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Duret Alexis

Adjoint scientifique

Main contract

Adjoint scientifique

Desktop: S135a

Haute école d'Ingénierie et de Gestion du Canton de Vaud
Route de Cheseaux 1, 1400 Yverdon-les-Bains, CH

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Ongoing

Fostering increased DHN penetration: maximizing renewable share, decreasing temperature levels, identify synergies and integrate multiple injection points on the territory

AGP

Role: Co-applicant

Requérant(e)s: IESE, Capezzali Massimiliano, IESE

Financement: DIREN; VS - Institut Energie et environnement; Auto-fin IESE; Services Industriels de Lausanne; SFOE; Services Energies Yverdon

Description du projet : District heating networks (DHN) represent a crucial technology to attain significantly lower carbon footprint of the heating sector. Existing grids and their extensions, as well as new projects, are ex-pected to decrease distribution temperature levels decrease, in order to both improve efficiency and integrate a larger share of renewable and waste heat energy sources. The latter need to be quantita-tively characterized in order to be optimally integrated. In parallel, the potential synergies existing among small networks ' e.g. covering a few building blocks or one neighbourhood - need to be exploited, in terms of resources temporal availability and specific demand load profiles, in order to provide dynamic support, including possible storage capacities. FOSTER_DHN aims at developing the corresponding multi-grid and multi-temperatures design and simulation approaches as to gain a systemic understanding of DHN deployment and provide decision-support for local authorities and utilities.

Research team within HES-SO: Duret Alexis , Gendre Fabrice , Capezzali Massimiliano , Fesefeldt Marten , Jobard Xavier

Partenaires académiques: IESE; IGT; Capezzali Massimiliano, IESE

Durée du projet: 01.12.2022 - 31.05.2024

Montant global du projet: 262'165 CHF

Statut: Ongoing

Tâche IEA-SHC 68 - Efficient Solar District Heating Systems

AGP

Role: Main Applicant

Financement: IGT; OFEN

Description du projet : The objective of Task 68 is to promote the use of solar heat in DHN and to support the penetration of solar heat. Task 68 pursue mainly four objectives: 1. Efficiently providing the heat at the desired temperature level of district heating grids either directly through solar technologies or indirectly through a combination with other technologies (e.g. heat pumps) focusing on the system aspect. 2. Increasing the degree of digitalization of SDH systems in order to achieve a more efficient integration into district heating systems and a more efficient processing and use of data for evaluation, advanced controls and automatic fault detection. 3. Reducing costs of solar thermal plants to increase their economic attractiveness and competitiveness, and developing new financing and business models. 4. Disseminating the knowledge and results about the potential, areas of application, different solar technologies and their efficient combination with other technologies

Research team within HES-SO: Duret Alexis , Jobard Xavier

Durée du projet: 02.10.2022 - 28.02.2025

Montant global du projet: 27'950 CHF

Statut: Ongoing

Case studies Romandie: strategies and potentials of temperature reduction on existing district heating networks

AGP

Role: Main Applicant

Financement: OFEN

Description du projet : While reduction of DH (district heating) temperature is a priority for integration of renewable heat, it is conditioned by the temperature level of the individual substations. This issue is of particular concern for existing buildings, where distribution temperatures are known to be high, and where corrective actions within inhabited spaces is of particular complexity. Several techniques for temperature reductions at substation level have been proposed or are currently under investigation, but their actual implementation on existing DH substations depends to a large extent on pre-existing conditions. Furthermore, the actual benefit of temperature reduction at the level of the DH network, as well as interaction between temperature reduction strategies and other energy policy measures, need to be analyzed on specific case studies. Within this WP, these issues will be tackled by means of case studies on existing DH systems, in urban and rural context, requiring close collaboration with our cooperation partners.

Research team within HES-SO: Duret Alexis , Lasvaux Sébastien , Jobard Xavier , Masset Olivier

Partenaires professionnels: IGT

Durée du projet: 01.05.2021 - 31.12.2024

Montant global du projet: 40'000 CHF

Url of the project site: https://www.sweet-decarb.ch

Statut: Ongoing

Completed

Couplage direct d'un champ de modules PVT avec un système PAC utilisant des réfrigérants naturels pour le chauffage des bâtiments d'habitation collectif et la production d'eau chaude sanitaire

AGP

Role: Main Applicant

Financement: IGT; OFEN; Socle HEIG-VD Ra&D; IGT

Description du projet : L'objectif du projet TrisSolHP est de développer et d'évaluer les performances énergétiques, financières et environnementales, d'un système modulable de production de chaleur pour les bâtiments collectifs existant combinant en série une installation PVT avec une PAC R744 pour la production d'ECS et une PAC R290 pour le chauffage. L'utilisation de collecteur PVT spécialement optimisé pour maximiser l'échange de chaleur convectif avec l'air, permet de limiter la surface nécessaire. La combinaison de PAC utilisant des réfrigérants naturels permet de conserver de bons COP pour la production d'ECS et pour le chauffage sur une large gamme de température de source froide. Un COP annuel de 3.5 est visé. Le système de chauffage TriSolHP représente une alternative attrayante au PAC Air/Eau et pourrait contribuer à la décabornisation de la production de chaleur des bâtiments collectifs existants. Ce concept permet aussi de maximiser l'utilisation des toitures pour valoriser la ressource solaire.

Research team within HES-SO: Duret Alexis , Citherlet Stéphane , Dupont Gabriel , Da Riva Enrico , Guillaume Martin , Jobard Xavier , Pauletta Stefano

Partenaires professionnels: Groupe Système Energétique (GSE), UNIGE

Durée du projet: 01.09.2021 - 31.10.2023

Montant global du projet: 167'786 CHF

Statut: Completed

Potentiel du solaire thermique dans les chauffages

AGP

Role: Main Applicant

Financement: Socle HEIG-VD Ra&D; Auto-fin IGT; OFEN

Description du projet : Le but du projet SolCAD est d'analyser les opportunités et les limitations du développement du solaire thermique pour les chauffages à distance en Suisse. Pour produire l'évaluation la plus complète possible, quatre approches complémentaires sont utilisées : a) Une approche archétypale et cartographique à grande échelle, b) Une approche par étude de cas, c) Une analyse socio-économique des conditions-cadres et d) Une approche basée sur le partage d'expérience.

Research team within HES-SO: Wagner Guy , Duret Alexis , Citherlet Stéphane , Guillaume Martin , Jobard Xavier , Masset Olivier

Partenaires académiques: IGT; Duret Alexis, IGT

Durée du projet: 01.10.2019 - 31.10.2021

Montant global du projet: 93'927 CHF

Statut: Completed

Ecobilan Dynamique des Bâtiments (EcoDynBat)

AGP

Role: Collaborator

Requérant(e)s: IGT

Financement: SUPSI; OFEN; EMPA; Viteos; Socle HEIG-VD Ra&D; Auto-fin IESE; Auto-fin IGT

Description du projet : Le projet EcoDynBat a pour objectif d'étudier l'effet de la variabilité temporelle lors du calcul des impacts environnementaux de l'électricité consommée dans les bâtiments. Ce travail tient compte des fluctuations temporelles 1) de la production électrique nationale, 2) des importations d'électricité, 3) des pertes réseaux et de conversions, 4) de la production d'électricité décentrali-sée et 5) de la demande d'électricité au sein du bâtiment.

Research team within HES-SO: Périsset Blaise , Duret Alexis , Citherlet Stéphane , Lasvaux Sébastien , Padey Pierryves , Capezzali Massimiliano , Jobard Xavier , Goulouti Kyriaki

Partenaires académiques: IESE; IGT

Partenaires professionnels: losinger; Amstein + Walthert

Durée du projet: 15.11.2018 - 31.07.2020

Montant global du projet: 142'805 CHF

Publications liées:

Statut: Completed

Eco-habitat à haute efficacité énergétique utilisant au mieux les ressources locales et adapté au contexte sahélien

AGP

Role: Main Applicant

Financement: HEIG-VD; 2iE

Description du projet : Ce projet propose de concevoir et de développer des bâtiments écologiques adaptés au contexte sahélien en exploitant au mieux les ressources locales. Les bâtiments développés devront permettre de fournir à ses occupants un très bon niveau de confort (thermique, éclairage, ') tout en minimisant d'une part sa consommation énergétique et, d'autre part, son impact sur l'environnement. Il doit utiliser au mieux les ressources disponibles localement (éco-matériaux de construction, les ressources énergétiques tels que le solaire, ') tout en mobilisant des technologies simples, éprouvées. Ce projet a été structuré en deux axes. Un premier axe R&D durant lequel l'éco habitat sera développé et testé. Suivra un deuxième axe « renforcement des capacités » qui consistera principalement à disséminer les résultats du projet à travers deux sessions de formations continues.

Research team within HES-SO: Périsset Blaise , Garin Isabelle , Duret Alexis , Loperetti Murielle , Citherlet Stéphane , Bony Jacques , Favre Didier , Giorgi Morgane , Lasvaux Sébastien , Padey Pierryves , Eicher Sara , Zahar Skander , Guillaume Martin

Partenaires académiques: IGT; Duret Alexis, IGT

Durée du projet: 01.02.2012 - 30.09.2017

Montant global du projet: 559'240 CHF

Statut: Completed

Bâti-Tech - Face InTec: Développement d'un élément de façade à haute performance trifonctionnel

AGP

Role: Collaborator

Requérant(e)s: Lesbat

Financement: Socle VD Ra&D; Dir. générale de l'env. de l'état de Vaud (DGE)

Description du projet : L'objectif du volet 1 du projet Bâti-Tech est de modifier l'élément de façade Face InTec existant afin d'y ajouter la fonction "captage thermique" de l'énergie solaire reçue.

Research team within HES-SO: Bunea Mircea Stefan , Duret Alexis , Citherlet Stéphane , Bony Jacques , Affolter Jean-François , Favre Didier , Eicher Sara , Morey Philippe

Partenaires académiques: Lesbat; IESE

Partenaires professionnels: Alpiq InTec Romandie SA

Durée du projet: 01.07.2013 - 31.05.2017

Montant global du projet: 28'122 CHF

Statut: Completed

Bâti-Tech - Volet 3: Ecobilan et réduction des impacts environnementaux de la production de matériaux de construction écologiques

AGP

Role: Collaborator

Requérant(e)s: Lesbat

Financement: Arbio SA; Morandi; Socle VD Ra&D; Dir. générale de l'env. de l'état de Vaud (DGE); Magripol SA

Description du projet : L'objectif de ce troisième volet du projet Bâti-Tech est d'effectuer un écobilan selon les règles de l'art de cinq de ces produits. Ceux-ci devraient présenter des impacts environnementaux et une consommation d'énergie primaire inférieure aux produits standards du même segment de marché.

Research team within HES-SO: Périsset Blaise , Duret Alexis , Monney Isabelle , Citherlet Stéphane , Favre Didier , Lasvaux Sébastien , Ropp Julien

Partenaires académiques: Lesbat

Durée du projet: 01.07.2013 - 30.09.2016

Montant global du projet: 126'320 CHF

Publications liées:

Life cycle impact assessment of recycled concrete and comparison between three concrete production scenarios

Statut: Completed

Bâti-Tech - Histosol: Optimisation d'une nouvelle génération de collecteurs solaires invisibles

AGP

Role: Collaborator

Requérant(e)s: Lesbat

Financement: Socle VD Ra&D; Dir. générale de l'env. de l'état de Vaud (DGE)

Description du projet : L'objectif de ce deuxième volet du projet Bâti-Tech est d'optimiser et de réduire les coûts des collecteurs solaires Histosol. La réflexion se focalisera sur le transfert de chaleur entre la surface extérieure de la toiture et le collecteur de chaleur.

Research team within HES-SO: Bunea Mircea Stefan , Duret Alexis , Citherlet Stéphane , Bony Jacques , Favre Didier , Eicher Sara

Partenaires académiques: Lesbat

Durée du projet: 01.07.2013 - 31.12.2015

Montant global du projet: 395'450 CHF

Statut: Completed

2020

Development and testing of novel applications for adsorption heat pumps and chillers

Scientific paper ArODES

Xavier Jobard, Pierryves Padey, Martin Guillaume, Alexis Duret, Daniel Pahud

Energies, 2020, vol. 13, no. 3, article no. 615

Link to the publication

Summary:

This work aims at the development and the experimental characterization of new applications for adsorption heat pumps and chillers driven by industrial waste heat or renewable sources that can provide heating and/or cooling. Adsorption technologies offer the advantage of providing heating and cooling from low temperature sources below 100 °C without using refrigerant with high Global Warming Potential and with very low electricity consumption. Therefore, the technology enables the use of large untapped heat sources, increasing the energy efficiency of the heating and cooling sector with very limited impact on the environment. Several applications were investigated numerically for Switzerland using a simplified model of an adsorption heat pump. Four scenarios were identified as interesting: (1) the valorization of low-grade industrial waste heat in district heating networks, (2) energy efficiency improvement of district heating substations, (3) an autonomous adsorption heat pump with a wood pellets burner and (4) cooling applications. These scenarios were experimentally validated with a laboratory test of a commercial silica gel/water machine. Results show that there is a gap of up to 40% between the prediction of the simplified model and the experimental results. Therefore, there is huge potential to improve the performances of this commercial unit for these applications.

2022

Operability of district heating plants combining a large-scale solar thermal field with condensing wood chip boilers :

Conference ArODES

a case study in Switzerland

Xavier Jobard, Alexis Duret

Proceedings of EuroSun 2022

Link to the conference

Summary:

The subject of this work is the integration and operability of a large-scale solar thermal field with condensing wood chip boilers for district heating application in rural areas. Based on a case study in Switzerland, a largescale solar field is designed to be coupled with the existing heating plant composed of two wood boilers with external flue gas condensers. The operability of the new central heating plant is then assessed with numerical simulations carried out with TRNSYS. In a first step, two scenarios with two different solar fractions are simulated to analyze the performances of the solar system and the influence of the integration of the solar thermal field on the operation of the wood boilers. The main results are: 1) The specific productivity is between 450 and 500 kWh.m-2.y-1 for the considered operating temperatures and solar fractions. 2) The startup cycles are important if the heating needs in summer are not totally covered by the solar system. 3) After optimization of the controls, the startup cycles of the boilers in mid-season are very low.

Optimized adsorption heat pump for efficiency increase of district heating networks

Conference ArODES

Emanuele Piccoli, Romain Civioc, Sandra Galmarini, Xavier Jobard, Alexis Duret, Xavier Daguenet, Paul Gantenbein

Proceedings of EuroSun 2022

Link to the conference

Summary:

Adsorption heat pumps can provide cooling based on renewable district heat or waste heat, thus expanding the scope of district heating networks (DHN) and making better use of existing renewable heat sources. On the other hand, they can also provide heat while significantly reducing the return flow of the district heating network, thus increasing the efficiency of district heating supply. However, commercially available sorption machines are not designed for DHN. Therefore, new and sustainable adsorbent materials ideally suited for the temperatures and applications of district heating networks are developed and incorporated in a heat & mass exchanger designed for reversible adsorption heat pumps. The new sorption heat and mass exchanger is subjected to performance measurements. The results are used to carry out simulations to demonstrate the advantages of adsorption heat pumps for the supply of cooling and heating in district heating networks.

Performance monitoring of an 800m2 solar thermal plant with evacuated flat plate collectors coupled to a DHN

Conference ArODES

Alexis Duret, Xavier Jobard, Gauthier Demonchy, Stefano Pauletta

Proceedings of EuroSun 2022

Link to the conference

Summary:

The performances of a 800 m2 solar thermal plant coupled to a large District Heating in Geneva has been monitored for more than one year. The solar field is composed of 400 high performance evacuated flat plate collectors manufactured by TVP Solar. It has an average operating temperature above 80°C. This plant has been equipped with sensors to monitor and follow its performances over time. In 2021, the solar plant has injected 536 MWh in the DHN which corresponds to a specific yearly productivity of 684 kWh/m2 /y or 45 % of average efficiency. Performances were compared between 2021 and the first half of 2022, with no observed performance degradation. The monitoring will be pursued at least until the end of 2024.

2017

Medium temperature solar thermal installation for industrial thermal storage of bituminous products

Conference ArODES

Mircea Bunea, Catherine Hildbrand, Sara Eicher, Alexis Duret, Stéphane Citherlet

Proceedings of SES Solar World Congress 2017, 29 Oct.-2 Nov. 2017, Abu Dhabi, UAE

Link to the conference

Summary:

In this article, the performance analysis of a medium-temperature solar thermal installation integrated at the Colas Suisse SA industrial site in Yverdon-les-Bains (CH) is presented. The innovative collector system supplies energy for the temperature maintenance of bituminous products and provides part of the heating needs of the administrative building in the industrial site. The initial objective of Colas Suisse SA was to cover approximately 60% of the thermal energy demand of the site with solar energy. Field measurements provided an insight into the overall operation of the installation during 2015 to 2017. Despite improvement of the system, the performance of the collector field both in terms of energy and financial aspects was found below the expected values. On the other hand, simulations have shown the potential for improvement offered by the current installation. Despite nonoptimal operation of the solar installation, a life cycle impact assessment have indicated interesting potential primary energy savings and greenhouse gas reductions.

2015

Analysis of a medium temperature solar thermal installation with heat storage for industrial applications

Conference ArODES

Mircea Bunea, Catherine Hildbrand, Alexis Duret, Sara Eicher, Lionel Péclat, Stéphane Citherlet

Energy Procedia ; Proceedings of the 4th International Conference on Solar Heating and Cooling for Buildings and Industry (SHC 2015), 2-4 December 2015, Istanbul, Turkey

Link to the conference

Summary:

Willing to be an active participant to the Swiss strategy for sustainable development, Colas Switzerland SA, has decided to integrate a solar thermal installation in one of its bitumen storage industrial site. Situated in Yverdon-les-Bains (Switzerland), the solar installation aims to provide up to 60% of the thermal energy demand of the site. Coupled with a gas boiler, the solar collectors were designed to meet the energy needs of an onsite building, and to ensure constant temperature of a bitumen tank and two emulsions tanks (mixture of bitumen and water). In order to analyse and optimise the thermo-economic and environmental efficiency of this installation, a R&D project funded by the Swiss Federal Office of Energy was launched in 2014. This article gives an overview of the project objectives and describes the solar thermal installation and its operating modes. It also presents the numerical model and the first experimental results. First observations have revealed a thermal installation operating well behind its expected targets. Typically, the solar collector efficiency at temperatures above 200 °C is 50% lower than expected since it is operating under non-optimal conditions. Some technical dysfunctions have also been detected in the control system of one of the storage tanks. Consequently, a thorough evaluation of the operation of the installation was conducted to identify any other anomalies. In parallel to this work, the numerical model of the installation was developed and is currently under validation against the ongoing experimental measurements. Preliminary simulations of the installation in its current state have showed a solar yield nearly 2 times lower than expected, confirming the existence of anomalies in the running of the installation.

2014

Medium temperature solar thermal installation with thermal storage for industrial applications

Conference ArODES

Mircea Bunea, Alexis Duret, Stéphane Citherlet, Lionel Péclat, Elimar Frank

Proceedings of EuroSun 2014, 16-19 September 2014, Aix-les-Bains, France

Link to the conference

Summary:

In 2012, COLAS, the worldwide leader in the bitumen and road coatings sector, has decided to equip one of its regional sites with a solar thermal installation for temperatures up to 200°C. Coupled with a gas boiler, the solar collectors were installed with the dual purpose of meeting the thermal energy needs of a workshop building and to maintain two bitumen storage tanks above its melting point. This article gives a short description of the heating system at this industrial site and of its operating modes. It also describes the numerical model developed for detailed system simulation. First simulation results give a low annual solar heat gain of 94.6 kWh/m2 which is 2.6 times lower than initial estimations. Further investigations will be performed during the ongoing project in order to optimize the solar heat gain and to identify the reasons for this unsatisfactory result.

Achievements

Sans date

Symposium ER : Efficacité énergétique, énergies renouvelables et écobilan dans les bâtiments

2023 ; Conférence pour les professionnelles de la construction

Collaborateurs: Citherlet Stéphane, Duret Alexis

Link to the achievement

Le Symposium ER propose un tour d’horizon à travers des exemples concrets de réalisations dans le domaine de la construction durable. Cette biénale, dont la première édition a eu lieu en 2004, regroupe en moyenne 200 professionnels de la construction de Suisse Romande. Elle relaye l’information auprès des professionnels de la construction pour faire connaître, encourager et promouvoir des solutions existantes liées à l’efficacité énergétique, les énergies renouvelables et l’environnement appliquées au domaine du bâtiment. Ainsi, elle favorise la dissémination de techniques et des connaissances en matière d’innovation pour répondre aux problèmes énergétiques et environnementaux générés par le secteur du bâtiment.