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This paper presents the results of a comparative economic analysis of residential solar photovoltaic systems throughout the provinces of Canada in 2013 and 2016. The study was conducted using the discounted cash flow method. Basic economic theory involving the concepts of net present value, payback period, and internal rate of return was used, based on data from 2013 and 2016. The solar photovoltaic market is dependent on supporting policies and incentives. Thus, the relevant federal and provincial supporting policies for building implementation are briefly described and considered in the calculations. Results are presented in the form of summary tables showing selected major cities, classified into different categories, in terms of financial viability. The results show that in 2013 there were 9 cities out of 13 for which the payback period was expected to be higher than 30 years but in 2016, only Montreal PV projects remain infeasible. Furthermore, sensitivity analyses were conducted to establish new values for the selling price of electricity, initial cost of the proposed project, and percentage of subsidy required to ensure project attractiveness, that is, a short payback period of only 5 years for residential buildings.

International audience; The industrial sector is increasingly obliged to reduce its energy consumption and greenhouse gases emissions to contribute to the world organizations’ targets in energy transition. An energy efficiency solution lies in the development of thermal energy storage systems, which are notably lacking in the low-temperature range (50–85 °C), for applications such as district heating or low-temperature waste heat recovery. This work aims to bring a latent heat storage solution from material selection to prototype evaluation. The first part of this paper is dedicated to the characterization and aging of a phase change material selected from a screening of the literature (fatty acid mixture mainly composed by stearic and palmitic acid). Then, this material is encapsulated and tested in a prototype whose performances are evaluated under various operating conditions. Finally, a numerical model validated by the experimental results is used to explore the influence of a wider range of operating conditions, dimensioning choices, and material conductivity improvements.

The Inuit of the Canadian North live in isolated territories where there are no land routes. As a result, for the past few decades, they have been facing major adaptation challenges, particularly in terms of food and access to energy. Since June 2016, our research focuses on the potential of greenhouse farming in circumpolar territories with the case study of the cooperative greenhouse of Kuujjuaq (largest village in Nunavik in terms of population - 2375 inhabitants in 2011, latitude 58�� north and longitude 68�� west). Measurements in this greenhouse revealed a major problem: a temperature difference between day and night that was too large, hindering the development of crops. To address this, a thermal storage system was installed in October 2018. It is based on a rock bed of known porosity, positioned under the crop land, in which a heat transfer fluid that circulates, will allow the daily heat surplus to be stored during period with temperature peak, in order to reheat the greenhouse when the temperature in low, especially in the nighttime. The poster will focus on the performance of the system after two years of operation., Les Inuits du Nord canadien vivent sur des territoires isol��s o�� aucune route terrestre ne permet de se rendre. De ce fait, depuis les derni��res d��cennies ils affrontent de grands d��fis d���adaptation, notamment sur le plan de l���alimentation et de l'acc��s �� l'��nergie. Notre recherche s���int��resse depuis juin 2016 aux potentiels de la serriculture dans les territoires circumpolaires, avec comme cas d�����tude la serre coop��rative de Kuujjuaq (plus grand village du Nunavik en termes de population ��� 2375 habitants en 2011, latitude 58�� nord et longitude 68�� ouest). L���instrumentation de cette serre a permis de mettre en ��vidence une probl��matique majeure : un ��cart de temp��rature entre le jour et la nuit trop important, g��nant le d��veloppement des cultures. Pour y r��pondre, un syst��me de stockage de chaleur a ��t�� mis en place en octobre 2018. Il est bas�� sur un lit de roche de porosit�� connue, positionn�� sous la terre de culture, parcouru par un flux d���air servant de fluide caloporteur. Ce dispositif permet de stocker le surplus de chaleur journalier afin de combler le d��ficit nocturne. Le poster se focalisera sur les performances du syst��me apr��s deux ann��es de fonctionnement.

International audience; A novel prototype of a microcalorimetric cell with in-situ stirring has been developed to per-form DSC measurements under atmospheric or pressure conditions. After a brief technical description of the apparatus, preliminary tests are presented which analyzed the influ-ence of the stirrer rotation on the heat-flow signal. Experiments were then performed with complex fluids such as ice slurries and clathrate hydrates formed with cyclopentane and with carbon dioxide. They took place in stirred and non-stirred conditions and the results obtained were then compared. It was proven that the rotation of the microstirrer in the measuring cell does not disrupt the heat-flow signal during the analysis. As regards the prac-tical applications tested, the in-situ stirrer efficiently reduces crystallization metastability, increases the water-to-hydrate conversion, and reduces the amount of time needed for anal-ysis. The dissociation enthalpy of cyclopentane (CP) hydrates was measured at atmospheric pressure; it is effectively very difficult to analyze this system with non-stirred calorimetry techniques because the two liquid phases are immiscible. The experimental results, in good agreement with other data found in the literature, showed complete water-to-CP hydrate conversion within a short period of time using a simple protocol. Experiments were also performed under pressure to demonstrate that CO2 hydrate phase equilibrium data could be obtained rapidly and easily. It is therefore our opinion that the potential of this novel technology has been thoroughly demonstrated.

This research focuses on the potential of greenhouse cultivation in circumpolar territories. It begins with a survey that encompasses most of the northern greenhouses in North America. This review emphasizes the need for appropriate data and for the right energy system design. Next, the paper focuses on a case study located in Nunavik, which is the northern Inuit territory of the province of Quebec. The Kuujjuaq cooperative greenhouse has been instrumented since June 2016 to collect data on temperature and relative humidity throughout the growing season. These measures have highlighted a major problem: a temperature difference between day and night that is too large, hindering crop development. To counteract this thermal behavior, a heat storage system was designed, built and installed in October 2018. It is the first time that a rock and air-based sensible thermal energy storage system, taking into account local materials and resources, has been designed and built in a northern greenhouse. This paper presents its main characteristics as well as records of temperature changes throughout the growing season. Moreover, an energy balance is presented for three days at the beginning of June 2019.

In the north of Québec (Canada), off-grid aboriginal communities rely on diesel for both space heating and electricity production. Renewable alternatives are therefore necessary to reduce the impact of burning diesel in a region with strong population growth and increasing energy needs. The main challenges are the subarctic environment (more than 8000 heating degree days), the presence of permafrost and the lack of local expertise on drilling and installation of borehole heat exchangers.The communities of Kuujjuaq (58 °N) and Whapmagoostui-Kuujjuarapik (W-K, 55 °N) were chosen as case studies to evaluate the shallow geothermal potential and predict the long-term behaviour of ground source heat pumps (GSHP) and underground thermal energy storage systems (UTES). Local geology mainly consists of low permeable and thermally conductive crystalline bedrock (thermal conductivity of 2-4 W/mK) underlying highly permeable, frost-susceptible and poorly conductive marine sediments (thermal conductivity of 1-1.5 W/mK), generally not thicker than 30-40 m. Electrical resistivity tomography and ground penetrating radar surveys have been carried out to locally evaluate the presence of ice-rich ground that strongly depends on the local hydrogeological conditions. Average underground temperature in the first 100 m is around 1 °C in Kuujjuaq and 2 °C in W-K. Geothermal gradient and heat flux were estimated to be on average 15 °C/km and 40 mW/m2, respectively.Results of the studies carried out in these villages show that both GSHP and UTES are viable technologies to replace part of the current diesel consumption of residential buildings and drinking water facilities, with 10% to 50% primary energy saving depending on the technology. Fifty years’ life-cycle cost analyses demonstrated that the levelized cost of energy for GSHP and UTES is as low as 0.10 and 0.19 USD$/kWh, respectively, compared to the business-as-usual scenario standing at 0.21 USD$/kWh. It also turned out that the energy and drilling costs are key obstacles to a widespread deployment of these technologies in the North. A cost of 110 USD$/m has been defined as a threshold for getting interesting paybacks on the initial financial investment. UTES is also a valuable technology aiming to extend the growing season of community greenhouses in place in both Kuujjuaq and W-K. In Kuujjuaq, a coupled daily and seasonal heat storage is under study to provide renewable heat and help increase the food security in Nunavik.Future activities aim at the set-up of a first demonstration plant to be tested in a subarctic environment with underground close to permafrost conditions. A 200-m well will be drilled in 2020 in W-K and the installation of a borehole heat exchanger will be showcased for technological transfer. Conventional thermal response tests (TRT) and a novel approach of oscillatory TRT will also be carried out to evaluate the in-situ thermal conductivity and heat capacity.

Phase change materials (PCM) used in thermal energy storage systems present high storage capacity and require low temperature variation to allow effective heat charge or discharge density. However, these materials involve too low thermal conductivities ( −1 K −1 ) which can limit the heat transfer power between the heat transfer fluid and the phase change zone. In the first part of this study, high power level composites made of PCM (organic and also inorganic) and graphite have been elaborated in the thermal range from 50 to 350 °C in order to increase the effective thermal conductivity. In a second part, the assessment of their use as solar absorbers has been realized. Results show that these composites present high absorptance with respect to the whole solar radiation spectra. This allows new potentiality of integration of such materials in solar thermal processes offering a direct management of heat variation at the very first step of the process.

Among existing heat storage technologies, dual-media thermocline systems are considered an economical option, experimentally demonstrated at several scales. To obtain cost reduction for these storage systems, a part of the heat transfer fluid is replaced by a low-cost solid. The contact between these two media raises the question of their compatibility and behavior in time, as the storage performance directly depends on it. Ageing and compatibility tests have been performed at the laboratory scale with Jarytherm® DBT oil and various solid media. These tests, carried out at 340°C for 500 h, have shown the strong influence of the solid composition on its compatibility with oil. A strong incompatibility has been highlighted between Jarytherm® DBT oil and the selected natural rocks at 330°C, through chromatographic analysis and oil properties evaluation before and after ageing. To the contrary, glass, steel and alumina fared well, and are thus considered as promising storage media.

International audience; Disruptions in the way of life of indigenous peoples from the Far North have greatly affected their ability to meet their food needs. The implementation of community greenhouse and gardening projects is one of the initiatives taken to address this issue in Nunavik. Through a mixed-method approach, we analyze social benefits and challenges, as well as the potential food productivity and nutritional contributions of these projects. We discuss the potential of current greenhouse energy optimization scenarios and we address the benefits of Kuujjuaq's greenhouse in terms of carbon dioxide mitigation. Discussions with the local stakeholders highlighted technical challenges regarding the energy supply, its efficient management and the supply of soil in sufficient quantities. Our results highlight the interconnectedness and complexity of food and energy systems in Nunavik. They show that the establishment of local fresh food production corresponds to a need expressed by the residents and could bypass some of the difficulties associated with the conveyance and freshness of food sold at the supermarket. They also indicate that the implementation of such production poses many challenges that require taking into account the geographical isolation, the arctic climate and the availability of local resources.

International audience; Adjusting to global climate and socio-environmental changes has become a major issue for many societies, especially in the Arctic. Many Inuit wish to better understand the changes taking place. In 2013, an international Observatory of Human–Environment Interactions (OHMi) was established in Nunavik to identify these changes, study their cumulative impact on the socio-ecosystem and to help develop adaptation measures to improve the well-being of Inuit communities. To this end, a team of academics and local Inuit partners joined forces to develop an integrated, interdisciplinary, collaborative research program. Using a participatory action research (PAR) approach, the OHMi Nunavik set the following research priorities: elder-youth knowledge transmission, northern agriculture, preservation of Inuit culture, language and identity, protected areas, mining employment, natural hazards and risks, and wildlife vulnerability. By strengthening the collaborations between multidisciplinary Canadian and French research teams, the OHMi Nunavik program integrates local and scientific knowledge both in planning the research and in disseminating the results; L’adaptation aux changements climatiques et socio-environnementaux est devenue un enjeu majeur pour de nombreuses sociétés, notamment dans l’Arctique. De nombreux Inuit souhaitent mieux comprendre les changements qui se produisent. En 2013, un Observatoire international sur les interactions Homme-Milieu (OHMi) a été mis en place au Nunavik pour identifier ces changements, étudier leur impact cumulatif sur le socio-écosystème et pour aider à élaborer des mesures d’adaptation afin d’améliorer le bien-être des communautés inuit. À cette fin, une équipe d’universitaires et de partenaires Inuit locaux ont uni leurs forces pour développer un programme de recherche concerté, intégré et interdisciplinaire. En utilisant une approche de recherche-action participative, l’OHMi Nunavik a défini les priorités de recherche suivantes: transmission des connaissances entre les aînés et les jeunes, agriculture nordique, préservation de la culture, de la langue et de l’identité inuit, aires protégées, emplois dans les mines, risques naturels et vulnérabilité de la faune. En renforçant les collaborations entre les équipes de recherche multidisciplinaires canadiennes et françaises, le programme de l’OHMi Nunavik intègre les connaissances locales et scientifiques dans la planification de la recherche et la diffusion des résultats

Modeling the thermal behavior of a plant or devices using Phase Change Materials (PCM) requires to know their thermophysical properties. The Differential Scanning Calorimetry (DSC) is a technic largely used to investigate them. However, under the pretext to experiment with small samples, some authors consider the DSC curves as directly representing the properties of the materials without realizing that this interpretation is very often incompatible with the thermodynamics laws: as an example, although a pure substance melts at a fixed temperature T F , it is proposed a melting through a temperature range higher than T F and depending on the experiments (heating rates, sample masses...), for solutions the suggested characteristic temperatures are incompatible with the phase diagram, and also a hysteresis phenomenon is invented... In this paper, we demonstrate by a model coupling thermodynamics and conduction heat transfers, that the DSC curves are exactly compatible with the thermodynamics of phase changes (melting at fixed temperature for pure substances, in conformity with phase diagrams for solutions...). The cases of pure substances, saline solutions, substances with impurities or solid solutions are detailed. We indicate which information can, however, be given by the curves. We also propose a more sophisticated method by inverse calculations to determine the specific enthalpy whose all the thermodynamical properties can be deduced. Finally, we give some indications to understand and use the results indicating supercooling.

International audience

ACT; International audience

International audience; High pressure differential scanning calorimetry (HP-DSC) is of importance in several fields involving gas hydrates, such as oil and gas production, flow assurance, carbon dioxide capture and storage, CO2 hydrates reversible formation/dissociation for refrigeration loops.However, the technique suffered for some limitations linked to the fact that the gas hydrate formation in the calorimetric cell occurs at the gas-liquids interface, leading to problems such as inefficient gas dissolution, formation of a hydrate crust covering the gas/liquid interface, low hydrate to water conversion, and difficulties to crystallize these compounds even at low temperature. It is for example rather difficult to determine accurately the heat capacities and the enthalpies of formation/dissociation of several systems involving gas hydrates.To overcome such limitations, we present two prototypes of calorimetric cells equipped with an in-situ mechanical agitation system, which allow performing experiments under pressure (150 bar max). The first one is called MIXCEL®, and was developed for macro-calorimetry analysis (experiments carried out with a BT 2.15 Calvet Calorimeter from SETARAM Instrumentation). The second one, called MICROMIXCEL®, was developed for micro-calorimetry analysis (experiments carried out using a microDSC7 evo from Setaram Instrumentation). In this study, technical details of the two cells and results obtained both at macro and micro scales will be presented, and compared to the case with no agitation. Thermophysical properties of the cyclopentane hydrate (phase change enthalpy, and specific heat) will be given and commented. The use of such novel calorimetric cells opens a wide range of possibilities for complex systems, such as gas hydrates, which must be analysed in both pressurized and agitated conditions.

The use of phase change materials (PCMs) to increase solar domestic hot water (SDHW) system efficiency has been already studied by different ways. Some studies place the storage material in the water tank, others directly in the solar thermal collector. However both of them show that the effectiveness of such a use is not relevant. This paper is devoted to a new approach: the PCM is placed in the heat transfer fluid solar loop from the SDHW system. This configuration is studied under different weather conditions and system parameters. On the contrary to previous results, this parametric study highlights a significant increase of the system efficiency due to the PCM. Then, a genetic algorithm allows proposing an optimized system configuration.

International audience; Using direct steam generation in concentrated solar power plant leads to the development of new storage systems, which may include a latent heat thermal energy storage module. With this module, the behavior of the storage system matches the thermal behavior of the water used as heat transfer fluid. Sodium nitrate, which is already used in such lab-scale systems, is able to fulfill the conditions to assume the role of phase change material to store thermal energy. However, this material may evolve during its lifetime, either due to thermal decomposition or by corrosion phenomena, both leading to the reduction of nitrates to nitrites. Such evolution has been reported for the so-called "solar–salt" (NaNO3–KNO3 60:40 wt%), driving to the reduction of the melting temperature and latent heat. It is thus important to study the evolution of these properties in the case of sodium nitrate. The work proposed here aims to characterize sodium nitrate–nitrite mixture by differential scanning calorimetry for comparison with pure sodium nitrate (laboratory grade and industrial grade). Since the considered compounds are not at the eutectic composition, their melting does not occur at a fixed and single temperature. Thus, a calorimetric method using isothermal steps has been used in order to determine the evolution of involved energy during the melting of samples versus temperature for each sample. The results show the spreading of the melting over a range of temperature and the shifting of the liquidus to lower temperature when the sodium nitrite part increases. Moreover, a decrease in latent heat up to nearly 15% was observed.

This study presents two prototypes of calorimetric cells equipped with an in-situ mechanical agitation system, which allow performing experiments under pressure. The first system presented, called MIXCEL®, was developed for macro-calorimetry analysis (experiments carried out with a BT 2.15 Calvet Calorimeter from Setaram Instrumentation) and already patented in 2012 1. Concerning the micro-calorimetric agitated cell (called MICROMIXCEL®), it is the first time that such a system will be presented. This novel prototype was developed for micro-DSC analysis (experiments carried out with a DSC VII from Setaram Instrumentation). Both technical aspects, and results obtained at macro and micro scale with polyphasic complex systems (gas hydrates or ice slurries), are presented and discussed. The use of such calorimetric cells opens a wide range of possibilities for systems which must be analyzed in both pressurized and agitated conditions.

Thermal energy storage is now a key parameter to overcome the delay between energy supply and demand in many applications. To address this issue, the use of phase change materials (PCM) tends to be more and more common. Given the attempted objectives of such applications, performances of the PCM are a cornerstone of the whole system. Therefore, a correct determination of their intrinsic properties is crucial. To perform this step, one may use a calorimetry experiment. Unfortunately, the interpretation of the thermogram is not straightforward and consequently, when not feasible at all, estimations may be wrong. As an example, pure substance as sometimes said to melt at a non-uniform temperature (their enthalpy being smeared over several degrees), and binary solutions are associated with liquidus temperature and latent heat that do not match the correct form of their enthalpy. The present work proposes a new method to avoid such issues. To summarize the novelty of our approach, the main idea is to use an inverse method to identify the thermodynamical parameters of the sample through a matching step between the experimental curves and theoretical ones. It means that contrary to many others methods, we do not directly extrapolate the thermodynamical properties ( e.g. the enthalpy) from the thermogram. Instead, we suppose an a priori formulation of the enthalpy, based on thermodynamical principles. Thus the thermodynamical parameters are inputs of which only values are computed from the experiments. Capabilities of the method are shown on pure substances and binary solutions examples.

The overall objective of this work is to evaluate the potential of compressed expanded natural graphite (CENG) and phase change material (PCM) composites to improve the performance of solar domestic hot water (SDHW) systems. To achieve this target, an original approach has been chosen. Comparatively to other studies, in which the storage material is usually placed on top of the water tank, the proposed approach was to place the composite directly inside a flat plate solar collector in substitution to the traditional copper-based solar absorber. In a previous paper ( Haillot et al., 2011 ), elaboration and characterization of various composites led to the selection of three relevant composites suitable to their integration into a solar thermal collector. The present paper is devoted to the analysis of such a system to evaluate its actual performance. To reach this objective, a numerical model is proposed and its reliability validated by mean of corresponding experimental data. Despite the fact that under summer meteorological conditions the performed simulation highlights an increase of the system efficiency by adding a composite to the solar collector, the cumulative annual performance of such a system is penalized by low efficiency during winter time. However, the obtained simulated results allow us to offer a perspective of work that would maximize the benefits of adding storage composite to a SDHW system.

This work aims to evaluate the performance of a solar domestic hot water (SDHW) system including a latent storage material. The originality of our approach consists to place a composite made of compressed expanded natural graphite (CENG) and phase change material (PCM) directly inside a flat plate solar collector in order to replace the traditional copper-based solar absorber. According to this target, the study is composed of two steps: the composites preparation and characterization; and the analysis of the system to achieve optimal integration of the material in the process. The present paper is focused on the selection of the most promising composite to implement in the solar collector. In order to reach this objective, several composites based on CENG and various storage materials (paraffin, stearic acid, sodium acetate trihydrate and pentaglycerin) have been elaborated and characterized. The synthesis of all these measurements allowed us to select three composites whose characteristics match their integration into a solar thermal collector.

Latent heat storage systems, using phase change materials (PCMs), present the advantage of a high storage density at nearly constant temperature. They offer intrinsic advantages for heat storage in combination with steam as heat transfer fluid. Important applications of these storage systems are the areas of solar industrial process heat supply and heat recovery in industrial batch processes. The presented work aims to identify the most suitable PCMs, according to the studied temperature range (120–150 °C) and is based both on literature review and thermal analysis measurements. The thermal behaviour of eleven potential storage materials was studied by means of thermogravimetry (TG) and differential scanning calorimetry analysis (DSC), coupled with a quadrupole mass spectrometer (QMS). The paper emphasizes the importance of the measurement conditions on the results. In particular the impacts of the type of crucible (open/closed), the atmosphere (N2, N2/O2) and the cycling stability are presented.

Composite materials based on expanded natural graphite (CENG) and various phase change materials (PCM) have been developed for low temperature solar applications (323–373 K). The integration of such composite materials directly into the solar collector could allow new storage functionality. A numerical model has been developed to describe the materials behaviour. Composites properties are presented and discussed.

International audience; This paper makes a comparison between tetrahydrofuran (THF) and 1,3 dioxolane (DIOX) in terms of their respective performances as promoters for the formation of clathrate hydrates with CO2. The aim is to find products that can be substituted for THF, which is known to be harmful and difficult to handle. Drawing on a review of the chemical and physical properties of these two organic compounds, experiments were performed using high-pressure differential scanning calorimetry (DSC) and a batch reactor. Details of the thermodynamic equilibria of mixed THF+CO2 and DIOX+CO2 hydrates obtained with various additive concentrations are provided, along with hydrate kinetics data relating to the hydrate formation. The effect of the presence of an anionic surfactant, SDS (sodium dodecyl sulfate), on hydrate formation kinetics was also evaluated, showing that a combination of THF or DIOX and SDS is a very advantageous solution for accelerating hydrate formation. THF has been found to outperform DIOX as a hydrate promoter from both a thermodynamic, and a kinetic standpoint in presence of SDS. However, DIOX remains an interesting practical solution, due to the benefits offered as the least toxic and aggressive of these two organic compounds.

In this paper, a model is developed in order to determine the melting thermogram of a binary mixture, presenting a solid solution. Considering the case of an ideal solution, whose enthalpy function is analytically derived, we highlight the large differences existing between the thermogram and the derivative of the enthalpy function. The influence of the heating rates and the mass of the sample are analyzed for different concentrations. Finally, in the case of a thermodynamical equilibrium, we describe how to construct the phase diagram of the solution (liquidus and solidus temperatures, total latent heat).

Les hydrates de gaz sont des structures cristallines, composées d’un réseau tridimensionnel de molécules d’eau pouvant emprisonner sous certaines conditions de pression et température des molécules de gaz comme par exemple le méthane ou le dioxyde de carbone (CO2). Les recherches menées sur ces composés ont de nombreuses applications pratiques à fort impact économique dans les domaines du flow-assurance (prévention de la formation d'hydrates de gaz pour assurer la production de gaz ou de pétrole), du captage/stockage du CO2 (traitement et/ou stockage de gaz sous pression), de l’environnement (production d'énergie propre, transport et stockage de gaz), de l’énergie (exploitation des dépôts naturels d’hydrates représentant une source colossale de gaz naturel), et de l’industrie du froid (utilisation en tant que nouveaux Matériaux à Changement de Phase (MCP)). La plateforme CATHY met en synergie trois laboratoires (le LFC-R, le LaTEP et l’IPREM-ECP) de l’Université de Pau et des Pays de l’Adour (UPPA) pour l’étude et la caractérisation expérimentale des hydrates de gaz par plusieurs techniques complémentaires, mises en œuvre à différentes échelles, dans les domaines suivants : - micro et macro spectroscopie RAMAN pour l’analyse cinétique et structurale in-situ; - synthèse d’hydrates à échelle pilote et à l’échelle de la goutte ; - micro et macro calorimétrie (un brevet déposé) sous pression pour la détermination de propriétés thermodynamiques (diagrammes d’équilibre de phases, enthalpies, etc). Les différents équipements de la plateforme ainsi que des résultats expérimentaux caractéristiques de chaque technique seront illustrés et présentés pour l’hydrate de CO2.

International audience; The aim of this paper is to present an inverse identification method to determine specific enthalpy of PCM from calorimetry experiments. We will focus on the cases of pure substances and ideal binary solutions including the eutectic equilibrium. The corresponding direct model, based on energy balance, is first presented. A classical enthalpy method is then used, which presents the advantage of easily decoupling the thermal transfers from the specific energetic behavior of the material (i.e. thermodynamical phenomenon). In the second part of the paper, we will present the used inverse method (genetic algorithms). The sensibilities of the different parameters for the identification are analyzed. Finally, we will present the identification from DSC experiments (1) at different rates of heating for pure substances and (2) at different concentrations of aqueous solutions of N H 4 Cl. In each case, we identify the thermodynamical parameters of the model and compare the corresponding thermograms with the experimental ones. A good agreement is obtained for both cases

International audience; Originally applied to fields related to oil and gas production and flow assurance, high pressure differential scanning calorimetry (HP-DSC) has now been involved in several new studies such as carbon dioxide sequestration by CO2/CH4 exchange in naturally occurring gas hydrates or CO2 hydrate reversible formation/dissociation for refrigeration loops. However, the technique still has some limitations, which are linked to the fact that the gas hydrate formation occurs at the gas/liquid interface, and because the hydrate nucleation can be rather difficult in small volumes especially in quiescent conditions. It leads to several problems such as inefficient gas dissolution, long induction times, formation of a hydrate crust covering the gas/liquid interface, low hydrate to water conversion, etc. As a result, it is very difficult to determine accurately the heat capacities and the kinetics of formation/dissociation of several systems involving gas hydrates. This study presents two prototypes of calorimetric cells equipped with an in-situ mechanical agitation system, which allow performing experiments under pressure (150 bar maximum for the cells used in this work). The first system presented, called MIXCEL®, was developed for macro-calorimetry analysis (experiments carried out with a BT 2.15 Calvet Calorimeter from SETARAM Instrumentation). Very recently, we have developed a novel prototype of micro-calorimetric agitated cell (called MICROMIXCEL®) for microDSC analyses (experiments carried out using a microDSC7 evo from SETARAM Instrumentation). Both technical aspects, and results obtained at macro and micro scales with gas hydrate systems are presented and discussed.

International audience; Les hydrates de gaz sont des composés cristallins qui se forment sous certaines conditions (généralement sous haute pression et basse température), lorsque des molécules d'eau sont en contact avec de petites molécules de gaz. Lors de leur formation, l'eau (molécule hôte) forme alors un réseau constitué de plusieurs cages, dans lesquelles sont piégées les molécules de gaz (molécules invitées) comme par exemple le méthane, l'éthane ou le propane, mais également les gaz acides à savoir le dioxyde de carbone ou le sulfure d'hydrogène. Ce type de structure aux propriétés intéressantes présente un large spectre d'applications pratiques, en particulier pour le captage, le transport et le stockage du CO2. Certaines propriétés thermodynamiques de ces hydrates de gaz (comme par exemple les données d'équilibre de phase, les enthalpies de formation, les chaleurs spécifiques, etc.), dont la connaissance est indispensable pour les applications visées, peuvent être obtenues par calorimétrie. En revanche, un des inconvénients majeurs des cellules calorimétriques sous pression actuellement sur le marché, est leur absence d'agitation, ce qui peut s'avérer problématique dans certains cas (solubilité du CO2 contrôlée par la diffusion, problème de métastabilité à la cristallisation, etc). Dans un premier temps, ce travail consiste à présenter les détails techniques d'un nouveau prototype de cellule calorimétrique récemment breveté, agitée mécaniquement, fonctionnant sous pression, et compatible avec le calorimètre BT 2.15 de la société Setaram. Dans un second temps, les potentialités de ce nouveau dispositif sont évaluées pour l'hydrate de CO2 en termes de temps d'induction à la cristallisation (avec/sans agitation et comparaison avec la micro HP-DSC), et de données d'équilibre de phase.

Due to the difficult access to their territories, Northern Canada’s Inuit have faced major adaptation challenges in recent decades, notably in terms of food and energy. Traditional food from hunting, fishing and gathering activities is increasingly difficult to obtain, while European and Canadian foods brought by air or by sea are increasingly expensive. Culture in greenhouses appears as a solution allowing to improve access to fresh vegetables by reducing the ecological and financial costs linked to the transportation of these.The scientific literature on the physical study of northern greenhouses and energetic data (temperature, electricity consumpion, etc.) is scarce. The first part of this thesis has to do with the pinpointing of northern greenhouses existing in North America and shows that this subject is relatively recent. On the other hand, this literature review revealed that the majority of counted greenhouses are not adapted to a cold climate, hence short growing seasons.The second part of this work focuses on the experimental aspect. Data coming from an instrumentation campaign in a northern greenhouse were analysed to demonstrate the relevance of the establishment of a daily thermal energy storage (TES) system. The dimensioning and construction of this system using air as a coolant fluid and local rocks as storage material are also presented. The instrumentation of the rockbed which stores heat has allowed to study energetical data during charge and discharge phases of the stock. This analysis demonstrated the positive impact of the set up of the TES system on the thermal behavior of the greenhouse.The last part of this work concerns the modeling of the thermal behavior of the greenhouse and the TES system. As a matter of fact, the numerical simulation of the climate in a greenhouse is basic in order to understand the improvement mechanisms of existing greenhouses and/or to optimize the conceiving of enclosures for vegetable production in a northern environment. Indeed, a nodal model of the greenhouse and an independent model of the TES system are detailed and validated. A process of calibration about the numerical values of the models’ parameters is also developed to improve the performances of these models.; Vivant sur des territoires isolés où aucune route terrestre ne permet de se rendre, les Inuits du nord canadien (Nunavik) font face, depuis les dernières décennies, à de grands défis d’adaptation, notamment sur le plan de l’alimentation et de l'accès à l'énergie. La nourriture traditionnelle issue des activités de chasse, de pêche et de cueillette est de plus en plus difficile à obtenir, tandis que les aliments euro-canadiens apportés par avion ou par bateau coûtent de plus en plus cher. La serriculture apparaît alors comme une solution permettant d'améliorer l'accès aux légumes frais en réduisant les coûts écologique et financier liés au transport de ces légumes.La littérature scientifique portant sur l'étude physique des serres nordiques et les données énergétiques (température, consommation d’électricité, etc.) sur le sujet sont rares. Dans un premier temps, nous avons recensé les serres nordiques existantes d'Amérique du Nord, et nous avons montré que le sujet est relativement récent. Par ailleurs, cette revue de littérature a révélé que la majorité des serres dénombrées ne sont pas adaptées au climat froid, conduisant à des saisons de cultures courtes. Ensuite, nous avons abordé l'aspect expérimental. Les données issues d'une campagne d’instrumentation de la serre nordique de Kuujjuaq ont été analysées afin de démontrer la pertinence de l'installation d'un système de stockage thermique journalier. Le dimensionnement et la construction de ce dernier, utilisant l'air comme fluide caloporteur et des roches locales en tant que matériau de stockage, sont également présentés. L'instrumentation du lit de roches stockant la chaleur a permis l'étude des données énergétiques durant les phases de charge et de décharge du stock. Cette analyse a démontré l'impact positif de l'installation du système de stockage sur le comportement thermique de la serre. Enfin, nous avons modélisé le comportement thermique de la serre et du système de stockage. En effet, la simulation numérique du climat sous serre est essentielle afin de comprendre les mécanismes d'amélioration des serres existantes et/ou d'optimiser la conception des enceintes de production végétale en milieu nordique. Ainsi, un modèle nodal de la serre et un modèle du système de stockage sont détaillés et validés. Un processus de calibration portant sur les valeurs numériques des paramètres des modèles est également développé afin d'en améliorer les performances.