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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. Practical Applications: District heating (DH) pipes consist of a steel pipe surrounded by insulating foam and a casing. This design requires satisfactory adhesion between the components to achieve good long-term performance. The use of DH pipes in a reliable and cost-effective way as long as possible requires planned and selective replacement of worn-out parts. A prerequisite to accomplish this is reliable information about the functional status and remaining service life of different parts of existing networks. Pipeopsy is a new field test method that provides valuable information on whether adhesion strength between insulation foam and steel pipe is at a satisfactory level. In addition, chemical analysis provides information on the degree of degradation of the foam closest to the steel pipe. If a similar return pipe can be evaluated, conclusions can be drawn about the extent of reduction in adhesion and whether it is due to degradation of the insulation foam. With this information, the remaining lifetime of the supply pipe can be estimated. Using the Pipeopsy method, testing can be performed at a small cost, using simple mobile tools and without shutting down the operation. Therefore, this method is the only one of its kind that can be used on a large scale. [ABSTRACT FROM AUTHOR]

Background: While energy communities working on electricity provision have been extensively studied, thermal energy communities (TECs) focusing on bringing district heating (DH) systems to decarbonise heat systems in buildings have been relatively under-researched. This study addresses this gap by presenting the first comprehensive examination of key factors influencing the emergence and development of TEC projects in Denmark, Germany, and the Netherlands. The study uses an established analytical framework from previous research encompassing seven dimensions: market structure, hard- and soft institutions, financing, physical infrastructure, capacity, and interactions with other stakeholders. Data are gathered through a literature review and interviews. Results: TECs have emerged at different times in each country, shaped by contextual circumstances and diverse forms of institutional support. Elements that have supported the development of TECs are regulatory frameworks promoting DH growth, heat decarbonisation policies, economic incentives to use waste heat in plants, targeted financing mechanisms, and assistance to enhance the capacity of TECs. External factors such as high oil prices, seismic events, and recent rising energy prices have also spurred project initiation. TECs also rely on additional factors for success, including organisational and entrepreneurial abilities to engage with stakeholders, gain social acceptance, and secure commitment from community members. Involvement from local government, intermediary organisations, and private companies is crucial for TEC implementation. Among the studied countries, Danish TECs stand out as the most developed, benefiting from a stable policy environment, decades of experience with DH and TEC, and positive societal perceptions. Conversely, Dutch and German TECs face challenges because of the early stage of their heat transition, dealing with financial obstacles, underdeveloped policies, unfamiliarity with DH technology and with TECs, as well as the need for expensive infrastructure changes. Shared challenges across regions include capacity limitations in small projects and implementing cost-effective, local, and sustainable heat sources. Conclusions: In light of the study's findings, policymakers must consider establishing stable, integral and flexible policies supporting heat decarbonisation and TECs, addressing TECs' reliance on limited capacities, involving TECs in local heat municipal plans, and facilitating high DH connection rates where DH is the most cost-effective solution from a socio-economic perspective. [ABSTRACT FROM AUTHOR]

The integration of energy generation and consumption is one of the most effective ways to reduce energy-system-related waste, costs, and emissions in cities. This paper considers a university district consisting of 32 buildings where electrical demand is currently met by the national grid, and 31% of thermal demand is supplied by a centralized heating station through a district heating network; the remainder is covered by small, dedicated boilers. Starting from the present system, the goal is to identify "retrofit" design solutions to reduce cost, environmental impact, and the primary energy consumption of the district. To this end, three new configurations of the multi-energy system (MES) of the district are proposed considering (i) the installation of new energy conversion and storage units, (ii) the enlargement of the existing district heating network, and (iii) the inclusion of new branches of the electrical and heating network. The configurations differ in increasing levels of integration through the energy networks. The results show that the installation of cogeneration engines leads to significant benefits in both economic (up to −12.3% of total annual costs) and energy (up to −10.2% of the primary energy consumption) terms; these benefits increase as the level of integration increases. On the other hand, the limited availability of space for photovoltaics results in increased CO2 emissions when only total cost minimization is considered. However, by accepting a cost increase of 8.4% over the least expensive solution, a significant reduction in CO2 (−23.9%) can be achieved while still keeping total costs lower than the existing MES. [ABSTRACT FROM AUTHOR]

The increasing demand for sustainable energy solutions has spurred significant interest in cogeneration technologies. This study introduces a novel integrated organic Rankine cycle (ORC) and vapor compression cycle (VCC) system, specifically designed to enhance energy efficiency and reduce greenhouse gas emissions in industrial applications and district heating systems. The key innovation lies in the development of an advanced coupling mechanism that seamlessly connects the ORC and VCC, enabling more efficient utilization of low-grade heat sources. By optimizing working fluid selection and implementing a shared shaft connection between the ORC turbine and VCC compressor, the system achieves dual functionality—simultaneous electricity generation and cooling—with higher efficiency than conventional methods. Thermodynamic analyses and experimental results demonstrate that the proposed ORC–VCC system can significantly reduce operational costs and decrease reliance on fossil fuels by leveraging renewable energy sources and industrial waste heat. Additionally, the study addresses integration challenges by introducing specialized components and a modular design approach that simplifies installation and maintenance. This innovative system not only enhances performance but also offers scalability for various industrial applications. By providing a detailed evaluation of the ORC–VCC integration and its practical implications, this work underscores the system's potential to contribute substantially to a sustainable energy transition. The findings offer valuable insights for future research and development, highlighting pathways to overcome existing barriers in cogeneration technologies. [ABSTRACT FROM AUTHOR]

This paper explores the innovative application of Geographic Information Systems (GISs) to identify and utilize waste heat sources from railway and highway tunnels for fifth-generation district heating and cooling (5GDHC) systems. Increasing the number of prosumers—entities that produce and consume energy—within 5GDHC networks enhances their efficiency and sustainability. While potential sources of waste heat vary widely, this study focuses on underground car/railway tunnels, which typically have a temperature range of 20 °C to 40 °C. Using GIS software, we comprehensively analyzed tunnel locations and their potential as heat sources in Belgium. This study incorporates data from various sources, including OpenStreetMap and the European Waste Heat Map, and applies a two-dimensional heat transfer model to estimate the heat recovery potential. The results indicate that railway tunnels, especially in the southern regions of Belgium, show significant promise for waste heat recovery, potentially contributing between 0.8 and 2.9 GWh annually. The integration of blockchain technology for peer-to-peer energy exchange within 5GDHC systems is also discussed, highlighting its potential to enhance energy management and billing. This research contributes to the growing body of knowledge on sustainable energy systems and presents a novel approach to leveraging existing district heating and cooling infrastructure. [ABSTRACT FROM AUTHOR]

Retrofitting heat networks will play a major role in improving building performance and facilitating a net zero environment by 2050. A 94-dwelling social housing development based in the UK, was operating a heat network and experiencing significant issues with overheating, resident discomfort, and poor network efficiency. An Automatic Meter Reading (AMR) system was installed to baseline network performance and identify improvement opportunities. The data revealed the network was operating with a 74/66 °C temperature profile, and that the total network losses exceeded 1000 W/dwelling. This paper sets out the detailed methodology and considerations in retrofitting the heat network to enable future connections to low carbon heat sources such as heat pumps or low temperature district heating. Quality assurance was undertaken during the design, install and commissioning stages to facilitate the project's success and hit key milestones. At present, the operating temperatures have been reduced to a 55/37 °C flow and return temperature, enabling a gas consumption reduction of 38% and network heat loss reduction of over 90%, with heat losses currently at 56 W/dwelling. This data driven approach to retrofitting has simultaneously improved resident comfort, reduced heat costs and enabled a straightforward connection to low carbon heat sources when available. Practical Application: This paper outlines the interdependencies of typical issues on existing heat networks and the effect of these issues on operational performance, cost, carbon emissions and resident satisfaction. A methodology is given which outlines the importance of maximising heat network performance prior to moving to low carbon heat sources. The results of carrying out this methodology on an existing heat network act as an example to the industry showing that the 100 W/dwelling heat loss target in CIBSE CP1: heat networks code of practice can not only be achieved, but significantly improved upon in existing buildings. [ABSTRACT FROM AUTHOR]

As a newly widely used energy source, hydrogen has not yet been integrated with other energies efficiently, leading to low energy efficiency and high operating costs. This paper develops a novel cooperation model to coordinate electricity, hydrogen, and district heating systems and reduce operating costs. First, the mathematical model of electricity, hydrogen, and district heating systems coupled by electrolysers is established, and the bidirectional heat exchange (BHE) between hydrogen production and district heating networks (DHNs) is proposed. Then, a dual‐layer model predictive control (DLMPC) method is proposed for the integrated electricity, hydrogen, and heating microgrid (IEHHM) scheduling. The upper layer aims to deal with the hourly power variation and determine the IEHHM operation schedules, and the lower layer revises the power of electrolysers and combined heat and power (CHP) plants to follow the real‐time power variation of renewable energy generations (REGs). Simulation results show that: (1) BHE improves the thermal dynamics of electrolysers and DHNs, enhancing operational flexibility; (2) The DLMPC method enables timely adjustments to the dispatch schedule, reducing operating costs by responding to multi‐time‐scale power variations from REGs. [ABSTRACT FROM AUTHOR]

District heating and cooling networks distribute centrally generated heat through insulated pipes to multiple buildings, offering efficiency and reduced emissions, especially when using renewable heat sources. However, these systems face high upfront costs, heat loss during transport, and are most effective in densely populated areas. Despite interest in geothermal energy for district heating, empirical research on adoption factors is lacking. This review systematically examines literature to identify factors, opportunities, and challenges influencing geothermal energy adoption in district heating networks. Using the Web of Science database, 220 academic documents were analysed, highlighting common technical, economic, regulatory, and social challenges. The study also explores innovative technologies and methodologies for optimising geothermal district heating systems. It assesses the environmental, economic, and social benefits of geothermal systems over conventional heating and other renewable energy sources. Recommendations are made for policymakers, practitioners, and researchers to overcome barriers, address knowledge gaps, and foster collaboration for sustainable heating solutions. [ABSTRACT FROM AUTHOR]

District heating and cooling (DHC) systems are gaining importance due to their ability to integrate renewable and waste heat sources and connect with other infrastructures. However, the complexity of DHC systems rises as technical components and potential interactions grow, and energy demands increase. Heat transportation via water flow involves time- and temperature-dependent changes based on mass flow rates and heat losses, influenced by the dynamic properties of consumers and distribution pipes. To optimise DHC operations and simulate their complexities, dynamic modelling tools are necessary. However, dynamically simulating large-scale DHC networks are computationally demanding. One method to improve district heating networks (DHNs) is to replace dynamic pipe models with static models, simplifying the network's topological complexities. This paper proposes a framework for simulating DHNs using the NetworkX Python package to create and manipulate complex networks and the Modelica environment to simulate physical systems. The study highlights the constraints of the pipe replacement workflow due to its dependence on seasonal variation. The findings indicate that replacing pipe models can reduce CPU time by 30% to 65% in simulations, depending on the required accuracy during the summer season. [ABSTRACT FROM AUTHOR]

Weather forecasts are essential for district heating (DH) utility operations as they prepare the utility for future consumption, thus ensuring optimal operation by supplying sufficient heat while keeping costs low. Weather forecasts are usually converted into heat demand forecasts, which are used for production planning and control of the temperatures in the network. Hence, increasing the accuracy of weather forecasts will lead to improvements in the system's operational performance. However, numerical weather predictions (NWPs) are computed over the earth as grid values, and NWPs are designed for rural areas, not urban areas. Therefore, we propose to localise the weather forecasts to the urban environment by calibrating them using Model Output Statistics. We show that localising weather forecasts (removing the bias) leads to enhanced accuracy in the heat demand forecasts. In our case study, localised weather forecasts lead to an error reduction between 1.5% and 2.5% when compared to forecasts using uncalibrated NWPs. [ABSTRACT FROM AUTHOR]

Harsh winters, aging infrastructure, and the demand for modern amenities are major factors contributing to the deteriorating air quality in Bishkek. The city meets its winter heating energy needs through coal combustion at the central heating plant, heat-only boilers, and in situ heating equipment, while diesel and petrol fuel its transportation. Additional pollution sources include 30 km2 of industrial area, 16 large open combustion brick kilns, a vehicle fleet with an average age of more than 10 years, 7.5 km2 of quarries, and a landfill. The annual PM2.5 emission load for the airshed is approximately 5500 tons, resulting in an annual average concentration of 48 μg/m3. Wintertime daily averages range from 200 to 300 μg/m3. The meteorological and pollution modeling was conducted using a WRF–CAMx system to evaluate PM2.5 source contributions and to support scenario analysis. Proposed emissions management policies include shifting to clean fuels like gas and electricity for heating, restricting secondhand vehicle imports while promoting newer standard vehicles, enhancing public transport with newer buses, doubling waste collection efficiency, improving landfill management, encouraging greening, and maintaining road infrastructure to control dust emissions. Implementing these measures is expected to reduce PM2.5 levels by 50–70% in the mid- to long-term. A comprehensive plan for Bishkek should expand the ambient monitoring network with reference-grade and low-cost sensors to track air quality management progress and enhance public awareness. [ABSTRACT FROM AUTHOR]

Pool-type low-temperature heating reactor (PLTHR) has attracted considerable attention throughout the world due to its low operating parameters and satisfactory inherent safety in district heating. Exploring the dynamic performance of PLTHR is a prerequisite for designing control systems and developing operation strategies. Until now, the dynamic performance of the district heating system using a 400 MW pool-type low-temperature heating reactor (DHR-400) has not been fully discussed. Based on APROS software, a precise dynamic model for DHR-400 is constructed in this paper. The dynamic responses of DHR-400 under five external variables such as control rod reactivity, first loop flow rate, second loop flow rate, third loop flow rate, and return temperature at the third loop are investigated. The results revealed that the core power variation is not linear with the flow rate variation at the three loops. Core power variations are −16.27, −14.04, and −20.96 MW with a 30% reduction in flow rate at the first loop, the second loop, and the third loop, respectively. Considering safe operation, when there are minor fluctuations in the heating demand, the core power regulation method by adjusting the third loop's flow rate should be given priority without altering the position of the control rods. [ABSTRACT FROM AUTHOR]

The document "Grand Challenges in Heat Decarbonisation" discusses the significant role of heat in global energy consumption and the urgent need to decarbonize heat supply to achieve net zero greenhouse gas emissions by 2050. It highlights various challenges and alternative technologies for domestic heating, such as heat pumps, biomass boilers, and solar energy, emphasizing the importance of transitioning to low or zero carbon heating technologies. The document also addresses industrial heating challenges and the research perspectives on high temperature industrial heat pumps to recover waste heat and reduce GHG emissions in industrial processes. [Extracted from the article]

Increased use of cogeneration in district heating (DH) systems is important in the pursuit towards a low-carbon society, particularly in light of the ongoing electrification across multiple sectors. Apart from reducing CO2 emissions, cogeneration also contributes to additional income for the DH system owner. Nonetheless, it is important to be aware that the economic and environmental performance of DH systems are directly connected to the energy use within DH networks. This research investigates sector interactions associated with the introduction of a biomass combined heat and power (CHP) and residential energy renovation according to (life cycle cost) LCC optimum and Swedish energy targets, with a focus on CO2 emissions and the system cost of the energy utility company. The study object consists of a DH system in Visby, Sweden, and 920 historic residential building undergoing energy renovation. The results show a profitability of 905–915 MSEK for the DH system with the integration of a CHP. Global CO2 emissions decrease by 32.6–33.1 ktonnes/year, 9.0–9.2 ktonnes/year, and 19.9–20.1 ktonnes/year, for marginal coal-condensing power (limited biofuel), natural gas combined cycle power (limited biofuel), and European average production, respectively. In addition, sensitivity analyses confirm the benefits of cogeneration related to both economics and CO2 emissions based on changes in key parameters of the DH system. Highlights: This paper studies sector interactions between biomass CHP introduction and residential energy efficiency measures. The study object consists of a DH system in Visby, Sweden, and 920 residential buildings. Integrating a CHP decreases the DH system cost by 905–915 MSEK. Global CO2 emissions decrease by 9.0–33.1 ktonnes/year. The reduction in global CO2 emissions is closely linked to the method of CO2 accounting. [ABSTRACT FROM AUTHOR]

District heating systems play a crucial role in the European Union for sustainable energy practices by contributing to reducing carbon emissions and thus counteracting climate change. In most European countries, the energy consumption for heating is a topic that needs to be considered. Germany has recognized the need for more awareness among its citizens about district heating systems. Therefore, an interactive website was developed in close cooperation with the city of Weilheim in Bavaria, Germany. The goal is to inform citizens about the district heating system under construction. The website aims to improve user engagement through interactive features, including a quiz, an interactive calculator, and various animations and images. The application focuses on the primary energy sources biomethane, solar energy, wood chips, and the use of environmental heat through heat pumps. The website was evaluated at a local secondary school, which yielded positive feedback. [ABSTRACT FROM AUTHOR]

Fifth-generation district heating systems have appeared in the heating supply of modern cities. There is a growing demand for the use of renewable energy sources, the most significant of which is geothermal energy. Implementing district heating systems is very costly, and reducing investment and operating costs requires accurate forecasting of expected heating demands and uncertainty analysis. The design of district heating systems begins with determining the heat demand to be supplied. The heating demand maximum occurring with a 1% frequency (24-h duration) is called the representative heating demand. In our study, we deal with the probability theory of heating demands. Heating demands are also uncertain primarily due to the uncertainties in meteorological and weather characteristics and, in a mathematical sense, are random variables. We must emphasize that any description that follows a deterministic approach in determining heating demands does not meet the criteria of modern science and can lead to severe planning and operational errors. In our study, following a probabilistic approach, we present a mathematical model that allows the determination of heating demands using probabilistic tools. With the help of the model, we can determine the low-risk representative heat demand and, through this, assess whether the available heat production capacity is sufficient with the prescribed safety or whether its expansion is necessary. Furthermore, in operation, we can prepare with the least risk of the short- and long-term forecasted values of meteorological factors. In our study, using the presented probabilistic method, we proved that for the most common prefabricated housing units in Hungary (approximately 500,000), there is a 30% uncertainty in the representative—previously accepted as 5000 W—heat demand, which, if considered in operation, can avoid significant costs. Our investigations showed that under representative meteorological conditions, the standard deviation of the expected heat demand is 1119 W, while the expected value is 3700 W. With the help of the presented model, the errors and uncertainties in the parameters used to calculate heat demand can be extensively analyzed. [ABSTRACT FROM AUTHOR]

Miskolc, which is the focus of our investigation, is the fourth most populous city in Hungary and the center of one of the most underdeveloped NUTS2 (basic territorial category for the regional policy of the European Union) regions in the European Union. The socialist heavy industry played a decisive role in the development of the city, the decline of which also left deep traces in the city. In its current position, the city tries to manage its available resources as efficiently as possible, and the city management is open to the use of modern urban development tools. This is supported by the fact that Miskolc was the first Hungarian city to join the Green Cities for Sustainable Europe movement in 2011, and then in 2015, it joined the Triangulum project of the EU Smart Cities and Communities program as a follower city. In the process of becoming a smart city, the dimensions of environmental sustainability and energy efficiency were given a prominent role, which should not be surprising considering the traditions of the city. Within this, we must first mention the construction of the geothermal central heating system, with which the city really took significant steps in this field. The main goal of the study is to develop a new smart local concept closely linked to regional development and the key energy sector, through which the local adaptation of the defining elements of the internationally defined smart city in several forms for the city of Miskolc will be presented. In our study, we review how the results achieved by Miskolc so far and the development plans for the future fit in with the smart energy developments of smart cities. Before exploring the processes in Miskolc, we will deal in more detail with the possibilities inherent in district heating and geothermal energy utilization and Hungary's capabilities. [ABSTRACT FROM AUTHOR]

Demand response (DR) enhances building energy flexibility, but its application in hybrid heating systems with dynamic pricings remains underexplored. This study applied DR via heating setpoint adjustments based on dynamic electricity and district heating (DH) prices to a building heated by a hybrid ground source heat pump (GSHP) system coupled to a DH network. A cost-effective control was implemented to optimize the usage of GSHP and DH with power limitations. Additionally, four DR control algorithms, including two single-price algorithms based on electricity and DH prices and two dual-price algorithms using minimum heating price and price signal summation methods, were tested for space heating under different marginal values. The impact of DR on ventilation heating was also evaluated. The results showed that applying the proposed DR algorithms to space heating improved electricity and DH flexibilities without compromising indoor comfort. A higher marginal value reduced the energy flexibility but increased cost savings. The dual price DR control algorithm using the price signal summation method achieved the highest cost savings. When combined with a cost-effective control strategy and power limitations, it reduced annual energy costs by up to 10.8%. However, applying the same DR to both space and ventilation heating reduced cost savings and significantly increased discomfort time. [ABSTRACT FROM AUTHOR]

Large scale heat pumps (LSHP) have seen a rapid proliferation in recent years, with projects and initiatives aimed at integrating electrically driven LSHP into existing district heating networks (DHN). The financial advantages have driven most LSHP installations to be powered by electricity generated by on-site cogeneration (CHP), given CHP's dominant role in DHN. This LSHP + CHP combination poses the question, to what extent ecological improvements, measured as a reduction in specific CO2 emissions through LSHP operation can be achieved, contingent on the source of electricity and heat source employed. In this paper, the LSHP + CHP combination was generally analysed under usage of exergy analysis and a 2nd law derived method is presented. This method allows to evaluate the magnitude of CO2 reduction through LSHP operation across all common heat sources in 1st to 4th generation DHNs in conjunction with CHP. Results show, that in LSHP + CHP combination, heat from LSHP using either of the 2 heat sources ambient air or surfaced water, inevitably comes with higher specific CO2 emissions over the CHP heat. Only when using a sufficiently hot and emissions-free heat source, the LSHP heat from a LSHP + CHP combination can yield to an annual best case of half the CO2 emissions of the CHP. Importantly, the choice of power source has a far more significant impact, as LSHP powered by electricity from renewable energy sources achieve more than an eight-fold reduction in emissions compared to the LSHP + CHP combination. Therefore, power consumption with sufficiently low specific CO2 emissions out of external source is imperative to fully realize the ecological benefit of LSHP in DHN, underlining that the successful heat transition through LSHP relies heavily on the transformation of the electricity supply. Highlights: Based on the 2nd law a methodology is derived around exergy analysis, that enables a universal assessment of the ecological benefit of LSHP powered by CHP (Chapter 3). Graphs to determine every possible combination are presented (Chapter 4). Results are drawn for the most common CHP & LSHP including the most common types of heat source to grasp the scope of the discussed problematic. Ecological impact of LSHP in DHN are shown for comparison for most common types of CHP and LSHP- heat sources. [ABSTRACT FROM AUTHOR]

Electrification of district heating and deep integration of sectors of national economies are fundamental elements of the future smart energy systems. This paper discusses the problem of optimal sizing of large-scale high-temperature heat pumps using treated sewage water as a heat source in a coal-fired district heating system. The study presents an approach to modelling of heat pump system that enables techno-economic analysis for investment decision making. Such analysis is enabled by a black-box-type identification model of the selected industrial heat pump. The model was developed based on the data generated by physical modelling of the heat pump using Ebsilon Professional software. In addition, it is proposed that the heat pump system is integrated with a dedicated photovoltaic power plant. The case study takes into consideration site-specific technical, economic, ecological, and legal constraints, weather conditions, hydraulic performance of the heating network, and variability of loads within the sewage and the district heating systems. The results revealed that the proposed modelling approach is effective regarding multiple simulations and system optimisation. In addition, it was found that large-scale heat pump projects can be technically feasible and profitable if the heat pump is appropriately sized and operated. In the given case, the optimum size of the heat pump for a city of around 180 000 inhabitants is around 12 MW under maximum winter load. [ABSTRACT FROM AUTHOR]

Hydrodynamic models are used to analyse water networks (water distribution, drainage, surface water, district heating, etc.). The non-linear nature of water flows necessitates the use of iterative solution methods in hydraulic modelling. This requires a relatively large computational effort. To reduce this effort, networks, network forcing and/or the flow in networks are often simplified and analysed using the Graph Theory. The simplification options depend on the network characteristics. There are many topological features to describe Graph-based networks. In this paper, these characteristics are summarised, applied on 7 urban drainage networks and discussed. As the topological features do not describe the networks in a uniform manner, a new type of topological characterisation of looped drainage networks (Network Linearisation Parameter, NLP) is proposed based on linearized hydraulics and bottlenecks identified in paths to outfalls. [ABSTRACT FROM AUTHOR]

This review presents a comprehensive examination of recent advancements and findings related to return-temperature reduction in District Heating (DH) systems, with a focus on enhancing overall system efficiency at end-user sites. The review categorizes and clarifies various return-temperature reduction techniques, emphasizing aspects such as building energy performance, heat emitters, thermostatic radiator valves, and substation units. One shall note that return temperature is not a parameter that can be directly controlled within a DH system; instead, it is influenced indirectly by adjusting various system parameters throughout the design, commissioning, operation, and control phases. Key insights include the direct impact of heat demand on return temperatures; the pivotal role of indoor heating systems in optimizing thermal energy use in relation to heat demand; the significance of thermostatic radiator valves in regulating heat output and maintaining low return temperatures; the advantages of ventilation radiators and add-on fans in enhancing radiator efficiency; the necessity for effective substation operation to improve system cooling capacity; and the critical role of operational control strategies in achieving optimal system performance. These findings underscore the need for integrated approaches in DH system design and operation to achieve lower return temperatures and improve overall system efficiency. [ABSTRACT FROM AUTHOR]

In response to global warming and the critical need for sustainable energy solutions, district heating systems (DHS) have emerged as an area of significant focus due to their potential to enhance resource efficiency, reduce carbon emissions, and improve economic outputs. This research addresses the critical issue of establishing a methodological framework for evaluating the efficiency of DHS as market relations evolve within the heating sector. The study's aim is to develop and validate methodological principles that assess the operational, economic, and technological dimensions of DHS in a competitive market landscape. The framework encompasses the complex interplay of regulatory frameworks, market dynamics, production technologies, and consumer engagement strategies. Key objectives include analyzing current challenges in implementing competitive market structures, justifying the non-linear nature of cost functions for energy producers, and developing criteria for the equitable distribution of thermal energy losses. The overarching goal is to strategically propel DHS towards greater efficiency and sustainability by using renewable energy sources (RES). The research utilizes simulation modeling in a case study of Irpin city, Ukraine, employing machine learning and computer vision technologies through the "Solvergy: Buildings" mobile application to provide rapid, detailed energy performance assessments. Results from the simulation in "Solvergy: Systems" software indicate benefits from the market conditions functioning in DHS, quantified at $727,120 per year, and highlight the cost-saving potential of the RES-based supply diversification structure. The relative market efficiency at 28.05% suggests that the market delivers high potential economic value relative to a scenario without market conditions. The study concludes that transitioning to market relations and integrating independent energy producers can lead to substantial system efficiency improvements, lower thermal energy prices, and enhanced sustainability in DHS. Suggested policy measures advocate for the modernizing of infrastructure and the implementation of efficient technologies within a competitive, consumer-oriented market environment, thereby facilitating the decarbonization process and optimizing system performance. [ABSTRACT FROM AUTHOR]

The pursuit of climate neutrality requires global systemic actions involving the use of solutions aimed at reducing emissions. Changes must be introduced in all sectors affecting climate change, namely power engineering and district heating, construction, transport, and industry, as well as agriculture and forestry. Analyzing the structure of final energy consumption in the EU by sector, it can be stated that households account for 27% of the total energy consumption. Comprehensive actions are needed to increase the energy efficiency of buildings. The aim of this paper was to indicate aspects of improving energy efficiency in buildings and their equipment, taking into account the striving for climate neutrality. Analyzed possibilities and conditions of using various solutions of energy-efficient systems aimed at increasing energy resilience and security and preventing environmental degradation. Particular attention was paid to construction and material solutions, as well as installation solutions, which increased the accumulation and energy efficiency of the building. These activities are closely related to the conditions and dynamics of the heat exchange process in the applied solutions and are also related to the factors influencing thermal comfort and energy consumption in buildings. Due to the growing popularity of modern information technologies and artificial intelligence in energy management in recent years, this article reviews the latest research in this area. One of the directions of future research indicated by scientists is autonomous building control in real time, adapting to the momentary needs of users. The analysis of the possibilities of using modern energy efficiency solutions in buildings conducted in this work may be useful for optimizing heat and energy management models and models of society's consumption as an element of energy transformation towards climate neutrality and counteracting the deepening of energy poverty. [ABSTRACT FROM AUTHOR]

The integration of renewable energy sources (RESs) is rapidly increasing within energy systems worldwide. However, this shift introduces intermittency and uncertainty on the supply side. To hedge against RES intermittency, demand-side flexibility introduces a practical solution. Therefore, further studies are required to unleash demand-side flexibility in power systems. This flexibility is relevant across various sectors of power systems, including residential, industrial, commercial, and agricultural sectors. This paper reviews the key aspects of demand-side flexibility within the residential sector. To achieve this objective, a general introduction to demand flexibility across the four sectors is provided. As a contribution of this paper, and in comparison with previous studies, household appliances are classified based on their flexibility and controllability. The flexibility potential of key residential demands, including heat pumps, district heating, electric vehicles, and battery systems, is then reviewed. Another contribution of this paper is the exploration of demand-side flexibility scheduling under uncertainty, examining three approaches: stochastic programming, robust optimization, and information-gap decision theory. Additionally, the integration of demand flexibility into short-term electricity markets with high-RES penetration is discussed. Finally, the key objective functions and simulation software used in the study of demand-side flexibility are reviewed. [ABSTRACT FROM AUTHOR]

Energy poverty, i.e., inefficient heating and insufficient access to energy services, can turn a shelter into a health hazard. We find that substandard housing and ineffective heating is associated with a higher risk of poor health in an urban context. We surveyed people living in two middle-sized cities in a coal-dependent region of Poland and used objective and subjective indicators of energy poverty and self-assessed health status. We demonstrate that people who live in substandard housing are more likely to exhibit poor musculoskeletal and cardiovascular outcomes, by 10 and 6 pp, respectively than otherwise similar people living in suitable housing conditions. We show that energy-poor people who use coal or a wood stove have a 24 pp higher likelihood of respiratory disease than the energy-poor who live in flats connected to district heating. We also find that a significant amount of the explained variance in the probability of respiratory disease is attributable to energy poverty. To improve the housing conditions and reduce the risk of poor health outcomes, we recommend two policy instruments: 1) a full subsidy for thermal retrofits and connecting multi-family buildings to the district heating network and 2) a targeted energy voucher for clean heating. [ABSTRACT FROM AUTHOR]

High-temperature geothermal energy is precious renewable resource for heating. Reducing the return temperature of geothermal water is an important way to maximize geothermal heating potential and expand the heating area. Considering that existing buildings generally use high-temperature radiators and other heating terminals, while newly constructed buildings mostly use low-temperature floor heating terminals, the required supply water temperatures for these two types differ. In response to this, a geothermal energy-driven dual-temperature district heating substation system with a single absorption heat pump and two heat exchangers is proposed. This system aims to produce dual-temperature hot water for both high and low-temperature heating terminals and reduce the return temperature of geothermal water. Simulation results shows that when the geothermal outlet water is 100 ℃, and the secondary network's high- and low-temperature terminal supply water temperatures are 50 ℃ and 35 ℃ respectively, the return temperature of geothermal water in the dual-temperature district heating substation can be reduced to 20. 1 ℃. Compared to a substation using two serial heat exchangers, the proposed can lower the geothermal water return temperature by 14. 9 ℃, reduce the geothermal water flow rate by 18. 6%, and improve COP by 11%, demonstrating significant energy-saving advantages. Variable working condition analysis indicates that promoting the use of low-temperature heating terminals helps further reduce the return temperature of geothermal water, increase the heat supply to users, and improve the COP of the dual-temperature heating substation. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANNs) can be used for accurate heat load forecasting in district heating systems (DHSs). This paper presents an application of a shallow ANN with two hidden layers in the case of a local DHS. The developed model was used to write a simple application in Python 3.10 that can be used in the operation of a district heating plant to carry out a preliminary analysis of heat demand, taking into account the ambient temperature on a given day. The model was trained using the real data from the period 2019–2022. The training was sufficient for the number of 150 epochs. The prediction effectiveness indicator was proposed. In the considered case, the effectiveness of the trained network was 85% and was better in comparison to five different regression models. The developed tool was based on an open-source programming environment and proved its ability to predict heating load. [ABSTRACT FROM AUTHOR]

The article presents an analysis of changes in energy efficiency of new office buildings designed and constructed during the implementation period of the Energy Performance of Buildings Directive (2014–2024). Common criteria on energy efficiency were collected from Energy Performance Certificates (EPCs) and processed. The changes in final and primary energy for space heating, cooling and hot water production of certified office buildings were determined, and the improvements in buildings, their energy systems and energy sources were analysed. It was determined that buildings of Class C, designed between 2006 and 2017, showed an average thermal energy consumption for heating of 61, for cooling of 13 and for hot water production of 30 kWh/(m2·year), while buildings of Class A++, designed after 2020, consumed, respectively, 6, 9 and 17 kWh/(m2·year). The main reasons for these changes in energy consumption are the significant improvement of thermal insulation, increase of renewable energy in the heat supplied by district heating, the use of heat pumps for cooling, more efficient hot water boilers and optimized and insulated distribution pipelines. Even better results were hindered by the increased area of glazing, insufficient use of solar protection, users' preference for buildings of complex shape, and technically complicated electricity production. The results revealed that EPCs are an appropriate database for the analysis of changes in energy efficiency of buildings and for setting tasks for further improvement. [ABSTRACT FROM AUTHOR]

The editorial in "Frontiers in Energy Research" discusses the challenges faced by the global energy sector, emphasizing the need for innovative solutions in energy systems engineering due to greenhouse gas emissions and resource scarcity. The research presented in the editorial showcases advancements in modeling, control strategies, and technological integration to enhance energy systems' efficiency, stability, and sustainability. Various studies highlighted in the editorial focus on topics such as power system stability analysis, district heating systems, carbon capture technologies, microgrid management, oil recovery mechanisms, and hydrogen energy storage optimization. These contributions offer valuable insights for researchers, practitioners, and policymakers working towards more sustainable and efficient energy systems. [Extracted from the article]

Fouling of heat exchangers in the chemical industry, oil & gas industry, district heating, power plants, among others, results in a loss of performance which leads to production stops for cleaning and therefore increased operation costs. One approach to mitigate fouling is to alter the properties of the metal surface. A coating to be successful in any plate heat exchanger (PHE) application needs to have a good adhesion to the metal but also keep the heat transfer through the metal plates as unaltered as possible. This requires a thin coating with a relatively good thermal conductivity. The plates in a PHE are subjected to plate-to-plate contact point wear when in operation which also puts an extra requirement for the coating. To be suitable, the coating needs to have a good mechanical stability to resist this plate-to-plate wear. Alfa Laval has a long experience in coating plates for diverse applications and in this paper two case studies will be presented. One in the paper industry and the other in the biofuel industry. A new type of multilayer Teflon™ coating from Chemours was used, specifically designed to show excellent fouling release properties along with limited thicknesses (30–50 microns). [ABSTRACT FROM AUTHOR]

Geothermal energy is a unique energy source in the energy policy mix that would help the clean energy transition and energy independence, supporting the energy needs in heating and electricity. Although there have been studies on the opportunities and challenges of renewable energy, this paper is the first paper that concentrates on geothermal energy for three distinct countries, Italy, Belgium, and Iceland, for the first time. Using semi-structured interviews that will cover the stakeholders representing the quadruple helix (academia, citizens, policymakers, and industry), this paper aims to find the unique and common opportunities and barriers the geothermal sector has. Shared challenges include financial barriers, regulatory complexities, environmental issues, and the need for improvement in the social acceptability of geothermal energy. Despite these challenges, geothermal energy, a promising energy source for clean transition, could create opportunities like improved household welfare through combined uses in district heating and electricity and have the potential to generate employment opportunities. [ABSTRACT FROM AUTHOR]

The study performs energy and exergy analyses for each component such as boilers, buildings, distribution networks and heat exchangers of a new generation district heating system. Energy and exergy efficiencies are compared for all system components, and energy and exergy losses are presented using Sankey and Grassman diagrams. Three flue gas condensers with finned bundles are designed for different capacities of boilers that intend to recover water and heat from the waste flue gas in the district heating system due to high flue gas energy losses. Colburn-Hougen and one-dimensional finite difference methods are used to design the flue gas condensers with the MATLAB program. The exergy analysis showed that the exergy input to the system is lost by 4.52% from the distribution networks, 4.15% from all buildings and 2.18% from the flue gas. In the system, the energy and exergy efficiencies of the boilers are calculated to be 87.23% and 17.32%, respectively, and the heat loss from the flue gas is found to be 12%. The design results show that the values of mass convection coefficient (km) for all flue gas condensers decrease from 0.0706 at the inlet condensation zone to 0.0354 towards the outlet. The total condensation rate and condensation efficiency are found to be 86 kg/h and 60%, respectively, for the 2500 kW boiler. [ABSTRACT FROM AUTHOR]

This research provides techno-economic assessment of three different heat pump systems within the transition in energy markets. The assessment is carried out using a generic Microsoft EXCEL tool, which is widely applicable for cases with different scale, heat sources and output temperatures. The tool includes profitability and performance calculation for selected refrigerant conditions and components. The main objective of the tool is to calculate COP accurately from enthalpies for given demand and temperatures instead of using Carnot's efficiency. In the tool, the price of the electricity is evaluated based on few different scenarios reflecting the development of electricity prices to comprehensively assess the long-term profitability of the selected three heat pump systems. The performance and flexibility of the ground source heat pump in the same building is evaluated using the tool within three different cases: ground source heat pump, ground source heat pump and thermal energy storage, and hybrid operation combining ground source heat pump and district heating. As a conclusion thermal energy storage along with ground source heat pump improves the flexibility of the system the most and reduce the dependency between electricity prices and system profitability. Thermal energy storage along with heat pump decreased the annual heating cost up to 28% compared to using solely heat pump. [ABSTRACT FROM AUTHOR]

Aligning with the decarbonization roadmap of the EU and fifth-generation district heating systems, an exergy-based optimization and decision-making model was developed for minimum CO2 emission responsibilities. Nine environmental, thermal, and electromechanical constraints were applied. Seven cases are presented, including sewer heat in Bavaria and Toronto, Jincheon eco-friendly energy town, low enthalpy geothermal heat, a data center, waste incineration plant in Amsterdam, waste heat from the stack of a coal-fired power plant, and building-scale utilization of building wastewater. Sample calculations show that the maximum carbon footprint belongs to the sewer heat system, because of the larger temperature peaking requirement. The minimum carbon footprint belongs to the geothermal heat utilization system. [ABSTRACT FROM AUTHOR]

• Two comparable high-temperature heat pumps at different scales are investigated. • Both heat pumps show similar COP trend lines depending on the temperature lift. • Differences in heat losses and heat transfer are related to volume-to-surface ratios. • Experimental data for a water-cooled compressor show promising results. • Analysis of over 200 data points shows the possibility of upscaling laboratory results. High-temperature heat pumps (HTHP) are crucial for decarbonizing district heating and industry. Hence, a reliable performance estimation considering effects of scaling is of interest for cost-efficient system integration. This study compares two laboratory HTHPs with the same refrigerant R1233zd(E). These systems have a similar plant design but a capacity scale factor of 3.2. The aim is to evaluate scale effects and make general valid statements about the challenges of upscaling laboratory test results. The analyses show that it is essential to distinguish between design effects like temperature differences at the pinch point or different heat exchanger surfaces and scale effects like relative heat losses and efficiencies of components and the system. At the component level, large surface reserves in the heat exchangers lead to 3–5 K smaller approach temperature differences in the lower capacity HTHP. At the system level, the relative heat losses are about 15 % higher than in the system with a larger capacity. The coefficient of performance of both HTHPs shows a similar trend as a function of the temperature lift from the heat source to the sink. Cross-referencing these performance results with over 200 data points from the literature, validated the possibility of upscaling. [ABSTRACT FROM AUTHOR]

The study was carried out to evaluate theoretically and in laboratory conditions the capacity of a hybrid heating and cooling system that sustainably uses thermal energy extracted from surface waters in order to decarbonize buildings located near water sources. The novelty of the research consists in the realization of two experimental systems, one for the rapid evaluation of the performance of the water–water heat pump heating system and one for the evaluation of the operating behavior of a cooling system with fan coil units. Starting with the heating and cooling demand, and the climatic and hydrological local characteristics, a hybrid system model for the heating and cooling of the analyzed building was established and implemented. The forecasted energy consumption and CO2 emissions for the operation of the new equipment were compared with the historical values of the old systems with which the building was equipped (thermal energy supply from the district heating and cooling system with an air conditioning unit). Also, the results were extrapolated for forecasting the energy potential of the surface waters. The study highlights a percentage reduction in annual energy consumption of 67.71% and CO2 emissions of 80.13% through the implementation of the hybrid system. [ABSTRACT FROM AUTHOR]

Europe prioritizes energy efficiency for sustainable development and climate action, with buildings consuming 40% of the EU's energy and contributing over 30% of CO 2 emissions. To address this, the EU implements policies targeting energy efficiency across sectors like industry, transportation, and district heating. The Energy Efficiency Directive mandates reductions in energy consumption, promoting measures such as energy audits and performance standards. Initiatives like the European Green Deal and Renovation Wave Strategy underscore the importance of energy efficiency in achieving carbon neutrality. District heating systems play a vital role in this strategy, offering Efficient heating solutions for urban areas, and optimizing their operation is a key focus of research. Techniques include mathematical modeling, advanced control strategies, and integration of renewable energy sources. This work focuses on the application of a digital twin to model the district heating network combined with prediction tools to enhance system efficiency. A procedure to integrate physics (white-box) and data-driven (black-box) approaches to foster better-informed decisions in the optimal energy resources management is presented. [ABSTRACT FROM AUTHOR]

To accelerate the transition toward zero net carbon emissions, developing the technologies which are already mature enough to be integrated technologically and economically in existing systems is essential. Most of the recent studies are focusing on large scale energy systems which require lot of assumptions such as linear approximations. This paper presents the economical optimization of combined thermal and electrical supply of multiple cities in Japan through utilization of combined heat and power boilers. A nonlinear approach is used to consider phenomena including combustion efficiencies variations or effect of scale. Different technologies of combined heat and power are modeled with different properties and fuels such as household wastes and multiple biomass woods. The cost is used as the objective function to minimize considering current energy costs. With each boiler modeled and sized, optimization results show an optimal operation of 100% renewable resources, especially biomass power with accurate indicators on the operating mode of those technologies. [ABSTRACT FROM AUTHOR]

The global energy transition requires efficient seasonal energy storage systems (SESSs) to manage fluctuations in renewable energy supply and demand. This review focuses on advancements in SESSs, particularly their integration into solar district heating systems, highlighting their role in reducing greenhouse gas emissions and enhancing energy efficiency. Tanks are the most suitable solutions for seasonal storage, as they can be implemented regardless of location for volumes up to 100,000 m3. However, pits are the most optimal solutions in terms of cost and size, as they can be constructed for volumes up to 200,000 m3. This review analyses key performance indicators such as energy efficiency, cost-effectiveness, and environmental impact, drawing on case studies from countries like Denmark and Germany. Notable findings include Denmark's Silkeborg system, which supplies 22,000 households and reduces CO2 emissions by 15,000 tons annually. Challenges such as high initial costs and system maintenance remain, but coupling SESSs with heat pumps enhances thermal stratification within SESSs. This approach can reduce the annual cost by up to 9% and the purchase cost of energy by 23%. Future research should focus on innovative materials, system design optimization, and supportive policies to enhance adoption. In conclusion, advancing SESS technologies and integrating them into renewable energy systems is necessary for achieving sustainable energy solutions and mitigating climate change impacts. [ABSTRACT FROM AUTHOR]

Employing sustainable energy systems is a must fact of the current years. Urban districts can lead the decarbonization process of cities to allow the development of decentralization energy systems such as district heating. On the other hand, the exergy analysis combined with energy evaluation can be a suitable way to investigate the efficiency and flexibility of an energy system. In this framework, this study investigates the optimal energy and storage systems to feed a district heating network. Four types of energy systems were analyzed, such as boilers, cogeneration plants, solar systems and the combination of them. The size of the thermal energy storage of the network is investigated in terms of volume and temperature. In parallel, the exergy efficiency of all the systems was calculated. The optimal heating system configuration to feed the studied district heating is the cogeneration plant with solar collectors, according to both the temperature trend fluctuation and exergy efficiency of the system. Moreover, the employment of thermal energy storage is crucial to face the renewable energy source's variability. As a further investigation, additional exergy indicators can be studied to underline the performances of such an decentralized energy system to increase the quality of the built environment. [ABSTRACT FROM AUTHOR]

Achieving a zero-emission building heating sector requires numerous strategies and detailed energy planning, in order to identify the optimal decarbonisation pathway. This work aims to assess the impact of district heating expansion and the implementation of energy-saving measures on the decarbonisation of the Italian building stock by 2050, analysing their combined impact, reciprocal effects, and technical–economic implications on the entire national energy system. The scenarios have been implemented and simulated with the H2RES software, a long-term energy planning optimisation model, built for the Italian national energy system. Results indicate that it is possible to decarbonise the heating system in an efficient and cost-effective manner by the year 2040. Heat pumps represent the optimal technology at both centralised and decentralised levels. District heating expansion is a priority for the decarbonisation of the building stock, allowing us to reduce costs, exploit thermal storage systems and provide system flexibility. In the best scenario, 40% of the Italian heat demand can be supplied by fourth-generation district heating. Energy-saving measures can reduce heat demand and primary energy but at higher annual costs and with a significant increase in investment. The combined simulation of the strategies within an optimisation model of the entire energy system enables the accurate assessment of the real impact of the various measures, considering their reciprocal effects and technical–economic implications. [ABSTRACT FROM AUTHOR]

The utilization of the district heating system (DHS) thermal inertia is greatly influenced by heating regulation modes and time steps, however, which has been rarely analysed in almost all integrated heat and power dispatch system (IHPD) models, for the purpose of wind power integration. In this study, an IHPD model considering the thermal inertia of the DHS was established, in which a data interaction problem amongst the power sources, heat sources and district heating networks was solved. Thereafter, four most commonly used heating operation modes and different heating regulation time steps were applied to the IHPD model, respectively, to analyse and compare their effects on the IHPD system under different operation conditions, mainly considering the operation cost and the wind power integration. Results of the case studies showed that the variable flow and variable supply temperature mode produced the lowest operation cost of the IHPD system during a whole heating season. Consequently, this mode is recommended to be applied in the optimization operation of the IHPD system with the wind power integration. Meanwhile, a heating regulation time step within 3 h could make full use of the DHS thermal inertia, thus to improve the operational flexibility of the IHPD system. [ABSTRACT FROM AUTHOR]

The paper presents the determination of the simultaneity factor in district heating systems based on the simultaneous heat demand level of a group of consumers. The simultaneity factor is formed on a probability theory basis, involving a prescribed risk. The simultaneity factor is a ratio that indicates the proportion of the aggregated nominal heat demand of consumers that occurs at a specific time. As known, the simultaneity factor is less than one. Knowledge of the simultaneity factor allows us to uncover performance reserve capacity in a district heating system. This way, there are often opportunities for expanding district heating systems, connecting new consumers, and improving the economic efficiency of operation. [ABSTRACT FROM AUTHOR]

Recent technologies of district heating and cooling (DHC) systems integrate renewable energy sources and connect multiple heat producers and consumers to the same network. The resulting interactions may therefore cause the fluid in the pipe, or the energy carried by the system, to flow in both directions. This article presents a newly developed analytical method for evaluating the hydraulic states in DHC networks with bidirectional mass and energy flows. The formulation of the method is presented in detail and is mainly based on the definition of two functions, namely, the flow-pressure function and the bifurcation function. The former describes the relationship between the pressure drop and the mass flow rate in a circular pipe segment, whereas the latter finds the sum of all pressure differences in a closed loop and has a single unique zero that determines the unknown mass flow rate to fulfill network mass balance. Several examples are provided to demonstrate the applicability of the method to single- and multi-looped network topologies. The method enables robust and fast calculations for virtually any network configuration with any number of connected prosumers. It can be easily implemented in any design and simulation tool to account for steady-state or dynamic situations. [ABSTRACT FROM AUTHOR]

Advanced control strategies for delivering heat to users in a district heating network have the potential to improve performance and reduce wasted energy. To enable the design of such controllers, this paper proposes an automated plant modeling framework that captures the relevant system dynamics, while being adaptable to any network configuration. Starting from the network topology and system parameters, the developed algorithm generates a state-space model of the system, relying on a graph-based technique to facilitate the combination of component models into a full network model. The accuracy of the approach is validated against experimental data collected from a laboratory-scale district heating network. The verification shows an acceptable average normalized root-mean-square error of 0.39 in the mass flow rates delivered to the buildings, and 0.15 in the network return temperature. Furthermore, the ability of the proposed modeling technique to rapidly generate models characterizing different network configurations is demonstrated through its application to topology optimization. The optimal design, obtained via a branch and bound algorithm, reduces network heat losses by 15% as compared to the conventional length-minimized topology. [ABSTRACT FROM AUTHOR]

Large-scale high back pressure cogeneration units can make full use of the waste heat of the spent steam to reduce the unit's cold-end losses, improve the field utilization rate, and heating efficiency, the energy saving effect is remarkable. The 2×350 MW cogeneration unit of a power plant is modeled as an example. The boundary conditions of the heat network are calculated according to the ambient temperature, and the thermal economy and exergy efficiency of the condensing unit and the high back pressure unit are analyzed during the heating period, to obtain the advantages of the high back pressure unit during the heating period. In turn, the study presents the high back pressure unit extracts steam distribution method is adjusted to optimize the operation strategy during the heating period. The results indicate that: after adopting high back pressure operation during the heating period, the average power generation increased by 24.5 MW compared to the condensing unit, the average reduction in coal consumption for power generation is 97.5 g/kWh, exergy efficiency increased by an average of 9.4%, exergy efficiency of the unit's heating network has increased by an average of 19.2%. After the unit adopts optimized allocation of extraction load, the average coal consumption for power generation is reduced by 0.69 g/kWh on the basis of high back pressure heating operation. The average efficiency improvement of steam-water exergic is 0.44%, while the efficiency average improvement of heating networks is 0.6%, with a maximum increase of 1.4 MW of exergy energy. [ABSTRACT FROM AUTHOR]

The LDR-50 low-temperature nuclear reactor is designed for the Finnish and European district heating markets, as an environmentally sustainable heating option for the 2030s. While the carbon footprint of conventional electricity-producing reactors is known to be small, there have been no comprehensive studies on the emission reduction potential when the technology is applied to the heating sector. This paper aims to fill this knowledge gap by means of life cycle assessment (LCA) analysis. The carbon footprint of the LDR-50 heating plant is evaluated, and compared to conventional heating fuels, direct electric heating, and heat pumps. The results of the analysis show that the life cycle CO2 emissions are low, although there are still significant uncertainties related to the construction phase, due to missing data. In addition to carbon footprint, the analysis is also extended to other adverse environmental impacts. It is concluded that significant reductions in CO2 emissions can be achieved by replacing fossil heating fuels with nuclear energy. The technology is considered a viable option alongside biofuels and heat pumps. The overall environmental impacts are low, and the production does not compete for low-carbon electricity or scarce natural resources. [ABSTRACT FROM AUTHOR]