lahde - Laboratory for refrigeration and district energy

Response of energy solutions to climate change

lahde — Thu, 06 Jun 2024 06:08:51 +0000

The Slovenian Energy Association (SZE) successfully hosted the SZE 2024 International Conference from June 2 to June 4, 2024, at the Grand Hotel Bernardin in Portorož, Slovenia. This prestigious event was organized in collaboration with Kronoterm, the main sponsor.

Our group presented the latest findings from the 3Diverse project, which focused on reducing the supply and return temperatures within an isolated branch of a district heating network.

The 3DIVERSE project (LIFE21-CET-PDA-3DIVERSE) has received funding from the European Union’s LIFE programme under the grant agreement Nº 101077343.

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Students on a visit to Kronoterm and Hisense Gorenje Europe

lahde — Mon, 06 May 2024 05:29:32 +0000

On Friday, April 19, 2024, we had an exceptional opportunity to expand our professional knowledge with students by visiting two leading companies in the industry. Students had the exclusive opportunity to learn about the internal operations and processes at the Hisense Gorenje corporation, which, among other things, is involved in the production of refrigerators. Additionally, we visited Kronoterm, a company specialized in the production of advanced vapor-compression heat pumps. Here, they had the chance to familiarize themselves with advanced technologies and innovative approaches used by the companies in the development of their products.

The visit to both companies provided students with valuable insights into real industrial processes and offered them the opportunity to connect theoretical knowledge gained at the university with practical experiences from the working environment. Such experiences play a crucial role in shaping future professionals and innovators in the field of engineering.

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Small demonstrator of a thermoelectric heat-pump booster for an ultra-low-temperature district-heating substation

lahde — Sat, 16 Mar 2024 19:57:01 +0000

The article Small demonstrator of a thermoelectric heat-pump booster for an ultra-low-temperature district-heating substation represents, as first in the world, experimental proof which demonstrates the effective use of thermoelectric heat pumps in a 4th or 5th generation district heating systems. The article was published in the journal Applied Energy (IF=11.2).

The investigation was carried out by the researchers of the Laboratory for refrigeration and district energy (Process Engineering) in cooperation with the company Danfoss Trata d.o.o.

One of the most important measures for the energy efficiency of district heating systems is to reduce the supply and return temperatures of the system. The 4th generation district heating systems operate at supply temperatures of 50 to 60 °C, which enables better utilization of renewable and waste heat sources. In the 5th generation, supply/return temperatures are significantly lower (< 30°C). These temperature levels lead to the need for a local increase in the heating temperature (e.g. for the sanitary hot water), which is solved by using auxiliary heat pumps or so-called ˝booster’s˝. Energy-consuming electric heaters or fuel-burning boilers are most often used to raise the temperature, while heat pumps are an alternative. Among the latter, vapor-compression heat pumps are in use, but they use environmentally unfriendly or toxic and flammable refrigerants, are noisy and cause vibrations, which negatively affects the comfort of living in the living environment.

In the published research, the researchers present the development and operation of a demonstration thermoelectric (Peltier) heat pump booster (TE-HP), which can serve as an auxiliary heat pump in the substation of the 4th or 5th generation district heating system. An extensive parametric experimental analysis is presented in terms of heating capacities, flow rates, supply water temperature increase and efficiencies.

The developed TE-HP demonstrates many advantages over the comparable state-of-the-art, namely extreme compactness, silent operation without moving parts and vibrations, high efficiency of operation and the use of environmentally friendly recyclable refrigerants without discharges into the environment. It operates in the range of heating powers up to 650 W and the highest temperature increase of the supply water up to 50 K. At a temperature increase of the supply water by 10-15 K, it operates with a heating coefficient of performance (COP) between 2 and 2.4, which represents the ratio between the obtained heat and the electrical input energy, which significantly outperforms any direct conversion of fuels or electricity to heat, which has a COP ratio < 1.

The article is available at: https://doi.org/10.1016/j.apenergy.2024.122899

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The launch of Heat4energy project

lahde — Thu, 01 Feb 2024 20:37:58 +0000

TU Delft leads HEAT4ENERGY, a European consortium, dedicated to develop thermomagnetic devices and novel materials to harvest heat from data centres, food, pulp and paper industries and convert this waste heat to electricity. This project ticks all the boxes: energy transition, decarbonising, low and high power devices for conversion of waste heat to electricity, energy storage, finding alternatives for critical raw materials, developing new materials and most important of all: training of a next generation of European experts.

On 30-31 January 2024, the HEAT4ENERGY project has been officially kicked off. HEAT4ENERGY is a 4-year EU-Horizon Europe MSCA Doctoral Network project aiming to train a new generation of enablers for the European Energy Transition. They will acquire these skills in practice by addressing the challenge of making the first realistic and energy efficient thermomagnetic devices for converting low grade waste heat (<100°C) to electricity. They will also learn how to upscale these and advance the technology to a viable market level. They will obtain the interdisciplinary competence required to bring this green technology to a mature level, and career perspectives in both the academic and non-academic sectors delivering the European Green Deal.

Carbon neutrality

The production and use of energy account for more than 75% of the EU’s greenhouse gas emissions. Decarbonising the EU’s energy system is therefore critical to reach our 2030 climate objectives and the EU’s long-term strategy of achieving carbon neutrality by 2050. Obviously solar and wind power will play an important role in any future energy scenario, but such intermittent sources present significant challenges in energy transport and storage. At the same time, a vast amount of low-grade heat is generated, e.g. in data centres, food, pulp and paper industries, and is available 24/7. Converting even only a small percentage of this heat into electricity is significant due to the sheer amount of heat wasted just above ambient temperature. However, efficient technologies to convert this low-grade heat in an economically sound way are lacking. Within this project, we will develop thermomagnetic energy harvesting from current TRL 3/4 proofs of principle to an efficient and cost competitive TRL 6/7 technology.

Demonstrators for conversion of waste heat to electricity

We will construct and experimentally validate three efficient demonstrators for the conversion of waste heat into electricity in the power range of 10 μW, 1 W and 100 W.

Andrej Kitanovski, University of Ljubljana: We will show that thermomagnetic energy harvesting can be an energy-efficient and compact technology capable of addressing existing and future power generation challenges. Special attention will be paid to the utilization of various low grade heat sources from a minimum of 40 to a maximum of 100 °C, which account for about 40 % of waste heat from industrial processes. For these, especially below 60-80°C, there is a lack of available, scalable, cost-effective and energy-efficient technologies for the conversion of waste heat into electricity. We will train PhD students and enable knowledge and technology transfer in the multidisciplinary fields of model-based engineering, fabrication technology, characterization and evaluation of innovative thermomagnetic generators from micro to macro scale.

Tailor made Materials

Materials research will focus on materials preparation, shaping and functional characterization.

Anja Waske, Bundesanstalt für Materialforschung und -prüfung (BAM): “In the work package materials fabrication and characterization, an interdisciplinary team from materials science and engineering together with industrial partners will develop optimal materials and shapes for a new generation of thermomagnetic energy harvesting devices. We will synthesize, shape and characterize thermomagnetic materials and parts that efficiently transfer waste heat and convert it into electrical energy. Additionally, the parts must sustain numerous thermomagnetic cycles with negligible mechanical fatigue or corrosion. In-situ experiments in the final demonstrators will show the performance of these tailor made materials.”

Materials design and modelling

Focus is on the combination of physics simulations spanning different length scales and machine learning based optimization of chemical compositions and microstructures for materials.

Gilles de Wijs, Radboud University: “In this project we aim to predict optimal thermomagnetic materials, tailored to the operating conditions and system dimensions, using an extended in silico scanning method end exploiting novel AI. It is an exciting collaboration, joining key computational expertise from groups in Austria and The Netherlands.”

Engaging industry

The increasing cost for energy makes their efficient use decisive for all types industry. This includes the need for recovering waste heat, but in particular for low-grade waste heat no mature technology is available today.

Sebastian Fähler, Helmholtz-Zentrum Dresden-Rossendorf: “As our project aims to close this gap, we appreciate to come into contact with industrial partners. A collaboration is of particular interest for industries not yet recovering their large amount of waste heat, requiring off-grid electricity and to power IoT, or developing other heat recovery devices. We expect benefit for both, as we learn more on dedicated requirements and can then address these particular needs. Collaboration is possible by participating in workshops, discussing in panels, or by additional joint projects.”

Training of a next generation of experts

Franca Albertini, Consiglio Nazionale delle Ricerche: “The European Energy Transition relies on a new generation of highly educated professionals active in all the societal sectors (e.g. industry, public institutions, academia) and able to evaluate and adopt new energy technologies and strategies. To achieve this goal HEAT4ENERGY Doctoral Network training is multidisciplinary and include different fields of engineering, physics and material science, combined with specific teachings focused on innovation and entrepreneurship, sustainable development and environmental protection. ”

Broad representation of specialists on thermomagnetic materials

An interdisciplinary consortium, lead by Delft University of Technology, including Karlsruher Institut für Technology, Consiglio Nazionale delle Ricerche, Helmholtz-Zentrum Dresden-Rossendorf, Bundesanstalt für Material-forschung und –prüfung, Univerza V Ljubljani, Radboud University, Centre National de la Recherche Scientifique CNRS, Universitat fur Weiterbildung Krems, Magneto B.V., memetis GmbH, Magnoric, Universita Degli Studi di Parma, Technische Universität Dresden, Université Grenoble Alpes and Technische Universität Wien address all major challenges for this emerging technology, which requires innovative designs of more efficient thermomagnetic generators, that are intimately connected with tailored thermomagnetic materials. Prof. E.H. (Ekkes) Brück of Delft University of Technology will be the coordinator of the 2.7 M€ project funded by European Commission under Grant Agreement no. 101119852.

Funding

The Marie Skłodowska-Curie Actions of the European Commission fund excellent research and innovation and equip researchers at all stages of their career with new knowledge and skills, through mobility across borders and exposure to different sectors and disciplines. The MSCA help build Europe’s capacity for research and innovation by investing in the long-term careers of excellent researchers.

Contact

Prof. Dr. Ekkes Brück, e-mail: e.h.bruck@tudelft.nl, telephone +31 (0)15 278 3158.

HEAT4ENERGY LinkedIn: https://www.linkedin.com/company/heat4energy/

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We attended the Dresden Days of Magnetocalorics DDMC2023

lahde — Fri, 17 Nov 2023 09:26:44 +0000

LAHDE concluded an enlightening visit to the conference in Dresden, which took place on November 13-14.

Our team members demonstrated their expertise with interesting contributions:

Prof. Dr. Andrej Kitanovski took to the stage as an invited speaker

Title of the lecture: Magnetocalorics and thermomagnetics: the past, the present and the future

Dr. Katja Klinar

Title of the lecture: Ferrofluidic thermal switch for high operating frequencies

Title of the poster: Evaluation of caloric devices with TCCbuilder software: a step-by-step guide

Dr. Urban Tomc

Title of the lecture: Digital Microfluidic Thermal Switch and Magnetocaloric Cooling Device

Dr. Stefano dall’Olio

Title of the lecture: Design and performance of a shell-and-tube-like elastocaloric regenerative cooler/heat pump

Blaž Velkavrh

Title of the poster: Dielectric thick films for fluidic thermal switches in magnetocaloric cooling device

The conference ended with a visit to the high magnetic field laboratory with magnetic fields of up to 100 T. Our group photo captures the essence of this experience and shows the LAHDE team in the capacitor bank.

We would like to express our gratitude to the organizers (the HZDR team) for impeccably arranging the conference. Everything was exceptionally well-executed, with meticulous attention to detail, and we particularly appreciated the quality of the sweets during the coffee breaks.

Last but certainly not least, we thoroughly enjoyed the presentations featuring the main players in the market: Magnotherm, Magnoric, and Magneto. The magnetically cooled coffee and beer from Magneotherm’s Polaris were not only refreshing but also served as a source of inspiration.

We are grateful for the opportunity to share knowledge and explore the future of magnetocalorics!

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LAHDE received support from the Innovation Fund of University of Ljubljana

lahde — Thu, 09 Nov 2023 11:07:25 +0000

The visibility of our work continues – we celebrate our latest achievement!

LAHDE members (Prof. Dr. Andrej Kitanovski, Dr. Katja Klinar, Katja Vozel) have once again received support from the Innovation Fund of University of Ljubljana, this year for the project TEcomfort: the compact unit for low-temperature heating and cooling systems.

The purpose of this funding remains unchanged – to bridge the gap between science and industry. At LAHDE we are well aware of the gap, which is why we are not only involved in basic science but also in applied research. While we remain committed to the pursuit of knowledge, we are constantly monitoring industry trends and looking for breakthrough opportunities.

We look forward to the promising discoveries and collaborations that lie ahead as we continue our mission of bringing science and industry together. LAHDE members ( have once again received support from the Innovation Fund of University of Ljubljana.

We look forward to the promising discoveries and collaborations that lie ahead as we continue our mission of bringing science and industry together.

Image source: UL Knowledge Transfer Office

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Phase change materials for improvement of thermal comfort and energy efficiency in buildings

lahde — Thu, 05 Oct 2023 07:14:37 +0000

Researchers of Laboratory for Refrigeration and District Energy (LAHDE, process engineering) participated in a research on improving thermal comfort and energy efficiency in buildings using phase-change materials. The research was carried out in Laboratory for Heating, Sanitary, Solar and Air Conditioning Engineering (LOSK, process engineering), also by participation of researchers from the Faculty of Civil Engineering and the National School of State Public Works (ENTPE) from France. The research was published in the journal Sustainable Cities and Society (IF=11.7).

Today, lightweight prefabricated buildings (frame structure and low-density thermal insulation as the predominant material in the wall composition) and buildings with a high proportion of window area are popular structural concepts. During the cooling season, lightweight prefabricated buildings can easily overheat as the buildings have a high thermal response due to low thermal storage. In contrast to active systems, passive systems (phase change materials (PCMs), which have a high thermal capacity at a selected phase change temperature) do not consume electricity to operate. PCMs serve as an alternative to a cooling system and can be implemented in active building systems or in building elements where buildings are cooled passively.

In this research a so called Active-Passive System (APS) was designed for passive cooling of the building interiors and active regeneration at night. In order to ensure sufficient cooling effect of the system in the daytime cycle, the PCM has to be fully solidified in the nighttime cycle. To improve the heat transfer from the PCM at night, a ventilated air gap was installed behind the wall and ceiling substructure of the PCM to cool the PCM with outdoor air.

The APS was investigated and designed based on a systematic literature review, an experimental investigation, a parametric analysis performed by a numerical model with computational fluid dynamics analysis, and a calculation of the energy use and operating costs of the APS.

Link to the article: Parametric study of an active-passive system for cooling application in buildings improved with free cooling for enhanced solidification – ScienceDirect

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Open Labs Day to mark the start of the new academic year

lahde — Tue, 03 Oct 2023 08:53:23 +0000

Yesterday we were delighted to welcome the start of the new academic year and celebrate it with a special event – Open Lab Day!

Our lab also opened its doors to give the new students a glimpse into the various exciting projects and experiments we are conducting. Some of the research highlights were enthusiastically and confidently presented to the freshmen by new LAHDE team members Mihael Blatnik and Matevž Cimermančič, both PhD students.

May the new academic year be full of knowledge, research and personal development. Good luck to all students in this wonderful academic year!

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Successful completion of ICR2023

lahde — Wed, 30 Aug 2023 13:29:43 +0000

We are pleased to announce that the LAHDE team has successfully completed its active participation in the 26th International Congress on Refrigeration (ICR 2023) in stunning Paris! This unique and extremely important meeting takes place every 4 years, and perhaps this year was all the more special because it returned to its birthplace. The Congress was founded in Paris in 1908 and was last held there 40 years ago.

Our team had the opportunity to participate in a variety of lectures and workshops (you can read about which lectures we gave here) that showcased the latest innovations in refrigeration technology. Attending the congress was an invaluable experience that allowed our experts to deepen their knowledge and network with fellow researchers from around the world.

The congress provided insight into the latest technologies, sustainable approaches and future challenges to be faced in the field of refrigeration. Discussions covered all aspects, from energy efficiency to environmental sustainability. We also had the opportunity to network with colleagues and partners from the industry and share valuable experiences that will certainly contribute to the further progress of our group.

We are already looking forward to the next 27th edition of the Congress in Seoul in 2027, and we are confident that we will actively participate and contribute to the discussions and innovations in refrigeration. Our commitment to progress and sustainable development remains unwavering.

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Design and comparison of electro-permanent magnetic field sources for magnetocaloric heat pumps

lahde — Fri, 18 Aug 2023 08:33:57 +0000

Researchers at the Laboratory for Refrigeration and District Energy (LAHDE, Process Engineering), in collaboration with researcher from the Laboratory for Structure Evaluation (LAVEK), have conducted a comprehensive study of the design, numerical analyses and experimental validation of various electro-permanent magnetic structures that can be used in magnetocaloric refrigeration. The research was published in Journal of Magnetism and Magnetic Materials (IF = 3.097).

Most magnetic field sources currently used in conceptual magnetic cooling devices require moving parts, which produce noise, vibrations and require maintenance. Furthermore, the operating frequency of such magnetic structures is relatively low and limited by aspects of the mechanical construction. Unlike any magnetic structure currently used in a magnetocaloric refrigeration device, the presented structure consists of a hybrid assembly of an electromagnet and a permanent magnet. We report on how different configurations of permanent magnets and the windings of electromagnets, including the air gaps, affect the energy efficiency, the input power and the total mass of the magnetic field source. Some guidelines for future research and the development of electro-permanent magnetic field sources for magnetocaloric refrigeration and heat pumps are presented, supported by information on how such structures can enable higher operating frequencies that could increase the compactness of future magnetocaloric devices.

Link to the article: Design and comparison of electro-permanent magnetic field sources for magnetocaloric heat pumps – ScienceDirect

Figure: Twelve electro-permanent magnet design concepts (3D models) evaluated in this study.

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