Dirk Mueller

Dirk Mueller
RWTH Aachen University · E.ON Energy Research Center

Univ.-Prof. Dr.-Ing.

About

799
Publications
105,356
Reads
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4,911
Citations
Citations since 2016
414 Research Items
4389 Citations
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800
20162017201820192020202120220200400600800

Publications

Publications (799)
Article
In this work, an open source platform, based on the FIWARE software framework and other open source components, is used to perform experimental cloud control on two use cases from the smart building and smart grid domains. All communication between the platform and the field layer is realized via the public internet and therefore encryption, authen...
Article
Mit Modernisierungsfahrplänen lässt sich die Emissionseinsparung einzelner Gebäude langfristig bis zur Klimaneutralität planen. In Anbetracht von Energiekrise und Fachkräftemangel zeigt dieser zweite Teil auf, inwieweit unterschiedliche Energiepreisstrukturen sowie die begrenzte Verfügbarkeit von Erdgas diese Fahrpläne beeinflussen, und wie sich be...
Conference Paper
Full-text available
The development of current building energy system operation has benefited from: 1. Informational support from the optimal design through simulation or first-principles models; 2. System load and energy prediction through machine learning (ML). Through the literature review, we argue that a gap existed in current control strategies and algorithms: M...
Preprint
Full-text available
Open-source modeling libraries facilitate the standardization and harmonization of model development. In the context of building energy systems, Modelica is a suitable modeling language as it is equation-based and object-oriented. As an outcome of the IBPSA project 1 cooperation, four open-source modeling libraries have been successfully deployed w...
Article
To stop climate change caused by the anthropogenic greenhouse effect, the amount of research project funding to develop and demonstrate solutions for carbon emission reduction has increased. Focused topics and procedures of research projects are always presented in text-based descriptions. Natural language processing offers the possibility to proce...
Article
Full-text available
Due to its potential benefits in data transparency, maintenance, and optimization of operation, the Internet of Things (IoT) has recently emerged in the building automation system (BAS) domain. However, while various IoT devices have been developed, the integration into BAS remains a challenging task due to the variety of conventional interfaces us...
Article
Full-text available
The ambitious climate targets of the European Union emphasise the necessity to reduce carbon dioxide emissions in the building sector. Therefore, various sustainable heat sources should be used in existing district heating systems to cover the heat demands of buildings. However, integrating on-site heat sources into large existing district heating...
Preprint
Full-text available
Advanced building control strategies like model predictive control and reinforcement learning can consider forecasts for weather, occupancy, and energy prices. Combined with system and domain knowledge, this makes them a promising approach to reduce buildings' energy consumption and CO2 emissions. For this reason, model predictive control and reinf...
Article
Mit Modernisierungsfahrplänen lässt sich die Emissionseinsparung einzelner Gebäude langfristig bis zur Klimaneutralität planen. Viele Entscheidungen hinsichtlich Anlagentechnik, Energieträger und Dämmniveau müssen zielgerichtet getroffen werden. Statt nur einzelne mögliche Entscheidungen zu erwägen, können mithilfe mathematischer Optimierungsmodell...
Article
Model predictive control can reduce heating systems' operating costs and energy consumption. This is especially true for heat pumps, whose operation efficiency highly depends on the heating system's boundary conditions, i.e., the source and sink temperatures. This paper investigates how optimizing setpoint values of supply temperatures given differ...
Article
Full-text available
Back-up heaters are essential for sustainable retrofit heat pump systems to achieve low capital costs and high system temperatures. Despite its importance, current literature focuses primarily on single aspects of the interaction between the back-up heater and the heat pump system. Furthermore, influences of varying scenarios are typically not cons...
Article
This work presents an approach to the contextual integration of fluid selection and compressor design for the cycle design of efficient industrial heat pumps. The vapor-compression cycle of an air-water heat pump operated at 42 °C source and 82 °C target temperature is investigated as a theoretical case study. An optimization study is performed, wh...
Article
Full-text available
5th generation district heating and cooling (5GDHC) networks are a promising technology to decarbonize the heating and cooling supply of buildings and districts. Up to today, only a small number of 5GDHC networks have been built, mostly in Switzerland and Germany. As a result, there are substantial uncertainties and knowledge gaps in the planning a...
Presentation
A promising way to make use of waste heat sources is to distribute the heat to nearby buildings via district heating systems to cover the heat demands of the buildings. The integration of a waste heat source into an existing district heating system has to be studied in advance in order to avoid difficulties during network operation and to guarantee...
Article
Full-text available
During the SARS-CoV-2 pandemic, large-scale events were initially suspended categorically without consideration of ventilation technology. In this study, CO 2 concentrations were measured during three trade fairs in the fall of 2021 at Messe Frankfurt with the aim of assessing air mixing and dilution of loads emitted through human respiration. 24 s...
Article
Full-text available
Time series forecasting is fundamental for various use cases in different domains such as energy systems and economics. Creating a forecasting model for a specific use case requires an iterative and complex design process. The typical design process includes five sections (1) data preprocessing, (2) feature engineering, (3) hyperparameter optimizat...
Article
Full-text available
Zusammenfassung Aufgrund des russischen Angriffs auf die Ukraine ist mit einer deutlichen Verknappung und weiteren Verteuerung des Erdgases in Deutsch-land zu rechnen. Neben der Industrie und dem Bereich Gewerbe, Handel und Dienstleistungen können die privaten Haushalte erhebliche Einsparungen im Gasverbrauch für Raumwärme und Trinkwarmwasser durch...
Conference Paper
Model predictive control (MPC) is a promising approach to reduce energy usage in buildings and provide grid flexibility. However, MPC in buildings requires a high modeling effort and struggles with reliability and scalability. Distributed control architectures can help to alleviate these problems. Existing work for distributed building MPC mainly f...
Conference Paper
Full-text available
Heat pumps are the key to sustainable heating and cooling applications in all sectors. Today, heat pump testing depends on fixed steady-state conditions which are forced by external manipulation. However, there are no steady-state fixed operating points in the field during operation. To capture inherent effects of unfixed operation, load-based test...
Article
Full-text available
In dieser Veröffentlichung der BF2020 werden kurzfristige Maßnahmen zur Steigerung der Energieeffizienz im Betrieb von Gebäuden und Quartieren aufgezeigt. Zur Ermittlung wurden im Rahmen des 11. Projektleitungstreffens Energiewendebauen Kurzfragebögen unter den Teilnehmenden verteilt. Vertreter aus 46 Verbundprojekte haben an der Befragung teilgeno...
Article
This paper presents a nonlinear hybrid Model Predictive Control (MPC) approach for building energy systems based on Modelica. The MPC approach takes into account two characteristics that are very common for building energy systems: nonlinearities (inherent in the building envelope and Heating, Ventilation and Air Conditioning (HVAC) systems) and di...
Conference Paper
Worldwide, buildings contribute to about 40% of the global CO2 emissions. Efficient control algorithms like model predictive control (MPC) are a promising approach to reduce CO2 emissions in the building sector. Using MPC, the thermal building mass can be exploited to store energy and offer flexibility for the electric grid, which is essential for...
Conference Paper
Design decisions concerning future energy systems of existing buildings must be made to realize necessary building modernizations. Previous research has mainly used single-year investment approaches for these design decisions. This approach cannot consider parameter changes over time, such as energy price changes. The uncertainty of these parameter...
Preprint
Full-text available
5th generation district heating and cooling (5GDHC) networks are a promising technology to decarbonize the heating and cooling supply of buildings and districts. Up to today, only a small number of 5GDHC networks have been built, mostly in Switzerland and Germany. As a result, there are substantial uncertainties and knowledge gaps in the planning a...
Conference Paper
Full-text available
Selecting a suitable fluid for heat pump applications is essential due to the strong influence of the fluid on the overall cycle performance. According to the current state of research, typically, fluid selection bases on the simple refrigeration cycle assessment. However, the flow sheet strongly influences the performance of each fluid and vice ve...
Conference Paper
Increasing volatility in electricity generation makes an increasing degree of flexibility on the consumer side necessary. There are many methods to solve the resulting optimization problem, all of which have their own advantages and disadvantages. Rule-based Control is unsuitable for optimal integration of dynamic constraints, and the promising Mod...
Conference Paper
Heat pumps are important for decarbonizing the building stock by electrifying the heat supply to buildings. To exploit the full potential of heat pump energy systems, the systems must be carefully designed and operated. Mathematical Optimization can be used to determine the best design and operating strategy for a specific system. Mixed-integer lin...
Conference Paper
To decarbonize the building sector, using waste heat sources in district heating systems is crucial for the future efficient and sustainable heat supply of buildings. This paper investigates a possible integration of a large waste heat source into an existing local district heating system on the research centre campus in Jülich, Germany. The new en...
Conference Paper
Model predictive control is well suited to control building energy systems efficiently. However, it still lacks commercial relevance due to the high modeling effort. This article presents a methodology to reduce the modeling effort by combining data-driven and physics-based process models in a hybrid MPC scheme. Data-driven models like artificial n...
Conference Paper
Full-text available
In the building energy sector, electrically driven heat pump systems contribute significantly to reducing greenhouse gas emissions by the replacement of conventional systems. To accelerate the replacement, both the capital and the operating costs are decisive for a purchase decision. Besides reducing capital costs by i.e. increasingly advanced prod...
Conference Paper
Full-text available
Today, the testing and rating of heat pumps are based on steady-state measurements, which are very well established in standards worldwide and are considered reproducible. However, the high market penetration of inverter-driven heat pumps raised concerns among researchers and policymakers about whether fixed frequency testing is representative of r...
Conference Paper
The development of appropriate control strategies for building energy systems has been a challenging issue for the traditional planning process of building automation, especially facing the increasing complexity of building energy conversion and distribution systems. Regarding this problem, the MODI-method has been introduced in previous work to en...
Conference Paper
Modern air handling units are usually equipped with free-running radial fans, that are mounted in an open air duct. Depending on the fan’s operating point a significant amount of the energy is present in the form of dynamic pressure at the exit of the impeller. This paper investigates the implementation of additional flow guiding bodies (pressure r...
Conference Paper
To meet the rising comfort requirements of non-residential buildings like office buildings mechanical ventilation in the form of e.g. air handling units (AHU) is needed. As of today, the fans in AHUs are designed for a specified operating point. The real operating range does rarely match this design point, which causes the fans operating in ranges...
Conference Paper
This work presents an approach to the contextual integration of fluid selection and compressor design for the cycle design of efficient industrial heat pumps. The vapor-compression cycle of an air-water heat pump operated at \SI{42}{\celsius} source and \SI{82}{\celsius} target temperature is investigated as a theoretical case study. An optimizatio...
Article
Full-text available
District heating and cooling (DHC) networks, and in particular, the fifth generation of DHC networks, offer great potential in increasing the overall system efficiency and reducing CO2 emissions in the heating and cooling of urban districts. Due to the growing complexity of these energy systems, the use of new planning methods, such as the use of d...
Conference Paper
Full-text available
Due to current regulations, alternative working fluids for heat pump systems have to be identified. Thereby, hydrocarbons (HC) and hydrofluoroolefins (HFO) are possible solutions. However, both fluid categories are at least mildly flammable and thus, result in additional safety regulations. In particular, regulations includes refrigerant charge lim...
Conference Paper
Full-text available
During operation of air-source heat pumps under certain operating conditions frost forms on the evaporator fins. The frost decreases system efficiency and must therefore be removed at frequent intervals to achieve energy-efficient and thus economical operation. Compared to a conventional time-controlled defrosting strategy, in which a defrosting pr...
Presentation
Full-text available
Within the present investigation, we evalute the interactions between the refrigerant, and the cycle configuration. The investigation includes three cycle configurations - the simple cycle, an internal heat exchanger cycle and a vapor injection cycle. We evaluate the seasonal coefficient of performance based on EN 14825 for binary mixtures based o...
Conference Paper
Due to political regulations, environmentally friendly refrigerants must replace conventional alternatives (i.e., R134a) in heat pumps. Especially in residential applications, many theoretical studies in the literature prove that hydrocarbons meet many requirements and have suitable thermodynamic properties to increase the efficiency of refrigerati...
Article
Optimizing the operation of building energy systems holds great potential to reduce energy consumption in buildings. However, this requires detailed system information, such as the relationship of sensor data. Automatic detection of this information requires monitoring data from buildings, which is rarely available in the needed quality for automat...
Article
Full-text available
The working fluid in heat pumps is subject to a variety of requirements that must be met for efficient and safe operation. Furthermore, the number of market-available working fluids is continuously increasing due to the development of new mixtures. Therefore, this paper screens the market for alternative working fluids. Additionally, the performanc...
Article
Full-text available
In order to reduce energy consumption and CO 2 emissions in the building sector, more and more renewable energy sources are integrated into energy systems. Especially geothermal fields combined with heat pumps are able to supply buildings with heat and cold at low carbon emissions. However, using geothermal fields as heat and cold source influences...
Article
In non-residential buildings, many factors affect thermal and electrical loads. Some of these factors are not known during the planning process but are essential for a proper energy system design. Conducting a simulation- and optimization-based sensitivity analysis, this study investigates the effects of usage intensity and weather uncertainties on...
Conference Paper
Full-text available
Air-to-water heat pumps with natural refrigerants are subject to dynamic boundary conditions. Thus, many disturbance variables influence heat pump control and lead to uncontrollable operation. The expansion valve control is essential for the compressor's efficiency and operational reliability. On the one hand, a sufficient degree of superheat is ne...
Preprint
Full-text available
CO2 pricing enables building owners to benefit from reduced emissions. Changing power plant mix leads to dynamic CO2 factors and price signals that PV-battery systems can exploit. The system's size and CO2 prices influence profitability. So far, no study exists assessing CO2 pricing's influence on PV-battery systems' optimal sizing and operation. W...
Preprint
Model predictive control (MPC) is an effective method to optimize building operation. However, the transfer into practice is difficult due to missing know-how, high modeling effort, and high hard-and software requirements. In this context, approximation of MPC is a promising alternative. By training, e.g., a machine learning algorithm to predict th...
Article
Full-text available
Integrating renewable energy sources is a crucial component in reducing CO2 emissions in the building sector. In particular, shallow geothermal energy is expected to play a significant role in the regenerative energy supply of buildings. An effective control strategy for the geothermal field is crucial to reduce the overall energy consumption. This...
Conference Paper
Full-text available
Germany had 479 shopping centers mostly located in urban cities. According to STASTICA, the number of shopping centers was doubled in the last decade. For consumers, good indoor air quality (IAQ) is a basic requirement for their shopping experience. This leads to very high air exchange rates for current operation of HVAC systems in shopping centers...
Article
Vapor compression cycles have gained high importance due to increasing concerns regarding the decarbonization of heating and cooling applications. Typically, vapor compression cycles operate under dynamic conditions, making it difficult to predict their performance accurately. Dynamic simulation models present a decent solution for increasing the r...
Article
Full-text available
Middleware platforms are key technology in any Internet of Things (IoT) system, consider- ing their role in managing the intermediary communications between devices and applications. In the energy sector, it has been shown that IoT devices enable the integration of all network assets to one large distributed system. This comes with significant bene...
Preprint
Full-text available
Aufgrund der SARS-CoV-2-Pandemie wurden Veranstaltungen in öffentlich zugänglichen Räumen zunächst vielerorts kategorisch ausgesetzt. Individuelle technische Ausstattungen und vorhandene Lüftungsanlagen wurden dabei oft nicht berücksichtigt, obwohl das Infektionsrisiko durch Lüftung und Luftreinigung deutlich gesenkt werden kann. Die Veranstaltung...
Article
Free available until 05.07.2022 at https://authors.elsevier.com/a/1f51L1HudN80Um . Thermophysiological comfort models allow the prediction of subjective thermal sensation for transient and inhomogeneous boundary conditions for a defined validation range. However, their validation ranges are relatively limited due to only low availability of high q...
Article
To reduce the energy consumption of building energy systems, efficient and well-tuned control strategies are needed. However, developing and benchmarking control strategies is a challenging task. Here, simulation-based controller tuning and testing is beneficial and more cost-efficient compared to experiments. However, generating a model for this p...
Article
In practice, there are methods such as EN 15450 designing a heat pump system consisting of a heat pump, auxiliary heater, and thermal energy storage. In heat pumps, the refrigerant has a significant impact on the overall efficiency and thus on its sustainability. However, refrigerant selection is not considered in standard design procedures. Moreov...
Article
Full-text available
Heat pumps are a key technology to accelerate the defossilization of all sectors. Especially in residential applications , heat pumps serve as exchange technology for conventional heating technologies. The operation of heat pumps requires a refrigerant that significantly determines the system's efficiency. However, the refriger-ant choice is comple...
Article
Full-text available
With regard to climate change, it is imperative to reduce greenhouse gas emissions. One solution approach is to increase energy efficiency in buildings. Buildings contribute a high share of the total global energy usage. As the rate of new building constructions is low, measures applicable to existing buildings become paramount. Before applying new...
Conference Paper
Die akustische Geräuschentwicklung bei Luftdurchlässen führt zu einer Beeinträchtigung in einer produktiven Arbeitsumgebung und verursacht damit einen erheblichen Limitierungsfaktor in Lüftungssystemen. Luftdurchlässe stellen die letzte Komponente eines Luftverteilsystems dar und werden häufig in Decken eingebaut und dienen der Verteilung von frisc...
Article
Decreasing CO2-Emissions is a common goal for efficient energy system design and operation. An efficient design for the heating sector are 4th-generation district heating networks with waste heat integration. This paper focuses on operational optimization of a 4th-generation district heating network with regards to temperatures and use of thermal i...
Article
This paper presents a distributed Model Predictive Control (MPC) approach for multi-zone building energy systems based on nonlinear Modelica controller models. The method considers both thermal and hydraulic coupling among different building zones. The iterative and parallel distributed optimization approach builds upon an uncooperative approach fo...
Preprint
Full-text available
Die anhaltende SARS-CoV-2-Pandemie und deren Eindämmung hat zu einer intensiven Diskussion der Lüftung von Innenräumen geführt. Aufgrund der nach wie vor eingeschränkten Impfmöglichkeiten für Kinder und Jugendliche sind vor allem Schulen in den Fokus gerückt, da in einer Unterrichtssituation ein erhöhtes Risiko der Infektionsausbreitung vorliegt. I...
Preprint
Full-text available
Im Rahmen der durch COVID-19 verursachten Pandemie wird in vielen Bundesländern über Nachrüstung von Lüftungstechnik in Schulen diskutiert. Dabei werden am Markt unterschiedliche Systeme angeboten, die sich von einem sehr einfachen Abluftsystem bis hin zu Zu- und Abluftanlagen mit Filtern, Schalldämpfern und Optionen zur Wärmerückgewinnung erstreck...
Preprint
Full-text available
Time series forecasting is fundamental for various use cases in different domains such as energy systems and economics. Creating a forecasting model for a specific use case requires an iterative and complex design process. The typical design process includes the five sections (1) data pre-processing, (2) feature engineering, (3) hyperparameter opti...
Article
Aiming at an emission-free building energy supply, air-source heat pump systems (HPSs) are promising to replace conventional technologies such as gas boilers. Currently, the overall costs of HPSs are higher than the costs for conventional systems, inhibiting HPS market penetration in existing buildings. Increasing the profitability of HPSs by reduc...