HEAT EXCHANGERS - Laboratory for refrigeration and district energy

High-temperature electrocaloric heat pump presented at the High-temperature heat pump symposium

admin — Fri, 23 Jan 2026 09:56:23 +0000

Researchers from the Laboratory for Refrigeration and District Energy (LAHDE) have visited High-temperature heat pump symposium in Copenhagen, Danmark. The event offered an excellent overview of the latest research and industrial developments in high-temperature heat pumps, with many insightful discussions and opportunities to exchange perspectives with experts from industry and academia.

We were pleased to present our work on solid-state electrocaloric heat pump in the poster session and to receive valuable feedback that will support our ongoing research. Many thanks to the organizers for a well-structured and high-quality symposium, and to all colleagues for the engaging discussions.

The post High-temperature electrocaloric heat pump presented at the High-temperature heat pump symposium first appeared on Laboratory for refrigeration and district energy.

A completed research secondment at the Bundesanstalt für Materialforschung und -prüfung (BAM)

admin — Tue, 13 Jan 2026 11:16:20 +0000

Our PhD student Kamyar Dobakhti recently completed a research secondment at the Bundesanstalt für Materialforschung und -prüfung (BAM). This secondment provided valuable hands-on experience in X-ray tomography and Life Cycle Assessment (LCA) methodologies relevant to thermomagnetic heat exchanger development.

During his stay at BAM, Kamyar visited several X-ray tomography facilities and a mechanical testing setup, gaining in-depth insight into tomography procedures for structural characterization and defect analysis. Close collaboration with experts in the field enabled a detailed understanding of how these techniques can be applied to optimize manufacturing parameters and material design.

Furthermore, precise geometrical parameters extracted from the X-ray tomography data were directly incorporated into numerical simulations. The primary focus of the secondment was the development of a numerical model to evaluate the heat transfer characteristics of different heat exchanger geometries, supporting the optimization of thermomagnetic heat exchanger performance.

A heartfelt thank you to Dr.-Ing. Anja Waske, Heike Q. and Savvina Papaioannou from BAM for their warm welcome and support. I also want to express my gratitude to our group leaders, the Laboratory for Refrigeration and District Energy, and the entire team for providing me with this incredible opportunity.

The post A completed research secondment at the Bundesanstalt für Materialforschung und -prüfung (BAM) first appeared on Laboratory for refrigeration and district energy.

Ultra-high-temperature electrocaloric heat pump

admin — Mon, 05 Jan 2026 09:01:01 +0000

Researchers from the Laboratory for Refrigeration and District Energy (LAHDE) have published first study on high-temperature electrocaloric heat pump in Journal of Energy conversion and management, one of the world’s leading scientific journal in the field of energy.

Nearly a quarter of waste heat is generated at temperatures exceeding 300 °C, yet conventional heat pump technologies remain inefficient in recovering and utilizing heat from such high temperature sources. In this study, we introduce a novel electrocaloric heat pump designed to operate with heat sources and sinks at ultra-high temperatures. The proposed heat pump system incorporates an active electrocaloric regenerator featuring PbZr_0.52Ti_0.48O₃ (PZT) epitaxial thin-film multilayers, which exhibit a superior electrocaloric adiabatic temperature change of 11.03 K at 402 °C (675 K), and pressurized helium gas as the working fluid. We conducted a parametric analysis to simulate the performance of the ultra-high-temperature electrocaloric heat pump and identified the optimal conditions for single- and multi-stage configurations. The single-stage setup achieved a maximum heating COP of 7.8 at a 30 K temperature span across the regenerator at a heat source temperature of 660 K. In comparison, the multi-stage configuration yielded the highest heating power 113.3 W/kg_EC and a max. COP 2.7 between 630 and 690 K. This study established a foundation for notable advancements in ultra-high-temperature heat pumps by employing electrocaloric energy conversion.

Link: https://www.sciencedirect.com/science/article/pii/S019689042501338X

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SDEWES 2024

admin — Mon, 16 Sep 2024 05:20:19 +0000

The SDEWES 2024 conference in Rome was a truly remarkable event, bringing together leaders, researchers, and professionals dedicated to advancing sustainable development and energy systems. As one of the premier conferences in this field, SDEWES provided a unique platform for exchanging cutting-edge ideas and fostering collaborations that can drive global change.

Throughout the conference, a wide range of topics were covered, from renewable energy integration and smart grids to circular economy principles and sustainable urban planning. The diversity of perspectives and the depth of the discussions were nothing short of inspiring. It was clear that the collective expertise and passion of the attendees are key to addressing the complex challenges we face in creating a more sustainable future.

The LAHDE’s contribution to the conference was a presentation by Katja Klinar, who shared insights on “Heat Pump Modelling in District Heating and Cooling Grid.” This work is a crucial part of the SenergyNets project, which is paving the way for more efficient and sustainable energy systems.

Attending SDEWES 2024 was a powerful reminder of the importance of collaboration across disciplines and borders. The ideas and connections forged here will undoubtedly have a lasting impact on the future of sustainable energy and development.

Looking forward to continuing the journey with this incredible community and applying the insights gained from this experience.

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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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LAHDE annual report: 2021

lahde — Thu, 06 Jan 2022 16:30:09 +0000

LAHDE Scientific annual report:

Published papers

MAIORINO, Angelo, DEL DUCA, Manuel Gesù, TOMC, Urban, TUŠEK, Jaka, KITANOVSKI, Andrej, APREA, Ciro. A numerical modelling of a multi-layer LaFeCoSi active magnetic regenerator by using artificial neural networks. Applied thermal engineering, ISSN 1359-4311. [Print ed.], Oct. 2021, vol. 197, str. 1-13, ilustr. https://www.sciencedirect. com/science/article/pii/S1359431121008103?utm_campaign=STMJ_AUTH_SERV_PUBLISHED&utm_medium=email&utm_acid=104953246&SIS_ID=&dgcid=STMJ_AUTH_ SERV_PUBLISHED&CMX_ID=&utm_in=DM168036&utm_source=AC_, doi: 10.1016/j.applthermaleng.2021.117375
POREDOŠ Primož, PETELIN, Nada, ŽEL, Tilen, VIDRIH, Boris, GATARIĆ, Pero, KITANOVSKI, Andrej. Performance of the condensation process for water vapour in the presence of a non-condensable gas on vertical plates and horizontal tubes. Energies, ISSN 1996-1073, Apr. 2021, vol. 14, iss. 8, str. 1-28, ilustr. https://www.mdpi.com/1996-1073/14/8/2291, doi: 10.3390/en14082291.
LORBEK, Luka, KATRAŠNIK, Tomaž, KITANOVSKI, Andrej. Impact of neglecting the variations in the relative surface roughnesses of capillary tubes on the accuracy of a capillary tube model. International journal of refrigeration, ISSN 0140-7007. [Print ed.], Sep. 2021, vol. 129, str. 194-203, ilustr. https://www.sciencedirect.com/science/article/pii/S014070072100147X#ack0001, doi: 10.1016/j.ijrefrig.2021.04.022
SWOBODA, Timm, KLINAR, Katja, ABBASI, Shahzaib, BREM, Gerrit, KITANOVSKI, Andrej, MUÑOZ ROJO, Miguel. Thermal rectification in multilayer phase change material structures for energy storage applications. iScience, ISSN 2589-0042, 2021, vol. 24, iss. 8, str. 1-14, ilustr. https://www.sciencedirect.com/science/article/pii/S2589004221008117, doi: 10.1016/j.isci.2021.102843
SWOBODA, Timm, KLINAR, Katja, KITANOVSKI, Andrej, YALAMARTHY, Ananth Saran, MUÑOZ ROJO, Miguel. Solid-state thermal control devices. Advanced electronic materials, ISSN 2199-160X, Mar. 2021, vol. 7, iss. 3, f. 1-28, ilustr. https://onlinelibrary.wiley.com/doi/10.1002/aelm.202000625, doi: 10.1002/aelm.202000625.
KLINAR, Katja, SWOBODA, Timm, MUÑOZ ROJO, Miguel, KITANOVSKI, Andrej. Fluidic and mechanical thermal control devices. Advanced electronic materials, ISSN 2199-160X, Mar. 2021, vol. 7, iss. 3, f. 1-30, ilustr. https://onlinelibrary.wiley.com/doi/10.1002/aelm.202000623, doi: 10.1002/aelm.202000623.
ŠADL, Matej, TOMC, Urban, URŠIČ NEMEVŠEK, Hana. Investigating the feasibility of preparing metal-ceramic multi-layered composites using only the aerosol-deposition technique. Materials, ISSN 1996-1944, Aug. 2021, vol. 14, iss. 16, str. 4548-1-4548-10, ilustr. https://www.mdpi.com/1996-1944/14/16/4548, doi: 10.3390/ma14164548
GATARIĆ, Pero, LORBEK, Luka. Evaluating R450A as a drop-in replacement for R134a in household heat pump tumble dryers. International journal of refrigeration, ISSN 0140-7007. [Print ed.], Aug. 2021, vol. 128, str. 22-33, ilustr. https://www.sciencedirect.com/science/article/pii/S0140700721001195, doi: 10.1016/j.ijrefrig.2021.03.020.
AHČIN, Žiga, LIANG, Jierong, ENGELBRECHT, Kurt, TUŠEK, Jaka. Thermo-hydraulic evaluation of oscillating-flow shell-and-tube-like regenerators for (elasto)caloric cooling. Applied thermal engineering, ISSN 1359-4311. [Print ed.], May 2021, vol. 190, str. 1-15, ilustr. https://www.sciencedirect.com/science/article/pii/S135943112100291X, doi: 10.1016/j.applthermaleng.2021.116842.
MAIORINO, Angelo, DEL DUCA, Manuel Gesù, TOMC, Urban, TUŠEK, Jaka, KITANOVSKI, Andrej, APREA, Ciro. A numerical modelling of a multi-layer LaFeCoSi active magnetic regenerator by using artificial neural networks. Applied thermal engineering, ISSN 1359-4311, Oct. 2021, vol. 197, str. 1-13, ilustr. https://www.sciencedirect. com/science/article/pii/S1359431121008103?utm_campaign=STMJ_AUTH_SERV_PUBLISHED&utm_medium=email&utm_acid=104953246&SIS_ID=&dgcid=STMJ_AUTH_ SERV_PUBLISHED&CMX_ID=&utm_in=DM168036&utm_source=AC_, doi: 10.1016/j.applthermaleng.2021.117375.
PORENTA, Luka, LAVRENČIČ, Marko, DUJC, Jaka, BROJAN, Miha, TUŠEK, Jaka, BRANK, Boštjan. Modeling large deformations of thin-walled SMA structures by shell finite elements. Communications in Nonlinear Science and Numerical Simulation, ISSN 1007-5704, okt. 2021, vol. 101, no. 105897, str. 1-29, ilustr. https://repozitorij.uni-lj.si/IzpisGradiva.php?id=127201, doi: 10.1016/j.cnsns.2021.105897.
MASCHE, M., IANNICIELLO, Lucia, TUŠEK, Jaka, ENGELBRECHT, Kurt. Impact of hysteresis on caloric cooling performance. International journal of refrigeration, ISSN 0140-7007. [Print ed.], Jan. 2021, vol. 121, str. 302-312, ilustr. https://www.sciencedirect.com/science/article/pii/S0140700720304229?via%3Dihub#!, doi: 10.1016/j.ijrefrig.2020.10.012.
NAVICKAITE, Kristina, IANNICIELLO, Lucia, TUŠEK, Jaka, ENGELBRECHT, Kurt, BAHL, Christian Robert Haffenden, PENZEL, Michael, NESTLER, Klaus, BÖTTGER-HILLER, Falko, ZEIDLER, Henning. Plasma electrolytic polishing of nitinol : investigation of functional properties. Materials, ISSN 1996-1944, Oct. 2021, vol. 14, iss. 21, str. 1-13, ilustr. https://www.mdpi.com/1996-1944/14/21/6450, doi: 10.3390/ma14216450.

Granted patent

Micro-magnetocaloric device EP3106781B1

New projects

TCCbuilder: Odprtokodno simulacijsko orodje za toplotne tokokroge
Novo MHD-toplotno stikalo za nekonvencionalni magnetni hladilni sistem (MHD magcool), BI-DE/21-22-008

Conferences

KITANOVSKI, Andrej. The future of magnetic refrigeration and heat pumping. V: Advances in magnetics 2020-21 : June 13-16, 2021 : book of abstracts. [New York: IEEE]. 2021, str. [68]. http://aim2020.poliba.it/wordpress/program/program-overview/?fbclid=IwAR2pXtjkBn1cwQUsqf13mXZsPKhM20tkwMYFIExuG5751nff6RqN9CpeUTg.
NOSAN, Simon, TOMC, Urban, KLINAR, Katja, KITANOVSKI, Andrej. New concept of electromagnetic field source for magnetic refrigeration. V: Book of abstracts : CHC Eurotherm Seminar, July 13-15, 2021. [S.l.]: Eurotherm. 2021, str. [4]. https://eurotherm.et.utwente.nl/index.php/book-of-abstracts/.
TOMC, Urban, DALL´OLIO, Stefano, KLINAR, Katja, NOSAN, Simon, ERJAVEC, Urška, ŠADL, Matej, URŠIČ NEMEVŠEK, Hana, KITANOVSKI, Andrej. Cool future: magnetocaloric devices based on static and rare earth free magnetic field sources. V: Book of abstracts : CHC Eurotherm Seminar, July 13-15, 2021. [S.l.]: Eurotherm. 2021, str. [5]. https://eurotherm.et.utwente.nl/index.php/book-of-abstracts/.
SWOBODA, Timm, KLINAR, Katja, KITANOVSKI, Andrej, MUÑOZ ROJO, Miguel. High asymmetric heat transport in multilayer phase change materials. V: 2021 Virtual MRS Spring Meeting & Exhibit : April 17-23, 2021. [Warrendale (PA)]: Materials Research Society. 2021, str. [629-630]. https://www.mrs.org/docs/default-source/meetings-events/spring-meetings/2021/abstract-book.pdf?sfvrsn=66f9da0c_2, https://www.mrs. org/meetings-events/spring-meetings-exhibits/2021-mrs-spring-meeting/call-for-papers/symposium-sessions-detail?code=NM08.
DALL´OLIO, Stefano, TOMC, Urban, KLINAR, Katja, KITANOVSKI, Andrej. Design, enhanced thermal and flow efficiency of an active magnetic regenerator. V: Advances in magnetics 2020-21 : June 13-16, 2021 : book of abstracts. [New York: IEEE]. 2021, str. [72]. http://aim2020.poliba.it/wordpress/program/program-overview/?fbclid=IwAR2pXtjkBn1cwQUsqf13mXZsPKhM20tkwMYFIExuG5751nff6RqN9CpeUTg.
NOSAN, Simon, TOMC, Urban, KLINAR, Katja, KITANOVSKI, Andrej. New concept of electromagnetic field sourcefor magnetic refrigeration. V: Advances in magnetics 2020-21 : June 13-16, 2021 : book of abstracts. [New York: IEEE]. 2021, str. [192]. http://aim2020.poliba.it/wordpress/program/program-overview/?fbclid=IwAR2pXtjkBn1cwQUsqf13mXZsPKhM20tkwMYFIExuG5751nff6RqN9CpeUTg.
KLINAR, Katja, VOZEL, Katja, KITANOVSKI, Andrej. Numerical tool for evaluation of static thermal switches in caloric refrigeration and heat pumping. V: Book of abstracts : CHC Eurotherm Seminar, July 13-15, 2021. [S.l.]: Eurotherm. 2021, str. [40]. https://eurotherm.et.utwente.nl/index.php/book-of-abstracts/.
POREDOŠ, Primož, MAROVT, Franc, KITANOVSKI, Andrej, POREDOŠ, Alojz. Analiza izboljšanja energetske učinkovitosti toplotne črpalke zrak-voda z glikolskim prenosnikom toplote = Analysis of energy efficiency improvement of air water heat pump with glycol heat exchanger. V: Mednarodna konferenca SZE : Oskrba ter raba energije v pametni stavbi in domu : Portorož, 28.-29. junij 2021 = International Conference of SZE : Energy supply and use in smart buildings and homes : Portorož, 28.-29. June 2021 : zbornik prispevkov. Ljubljana: Slovensko združenje za energetiko. 2021, str. 78-79, ilustr.
GATARIĆ, Pero, POREDOŠ, Primož, KITANOVSKI, Andrej. Analiza izboljšanja energetske učinkovitosti sušilnega stroja s toplotno črpalko z uporabo okolju prijaznejšega hladiva R450A = Improving the energy efficiency of a heat pump dryer using the environmentally friendly refrigerant R450A. V: Mednarodna konferenca SZE : Oskrba ter raba energije v pametni stavbi in domu : Portorož, 28.-29. junij 2021 = International Conference of SZE : Energy supply and use in smart buildings and homes : Portorož, 28.-29. June 2021 : zbornik prispevkov. Ljubljana: Slovensko združenje za energetiko. 2021, str. 96-97, ilustr.
DALL´OLIO, Stefano, TOMC, Urban, KLINAR, Katja, NOSAN, Simon, KITANOVSKI, Andrej. Unconventional magnetocaloric wine cooler initial performance. V: THERMAG IX : 9th IIR International Conference on Caloric Cooling and Applications of Caloric Materials : virtual conference, June 7-11, 2021, College Part, Maryland, USA, str. 120. https://files.constantcontact.com/8d76dc76201/86788d2d-77ec-4dfa-9ca9-894a21e814d5.pdf.
TOMC, Urban, ŠADL, Matej, KLINAR, Katja, URŠIČ NEMEVŠEK, Hana, KITANOVSKI, Andrej. Digital microfluidics in magnetocaloric cooling. V: THERMAG IX : 9th IIR International Conference on Caloric Cooling and Applications of Caloric Materials : virtual conference, June 7-11, 2021, College Part, Maryland, USA, str. 128. https://files.constantcontact.com/8d76dc76201/86788d2d-77ec-4dfa-9ca9-894a21e814d5.pdf.
KUHELJ, Anja, SIMONIČ, Jasmina, DALL´OLIO, Stefano, KLINAR, Katja, PETELIN, Nada, KITANOVSKI, Andrej, MENCINGER, Jure, DREN, Dejan, BAČ, Vladimir. Enostavno orodje za določanje razporeditve cevi “skin” kondenzatorja na hladilnih aparatih = Simple tool for determining the pipe arrangement in the skin condenser for household refrigerators. V: Mednarodna konferenca SZE : Oskrba ter raba energije v pametni stavbi in domu : Portorož, 28.-29. junij 2021 = International Conference of SZE : Energy supply and use in smart buildings and homes : Portorož, 28.-29. June 2021 : zbornik prispevkov. Ljubljana: Slovensko združenje za energetiko. 2021, str. 92-93,
IANNICIELLO, Lucia, TUŠEK, Jaka, MAÑOSA, Lluís, VIVES, Eduard, ENGELBRECHT, Kurt. Elastocaloric materials for active cooling regenerators. V: Book of abstracts : CHC Eurotherm Seminar, July 13-15, 2021. [S.l.]: Eurotherm. 2021, str. [7]. https://eurotherm.et.utwente.nl/wp-content/uploads/2021/07/bookofabstracts1.pdf.
AHČIN, Žiga, LIANG, Jierong, ENGELBRECHT, Kurt, TUŠEK, Jaka. Thermo-hydraulic analysis of shell-and-tube-like geometries for elastocaloric regenerators. V: Book of abstracts : CHC Eurotherm Seminar, July 13-15, 2021. [S.l.]: Eurotherm. 2021, str. [11]. https://eurotherm.et.utwente.nl/index.php/book-of-abstracts/.
IANNICIELLO, Lucia, TUŠEK, Jaka, ENGELBRECHT, Kurt. Updated design of an active elastocaloric regenerator. V: THERMAG IX : 9th IIR International Conference on Caloric Cooling and Applications of Caloric Materials : virtual conference, June 7-11, 2021, College Part, Maryland, USA, str. 52. https://files.constantcontact.com/8d76dc76201/86788d2d-77ec-4dfa-9ca9-894a21e814d5.pdf.
MASCHE, M., IANNICIELLO, Lucia, TUŠEK, Jaka, ENGELBRECHT, Kurt. Numerical modelling of hysteresis in caloric materials for solid-state cooling. V: THERMAG IX : 9th IIR International Conference on Caloric Cooling and Applications of Caloric Materials : virtual conference, June 7-11, 2021, College Part, Maryland, USA, str. 100. https://files.constantcontact.com/8d76dc76201/86788d2d-77ec-4dfa-9ca9-894a21e814d5.pdf.
PORENTA, Luka, KABIRIFAR, Parham, ŽEROVNIK, Andrej, ČEBRON, Matjaž, ŽUŽEK, Borut, BROJAN, Miha, TUŠEK, Jaka. Durable elastocaloric effect in thin walled Ni-Ti tubes. V: THERMAG IX : 9th IIR International Conference on Caloric Cooling and Applications of Caloric Materials : virtual conference, June 7-11, 2021, College Part, Maryland, USA, str. 130. https://files.constantcontact.com/8d76dc76201/86788d2d-77ec-4dfa-9ca9-894a21e814d5.pdf.

Awards

Rector’s Award for the best innovation 2021 for EASE

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Condensation of water vapor from humid air inside vertical channels formed by flat plates

lahde — Sat, 01 Jan 2022 18:08:00 +0000

We published research on condensation of water vapor from humid air inside vertical channels formed by flat plates in collaboration with researchers from Shanghai University.

The research was published in iScience.

Link: https://www.sciencedirect.com/science/article/pii/S2589004221015352

Abstract

Condensation of humid air is an important process in thermal and process engineering and a subject of many currently research-intensive scientific domains, such as atmospheric water harvesting and seawater desalination. The nature of (water) vapor condensation in the presence of non-condensable gas (NCG) such as air differs significantly from the case with the pure, quiescent vapor condensation. In the literature, simple models that describe the forced flow condensation of water vapor in the presence of air on a series of vertical flat plates are hard to find. Here we present a simple and computationally efficient semi-empirical correlation describing forced flow condensation from humid air inside vertical channels formed by flat plates. The correlation accounts air as a non-condensing gas, different heights of vertical plates and different thermal-hydraulic parameters. The correlation has been experimentally validated and shows excellent agreement, as 90% of theoretically predicted values are within ±12% of experimental data.

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CHC Caloric Heating and Cooling seminar, Twente 2020

lahde — Wed, 28 Jul 2021 05:16:22 +0000

Eurotherm CHC (Caloric Heating and Cooling) 2020 is another scientific seminar that was postponed from last year to 2021. It took place virtually between 13 and 15 July. The LAHDE laboratory participated in 4 conference papers and an invited lecture:

Cool future: magnetocaloric devices based on static and rare earth free
magnetic field sources (Urban Tomc, Stefano Dall’Olio, Katja Klinar, Simon Nosan, Urška Erjavec, Matej Šadl, Hana Uršič, Andrej Kitanovski)
New concept of electromagnetic field source for magnetic refrigeration (Simon Nosan, Urban Tomc, Katja Klinar, Andrej Kitanovski)
Numerical tool for evaluation of static thermal switches in caloric
refrigeration and heat pumping (Katja Klinar, Katja Vozel, Andrej Kitanovski)
Elastocaloric materials for active cooling regenerators (Lucia Ianniciello, Jaka Tušek, Lluid Manosa, Eduard Vives, Kurt Engelbrecht)
Thermo-hydraulic analysis of shell-and-tube-like geometries for
elastocaloric regenerators (Žiga Ahčin, Jierong Liang, Kurt Englebrecht, Jaka Tušek)

Seminar information: https://eurotherm.et.utwente.nl/#page

The post CHC Caloric Heating and Cooling seminar, Twente 2020 first appeared on Laboratory for refrigeration and district energy.

Performance of the Condensation Process on Vertical Plates and Horizontal Tubes

lahde — Wed, 05 May 2021 08:02:12 +0000

The condensation of humid air is a crucial step in air conditioning and process engineering. However, the models that describe the condensation of vapour in the presence of a non-condensable gas require time-consuming numerical calculations that go beyond the Nusselt film theory. Only a small number of publications exist, where simple and computationally effective correlations for the condensation of water vapour in the presence of air are presented for specially designed condenser heat exchangers. Therefore, the objective of this paper is to extend the existing semi-empirical correlations for different geometries and process parameters. For the purpose of the study, an experimental setup with two different condenser heat exchangers based on vertical plates (height 74 mm) and horizontal tubes (3 tubes, diameter 40 mm and 7 tubes, diameter 15 mm) was built. Additionally, based on existing correlations, we developed two semi-empirical models that predict the condensation mass flux for the proposed geometries. Here, we report that the agreement between the experimental and theoretical values predicted by the new, semi-empirical correlations is excellent, with an average uncertainty of less than ±6%. Their usability was demonstrated by a possibly significant performance improvement of the condenser inside a condensation-type tumble dryer.

LINK: https://www.mdpi.com/1996-1073/14/8/2291

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Numerical and experimental investigation of roll-bond heat exchangers in ST, PV and PV/T modules (Energy Conversion and Management journal, IF 7.181)

lahde — Mon, 16 Mar 2020 11:47:46 +0000

The article: Numerical and experimental investigation of the energy and exergy performance of solar thermal, photovoltaic and photovoltaic-thermal modules based on roll-bond heat exchangers

has been published in Energy Conversion and Management journal (IF = 7.181, 2019, top 5%).

Link to the article*: https://authors.elsevier.com/c/1akEjin8VZz4e.

Abstract:

This paper presents numerical and experimental energy and exergy performance assessments of solar thermal (ST), photovoltaic (PV) and photovoltaic/thermal (PV/T) modules based on roll-bond heat exchangers having three different channel geometries: serial, parallel and bionic. The validation of a coupled numerical simulation encompassing the thermo-hydraulic and electrical properties shows that 78% of all the data lies within a ± 10% uncertainty. The thermo-hydraulic simulation shows that the lowest outlet-water temperature inside the absorber is for the case of the bionic absorber (average 44.1 °C vs. 46.5 °C for the serial). This geometry is also beneficial when considering pressure losses, since compared to the parallel configuration (average 778 Pa) the bionic has significantly lower pressure losses (average 385 Pa). The simulation of the electrical properties of PV/T with all three absorber types showed the highest average solar-to-electrical efficiency (14.5%) in the case of the bionic absorber compared to the PV/T with parallel and serial absorbers (14.4% and 14.3%, respectively). Finally, a set of experiments using the ST, PV and PV/T2 (the index 2 denotes a PV/T collector variant with a foil thickness of 0.3 mm, compared to the thickness of 0.4mm for PV/T1, positioned between the absorber and the PV cells) modules showed that the PV module, coupled with a bionic absorber plate, achieves the highest average electrical (PV – 8.5% vs. PV/T2 – 9.9%) and exergy (ST – 4.4% vs. PV – 9.2% vs. PV/T2 – 12.7%) efficiencies. Only in terms of the thermal efficiency, the PV/T is at a disadvantage to the ST (PV/T2 – 33.5% vs. ST – 61.4%) due to the air gap between the front glass and the absorber of the latter module.

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The post Numerical and experimental investigation of roll-bond heat exchangers in ST, PV and PV/T modules (Energy Conversion and Management journal, IF 7.181) first appeared on Laboratory for refrigeration and district energy.