in the office lively and enjoyable and helped me cope with the frustration in some periods. I thank Ken Church and Raymond Boulter from the Housing, Buildings, Communities and Simulation group at National Resources Canada, Ottawa, Canada, for their assistance during my 5-month external research stay (June-October 2011) and all the new friends I met in Canada. I acknowledge the pipe manufacturing company Logstor, which provided the district heating twin pipes used in the experiments. I extend my most sincere thanks and gratitude to my girlfriend Camilla, for bearing the unsociable aspects of a PhD project, for supporting me with patience and for accepting me as I am. My gratitude goes also to my sister Silvia and her family for believing constantly in my capabilities. Finally, I do not forget the friends and the other persons who make my life worth living and therefore my desire of knowledge alive: their names will not appear in this paragraph, but I will always keep them with me, together with the memories of the good time we spent together. I dedicate this work to my parents, Maria Letizia and Giuliano, whose example has been a model of modesty and dedication, qualities I tried to apply during my education as researcher. Copenhagen, 2nd April 2012 Alessandro Dalla Rosa vii Abstract PART I of this doctoral thesis consists of 6 chapters. Chapter 1 summarizes the main issues caused by the use of energy resources. They involve ecological, economic, demographical and socio-political topics that are linked together and define the background of the thesis. Chapter 2 describes the state-of-the-art of District Heating (DH) systems, with focus on the present and future situation in Denmark. The core of the thesis consists of the development of a new DH paradigm, the “Low- Temperature District Heating (LTDH)”, the study of its potential, and investigations of technical options which improve its applicability in terms of energy performance and socio-economy. Chapter 3 describes the whole idea about LTDH. Chapter 4 presents the hypotheses of the studies, draws the boundaries between the focus area of the thesis and other relevant aspects of the subject, describes the limitations of the work and lists the methods which were used. Chapter 5 explains the results of the scientific content reported in the articles in PART II. Article I introduces the technical and organizational strategies that can facilitate the establishment of a successful energy planning in a community. It analyses the state- of-the art in community energy planning, discusses critical issues, and points at the role of DH in moving towards sustainable heat supply. The articles II and III aim at providing science-based knowledge for the development of improved solutions for the DH networks; they focus on the performance simulation of DH pipelines through models for assessing the energy performance of innovative pipe geometries, materials or system configurations. The models were validated against experimental measurements on real DH pipes. Article II considers the detailed steady-state modelling and analysis of heat losses in pre-insulated DH pipes. Article III focuses on the modelling and computation of the transient heat transfer in service pipes, which are important elements of LTDH networks, particularly when supplying low heat density building areas. The purpose of article IV was to perform simulations and analyses about low-energy DH networks supplying heat to energy-efficient building areas in countries – such as Denmark – with an extensive existing DH infrastructure, quantify their technical and economic feasibility, and suggest strategies for optimizing their design and operation. Article V deals with the potential and barriers of implementing DH in Canada, where the DH market share is low. Technical-economic feasibility studies for DH networks supplying an urban area in the city of Ottawa were carried out, with particular