Tags:
Norwegian Nuclear Research Centre,
Nuclear and energy physics
Publications
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Lindholm, Dag; Arbes, Florian Maurits; Meir, Michaela Georgine; Rekstad, John; Sørheim, Einar Arne & Jensen, Øyvind
[Show all 9 contributors for this article]
(2025).
Toward a Digital Twin: Extrusion Die for Manufacturing Polyphenylene Sulfide Solar Thermal Collectors.
Polymer Engineering and Science.
ISSN 0032-3888.
p. 1–11.
doi:
10.1002/pen.70340.
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The European Union's commitment to increasing renewable energy use emphasizes the relevance of solar thermal collectors. A key component in flat-plate solar collectors is the absorber plate. Compared to traditional metal-based solar collectors, polyphenylene sulfide (PPS) offers several advantages including lower weight, easier installation, and strong thermal and corrosion resistance. However, extrusion of defect-free PPS plates is challenging. Accurate control of die exit temperatures and process conditions is crucial for producing high-quality PPS absorber plates, as even small deviations can cause slag deposition at the die exit. Detached slag deposits can lead to serious surface defects and costly production interruptions. A digital representation of the die allows estimation of how process-related factors affect PPS at the die exit. In this study, a detailed 3D model predicts temperatures that closely align with thermocouple data from a specific production run, revealing that measured die temperatures are about 10°C lower than the PPS die exit temperature. Melt inlet temperature and heater settings are shown to have significant impact on the die exit temperatures, while the effect of the ambient temperature is small. A non-intrusive POD-based reduced-order model enables real-time prediction of the die exit temperature, combining CFD data, interpolation, and sensor integration to support quality control and waste reduction in the extrusion process.
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Noorsumar, Gulshan; Adhikari, Sayan; Fjær, Hallvard Gustav; Jensen, Øyvind & Meir, Michaela Georgine
(2025).
Enhancing Extrusion Efficiency: Development of a Digital Twin for Glass Reinforced Polymer Processes Using Machine Learning and Real-Time Data Integration.
In Luby, Michael (Eds.),
TMS 2025 154th Annual Meeting and Exhibition Supplemental Proceedings.
Springer.
ISSN 9783031807480.
p. 620–633.
doi:
10.1007/978-3-031-80748-0_55.
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Steffen, Ronald; Meir, Michaela Georgine; Rekstad, John Bernhard & Röder, Beate
(2018).
Kinetics of degradation-induced polymer luminescence: A polyphenylene sulfide/elastomer blend under dry heat exposure.
Polymer.
ISSN 0032-3861.
136,
p. 71–83.
doi:
10.1016/j.polymer.2017.12.045.
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Carlsson, Bo; Meir, Michaela Georgine; Rekstad, John Bernhard; Preiss, Dieter & Thomas, Ramschak
(2016).
Replacing traditional materials with polymeric materials
in solar thermosiphon systems – Case study on pros and cons based on a total cost accounting approach.
Solar Energy.
ISSN 0038-092X.
125,
p. 294–306.
doi:
10.1016/j.solener.2015.12.005.
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The pros and cons of replacing traditional materials with polymeric materials in solar thermosiphon systems were analysed by adopting a total cost accounting approach. In terms of climatic and environmental performance, polymeric materials reveal better key figures than traditional ones like metals. In terms of present value total cost of energy, taking into account functional capability, end user investment cost, O&M cost, reliability and climatic cost, the results suggest that this may also be true when comparing a polymeric based thermosiphon system with a high efficient thermosiphon system of conventional materials for DHW production in the southern Europe regions.
When present values for total energy cost are assessed for the total DHW systems including both the solar heating system and the auxiliary electric heating system, the difference in energy cost between the polymeric and the traditional systems is markedly reduced. The main reason for the difference in results can be related to the difference in thermal performance between the two systems. It can be concluded that the choice of auxiliary heating source is of utmost importance for the economical competiveness of systems and that electric heating may not be the best choice.
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Rekstad, John Bernhard; Meir, Michaela Georgine; Murtnes, Espen & Dursun, Aylin Maria
(2015).
A comparison of the energy consumption in two passive houses, one with a solar heating system and one with an air-water heat pump.
Energy and Buildings.
ISSN 0378-7788.
96,
p. 149–161.
doi:
10.1016/j.enbuild.2015.02.059.
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Carlsson, Bo; Persson, Helena; Meir, Michaela Georgine & Rekstad, John Bernhard
(2014).
A total cost perspective on use of polymeric materials in solar collectors – Importance of environmental performance on suitability.
Applied Energy.
ISSN 0306-2619.
125,
p. 10–20.
doi:
10.1016/j.apenergy.2014.03.027.
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Kahlen, Susanne; Wallner, Gernot; Lang, R.W.; Meir, Michaela Georgine & Rekstad, John Bernhard
(2010).
Aging behavior of polymeric solar absorber materials: Aging on the component level.
Solar Energy.
ISSN 0038-092X.
84(3),
p. 459–465.
doi:
10.1016/j.solener.2010.01.003.
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Olivares, A; Rekstad, John Bernhard; Meir, Michaela Georgine; Kahlen, Susanne & Wallner, Gernot
(2010).
Degradation model for an extruded polymeric solar thermal absorber.
Solar Energy Materials and Solar Cells.
ISSN 0927-0248.
94(6),
p. 1031–1037.
doi:
10.1016/j.solmat.2010.02.001.
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Olivares, Lopez Andres F; Rekstad, John Bernhard; Meir, Michaela Georgine; Kahlen, Susanne & Wallner, Gernot
(2008).
A test procedure for extruded polymeric solar thermal absorbers.
Solar Energy Materials and Solar Cells.
ISSN 0927-0248.
92(4),
p. 445–452.
doi:
10.1016/j.solmat.2007.10.006.
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Abstract - An indentation test is proposed to study the degradation of extruded polymeric solar absorbers. The thermal degradation caused by accelerated aging is investigated. The results are compared with the thermal and mechanical impacts during the operation of the solar
collector.
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Meir, Michaela Georgine; Rekstad, John Bernhard; Olivares, Lopez Andres F; Schakenda, Jeanette A. & Kahlen, Susanne
(2005).
Facade integration of polymeric solar collectors.
Official Journal of the Lithuanian Applied Sciences Academy.
ISSN 1822-0754.
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Abstract – The present paper examines building integrated solar collectors with absorbers of polymeric materials. Efficiency measurements of façade-integrated collectors with non-selective black and spectrally selective coloured absorbers are carried out. The performance of the polymeric absorber was compared with solar glass and polycarbonate twin-wall sheets as collector cover. Simulations demonstrate a high solar fraction for a solar combisystem with façade collectors for a well-insulated house in a Nordic climate. Two examples of house concepts with façade collectors are presented which address a new type of customer than the solar enthusiasts with special interest in renewable energy.
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Kahlen, Susanne; Wallner, Gernot; Meir, Michaela Georgine; Rekstad, John Bernhard & Olivares, Lopez Andres F
(2005).
Characterization of polymeric materials for solar collector absorbers.
Official Journal of the Lithuanian Applied Sciences Academy.
ISSN 1822-0754.
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Abstract – The present paper describes the results of the selection and basic characterization of candidate polymers for solar absorber applications. Based on experiences with the Solarnor collector maximum temperatures of 80°C under operating conditions in water and 140°C under stagnation conditions in air were assumed. In addition to the currently used polyphenylene ether (PPE) blend further amorphous (polycarbonate, PPE belnds) and semi-crystalline polymers (polyamide, polyethylene, polypropylene) were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile testing. Except for crosslinked polyethylene (PE-X) and polypropylene (PP) copolymer grades, transition temperatures were found which are above the maximum service temperature of 140°C. For an amorphous PPE blend DSC was evaluated as a useful tool to determine annealing related physical aging effects. By DMA thermomechanical transitions close to ambient temperature were detected for the semi-crystalline polymers. Mechanical investigations revealed a more ductile behavior for the semi-crystalline polymers, but higher tensile strength values for the amorphous polymers.
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Furbo, Simon; Thür, Alexander; Fiedler, Frank; Bales, Chris; Rekstad, John Bernhard & Meir, Michaela Georgine
[Show all 10 contributors for this article]
(2005).
Competitive solar heating systems for residential buildings.
Official Journal of the Lithuanian Applied Sciences Academy.
ISSN 1822-0754.
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residential buildings”. The aim of the project is to develop competitive solar combisystems which are attractive to buyers. The solar combisystems must be attractive compared to traditional energy systems, both from an economical and architectural point of view. The project includes education, research, development and demonstration. The project started in 2003 and will be finished by the end of 2006. The participants of the project, which is financed by Nordic Energy Research and the participants themselves, are the universities: Technical University of Denmark, Dalarna University, University of Oslo, Riga Technical University and Lund Institute of Technology, as well as the companies: Metro Therm A/S (Denmark), Velux A/S (Denmark), Solentek AB (Sweden) and SolarNor (Norway). The project consists of a number of Ph.D. studies in Denmark, Sweden and Latvia, and a post-doc. study in Norway. Close cooperation between the researchers and the industry partners ensures that the results of the project can be utilized. By the end of the project the industry partners will be able to bring the developed systems onto the market. In Denmark and Norway the focus is on solar heating/natural gas systems, and in Sweden and Latvia the focus is on solar heating/pellet systems. Additionally, Lund Institute of Technology and University of Oslo are studying solar collectors of various types being integrated into the roof and facade of the building.
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Schakenda, Jeanette A.; Rekstad, John Bernhard; Spikkeland, Gunn; Meir, Michaela Georgine & Olivares, Lopez Andres F
(2005).
Energy metering in solar heating systems - A comparison of three methods.
Official Journal of the Lithuanian Applied Sciences Academy.
ISSN 1822-0754.
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Abstract – The EU directive on Energy Performance of Buildings inspired to investigate the possibilities of having a built-in low-cost energy metering function in the control unit of a solar thermal system. The principle is to use existing input signals received by the solar controller and verify an energy metering function for the solar system. Solar irradiation and temperatures have been measured and investigated. A method has been found where the energy gain is calculated using the temperature difference between the heat storage and the collector.
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Rekstad, John Bernhard; Meir, Michaela Georgine & Kristoffersen, A. R.
(2003).
Control and energy metering in low temperature heating systems.
Energy and Buildings.
ISSN 0378-7788.
35,
p. 281–291.
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Abstract
A new approach of temperature control and energy metering in low temperature heating (LTH) systems is presented. The required heat is
supplied in terms of energy pulses by intermittent operation of the circulation pump. The control unit calculates the heat demand from external
variables basically represented by the ambient air temperature. The parameters necessary for temperature control can be extracted when the heat
transfer coefficient and the heat capacity of the floor construction are known. Furthermore, the control strategy opens for energy metering in LTH
systems by means of the parameters heat carrier temperature and the duty cycle. The method is demonstrated to be at least accurate within 5%.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Low temperature heating; Floor heating; Hydronic systems; Outdoor temperature control; Floor controller; Energy metering; Energy monitoring;
Intermittent operation
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Henden, Lisa; Rekstad, John Bernhard & Meir, Michaela Georgine
(2002).
Thermal performance of combined solar systems with different collector efficiencies.
Solar Energy.
ISSN 0038-092X.
72(4),
p. 299–305.
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Abstract¿The performance of two kinds of solar systems for space- and
domestic hot water heating has been compared by computer simulations.
One system is a conventional radiator-based heating system with
collectors of ¿ideal¿ collector coefficients. The second system is a
low temperature heating system with solar collectors of moderate
efficiency. The investigation shows that the difference in performance
of the two systems is in the order of 1¿6%. Ó 2002 Elsevier Science
Ltd. All rights reserved.
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Meir, Michaela Georgine; Rekstad, John Bernhard & Løvvik, Ole Martin
(2002).
A study of a polymer-based radiative cooling system.
Solar Energy.
ISSN 0038-092X.
73,
p. 403–417.
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Abstract - A radiative cooling system consisting of unglazed flat plate radiators, water as heat carrier and a reservoir is presented. The radiators are twin-wall sheets made of a modified PPO (polyphenylenoxid) resin, which are proposed as low cost roof integrated modules. The thermal performance of a system with a radiator aperture area of 5.3 m2 and reservoir volume of 280 l has been investigated in experiments for Oslo climate. A parameterisation for the cooling performance of a tilted radiator surface for clear and cloudy atmospheres is proposed and applied to model the experimental results. The impact of the tilt angle, the aperture area and the reservoir volume on the cooling performance has been studied in simulations. The feasibility of a radiative cooling system designed for a single-family house at southern latitudes has been modelled. Except for mid-summer ambient temperature and high relative humidity, the simulations show that the radiative cooling system seems to cover the demand.
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Meir, Michaela Georgine; Rekstad, John Bernhard; Peter, Markus; Henden, Lisa & Sandnes, Bjørnar
(2002).
Determination of the performance of solar systems with the calorimetric method.
Solar Energy.
ISSN 0038-092X.
73(3),
p. 195–207.
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Abstract¿A calorimetric method is applied to determine the solar system performance by in-situ measured
data. The heat store is interpreted as a calorimeter and the information on charge and discharge is extracted
from the shape analysis of the heat store¿s temperature profile. The method is applicable to any heating system
which includes a heat store. In the present paper, this procedure is presented and applied to determine the solar
gain for a large solar system for domestic hot water preparation and a solar combisystem. The uncertainty of
this method is in the range of 6 10%. The results obtained by the calorimetric method are compared to
TRNSYS simulations.
¿2002 Elsevier Science Ltd. All rights reserved.
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Köhl, Michael; Meir, Michaela Georgine & Wallner, Gernot
(2012).
Polymeric Materials for Solar Thermal Applications.
Wiley-VCH.
ISBN 9783572332465.
393 p.
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Bridging the gap between basic science and technological applications, this is the first book devoted to polymers for solar thermal applications. Clearly divided into three major parts, the contributions are written by experts on solar thermal applications and polymer scientists alike. The first part explains the fundamentals of solar thermal energy especially for representatives of the plastics industry and researchers. Part two then goes on to provide introductory information on polymeric materials and processing for solar thermal experts. The third part combines both of these fields, discussing the potential of polymeric materials in solar thermal applications, as well as demands on durability, design and building integration. With its emphasis on applications, this monograph is relevant for researchers at universities and developers in commercial labs.
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Tomkiv, Yevgeniya & Meir, Michaela Georgine
(2026).
15 Years After Fukushima - Advancing Science & Global Collaboration.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7440366580175187968.
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It is 15 years since a tsunami and earthquake devastated the coast of the Fukushima prefecture, and led to the accident at the Fukushima Daichi Nuclear Power Plant. A team led by NNRC's Deputy Director Prof. Deborah Oughton is currently visiting the Institute of Environmental Radioactivity at Fukushima University (IER) to attend the 12th Annual Symposium, “Fukushima Voices: 15 years of Nature and Humanity” (https://lnkd.in/egm5JVFz), and to discuss future collaboration in research and education.
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Lind, Ole Christian & Meir, Michaela Georgine
(2026).
Research highlight in NATURE: PNAS study on the sunken submarine Komsomolets.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7447250454100606976.
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The study investigates the current status of the Soviet nuclear-powered submarine Komsomolets (K-278), which sank in the Norwegian Sea in 1989. Resting at a depth of 1,680 meters with both a nuclear reactor and two nuclear warheads on board, the wreck is a critical site for understanding long-term nuclear risks in the deep ocean.
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Paulsen, Wanja & Meir, Michaela Georgine
(2026).
𝐒𝐭𝐫𝐞𝐧𝐠𝐭𝐡𝐞𝐧𝐢𝐧𝐠 𝐍𝐨𝐫𝐰𝐚𝐲’𝐬 𝐍𝐮𝐜𝐥𝐞𝐚𝐫 𝐄𝐱𝐩𝐞𝐫𝐭𝐢𝐬𝐞: 𝐀 𝐉𝐨𝐢𝐧𝐭 𝐈𝐧𝐢𝐭𝐢𝐚𝐭𝐢𝐯𝐞 𝐛𝐲 𝐔𝐢𝐎, 𝐍𝐌𝐁𝐔, 𝐚𝐧𝐝 𝐃𝐒𝐀.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7449427917899522048.
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On April 9th, the Norwegian Radiation and Nuclear Safety Authority, Direktoratet for strålevern og atomsikkerhet (DSA), hosted in collaboration with Universitetet i Oslo (UiO) (UiO) and NMBU - Norwegian University of Life Sciences a strategic workshop "Sammen om å øke den nasjonale kompetansen i nukleære fag" (Together to strengthen the national competence in nuclear subjects) at Radisson Blu Plaza Hotel focused on master’s student supervision in businesses in the nuclear sector.
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Meir, Michaela Georgine
(2026).
10th anniversary of the Oslo Workshop on Nuclear Level Density and Gamma Strength.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7462823722547339264.
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The 10th anniversary of the Oslo Workshop on Nuclear Level Density and Gamma Strength, organized by Norwegian Nuclear Research Centre and University of Oslo took place throughout the week of 18–22 May. The workshop was opened by the Dean of The Faculty of Mathematics and Natural Sciences, Solveig Kristensen, who highlighted developments in our research field, the impact of the Oslo Method, and NNRC's societal mission.
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Meir, Michaela Georgine & Siem, Sunniva
(2026).
UiO and iThemba LABS: Formalizing a Decade of Scientific Collaboration.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7467550847309348864.
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The University of Oslo officially renewed the research partnership with iThemba LABS in South Africa. This milestone is the second renewal of a collaboration that first began in 2017. As Deputy Director at iThemba LABS Dr. Rudolph Nchodu, pointed out, this is now one of the largest collaborations we have in terms of the number of people involved. The formal signing by Vice Dean Øystein Prytz and Deputy Director Rudolph Nchodu provides a solid framework for the next five years, giving our joint research and student exchange programs the stability needed.
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Meir, Michaela Georgine & Brynildsen, Elisabeth
(2026).
From nuclear physics to smarter cancer treatment.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7467945495009726464.
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Nuclear technology master’s student Elisabeth Brynildsen defended her thesis on turning proton‑irradiated tantalum into new tools for cancer treatment and medical imaging. She investigates how to produce two promising isotopes, 177 Ta and 178Ta, and tests whether they could work for ultra‑precise therapy and SPECT scans. Her results add fresh data that can help develop safer and more effective radioactive drugs in the future.
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Theodossiou, Theodossis & Meir, Michaela Georgine
(2026).
Pioneering study on a small molecule called phenazine methosulfate (PMS).
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7472287357455650817.
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Members of our Norwegian Nuclear Research Centre community have co‑authored a pioneering study on a small molecule called phenazine methosulfate (PMS). The work conducted on brain cancer cells shows that PMS can briefly “jump‑start” energy production, even when the respirational energy systems are blocked by drugs ...
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Meir, Michaela Georgine & Tokstad, Camilla Almli
(2026).
Advancing Cancer Treatment with Nuclear Physics.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7477303373604614144.
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Camilla’s research, conducted at NNRC, Universitetet i Oslo (UiO) | University of Oslo and Berkeley Lab, provides a major boost for the future of targeted radionuclide therapy (TRT). Her work focused on the production of Antimony-119 (119Sb), a "perfect" candidate for cancer treatment because it emits Meitner–Auger electrons. These electrons deposit a high local dose of energy over a very short distance, allowing for the precise destruction of cancer cell DNA while sparing the surrounding healthy tissue.
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Meir, Michaela Georgine & Grieg, Claudia Emilia
(2026).
New Insights into Iodine: From Stellar Physics to Reactor Safety.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7477632298516127744.
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In her master's thesis, Claudia Grieg performed the first indirect measurement of the 132I (n,g) 133I astrophysical reaction rate. Working at the Oslo Cyclotron Laboratory, she utilized the Oslo Method to identify a low-energy enhancement (upbend) and a pygmy dipole resonance in the nucleus of 133I. This data is crucial for accurately modeling the i-process, bringing us closer to solving the mystery of the origin of heavy elements in our universe.
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Meir, Michaela Georgine & Görgen, Andreas
(2026).
New Insights into the Shape of Neutron-Rich Nuclei.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7491108539730583552.
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Just before summer William finished his master's degree studying the shape and structure of neutron-rich atomic nuclei. The work investigated excited states in the neutron-rich fission fragment ¹¹⁴Pd, measuring lifetimes in the picosecond range. The data were obtained in an experiment at GANIL in France, using the Advanced Gamma Tracking Array AGATA together with the VAMOS++ spectrometer, and analyzed using the recoil distance Doppler shift technique.
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Meir, Michaela Georgine
(2026).
Celebrating new research at NNRC!
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7503833920371621888.
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After the summer break, we had several research achievements to celebrate at the Norwegian Nuclear Research Centre (NNRC) at the University of Oslo: Three papers have been published, including one in Nature, with another also featured in Phys.org News. Two more papers have been accepted for publication and two additional manuscripts have been submitted to Physical Review C. The published papers cover nuclear structure, properties of exotic nuclei, nuclear astrophysics and nuclear fission - reflecting the broad research activities within our centre.
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Meir, Michaela Georgine; Olafsen-Solberg, Iris & Vatnar:, Samanta
(2026).
One centre, many opportunities — studying nuclear science with NNRC.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7506654029847130113.
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After completing their bachelor’s project together this spring, Iris Olafsen-Solberg and Samanta Vatnar have now started the NukTek master’s programme at the Department of Physics, University of Oslo. Their bachelor’s project combined nuclear physics at UiO with radiochemistry at NMBU - Norwegian University of Life Sciences and investigated the production and separation of technetium-95m (Tc-95m) for environmental monitoring.
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Paulsen, Wanja & Meir, Michaela Georgine
(2026).
Upcoming experiment with scientists from the University of Naples Federico II and the Università di Catania in Italy at OCL.
doi:
https:/lnkd.in/p/eTXjq6E9.
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Last week, several scientists from the University of Naples Federico II and the Università di Catania in Italy visited the Norwegian Nuclear Research Centre and the Oslo Cyclotron Laboratory at the Universitetet i Oslo (UiO) | University of Oslo to prepare for an upcoming experiment. Through this collaboration, we will perform an alpha-scattering experiment on a magnesium target to investigate carbon-carbon fusion inside stars. When carbon fuses with carbon inside stars, magnesium becomes a gateway to elements such as neon and sodium. It is therefore very important to have a detailed understanding of the nuclear properties of magnesium. This gives us a better understanding of how the elements we and our Earth consist of were created
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Meir, Michaela Georgine & Hisanawi, Josef Ali Hasan
(2026).
From Maritime to Terrestrial Reactors: Making Better Use of Nuclear Fuel.
doi:
https:/www.linkedin.com/feed/update/urn:li:activity:7510673513075142658/.
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In his thesis, “Neutronic Analysis of a Hybrid Maritime–Terrestrial Fuel Cycle in Fluoride-Salt-Cooled High-Temperature Reactors”, Josef Hisanawi explored an innovative idea for making better use of nuclear fuel: Could fuel, first used in a compact reactor for maritime applications, be transferred to a larger land-based reactor and used further?
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Rekstad, John Bernhard; Ingvild, Skjelland; Meersman, Els De; Yves, Klinger & Meir, Michaela Georgine
(2016).
Auf dem Sonnendach - Modifizierte Hochleistungskunststoffe zur Extrusion von Solarthermie Anwendungen.
Kunststoffe.
ISSN 0023-5563.
2,
p. 77–79.
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Sonnenkollektoren können Solarenergie in thermische Energie für Heizungen und Warmwasseraufbereitung umwandeln. Der Solarabsorber muss dabei hohen thermischen und mechanischen Belastungen standhalten. Wurden für diese Anwendung bisher hauptsächlich Metalle eingesetzt, hat ein Forschungskonsortium nun spezielle Polymerblends dafür entwickelt. Im Vordergrund stand die effektive Extrusion eines Hochleistungskunststoffs zu großflächigen Doppelstegplatten.
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Meir, Michaela Georgine; Carlsson, Bo & Rekstad, John Bernhard
(2013).
Life-cycle assessment of polymeric thermosiphon collectors.
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Meir, Michaela Georgine; Rekstad, John Bernhard; Dursun, Aylin Maria & Murtnes, Espen
(2013).
Polymeric solar collectors or heat pump? - Lessons learned from passive houses in Oslo.
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Meir, Michaela Georgine
(2008).
IEA-SHC Task 39: State of the Art, Polymeric Materials in solar thermal collectors.
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Meir, Michaela Georgine; Rekstad, John Bernhard; Gjessing, Jo & Rumler, Nele
(2008).
Overheating protection of polymeric solar collectors by triggered ventilation.
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Meir, Michaela Georgine & Rekstad, John Bernhard
(2008).
IEA-SHC Task 39: Polymeric solar thermal Collectors - State of the Art.
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Rekstad, John Bernhard; Meir, Michaela Georgine; Olivares, Lopez Andres F & Gjessing, Jo
(2007).
Polymeric materials in solar collectors.
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The paper outlines the impact of temperature on polymeric solar thermal collectors, and methods to reduce the thermal degradation.
If solar thermal shall play the role in the future that is desired and forecasted, new materials will be required. Both the IEA's-Solar heating and Cooling Programme and EU’s 7 Framework Programme focus on polymeric collectors. The main barrier for a full breakthrough for the polymer solution is the temperature sustainability in situations where stagnation temperatures occur. This problem is significantly smaller for Nordic climate than at for latitudes further south. The strong engagement revealed by leading industries in the polymer sector can be an inspiration and opportunity for scientific and technical Nordic research groups to take a frontier position in this field.
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Meir, Michaela Georgine; Rekstad, John Bernhard & Meek, Frode
(2007).
Energimålinger i boligene i Bjørnveien 119.
Arkitektur N.
ISSN 1504-7628.
p. 49–49.
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Furbo, Simon; Rekstad, John Bernhard; Meir, Michaela Georgine; Bales, Chris; Blumberga, Dagnija & Thür, Alexander
[Show all 8 contributors for this article]
(2006).
Nordic Energy Research Cooperation on Solar Combisystems.
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This paper describes ongoing research on solar combisystems for the Nordic and Baltic countries carried out within the projects “Competitive solar heating systems for residential buildings” and “Solar thermal components adapted to common building standards”. The aim of the projects is to develop competitive solar combisystems which are attractive to buyers and to educate experts in the solar heating field.
The participants of the projects, which are financed by Nordic Energy Research, Nordic Innovation Centre and the participants themselves, are the universities: Technical University of Denmark, Dalarna University, University of Oslo, Riga Technical University and Lund Institute of Technology, as well as the companies: Metro Therm A/S (Denmark), Velux A/S (Denmark), Solentek AB (Sweden), SolarNor (Norway) and SIA Grandeg (Latvia).
The projects include education, research, development and demonstration. The activities started in 2003 and will be finished by the end of 2006. The projects consist of a number of Ph.D. studies in Denmark, Sweden and Latvia, and a post-doc. study in Norway. Close cooperation between the researchers and the industry partners ensures that the results of the projects can be utilized. By the end of the projects, the industry partners will be able to bring the developed systems into the market.
In Denmark and Norway the research and development focus is on solar heating/natural gas systems, and in Sweden and Latvia the focus is on solar heating/pellet systems. Additionally, Lund Institute of Technology and University of Oslo are studying solar collectors of various types being integrated into the building.
Keywords: Solar combisystems, Nordic research cooperation.
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Kahlen, Susanne; Wallner, Gernot; Meir, Michaela Georgine; Rekstad, John Bernhard & Olivares, Lopez Andres F
(2006).
Aging behavior of polymeric materials for solar-thermal applications – Effect on ultimate mechanical properties.
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There is a high potential for innovative advancements by the proper integration of polymeric materials is to be expected for solar-thermal components and systems. The wide range of properties may be realized by polymeric materials combined with their cost efficiency, high flexibility with regard to processing and the high potential for multi-functional integration. The advantages related to the use of polymers in solar-thermal components and systems include functional improvements, system cost reductions and - last but not least - more design freedoms to meet the aesthetic demands of architects and end-users. While polymers are already extensively used in unglazed swimming-pool collectors, only a few all-polymeric glazed solar-thermal collectors are currently commercially available. The one investigated in the present paper, launched by Solarnor (Norway), consists of a twin-wall glazing, made of polycarbonate, and an extruded absorber sheet with injection moulded endcaps, made of a blend of polyphenylene ether and polystyrene (PPE+PS). The main objective of this paper is to develop and apply characterization methods which allow for a quality assurance testing of the polymeric absorber on component level.
The overall performance of polymeric solar absorbers is affected by the material used and by the processing procedures applied. Based on the relevant and partly standardized procedures for the quality assurance testing of plastics pipes, various thermoanalytical and mechanical methods have been evaluated and adopted for the testing of polymeric absorber sheets made of a PPE+PS blend. To characterize the basic polymer and the effects of processing on the morphology, dynamic mode thermoanalytical test methods requiring small samples have been applied. To check the extruded absorber sheet as to effects of sheet geometry and processing conditions, mechanical tests in bending and impact mode were developed and applied to specimens taken from different positions of the absorber sheet. For a full-scale test of the absorber including the extruded sheet and the joined injection moulded endcap an internal pressure testing procedure with water inside and ambient air at 80°C was adopted and applied to absorbers taken from two production series.
By thermoanalysis the effect of post-processing treatment could be reflected for extruded absorber sheets annealed at various temperatures below the glass transition temperature of the PPE+PS blend. The size of the endothermic peak, superimposed the endothermic step of the glass transition, allows for the description of processing and annealing induced morphological changes within the amorphous polymer. The mechanical stability of the absorber was investigated by monotonic tensile testing and impact testing. Internal pressure testing revealed differences for absorber sheets from different production series.
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Meir, Michaela Georgine & Rekstad, John Bernhard
(2005).
Challenges when using polymeric materials in solar collectors.
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Kahlen, Susanne; Meir, Michaela Georgine; Rekstad, John Bernhard & Olivares, Lopez Andres F
(2005).
Characterization of polymeric materials for solar collector absorbers.
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Abstract – The present paper describes the results of the selection and basic characterization of candidate polymers for solar absorber applications. Based on experiences with the Solarnor collector maximum temperatures of 80°C under operating conditions in water and 140°C under stagnation conditions in air were assumed. In addition to the currently used polyphenylene ether (PPE) blend further amorphous (polycarbonate, PPE belnds) and semi-crystalline polymers (polyamide, polyethylene, polypropylene) were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile testing. Except for crosslinked polyethylene (PE-X) and polypropylene (PP) copolymer grades, transition temperatures were found which are above the maximum service temperature of 140°C. For an amorphous PPE blend DSC was evaluated as a useful tool to determine annealing related physical aging effects. By DMA thermomechanical transitions close to ambient temperature were detected for the semi-crystalline polymers. Mechanical investigations revealed a more ductile behavior for the semi-crystalline polymers, but higher tensile strength values for the amorphous polymers.
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Meir, Michaela Georgine
(2005).
Facade integration of polymeric solar collectors.
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Abstract – The present paper examines building integrated solar collectors with absorbers of polymeric materials. Efficiency measurements of façade-integrated collectors with non-selective black and spectrally selective coloured absorbers are carried out. The performance of the polymeric absorber was compared with solar glass and polycarbonate twin-wall sheets as collector cover. Simulations demonstrate a high solar fraction for a solar combisystem with façade collectors for a well-insulated house in a Nordic climate. Two examples of house concepts with façade collectors are presented which address a new type of customer than the solar enthusiasts with special interest in renewable energy.
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Meir, Michaela Georgine; Rekstad, John Bernhard & Svåsand, Eldrid
(2004).
Facade integration of coloured polymeric collectors.
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Abstract - The present paper studies the performance of façade integrated solar collectors with absorbers of polymeric materials. Absorbers with different colours have been integrated in a timber-frame wall with and without ventilated cavity. The temperature and the relative humidity have been measured in several layers of the wall construction behind the integrated collectors. The objective was to determine whether non-ventilated integration is possible in a wooden construction under Nordic climate. It was found that omitting the ventilated cavity did not represent a risk for high relative humidity and condensation inside the wall construction. The integrated collector façade improved the U-value by more than 15% without that additional thermal insulation was added to the wall. Simulations have shown that façade integration can be a way to overcome the mismatch between the availability of solar energy and the heating demand.
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Meir, Michaela Georgine
(2004).
Internasjonal satsning på kombinerte solvarmeanlegg, Visjoner - muligheter - begrensninger.
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Meir, Michaela Georgine
(2004).
Lectures Part 1: Development of a polymer collector with glazing Part 2: On drain-back systems with polymer collectors Part 3: Roof- and façade integration of solar thermal collectors Part 4: Building integration of solar collectors and aesthetics.
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Meir, Michaela Georgine
(2004).
Combined solar systems with polymer collectors - Examples of applications and measurements.
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Meir, Michaela Georgine; Rekstad, John Bernhard & Kristoffersen, Astrid
(2004).
A non-pressurized heat store with immersed DHW-tank.
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Extended Abstract - The present study investigates the thermal performance of a new heat store for solar heating systems for combined domestic hot water preparation and space heating (solar combisystems). The work is part of the project REBUS [1], a collaboration between academic institutions and industry in Denmark, Latvia, Norway and Sweden, financed by Nordic Energy Research. One of the targets of REBUS is the development and demonstration of solar combisystems in new and well-insulated buildings providing solar fractions of 50% or more of the total annual heat demand under typical Nordic climate.
A large solar fraction under these climatic conditions requires relatively large heat storage volumes, typically 10 liters of water per square meter heated floor area. Costs and space requirements make square-shaped, non-pressurized heat stores to a favorable design. Such heat stores are used in combination with drain-back (solar) systems by the participating Norwegian company Solarnor.
The present experiments were carried out with the heat store shown in Figure 1. The special design, a top-insulated DHW tank, which is immersed in the buffer store, allows different temperature levels in the upper half of the DHW tank and the surrounding heat store volume. The solar collector delivers heat to the non-pressurized store volume. A high flow rate in the collector loop prevents thermal stratification during the charging phase so that "solar energy" is transferred to the DHW tank through the lower part of the tank.
The auxiliary energy is transferred by the heated water, first passing the spiral heat exchanger in the insulated, upper part of the DHW tank, and then entering the bottom of the heat storage tank. The challenge is to enable full control of the heat transfer to the DHW and the main store volume in order to minimize the amount of auxiliary heat.
Different geometries and flow velocities were investigated in order to determine the optimal conditions for heat transfer control by creating a "jet stream" with defined momentum entering the heat store at point A in Fig. 1. The spatial parameters as well as the temperature difference between the jet stream and the surrounding water in the storage tank have effect on the perturbation of the jet stream between the points A and B in Fig. 1.
In a typical sequence, the DHW tank is first heated to the desired temperature before a significant charging of the heat storage tank takes place. In the present experiments, a simple constant-power gas burner was used. The results confirm that good power control and consequently economical use of auxiliary heat sources is achievable with this simple and cost-saving concept.
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[1] Competitive Solar Heating Systems for Residential Buildings (REBUS), http://energi.fysikk.uio.no/rebus
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Meir, Michaela Georgine & Rekstad, John Bernhard
(2003).
Der Solarnor Kunststoffkollektor- The development of a polymer collector with glazing.
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Today the application of plastics as solar collector material is mainly related to swimming pool collectors. In Austria the total installed area of pool collectors was approximately 580 000 m2 in 2001 with a market share of 25% compared to glazed and vacuum collectors (Faninger, 2002). These collectors consist of unglazed polypropylene absorbers and are used for outdoor swimming pool heating during the warm season of the year. These collectors are cost-effective, but due to the material properties the use is limited to applications where glazing is not needed.
In 1995, a development of a polymeric absorber material for glazed solar collectors started in a collaboration between General Electric Plastics Europe, the Norwegian company Solarnor AS and the Group of Energy Physics at the University of Oslo under the frame of the EUREKA projects E!1315-PISC (PISC, 1995) continued by E!2286-EASP (EASP, 2002).
The development of Solarnor�s polymer collector was motivated by the demands for solar heating systems for Nordic climate, mainly to provide domestic hot water of temperatures up to approximately 60ºC and to heat buildings to an indoor temperature in the range of 20-25ºC. This is basically a "low temperature heating" demand and could be covered by a solar collector of moderate efficiency. As the collector areas of such systems normally cover a large surface area of the building, it is important to consider aesthetics and the architectural integration of collectors into the roof or facade by substituting conventional building materials. Hence, the collector materials should fulfil the demands of standard building elements. Further the modules should offer flexibility with regard to dimensions, low weight, easy handling and be cost-competitive to conventional energy sources.
Polymeric collectors produced by extrusion were considered to meet these requirements more than metal collectors. The development was also strongly influenced by the Norwegian energy market where abundant and low cost hydroelectric power was available (approx. 0.06 EURO/kWh until 2002) and approximately 80% of the buildings in Norway were heated by direct electric heating. A major obstacle was also that water-based heating systems, which are necessary for solar heating systems, have rarely been installed in new houses since 1960. Hence, the collector- and system costs were playing a major role in the development of the Solarnor collector. Besides Solarnor in Norway, there are only few companies known producing polymeric collectors with glazing.
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Kovacs, Peter; Weiss, Werner; Bergmann, Irene; Meir, Michaela Georgine & Rekstad, John Bernhard
(2003).
Chapter 5: Building-related aspects of solar combisystems.
In Weiss, Werner (Eds.),
Solar Heating Systems of Houses - A Design Handbook for Solar Combisystems.
James & James (Science Publishers).
ISSN 9781902916460.
p. 93–124.
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Meir, Michaela Georgine; Rekstad, John Bernhard; Sandnes, Bjørnar & Peter, Markus
(2001).
Das Klosterenga-Projekt in Oslo - Raumheizung im Norden.
Das erneuerbare Energien Magazin.
ISSN 1436-8773.
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Das Mehrfamilienhaus Klosterenga ist ein Forschungsprojekt, das
ökologische Baumaßnahmen mit urbaner Revitalisierung eines Osloer
Stadtteils verbindet. Ein Ziel war, den Endenergiebedarf des Wohnhauses
um 40% in Bezug auf die gegenwärtig in Norwegen gültige
Wärmeschutzverordnung zu senken. Zur Nutzung der Sonnenenergie für
Raumwärme und Brauchwassererwärmung wurden passive und aktive
Solarsysteme installiert. Die Energieversorgung von Klosterenga ist zu
100% CO2 neutral
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Meir, Michaela Georgine
(2000).
Research on solar heating-, radiative cooling- and low temperature heating systems, and on system simulation codes - solenergiprosjektet ved Universitetet i Oslo.
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Meir, Michaela Georgine
(2000).
Energy monitoring at the Klosterenga Green Building Project with the calorimetric method.
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Meir, Michaela Georgine; Sandnes, Bjørnar; Rekstad, John Bernhard & Peter, Markus
(2000).
Das Klosterenga Projekt - Solarunterst¿tzte Raumheizung in Norwegen.
Das erneuerbare Energien Magazin.
ISSN 1436-8773.
2000(4),
p. 22–24.
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Das Mehrfamilienhaus Klosterenga ist ein Forschungsprojekt, das ¿kologische Bauma§nahmen mit urbaner Revitalisierung eines Osloer Stadtteils verbindet. Ein Ziel war, den Endenergiebedarf des Wohnhauses um 40% in Bezug auf die gegenw¿rtig in Norwegen g¿ltige W¿rmeschutzverordnung zu senken. Zur Nutzung der Sonnenenergie f¿r Raumw¿rme und Brauchwassererw¿rmung wurden passive und aktive Solarsysteme installiert. Die Energieversorgung von Klosterenga ist zu 100% CO2 neutral. ************ The Klosterenga residence represents a pioneer project of ecological dwellings as a part of urban revitalisation in the centre of Oslo. The project aim was among others to reduce to total energy consumption related to the building by 40%. The combined solar system for domestic hot water pre-heating and floor heating is presented, further the experiences from the energy monitoring during the first months.
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Meir, Michaela Georgine; Rekstad, John Bernhard & Sandnes, Bjørnar
(2000).
Solar Combisystems for a multi-apartment building - The Klosterenga residence in Oslo.
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The Klosterenga residence represents a pioneer project of ecological
dwellings as a part of urban revitalisation in the centre of Oslo. The
project aim was among others to reduce to total energy consumption
related to the building by 40%. The combined solar system for domestic
hot water pre-heating and floor heating is presented, further the
experiences from the energy monitoring during the first months.
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Sandnes, Bjørnar; Mullane, Rory; Rekstad, John Bernhard & Meir, Michaela Georgine
(2000).
Phase change materials for storage of solar heat.
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Energy storage capacity and charge/discharge rates of a combined latent
heat and water storage system were investigated experimentally. A 1000
L storage tank developed for effective solar energy utilization was
partly filled with latent heat capsules (STL) and the temperature
development during charge and discharge monitored. The PCM/water
storage system increased energy storage capacity (1.7-fold) compared to
an equivalent volume of water. The charge/discharge rates were
acceptable with respect to solar energy collection, providing direct
circulation of tank water in the solar collectors which enhances
convective heat transport between PCM and water.
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Sandnes, Bjørnar; Meir, Michaela Georgine; Rekstad, John Bernhard & Bjerke, Bård
(2000).
Klosterenga Økologiboliger - En første analyse av soloppvarmingssystemet.
[Radio].
Universitetet i Oslo : USBL.
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The Klosterenga residence represents a pioneer project of ecological
dwellings as a part of urban revitalisation in the centre of Oslo. The
project aim was among others to reduce to total energy consumption
related to the building by 40%. The combined solar system for domestic
hot water pre-heating and floor heating is presented, further the
experiences from the energy monitoring during the first months.
Foreliggende rapport inneholder systembeskrivelsen og en første analyse
av solvarmesystemet.
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Rekstad, John Bernhard; Henden, Lisa; Imenes, Anne Gerd; Ingebretsen, Finn & Meir, Michaela Georgine
(1999).
Effective Solar Energy Utilisation - More Dependent on System Design than Solar Collector Efficiency.
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A new concept for a combined space heating and domestic hot water solar
system based on polymer solar collectors and low temperature utility
system is presented. Experimental results from laboratory as well as
from systems in the field demonstrates that the performance is
comparable to the performance of conventional systems with high
efficiency collectors connected to high temperature utility systems.
These results agree with the results of simulations carried out for
different system configurations and operating temperatures.
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Peter, Markus; Henden, Lisa; Meir, Michaela Georgine & Rekstad, John Bernhard
(1999).
Advanced Polyphenylenoxide and Polycarbonate Thermoplastics for Solar Collectors.
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Meir, Michaela Georgine; Storås, Harald & Rekstad, John Bernhard
(1999).
Combined Solar Heating and Radiative Cooling System.
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The radiative cooling potential of flat-plate coolers of polymer
plastics has been investigated. The cooling radiators are part of a
complete heating and cooling system with water as heat transfer medium.
This system consists of solar collectors and radiative coolers with
optimal thermal coupling to a hydronic floor system. The radiator¿s
stagnation temperature of 5-7 K under ambient air temperature during
night-time is demonstrated. The cooling power at ambient temperature
found under favourable climatic conditions is ca. 40 W/m2. The system
seems to be able to cover the need for cooling at locations where the
night temperature decreases to 20ºC with moderate relative air
humidity.
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Dursun, Aylin Maria; Rekstad, John Bernhard & Meir, Michaela Georgine
(2013).
Natural circulating flat plate collectors : Investigations of a new material and performance simulations.
Universitetet i Oslo.
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Solar energy can be utilized to heat water with the use of flat plate collectors. Effort is made to reduce the cost of solar water heating technology in order to make it economically competitive to conventional energy. An absorber material is tested on component level and performance related aspects are studied. The material has a lower price than the polymer materials currently used in glazed collectors, and therefore it has the potential to lower the cost of solar flat plate collectors. The performance related aspects are tested on a partially glazed, natural circulating flat plate collector, referred to as the Duo-Collector. The aim of letting the collector be partially glazed is to prevent the heat carrier from boiling. Samples cut from an extruded absorber sheet were exposed to 140 degrees Celsius and 150 degrees Celsius for different periods of time. These were used to map the mechanical properties of the material. The samples exposed to 150 degrees Celsius were used to map dimensional and optical changes. The results from the material-related studies on component level show that no failure occurs for any of the ageing periods which were realized in the time frame of the present work. The extruded absorber sheet has a sufficiently high absorptance and dimensional stability. These findings have strengthened the material's position as a candidate for use in solar thermal applications. The performance of the Duo-Collector has been simulated with MATLAB. It is found that the system is suitable as a method for preventing the fluid in the collector from boiling. The efficiency of such a system was also investigated. For low operating temperatures the efficiency of a Duo-Collector is approximately equal to the efficiency of a fully glazed or an unglazed collector. The efficiency of all the collectors decrease with increasing operating temperatures, and the efficiency of the Duo-Collector is between that of a fully glazed and that of an unglazed collector for all operating temperatures above approximately 10 degrees Celsius. Under certain circumstances the Duo-Collector can cool the water. This effect needs to be investigated further. Since only steady-state conditions are studied in this work, further analysis must be performed to compare how the Duo-Collector performs for different applications.
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Seljom, Pernille Merethe Sire; Rosenberg, Eva; Fidje, Audun; Meir, Michaela Georgine; Haugen, Jan Erik & Jarlseth, Thore
(2010).
Final report: The effect of climate change on the Norwegian Energy System towards 2050.
Institutt for energiteknikk.
ISSN 9788270178223.
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Meir, Michaela Georgine
(2002).
On creating thermal comfort without energy use.
FACULTY OF MATHEMATICS AND NATURAL SCIENCES.
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The subject of this thesis is the experimental and theoretical study of systems that permit the efficient utilization of low-valued energy sources, as solar energy and the effect of radiative cooling, for providing thermal comfort in buildings. The aim is to gain more understanding of these sources when applied with heating and cooling systems with large heat transfer surfaces.
A new strategy for power control and individual energy metering in systems with small driving temperature differences is proposed and investigated.
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I doktorarbeidet drøftes muligheter for å skape komfortabel innetemperatur i bygninger ved minimal bruk av konvensjonelle energikilder som el, kull, olje og gass. Byggets tak og fasader kan brukes til å høste solenergi til oppvarming, eller til kjøling ved å utnytte energistrømmer som transporterer varme fra flater mot en kaldere nattehimmel. De teoretiske beregninger underbygges med eksperimenter utført så vel på bygninger i alminnelig bruk som i laboratorium.
Effektiviteten til systemer som gjør bruk av disse naturlige energistrømmer blir vesentlig høyere dersom en utformer oppvarmingssystemet eller kjølesystemet slik at tilstrekkelig varme overføres ved relativt små temperaturdifferenser mellom varmebærer og rom. Doktorarbeidet viser at det har større betydning å sørge for riktig dimensjonering og godt samvirket mellom systemets komponenter enn at virkningsgraden til solfanger eller kjølepanel forbedres med noen prosent.
Systemer som arbeider med små temperaturdifferenser introduserer nye utfordringer med hensyn til temperaturstyring og til måling av brukt energi. Det presenteres og demonstreres nye løsninger for styring og energimåling der energien fordeles ut fra framtidige behov beregnet på grunnlag av utettemperatur, solinnstråling gjennom vinduer og eventuelt vindhastighet. Ved å levere energipakker i stedet for kontinuerlig energioverføring kan energiforbruket bestemmes vesentlig enklere og mer nøyaktig enn det som ellers er mulig i systemer der temperaturdifferensene er små.
Det vitenskapelige arbeidet har gjennom hele prosessen med teoriutvikling og laboratorieeksperimenter rettet seg mot muligheter for praktisk anvendelse og demonstrasjon. Det har vært en betydelig inspirasjon i at de løsninger som er utviklet allerede er tatt i bruk i prosjekter som Klosterenga i Oslo og Det Norske hus i European Village i Malmö.
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Sandnes, Bjørnar; Meir, Michaela Georgine; Rekstad, John Bernhard & Bjerke, Bård
(2001).
Klosterenga Økologiboliger - Analyse av solvarmesystemet.
Fysisk Institutt.
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