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PEOPLE@HES-SO – Annuaire et Répertoire des compétences
PEOPLE@HES-SO – Annuaire et Répertoire des compétences

PEOPLE@HES-SO
Annuaire et Répertoire des compétences

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Courret Gilles

Courret Gilles

Professeur HES associé

Compétences principales

Physique appliquée

Thermodynamique

Efficience énergétique

Technologies à plasma

Chimie des plasmas

Eclairagisme

  • Contact

  • Enseignement

  • Publications

  • Conférences

Contrat principal

Professeur HES associé

Téléphone: +41 24 557 75 91

Bureau: T04

Haute école d'Ingénierie et de Gestion du Canton de Vaud
Route de Cheseaux 1, 1400 Yverdon-les-Bains, CH
HEIG-VD
BSc HES-SO en Energie et techniques environnementales - Haute école d'Ingénierie et de Gestion du Canton de Vaud
  • Physique de base
  • Physique appliquée
  • Eclairagisme
BSc HES-SO en Génie électrique - Haute école d'Ingénierie et de Gestion du Canton de Vaud
  • Physique appliquée
BSc HES-SO en Microtechniques - Haute école d'Ingénierie et de Gestion du Canton de Vaud
  • Physique appliquée

2023

Atmospheric plasma sources as potential tools for surface and hand disinfection
Article scientifique ArODES

Wolfram Manuel Brück, Alain Savary, Martine Baudin, Martine Emery Mabillard, Gilles Courret

Hygiene,  3, 4, 406-415

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Résumé:

Good hand hygiene has proven to be essential in reducing the uncontrolled spread of human pathogens. Cold atmospheric plasma (CAP) may provide an alternative to disinfecting hands with ethanol-based handrubs when handwashing facilities are unavailable. CAP can be safely applied to the skin if the energy is well controlled. In this study, radio frequency (RF) and direct current (DC) plasma sources were built with a pin-to-mesh electrodes configuration inside a fused silica tube with a 5 mm inner diameter. Microbiological assays based on EN 13697:2015+A1:2019 using Escherichia coli DSM 682 or Staphylococcus epidermidis DSM 20044 were used to examine the antimicrobial effect of various plasma conditions. Metal and silicone disks that model skin were used as inoculation matrices. The prototype air RF CAP achieved significant disinfection in the MHz range on stainless steel and silicone substrates. This is equivalent to half the performance of direct current CAP, which is only effective on conductive substrates. Using only electricity and air CAP could, with further optimization to increase its efficacy, replace or complement current hand disinfection methods, and mitigate the economic burden of public health crises in the future.

Désinfection par plasma froid à l'air ambiant pour l'hygiène des mains
Article professionnel ArODES

Gilles Courret, Alain Savary, Wolfram M. Brück, Martine Baudin, Martine Emery Mabillard

Bulletin d'information de l'Association québécoise pour l'hygiène, la santé et la sécurité du travail (INFOAQHSST),  27, 1, 10

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Résumé:

Face à l’épidémie de Covid-19, l’importance de l’hygiène des mains est sans cesse rappelée, le premier des gestes barrières étant en effet de se laver les mains très régulièrement. Bien que l'application de lotions à base d'alcool se soit révélée efficace, le lavage des mains suivi d'un séchage par jets d’air reste la méthode préférée. Les plasmas atmosphériques froids, dit aussi non-thermiques, utilisant l’air ambiant comme gas plasmagène peuvent constituer une alternative à la désinfection des mains lorsqu’il n’y a pas d’installations sanitaires à proximités. La puissance électrique est contrôlée de manière à éviter tout effet délétère sur la peau. Dans cette étude, nous avons testé divers générateurs produisant divers types de plasmas. Des essais microbiologiques basés sur la norme EN 13697:2015+A1:2019 ont été réalisés avec des microorganismes non-pathogènes, sur des surfaces en métal ou en silicone pour modéliser la peau. En utilisant des techniques d'induction électromagnétique dans la gamme des MHz, nous avons produit un jet stable de plasma froid d'air atteignant un niveau significatif de désinfection sur des substrats conducteurs et non conducteurs. La performance sur les surfaces en silicone est presque aussi élevée qu’avec des plasmas à courant continu qui eux, par contre, ne sont efficaces que sur les substrats conducteurs. Consommant uniquement de l'électricité, le plasma froid d’air ambiant pourrait remplacer ou compléter les méthodes actuelles de désinfection des mains et atténuer le fardeau économique des crises de santé publique à l'avenir.

Kaltplasmadesinfektion für die Hand- und Oberflächenhygiene
Article professionnel ArODES

Wolfram Manuel Brück, Gilles Courret

Lebensmittel-Technologie,  56, 2023, 9, 12-13

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Résumé:

Die Hochschule für Inegnieurwissenschaften der HES-SO Wallis und die Hochschule für Wirtschaft und Ingenieurwissenschaften des Kantons Waadt stellen ihre Desinfektionsmethode vor.

Désinfection par plasma froid pour l'hygiène des mains
Article professionnel ArODES

Gilles Courret, Alain Savary, Wolfram M. Brück, Martine Baudin, Martine Emery Mabillard

Revue polytechnique,  8, 36-40

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Résumé:

Face à l'épidémie de Covid-19, l'importance de l'hygiène des mains est sans cesse rappelée, le premier des gestes barrières étant en effet de se laver les mains très régulièrement. Bien que l'application de lotions à base d'alcool se soit révélé efficace, le lavage des mains suivi d'un séchage par jets d'air reste la méthode préférée. Les plasmas atmosphériques froids, dit aussi non thermiques, utilisant l'air ambiant comme gaz plasmagène peuvent constituer une alternative à la désinfection des mains lorsqu'il n'y a pas de sanitaires à proximité.

2021

Ré-échantillonage adaptatif pour la compression des données
Article professionnel ArODES

Petri Nikkola, Daniel Pesenti, Lucas Morin, André Dias, Gilles Courret

La revue polytechnique,  2021, no. 11, pp. 32-37

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Résumé:

Avec l'avènement de l'ère numérique, le stockage de données continue de croître rapidement, en particulier avec le développent des centres de données. Cet article présente les résultats d'une recherche menée à la Haute École d'Ingénierie et de Gestion du Canton de Vaud, visant à accroître la pertinence des enregistrements de séries numériques et à faciliter leurs exploitation en proposant un nouvel algorithme de compression par ré-échantillonage. Le prix de la mémoire numérique de masse n'a cessé de diminuer depuis plusieurs décennies [1], mais l'impact environnemental de cette révolution technologique est devenu un véritable problème [2,3] ; son efficacité doit être améliorée, une version détaillé de ces résultats a été récemment publiée dans la revue Array [4].

Adaptive resampling for data compression
Article scientifique ArODES

Daniel Pesenti, Lucas Morin, André Dias, Gilles Courret

Array,  2021, vol. 12, article no. 100076

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Résumé:

With the advent of the digital age, data storage continues to grow rapidly, especially with the development of internet data centers. The environmental impact of this technological revolution has become a problem. As the cost of digital recordings decreases, the amount of unnecessary data stored increases. This paper presents a new algorithm for compressing digital data series, which uses a local measure of relevance based on statistical characteristics. This compression produces non-uniform sampling with a density dependent on the relevance of the data, hence the adaptive feature of the algorithm. It works without any additional input and allows to build a data tree with progressive compression. Such a structure can feed multiscale analysis tools as well as selective memory release solutions for efficient archive management. Tests were carried out on two ideal noise-free signals as well as two real-world applications, namely compression of electrocardiograms retrieved from the PhysioNet database and compression of remote measurements provided by the constellation of ESA's Swarm satellites. Non-sparse type signals have been chosen in order to investigate compression performances in unfavorable conditions. Despite this, the number of samples has been reduced by more than half while maintaining the relevant characteristics of the signals. By reconstructing uniform samplings of the ideal noise-free signals, a measure of the compression error is obtained. Comparing the Fourier transforms of the original and the reconstructed signals, we further allow for future comparative analysis taking into account the ratio between the bandwidth and the sampling frequency of the original signal.

2020

Investigation of a molecular plasma from its acoustic response
Article scientifique ArODES

Gilles Courret, Petri Nikkola, Mirko Croci, Peter W. Egolf

IEEE Transactions on Plasma Science,  early access

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Résumé:

In developing a pulsed microwave lamp of 1 kW, fitted with a static electrodeless spherical bulb of glass, we discovered a phenomenon in which the plasma forms a ball at the bulb's center, despite the effect of gravity. The light is produced by plasma of sulfur, which is so hot that it might melt the bulb if it remained in contact with the glass, although it is fused quartz. In a preceding publication, we reported on photometric measurements showing the plasma response to the modulation of the microwaves. We have shown that the ball formation results from an acoustic resonance in a spherical mode. From a measurement of the resonance frequency, we have assessed the average value of the pressure inside the bulb. The plasma ball formation has been reproduced by another team of researchers with a similar setup but with a spinning bulb in order to stabilize the ball. From measurements of the oscillations of the ball diameter, they have shown that the acoustic amplitude inside the bulb can reach 180 dB (re 20 μPa). In our setup, we have not measured this feature. However, improving our model of the plasma modulation, we have also been able to assess the acoustic amplitude, and we have found results in an agreement, as shown in this article. In addition, our analysis suggests that stimulated emission is involved in the observed fast time scale modulation of the light emission.

Stocker le soleil dans de l’air
Article scientifique ArODES

Mirko Croci, Gilles Courret, Laurent Gravier, Dominique Bollinger

La Pensée écologique,  2020, vol. 1, no. 5, p. 6

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Résumé:

Le stockage des énergies intermittentes pose un réel problème notamment pour le solaire ou l’éolien. Des solutions Low-Tech, telles que le compresseur gravitaire présenté dans cet article, ouvrent la voie à de vraies solutions locales autonomes, pouvant s’affranchir des impacts importants des batteries habituellement utilisées. Il est aujourd’hui possible d’emmagasiner et restituer de l’énergie pneumatique avec une efficacité de l’ordre de 60 à 70%, lorsque la chaleur produite à la compression est gérée de façon astucieuse. Si, de surcroit, on combine cette solution de stockage avec des compresseurs spécialement conçus pour fonctionner avec des panneaux solaires photovoltaïques, le coût du kWh pneumatique peut devenir très compétitif… simple, ingénieux et économique.

2018

A translucent honeycomb solar collector and thermal storage module for building façades
Article scientifique ArODES

Peter William Egolf, Nicolas Amacker, Gregory Gottschalk, Gilles Courret, Arsene Noume, Kolumban Hutter

International Journal of Heat and Mass Transfer,  2018, 127, part A, pp. 781-795

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Résumé:

An innovative new translucent honeycomb solar collector and thermal energy storage module has been designed. The honeycomb module contains two different kinds of channels, namely empty ones and those that are filled with a Phase Change Material (PCM). The latter are sealed at the front and back side and, therefore, form chambers. Solar radiation enters the empty channels and is transmitted forward into them. The absorbed energy fraction at the side walls of these empty chambers leads to a melting of the PCM in their neighboring filled chambers, where then thermal energy is stored as latent heat. A heat transfer fluid, usually air, crosses the empty channels by forced convection and additionally charges or discharges the storage modules. Such elements are ideal to equip “intelligent” building façades in passive houses or then to form thermal storage elements in decentralized air-conditioning systems by integration into the façade of e.g. an office building. The article presents the new system and gives results on simplified two-dimensional spatial physical modeling, numerical simulation of charging and discharging modes and of a combined mode. Further work on full system performance, including the description of thermal behavior of buildings, is proposed for future work.

2017

On the plasma confinement by acoustic resonance :
Article scientifique ArODES
an innovation for electrodeless high-pressure discharge lamps

Gilles Courret, Petri Nikkola, Sébastien Wasterlain, Olexandr Gudozhnik, Michel Girardin, Jonathan Braun, Serge Gavin, Mirko Croci, Peter William Egolf

The European Physical Journal D,  2017, 71, 214

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Résumé:

In an applied research project on the development of a pulsed microwave sulfur lamp prototype of 1 kW, we have discovered an amazing phenomenon in which the plasma forms a ball staying at the center of the bulb despite gravity, thus protecting the glass from melting. In this paper, it is shown that this results from an acoustic resonance in a spherical mode. Measurements of the plasma response to short pulses are presented showing beats at the spherical resonance. It is demonstrated that the beats could result from the simultaneous excitation of two normal modes with a frequency difference of approximately 1%. One of the two frequencies matches precisely the microwave pulses repetition, a little below 30 kHz. Thus this one is due to a forced oscillation, whereas the other one is due to a free oscillation. The phase velocity of sound was calculated as a function of temperature in order to find the series of temperatures at which a resonance would occur if the bulb were an isothermal solid sphere. The mean temperature inside the actual bulb was determined from the only doublet of this series, that has characteristic frequencies close enough to cause the observed beats. In addition, one of these two modes has a spherical symmetry that can explain the plasma ball formation. The obtained mean temperature is consistent with the direct measurements on the bulb surface as well as with the temperature in the core of a similar plasma found in the literature. We have also proposed a model of the resonance onset based on the acoustic dispersion and the sound amplification due to electromagnetic coupling.

2014

High-frequency magnetocaloric modules with heat gates operating with the Peltier effect
Article scientifique ArODES

Peter W. Egolf, Laurent Gravier, Thibault Francfort, Anne Gabrielle Pawlowski, Gilles Courret, Mirko Croci

International Journal of Refrigeration,  2014, vol. 37, pp. 176-184

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Résumé:

Magnetic heat pumps, refrigerators and energy conversion prototypes, with an operation based on the magnetocaloric effect, usually show a restriction in their frequency of operation to a few Hertz. In 2010 it was proposed to apply thermal switches to overcome this barrier. In this article thermal switches built with Ni-nanowire Peltier elements are presented and the performance of such elements is discussed on a theoretical and experimental basis. Finally an approximate estimate of the performance of a magnetic refrigerator of the types built up to present is compared to that of a magnetic refrigerator applying nanowire thermal switches.

2012

The thermodynamics of devices with solid layered-bed magnetocaloric refrigerants
Article scientifique ArODES

Peter W. Egolf, Didier Vuarnoz, Laurent Gravier, Gilles Courret

International Journal of Refrigeration,  2012, vol. 35, no. 6, pp. 1506-1517

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Résumé:

In conventional refrigeration the use of the T–S diagram to determine thermodynamic cycle performance is a well accepted tool. This method is based on a single state description of the gaseous refrigerant during its cycling. Devices filled with a magnetocaloric refrigerant, due to slow diffusion and inhomogeneous temperature distributions, usually do not allow such a simple description. If the layered bed technique is applied, the situation is even more complex. The related problems are addressed and some new solutions are presented, e.g. a generalized T∗–S∗ diagram containing weights w∗. Furthermore, an analysis shows that an implementation of a layered bed of numerous weak magnetocaloric alloys does not substantially decrease the coefficient of performance, COP, compared to a single correspondingly better performing magnetocaloric material, but leads to an increase of the magnet size, the volume and the related price of a device. With devices operating with higher frequencies this can be counterbalanced and magnetic heating, refrigeration and energy conversion – with present available magnetocaloric materials – suddenly show a realistic chance for certain market penetrations.

2010

Lumière "solaire" sur commande
Article professionnel ArODES

Gilles Courret

IRO magazine,  2010, no. 21, p. 8

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2005

Heat exchange by mass transfer in isothermal environment :
Article scientifique ArODES
a two-parameters non-linear model

Gilles Courret, Derrick Ata-Caesar, Peter Egolf

International Journal of Heat and Mass Transfer,  2005, vol. 48, no. 25-26, pp. 5408-5416

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Résumé:

Thermal engineering in buildings has lead to the development of standards to determine the performance of radiators. With the breakthrough of techniques such as cooling ceilings, a slightly different need has appeared: the parameters of characterization have to be independent of the size of the radiator. This study meets this new requirement by modifying the standard two-parameters power law. It is found that the new parameters are also independent of the mass flow that irrigates the panels. Experiments have been performed to confirm this result. We believe that this model is also attractive to other types of isothermal heat sink.

2002

Anidolic daylighting systems
Article scientifique ArODES

Jean-Louis Scartezzini, Gilles Courret

Solar Energy,  2002, vol. 73, no. 2, pp. 123-135

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Résumé:

Non-imaging optics, well known for its application to solar concentrators, was used to set up novel daylighting systems that aim at an efficient collection and redistribution of the diffuse component of daylight. These devices, called anidolic systems (an: without, eidolon: image), were designed, installed and monitored on experimental test modules under clear and overcast sky conditions. Three different anidolic systems with different specific objectives were considered (anidolic ceiling, integrated anidolic system, anidolic solar blinds). Installed on 6.55-m deep rooms, the first two showed a significant improvement of daylight factors monitored in overcast conditions in comparison to a reference facade (conventional double glazing): a substantial improvement of the daylighting autonomy can be expected as a consequence. Higher work plan illuminances were observed for the third system under clear sky conditions, demonstrating sunlighting control capabilities that improve visual comfort and overall performance. The present article gives a description of these anidolic systems, as well as an overview of their luminous performance, assessed experimentally within the framework of IEA Task 21.

2001

Design of anidolic zenithal lightguides for daylighting of underground spaces
Article scientifique ArODES

Simone C. Molteni, Gilles Courret, B. Paule, L. Michel, J. L. Scartezzini

Solar Energy,  2001, vol. 69, suppl. 6, pp. 117-129

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Résumé:

Due to the congestion of contemporary large cities, the exploitation of the basement is strongly increasing. This is why, after subways and car parks, new public spaces like concert halls and auditoriums are getting common in downtowns’ basements. For this kind of building typologies, where windows are inadequate and skylights unsuitable, zenithal lightguides can be used to provide daylight. Their luminous performance can be improved by using sunlight trackers or static concentrators, which generally reduce the incoming of daylight during overcast conditions. The theory of anidolic optics (non-imaging optics), was used to overcome this difficulty. Scale models were used to assess their performances thanks to a scanning sky simulator. It was shown that the adjunction of an anidolic element to a plain zenithal lightguide improves its luminous performance: it provides an optimal concentration of sunlight for clear sky and a moderate reduction of the illuminance for overcast conditions. User-friendly abacuses were set up to support the design of anidolic zenithal lightguides in practice, including the shaping and the dimensioning of the device.

1998

Design and assessment of an anidolic light-duct
Article scientifique ArODES

Gilles Courret, Jean-Louis Scartezzini, David Francioli, Jean-Jacques Meyer

Energy and Buildings,  1998, vol. 28, no. 1, pp. 79-99

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Résumé:

The system presented here, called Anidolic Ceiling, was developed to show the viability of intensive use of daylight by overcast outdoor conditions in nonresidential buildings. This device consists of a light-duct that is integrated in a suspended ceiling and leads midway into the office. Anidolic (nonimaging optics) elements are placed on either end of the duct, on the outside to collect light rays from the sky and on the inside to control the direction of the emitted light. The present paper describes the system design, as well as an experimental assessment of its daylighting performance in a comparison of a prototype and a full-size conventional facade, for a 6.6-m deep room. Measurements by overcast sky have established that the daylight factor on the work plane 5 m from the window is more than doubled. In addition, a monitoring campaign has shown that 30% of the energy for lighting can be saved. The system was also assessed with regard to the user. Visual comfort measurements (Laboratoire d'Ergonomie de la Vision's (LEV) method) were carried out showing that for both clear and overcast outdoor conditions, the visual environment quality is objectively improved at the rear working place. Furthermore, 33 people tested both rooms one after the other. They were submitted to a series of visual acuity tests on printed paper and on a computer screen and had to fill in a questionnaire. A comparative study showed that the personal appreciation of the luminous environment is better in the room with an Anidolic Ceiling, with a significant reduction of reading errors both on paper and on the screen.

1996

Anidolic zenithal openings :
Article scientifique ArODES
daylighting and shading

Gilles Courret, B. Paule, J. L. Scartezzini

Lighting Research and Technology,  1996, vol. 28, no. 1, pp. 11-17

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Résumé:

Zenithal openings are attractive because they provide a high illuminance level. Nevertheless, this type of opening may create glare or overheating due to the penetration of direct sunlight. Conventional protective systems, north oriented sheds, unfortunately reduce the daylighting performance when the sky is overcast. On the other hand, movable blinds give a good compromise but introduce reliability and maintenance problems. In the present paper, a new concept of a top opening without moving parts is developed and analysed. Based on anidolic optics (non-imaging optics), this device gives efficient solar protection and reflects inside the building a large part of the diffuse natural light. In the present situation, the numerical simulations show that, in overcast conditions, this system is equivalent to horizontal glazing with a transmittance of 58%. Compared to sheds, this device increases significantly the building lighting autonomy and the visual comfort.

2024

Surface and hand disinfection using atmospheric plasma sources
Conférence ArODES

Wolfram Manuel Brück, Alain Savary, Martine Baudin, Martine Emery Mabillard, Gilles Courret

Proceedings of the 7th Global Public Health Conference (GLOBEHEAL 2024), 22-23 February 2024, Bangkok, Thailand

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2022

Plasma ball formation :
Conférence ArODES
an experimental technique to test radiative models in non-equilibrium plasmas

Gilles Courret, Petri Nikkola

Proceedings of the 9th International Workshop on Radiation of High Temperature Gases for Space Missions, 12-16 septembre 2022, Santa Maria, Portugal

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Résumé:

This article shows that a recent discovery in the field of molecular plasma, called Plasma Ball Formation (PBF), could provide a new experimental technique for testing collisional radiative models in nonequilibrium plasmas. Moreover, PBF could open a way to measure the bulk viscosity under controlled conditions, in addition to the sound velocity, thus providing an excellent opportunity to improve models used in numerical simulations of hypersonic flows.

Fast prototyping for atmospheric plasma sources integration into air hand dryers
Conférence ArODES

Abdel Majid Kassir, Joël Sonnard, Ludovic Roulin, Martine Baudin, Gilles Courret, Wolfram Manuel Brück

Proceedings of the irc 2022, XVI international research conference

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Résumé:

Motivated by the current COVID-19 pandemic and the need to find alternative methods to contain and battle it, the purpose of this innovative project is to conceive a disinfection module equipped with a cold atmospheric plasma source. Such a plasma source was developed for a potential integration into pulsed air hand dryers. This type of plasma is known for its ability to generate reactive oxygen and nitrogen species that initiate bio-molecular reactions involved in bacterial and viral deactivation mechanisms. This study shows how additive manufacturing helped accelerate the prototyping of a nozzle allowing the preservation of the plasma flow from circulation cells and external interferences in the discharge’s surrounding.

2010

A cable mounted bulb in high efficient sulphur lamps
Conférence ArODES

Gilles Courret, S. D. Marques Santos, L. Calame, Mirko Croci, Meyer A.

Proceedings of 16. Status-Seminar "Forschen für den Bau im Kontext von Energie und Umwelt"

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Résumé:

Plasma lamps have a high luminous efficiency. The plasma is microwave-induced. As an advantageous result, the bulb has no electrode, thus a quasi infinite life time. A second consequence is that half of the consumed energy is dissipated upstream the bulb by the ballast, mainly by the source of microwave (magnetron). By placing this part behind a false ceiling, we will thus cut down by half the cooling load due to lighting. But to reach this goal, the bulb has to be split off the ballast. In this purpose, a coaxial cable is used to transfer the microwave energy. This introduces however a dissipation that makes difficult the ignition of the lamp because the gas discharge breakdown in the bulb results from electromagnetic resonance. Even though the cable and the bulb coupling have been tuned to the magnetron frequency, no discharge appeared in continuous supply mode. But the ignition is obtained thanks to our new modulator, which is based on a solid-state switch of large bandwidth, by pulsing the magnetron. At a frequency of a few hectohertz with a duty cycle of 10% the lamp is ignited in less than a decasecond.

2008

Sustentation of a thermal plasma by acoustic resonance as a light source of high efficiency
Conférence ArODES

Gilles Courret, Laurent Calame, Jacques Croisier, Mirko Croci, Andreas Meyer

Proceedings of 15th Schweizerisches Status-Seminar "Energie und Umweltforschung im Bauwesen"

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Résumé:

This study deals with a new type of light source for indoor luminaries of high luminous efficiency. Unlike most low-energy lamps used nowadays, this one is free of pollutant. The light is emitted by a vapour of sulphur heated by microwave and enclosed in a bulb of fused quartz. In the present day commercialized versions, the bulb is rotating in order to avoid melting. In a recent study we have succeeded to avoid any mechanical motion as well as to reduce the nominal power without degrading the efficiency. Our innovation consists in fitting the power supply with a RF modulator. The system is designed to make vibrate the plasma in the ultrasonic frequency range. In the present study, new evidences of the ultrasonic vibrations of the plasma have been accumulated. First, the existence of a standing acoustic wave at particular tunings explains the effect of sustention that occurs then. Second, oscillations of the light have been observed at the very frequency of modulation. Making use of the conditions of acoustic resonance, we have also assessed that the mean electronic temperature lies around 8700 K. In addition, it is now clear that the cut-off frequency increases with pressure in large proportion. Hence the rise of pressure expands out of the centre only when it is lift enough so that the cut-off frequency exceeds the frequency of modulation, which happens with a certain delay. This analysis opens technical routes for improving the acoustic quality factor; this should enhance the luminous efficiency and also allow scaling down the bulb in order to decrease the wattage of the luminary.

2006

Environmental friendly high efficient light source
Conférence ArODES

Gilles Courret, Laurent Calame, Mirko Croci, Peter Egolf, Andreas Meyer

Proceedings of the 14. Schweizerisches Status-Seminar "Energie Und Umweltforschung Im Bauwesen"

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Résumé:

The search for high efficient types of light sources, suited to the indoor use, is in growth because this market is nowadays supplied mainly with fluorescent lamps (~80 lm/W ) although they contain pollutants. Alternatives based on sulfur vapor are currently in development in a number of countries. At high temperature, this vapor radiates a continuous spectrum that fits well onto the eye’s sensitivity range. The first commercialized sulfur lamp, the Solar-1000, outputs 110 lm/W at 1400 W in input. The attempt to launch a large commercialization failed for a lack of technical maturity: the bulb is hold in rotation, at 2500 t/min. We have succeeded to avoid any mechanical motion as well as to reduce the nominal power without degrading strongly the efficiency. The innovation consists in fitting the power supply with a radiofrequency modulator. The system is designed to make vibrate the plasma in order to create an ultrasonic wave inside the bulb. At the frequency where the acoustic absorption is maximal, the diatomic molecules are maintained out of thermodynamics equilibrium, and as a result, the luminous efficiency is increased. The experimental tests are positive. The efficiency of a static bulb has passed from 41 lm/W to 86 lm/W at 650 W in input of the magnetron. Furthermore, 68 lm/W has been reached at 490 W by scaling down the size of the bulb. If the magnetron had a cold cathode, a known technology, it would have been 91 lm/W at 610 W and 73 lm/W at 460 W.

2003

Experimental performance of daylighting systems based on nonimaging optics
Conférence ArODES

Jean-Louis Scartezzini, Gilles Courret

Nonimaging Optics: Maximum Efficiency Light Transfer VII

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Résumé:

Non imaging optics has established a reliable and sound framework for the design of efficient lighting systems in different application fields (nuclear physics, solar concentrators, electric lighting appliances,etc.). Based on its outstanding features, novel daylighting devices (anidolic daylighting systems)were designed in order to achieve efficient collection and redistribution of the diffuse component of daylight within deep office rooms. Several devices were set up, optimised through computer numerical simulations, built at different scales (1:10 scale models, 1:1 scale test modules)and finally monitored under different weather conditions (clear and overcast skies). An overview of the high luminous performance achieved by these daylighting devices --a zenithal anidolic collector, an anidolic ceiling and facade integrated anidolic systems --in 6 to 7 meters deep rooms under typical Central European weather conditions will be given in this communication. It will be shown that a very significant improvement of daylight factors monitored at a 5 meter distance from the facade is achieved by theses systems in comparison to a conventional double glazing reference facade (doubling of the daylight factors on the work plane), which corresponds to a substantial improvement of the daylight provision in the deeper part of the room.A daylighting system (anidolic slats) that shows the limits of building integration for such systems,will be considered as well.

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