Group "Thermal Energy Systems"

Project description:

CEUS – Cryogenic hydrogen exergy utilisation system: Less heat rejection to ambient and more usable energy for propulsion

Can the exergy utilisation of cryogenic liquid hydrogen reduce the fuel requirements of future hydrogen aircraft?

• Funding: Deutsche Forschungsgemeinschaft, DFG as part of the Cluster of Excellence SE2A (Sustainable and Energy Efficient Aviation)

• Funding Code: Excellence Strategy EXC 2163/1, Project-ID, 390881007, DFG

• Time: 2023 - 2025

Contact Persons:

• Magnus Lenger
• Wilhelm Tegethoff

Initial situation, Problem and Motivation:

Compared to combustion engines, low-temperature polymer electrolyte membrane fuel cell systems (FCSe) have to release a relatively large amount of waste heat into the environment via their cooling system at a relatively low temperature level. The cooling capacity of a mobile FCS often limits its electrical output. Cryogenic hydrogen is therefore typically used as a sink for FCS waste heat, although this type of heat transfer almost completely destroys the hydrogen exergy. This project therefore investigates Cryogenic Exergy Utilisation Systems (CEUS), which convert parts of the FCS waste heat into electrical or mechanical energy on the one hand and use it for hydrogen conditioning on the other. By using a CEUS, the heat flow to be released into the environment is reduced and the power available to propel future aircraft is increased.

Research Goals:

The following overarching question is to be answered:

Can a CEUS be advantageously combined with the subsystems of future aircraft and what is the impact of this new technology on flight performance and fuel efficiency?

The following sub-goals were defined:

• Identification of suitable CEUS topologies, their processes, components and working media
• Estimation of efficiencies, technical performance, masses and volumes of selected CEUS topologies
• Investigation of the dynamic operating behaviour relevant to flight operations and relevant thermodynamic effects based on generic flight missions for selected CEUS topologies
• Derivation of design recommendations, operating and control strategies for a selected topology.

Project description

DEWAS - Research and development of a novel, application-specific and reliable concept for a scalable, decentralized hydrogen liquefaction plant

Within the DEWAS project, a laboratory-scale hydrogen liquefaction plant is being designed and built to enable the decentralized, demand-driven supply of liquid hydrogen for users from research and development in the Braunschweig area.

• Funding: Deutsche Bundesstiftung Umwelt (DBU)
• Duration: 10/2022 – 06/2025

Contact Persons:

Aike Tappe

Wilhelm Tegethoff

Project partners:

• TLK-Thermo GmbH
• WS Wärmeprozesstechnik

Background, Problems and Motivation:

With the growing importance of green hydrogen as an energy carrier, the need for research and development in connection with the various forms of hydrogen storage is also increasing. This also applies to cryogenic liquid hydrogen (LH2), which, due to its higher volumetric energy density compared to compressed gas storage systems, is being researched for use in air traffic, heavy goods traffic and as a form of transport storage, among other things.

There is a need for research and development in connection with LH2 in a variety of cross-sectional topics. These include mobile storage systems for LH2 made of composite materials and the question of how hydrogen can be supplied quickly and reliably from such storage systems for fuel cell systems and gas turbines, the development of cryogenic pumps, valves and heat exchangers as well as suitable measurement technology, the investigation of material compatibility and superconductor technology. In all these fields, the development of safety concepts for handling hydrogen is also essential. On the other hand, there are the high costs and the great effort involved in procuring LH2: Conventional suppliers usually deliver LH2 in relatively large quantities and customers have to install their own stationary storage systems.

Research Goals:

In the DEWAS project, a hydrogen liquefaction plant based on the Linde-Hampson process is being built and investigated. The operating costs and installation costs for this process promise favorable prices per kilogram for LH2 with small purchase quantities. Following the installation and commissioning of the plant on the “Wasserstoff Campus Salzgitter”, the aim is also to set it up directly at the consumer for local LH2 production. The aim is to provide access to research and development of LH2-based technologies to a broad spectrum of stakeholders with their individual issues.

Project description:

DUPRO – Design Environment and Diagnostic System for Batteries to Minimise Damage from Thermal Runaway and Propagation

DUPRO develops innovative solutions that enable early detection of thermal hazards in battery systems and proactively prevent them through targeted design during the development process of these systems.

• Funding: Federal Republic of Germany
• Time: 01 July 2024 to 30 June 2027

Contact Persons:

• Alexander Busch
• Dr.-Ing. Andreas Varchmin (TLK-Thermo GmbH)

Project Partners:

• TLK-Thermo GmbH
• Clausthal University of Technology, Energy Storage Technologies Research Centre (EST)
• Physikalisch-Technische Bundesanstalt (PTB, Dept. 3.5 Explosion Protection in Energy Technology)

Background, Problem Statement and Motivation:

Thermal runaway in battery cells can be triggered by various mechanisms and fault conditions and can therefore never be completely ruled out. The associated potential danger to the entire battery system should therefore be minimised through appropriate measures. If thermal runaway is not stopped, it leads to thermal propagation. Initially, a primary moderate self-heating occurs, which can still be counteracted by rapid intervention. This can help avoid highly exothermic chemical reactions at elevated temperatures, as well as major gas and particle emissions.

Thermal propagation can be prevented by reducing heat release and through good design that takes into account material selection, cooling topology, and operational strategies. A suitable diagnostic system can also provide early warnings. Regulations require that vehicle occupants be warned at least five minutes before a potentially dangerous propagation event.

In the long term, the goal must be to prevent propagation and uncontrolled emissions entirely and to avoid hazardous situations. New cell chemistries can contribute to safer battery systems. However, thermal runaway has been observed in all currently discussed material compositions (e.g. solid-state batteries, sodium-ion). The rapid pace of development in cell materials and passive safety components (e.g. ceramic intercell materials or fillers) calls for suitable design tools and diagnostic systems to enable safe and long-lasting battery storage. This could accelerate development processes, which are currently only feasible through laboriously prepared and largely computation-intensive individual simulations as well as very costly experiments.

Objectives and Approach:

To sustainably integrate battery safety and damage minimisation from thermal runaway into the development process, the DUPRO project aims to achieve the following two goals:

1. Design environment for the rapid development of safe battery systems including the BTMS. The design environment includes a model library, system synthesis tools, and user-guided software for model reduction, parameterisation, and the generation of operating strategies.
2. Embedded diagnostic system for model-based detection of critical self-heating and damage minimisation.

Project description:

ERNI: Detection of non-equilibrium states of refrigerant-oil mixtures for energy optimization and emission reduction of compact refrigeration systems

The properties of the refrigerant-oil mixture circulating in refrigeration circuits and its effects are largely determined by the absorption and desorption processes of the refrigerant in the oil, which are being specifically investigated as part of this project.

• Funding: Bundesministerium für Bildung und Forschung (BMBF), im Rahmen des KMU-innovativ: Energieeffizienz und Klimaschutz Förderprogramms  (FKZ:01LY2106B)
• Duration: 2021 bis 2024

Contact Persons:

• Daniel Domin
• Wilhelm Tegethoff

Project Partners:

• TLK-Thermo GmbH

Initial situation, Problem and Motivation:

In cold vapor systems, the energy efficiency, performance and system behavior are strongly influenced by the refrigerant charge. However, a significant proportion of the refrigerant dissolves in the existing lubricating oil, which leads to a reduction in the effective evaporating and condensing refrigerant mass in the system. In addition, the circulating refrigerant-oil mixture leads to increased pressure losses in the system and a possible increase in local heat transfer resistances, which can result in a reduction in performance and energy efficiency. The absorption and desorption processes of the refrigerant in the oil have an effect on the transport properties of the oil-rich phase and the effective refrigerant charge in the system. However, due to the significantly different rates of heat and mass transfer between the phases, unsaturated states can occur in the system. In available model libraries for the simulation of refrigeration, air conditioning and heat pump systems, the influence of oil is either approximated by mapping the cumulative oil quantity in the compressor sump using equilibrium substance data or completely neglected. Due to the significant amount of oil in compact chilled steam systems and the inadequate representation of the oil influence in models, there are visible differences between measurement and simulation results here in particular.

Research Goals:

The project has two main objectives. The first objective is to research new types of models that enable the mapping of unsaturated states of the refrigerant-oil mixture. The models will be used to evaluate the relevance of the unsaturated states. The second objective is to specifically reduce the oil charge in a compact refrigeration circuit and thus increase the performance of the system.

The following sub-goals were defined for this purpose:

•     Experimental determination of the thermophysical properties of a refrigerant-oil mixture and their modeling
•     Investigation of the absorption and desorption processes between the flowing phases of the mixture
•     Development of novel models taking into account the transport processes by means of phase-separate balancing
•     Derivation of simplified models
•     Experimental investigation of a compact refrigeration circuit with reduction of the oil charge to optimize performance
•     Comparison of the results from experiment and simulation

 Projektbeschreibung:

 Project description:

• FAME – Fuel cell propulsion system for Aircraft Megawatt Engine
• Funding: European Union (Clean Aviation)
• Duration: 2024 bis 2026

Contact Persons:

• Michael Meltzow
• Steffen Heinke
• Wilhelm Tegethoff

Project Partners:

• Airbus Operations GmbH (Koordinator)
• Airbus Operations SAS
• Airbus Operations SL
• Airbus Helicopters SAS
• Aerostack GmbH
• AVL List GmbH
• DIEHL Aviation Gilching GmbH
• DIEHL Aerospace GmbH
• DIEHL Aviation Laupheim GmbH
• Liebherr-Aerospace Toulouse SAS
• Liebherr-Electronics and Drives GmbH
• Magna Steyr Fahrzeugtechnik GmbH & Co KG
• Moteurs Leroy-Somer SAS
• SmartUp Engineering S.r.l.
• Woodward Poland Sp.z o.o.
• Woodward L’Orange GmbH – Affiliated entity
• Technische Universität Braunschweig
• Technische Universiteit Delft
• Politechnika Rzeszowska im Ignacego Lukasiewicza PRZ
• Università degli Studi di Napoli Federico II

Initial situation, Problem and Motivation:

The FAME funding project is part of the European Clean Aviation funding program. The overarching goal of this program is to reduce harmful emissions in aviation. In this context, the FAME project focuses on the development of an integrated hydrogen-electric engine for use in passenger aircraft. The aim is to build a prototype with a drive power of 1 MW. All components from the hydrogen storage system to the propeller will be covered.

A consortium of 21 European companies and universities is responsible for the implementation. TU Braunschweig is one of the project partners and is involved with a total of three institutes. The Institute of Thermodynamics is working on the analysis and optimization of membrane humidifiers for aviation fuel cell systems.

The membrane humidifier transfers water vapor from the humid cathode-side exhaust air to the dry supply air, thus preventing the fuel cell from drying out.

A consortium of 21 European companies and universities is responsible for the implementation. TU Braunschweig is one of the project partners and is involved with a total of three institutes. The Institute of Thermodynamics is working on the analysis and optimization of membrane humidifiers for aviation fuel cell systems.

The membrane humidifier transfers water vapor from the humid cathode-side exhaust air to the dry supply air, thus preventing the fuel cell from drying out.

Research Goals:

Existing membrane humidifiers are primarily intended for use in automotive applications. In contrast, FAME considers an application that involves a series of novelties. In addition to the stricter requirements in terms of weight, installation space, service life and safety, the influence of the unusually high operating temperatures of over 100 °C is of particular interest.

As part of the project, the previously unexplored behavior of humidifier membranes under these operating conditions is to be investigated experimentally. The measurement results obtained will then be used to develop and validate a CFD model of a humidifier. The CFD model will then be used to derive optimized humidifier geometries. The latter step is to be supported and accelerated by the use of more computationally efficient surrogate models.

Further Information:

https://www.clean-aviation.eu/fame

Project Description:

H2-iNFFra – H2 infrastructure at the NFF: Decentralized hydrogen liquefier

The H2-iNFFra project is upgrading the facilities for hydrogen research at the Automotive Research Center Niedersachsen (NFF).
The IfT is expanding a decentralized hydrogen liquefaction plant based on the Linde-Hampson process.

• Funding: Europäische Union, EFRE
• Time: 01/2025 - 12/2027

Contact Person:

• Wilhelm Tegethoff
• Aike Tappe

Project Partners:

• Technische Universität Carolo-Wilhelmina zu Braunschweig
  • Institut für Thermodynamik (IfT)

  • Institute of Internal Combustion Engines and Fuel Cells

• Niedersächsisches Forschungszentrum Fahrzeugtechnik (NFF)

• Fraunhofer IST

Initial situation, Problem and Motivation:

Anyone wishing to purchase liquid hydrogen in Europe at present must turn to the gas industry's major suppliers, who liquefy gray hydrogen centrally. Central liquefaction plants are characterized by low prices per kilogram for high purchase volumes. As a result of hydrogen losses due to boil-off gas being blown off, storage tanks have to be refilled several times a year. Decentralized hydrogen liquefaction plants can provide a remedy, as they enable the flexible provision of liquid hydrogen in terms of time and location using inefficient processes with cheaper components.

Research Goals:

In the H2-iNFFra project, an existing liquefier cryostat system for hydrogen developed at the Institute of Thermodynamics (IfT) will be expanded based on the Linde-Hampson process. To this end, the liquefaction rate and storage volume will be adapted to the partners' requirements and boil-off losses reduced through active reliquefaction. Two closed, pressure-controllable transport dewars will be used to store and distribute the liquid hydrogen.

The following research objectives are to be achieved with the infrastructure provided in this sub-project:

1.     Research into LH2 supply technology: decentralized LH2 generation, cryogenic refueling and tank systems, boil-off gas management including nano-materials and LH2 energy utilization.
2.     Research into cryogenic power electronics, superconducting vehicle electrical systems and superconducting electric motors.

Project description:

SKAiB - Scalable fuel cell systems for electric propulsion systems

The SKAiB project is researching the design of more environmentally friendly air transport through the use of hydrogen and fuel cell systems in passenger aircraft.

• Funding: Bundesministerium für Wirtschaft und Klimaschutz (BMWK) 
• Duration: 01/2022 - 06/2026

Contact persons:

• Steffen Heinke
• Jakob Trägner
• Fabian Klärchen
• Wilhelm Tegethoff

Project partners:

• Technische Universität Carolo-Wilhelmina zu Braunschweig
  • Institut für Thermodynamik (IfT)

  • Institut für Flugzeugbau und Leichtbau

  • Institut für Flugantriebe und Strömungsmaschinen (IFAS)
  • Institut für Strömungsmechanik (ISM)
• Airbus Operations GmbH
• TLK-Thermo GmbH
• Diehl Aviation Gilching GmbH
• Diehl Aviation Laupheim GmbH
• Diehl Aerospace GmbH
• Deutsches Zentrum für Luft- und Raumfahrt e.V.
• PACE Aerospace Engineering and Information Technology GmbH
• TU Dresden
• Aerostack GmbH

Starting point, problem, motivation:

A significant reduction in emissions is necessary to realise environmentally friendly aviation. One promising option for reducing emissions is the use of hydrogen in aviation, particularly in combination with fuel cells. There are currently no airworthy fuel cell systems available in the performance class required for passenger aircraft.

Objectives and approach:

The joint project SKAiB has the objective of advancing the development of a fuel cell system for the propulsion of passenger aircraft towards a relevant performance class while simultaneously increasing the degree of maturity up to airworthiness. The Institute of Thermodynamics (IfT) at TU Braunschweig is researching and evaluating fuel cell stacks and systems for aviation applications as part of the SKAiB project. The focus here is, on the one hand, on addressing aspects relating to alternative and innovative concepts for the water and thermal management of the fuel cell using simulative and experimental investigations and, on the other hand, on the model-based analysis and optimisation of the fuel cell stack for aviation applications. By using the models further refined in the project, the development processes of fuel cell systems suitable for aviation can be improved and accelerated in the future.

Projektbeschreibung:

TEN.efzn: Transformation des Energiesystems Niedersachsen - Forschungsplattform Wärme

The partners in the "heat" research platform are developing and researching innovative heat pump technologies for buildings and industry. Three institutes at TU Braunschweig are involved: the "Institute für Thermodynamic" (IfT), the "Institut für Elektrische Maschinen, Antriebe und Bahnen" (IMAB), and the affiliated institute "Steinbeis Innovationszentrum energieplus" (SIZ). These three partners are working together on a new type of compact plug & play heat pump technology from an interdisciplinary perspective. The heat pumps to be developed will be easily and quickly integrated into different building energy systems using standardised connections and construction units.The IfT is designing the innovative heat pump. The IMAB is developing and researching the associated power electronics to enable integration into future electrical energy systems. The SIZ is responsible for integrating the plug & play concepts into the heating and hot water systems of various buildings in accordance with their requirements.

Dr Wilhelm Tegethoff, spokesperson for the heat research platform, emphasises: ‘With our research, we are helping to ensure that buildings and industry can be supplied with heat in the future in a climate-neutral, efficient, cost-effective and needs-based manner.’

Contact Persons:

• Wilhelm Tegethoff
• Henrik Waßmuth
• Andreas Schulte

https://magazin.tu-braunschweig.de/en/pi-post/neuer-schwung-fuer-die-energieforschung/

Project description:

THEWA – Thermal management of hydrogen refueling station systems

The THEWA project researches hydrogen refueling stations and provides optimized overall system concepts for various applications.

• Funding: Ministry of Science and Culture of Lower Saxony (Germany) through "Niedersächsisches Vorab"
• Duration: 2021 bis 2026

Contact persons:

• Henrik Waßmuth
• Steffen Heinke
• Wilhelm Tegethoff

Project partners:

• TU Braunschweig/NFF: Institut für Automobilwirtschaft und Industrielle Produktion (AIP), Institut für Konstruktionstechnik (IK), Institut für Thermodynamik (IfT), Institut für Verbrennungskraftmaschinen (IVB)
• Artelia GmbH
• MAN Truck & Bus SE
• Maximator GmbH
• Shell Deutschland GmbH
• TLK-Thermo GmbH

Further information:

 https://www.efzn.de/forschung/energieforschung-im-efzn-verbund/wasserstoff/innovationslabore-fuer-wasserstofftechnologien/thewa-thermomanagement-von-wasserstoff-tankstellensystemen

Project description:

TOFEBAS – Synthesis and optimization of topologies and operating strategies for the thermal management of commercial vehicles with solid-state battery systems

The TOFEBAS project is researching new thermal management topologies, operating strategies and control strategies for various commercial vehicles with solid-state battery systems.

• Funding: European Union, ERDF
• Time: 2024 bis 2026

Contact Persons:

• Jan Friedrich Hellmuth
• Wilhelm Tegethoff

Project Partners:

• TLK-Thermo GmbH
• Volkswagen AG CoE Battery
• Konvekta AG
• ITK Engineering GmbH

Initial situation, Problem and Motivation:

The use of solid-state batteries in battery electric commercial vehicles enables longer ranges, greater safety and faster charging capability compared to conventional lithium-ion batteries. As they are to be used more frequently in the future, the design of the associated thermal management systems must be adapted. This is because the materials used in solid-state batteries have significantly different thermal properties: Higher operating temperatures and limit temperatures as well as altered anisotropic thermal conductivities, heat capacities and time constants.

The central component of a thermal management system for commercial vehicles is the switchable cold vapor process, in which cooling and heating power is made available. This power is not only required for heating and cooling the battery, but also for heating, cooling and dehumidifying the passenger compartment and for cooling the engine and power electronics e-components. All of these areas have specific requirements that must be taken into account in thermal management. The thermal properties of solid-state batteries lead to fundamental changes in the cold vapor process. Higher operating temperatures and the need for preheating require new topologies and operating strategies. This means that other refrigerants and components with modified control circuits are potentially required.

Research Goals:

As there are as yet no approaches in research for a new, holistic thermal management system for commercial vehicles with solid-state batteries, the applicants want to make a significant contribution to closing this gap with TOFEBAS. Three objectives are being pursued:

1. Provision of a design platform for the synthesis of topologies and operating strategies for the thermal management of commercial vehicles with solid-state batteries.
2. Provision of optimized topologies including dedicated operating strategies and control loops for three different commercial vehicles with solid-state batteries (e.g. long-distance bus, city bus, long-distance truck).
3. Provision of a guideline catalog for the synthesis of thermal management including topologies, operating and control strategies.

Project description:

TREWAS: Design software for efficient, safe and durable transient cryogenic hydrogen storage systems in aviation

The design of cryogenic hydrogen storage systems is complex and requires comprehensive software tools that are not yet available on the market. This is where TREWAS comes in with the development of design software that places a special focus on the dynamics, efficiency, safety and longevity of the systems.

• Funding: European Union, ERDF
• Time: 02/2025 – 01/2028

Contact Person:

• Aike Tappe
• Linda Geva

Project Partner:

• TLK-Thermo GmbH

Initial situation, Problem and Motivation:

In view of anthropogenic climate change, the need to reduce greenhouse gas emissions from air traffic through the use of non-fossil energy sources has become the focus of research and development in the field of aviation. Green hydrogen is seen as a promising energy source in this context. The hydrogen must be stored with sufficient volumetric energy density. Cryogenic storage systems, in which the hydrogen is stored at cryogenic temperatures, are particularly suitable for this purpose.

The storage and utilisation of cryogenic hydrogen in aircraft and the provision of the associated infrastructure at the airport present numerous technical challenges. In particular, the high demands placed on cryogenic H2 storage systems, such as dynamic, on-demand hydrogen withdrawal, safety and durability, as well as the energy efficiency of operation, are relevant to the design of these systems. When designing the storage systems, there are also many degrees of freedom with regard to the topology, component and material selection as well as the operating and control strategy. Determining these degrees of freedom while taking the requirements into account requires the use of powerful computer simulation models. Software that addresses all of these aspects is currently lacking on the market.

Research Goals:

The TREWAS project aims to develop a new type of design software for cryogenic hydrogen storage systems - with a particular focus on energy efficiency, safety and longevity. The initial focus is on the use of the software in the field of aviation; in the future, the software will be further developed so that it can also be used for applications such as heavy goods vehicles with PEM fuel cell drives and liquid hydrogen storage or transport tanks for large quantities of hydrogen.

Falls Sie weitere Informationen zu den Projekten benötigen sprechen Sie bitte Dr.-Ing. Wilhelm Tegethoff oder Dr.-Ing. Nicholas Lemke an.