Discharge performance of blended salt in matrix materials for low enthalpy thermochemical storage

A novel study is undertaken on low cost thermochemical storage which utilizes temperatures which are compatible with low grade renewable energy capture. The discharge performance of thermochemical storage matrix materials is assessed using a custom developed experimental apparatus which provides a means of comparing materials under scaled reactor conditions. The basic performance of three salts (CaCl2, LiNO3 and MgSO4) was investigated and their subsequent performance using layering and blending techniques established that the performance could be increased by up to 24% through the correct choice of mixing technique. Layering the CaCl2 on the LiNO3 provided the most efficient thermal release strategy and yielded a thermal storage density of 0.2 GJ/m3. The research also uniquely highlights the important finding that incorrect mixing of the materials can lead to a significant reduction in efficiency with freely mixed CaCl2 and LiNO3 possessing a storage capacity of less than 0.01 GJ/m3 as a result of chemical interactions between the deliquesced materials in close proximity. The paper has impact for the design and control of thermochemical storage systems as it clearly identifies how performance can be improved or degraded by the choice and the structuring of the materials

Ultrasounds assisted freezing. Influence of the oxygen content in the liquid on the ice crystals size in the solid.

National @ ENERGIE+AJHInternational audienceAbstract Samples of mannitol aqueous solution at various contents of dissolved oxygen were frozen with the help of ultrasounds and the ice crystals size distributions were measured by optical microscopy. Increasing the content in oxygen led to a fair decreasing of the average crystals size and an increasing of the homogeneity of the size of crystals within the sample. The average size appeared simply as inversely proportional to the oxygen content in the initial liquid solution. Keywords : ultrasounds, ice crystals, size distributio

Thermochemical heat storage : study of the water sorption properties of different materials

Le défi énergétique imposé par l’épuisement des énergies fossiles d’une part et par leur consommation croissante d’autre part, a favorisé l’apparition d’une gestion optimale de l’énergie basée sur l’utilisation de ressources propres et renouvelables telles que l’énergie solaire. Le secteur du bâtiment est le principal consommateur d’énergie. Une grande partie de cette énergie est consommée par les systèmes de chauffage. Par conséquent, une bonne gestion peut être réalisée grâce à l’utilisation des technologies de stockage thermochimique d’énergie. L’avantage principal d’utiliser ce type de système est la possibilité de stocker de la chaleur pendant la période de disponibilité maximale du rayonnement solaire, en été (étape de déshydratation) et la libérer pour chauffer une maison pendant la période hivernale (étape d’hydratation). L’amélioration des propriétés d’adsorption des matériaux pour le stockage thermochimique de la chaleur est l’objectif principal de ce travail. L’utilisation d’adsorbants poreux tels que les zéolithes dans le domaine du stockage saisonnier de la chaleur s’avère être une solution intéressante pour la réduction de la consommation d’énergie. Par ailleurs, le développement de nouveaux matériaux composites à base d’hydrate de sel a été étudié pour améliorer les capacités de stockage à la fois des matrices mésoporeuses et des hydrates salins. Une comparaison entre les différentes séries de matériaux de stockage thermochimiques sélectionnés et synthétisés a été réalisée, concernant l’impact de la nature et de la quantité de sel ajouté et des propriétés physicochimiques des matériaux poreux sur leurs densités de stockage de chaleur et leurs capacités de sorption d’eau. Afin de mieux comprendre le comportement d’adsorption-désorption, les différents types de matériaux de stockage sélectionnés ont été caractérisés d’un point de vue structural et textural en utilisant des techniques appropriées et par adsorption de la vapeur d’eau en utilisant un analyseur thermique TG-DSC 111 de Setaram. Des cycles successifs d’hydratation (à 20°C) / déshydratation (à 150°C) ont été effectuésThe energy challenge imposed by exhaustion of fossil fuels and their increasing consumption has favored the emergence of optimal energy management based on the use of alternative resources such as solar energy. The household sector is the main consumer of energy. A large part of this energy is consumed by heating systems. Therefore, good management can be achieved through the use of thermochemical energy storage technology. The main advantage to use this type of system is the possibility to store heat during the maximum availability of solar radiation in summer (dehydration step) and release the energy on demand for heating houses in winter (hydration step). The improvement of the adsorption properties of materials for thermochemical heat storage is the main objective of this work. The use of porous adsorbents such as zeolites in the field of seasonal heat storage is an attractive solution for the reducing of energy consumption. On the other hand, the development of new composite materials based on hydrate salt is made to improve the heat storage capacities of both pure mesoporous host matrix and hydrate salt. A comparison among different series of thermochemical storage materials selected and synthesized was done by analyzing the impact of salt addition and physico-chemical properties of porous materials on the heat storage and water sorption performances. In order to understand the adsorption-desorption behavior, different kinds of materials were characterized in their structural, textural and surface properties by using appropriate techniques and by adsorption of water vapor using a Setaram TG-DSC 111 apparatus. Successive cycles of hydration (at 20°C) / dehydration (at 150 °C) were performe

Thermochemical heat storage capacity of nanoporous molecular sieves: effect of NaOH addition

SSCI-VIDE+ATARI+AAU:SBE:International audienceThe water vapor sorption capacity and corresponding generated heat amount are the most important properties for adsorbents in thermochemical heat storage systems [1,2]. In order to understand the adsorption/desorption behavior of three nanoporous molecular sieves such as 5A, mordenite and natural clinoptilolite (with different structures, Si/Al ratios and balancing cations), the pure zeolites and their composites (containing 5 and 10wt% of NaOH) were characterized in their structural and surface properties by using appropriate techniques (N2 adsorption isotherms at -196°C, and XRD, and (MAS) NMR). The adsorption of water was performed using a Setaram TG-DSC 111 apparatus. Three successive cycles of hydration (at 20°C) / dehydration (at 150 °C) were carried out to check the stability of the system in conditions close to those used in adsorption heat pumps.The measured heats of dehydration vary in the 183-614 kJ kg-1sample range for the various samples that present also different water vapor sorption capacities (from 0.08 to 0.14 kgH2O kg-1sample). The water adsorption/desorption behavior of the zeolites was related to the porous structure and to the Si/Al ratio. These features characterize the affinity of zeolite to water. The experimental results showed that the impregnation of the three kinds of nanoporous zeolites with different amounts of sodium hydroxide affects the sorption characteristics of the composites due to the possible blockage of zeolite pores that limits the access of water molecules.References1.Whiting G, Grondin D, Stosic D, Bennici S, Auroux A. Zeolite-MgCl2 composites as potential long-term heat storage materials: Influence of zeolite properties on heats of water sorption. Solar Energy Materials and Solar Cells 2014; 128: 289-295.2.Jabbari-Hichri A, Bennici S, Auroux A. Water sorption heats on silica-alumina-based composites for interseasonal heat storage. Journal of Thermal Analysis and Calorimetry 2014; 118: 1111-1118.PEquipeDeRecherch

Effect of NaOH addition on the thermochemical heat storage capacity of nanoporous molecular sieves

SSCI-VIDE+ATARI+AJH:AAU:SBEInternational audienceThe water vapor sorption capacity and corresponding generated heat amount are the most important properties for adsorbents in thermochemical heat storage systems. In order to understand the adsorption/desorption behavior of three nanoporous molecular sieves such as 5A, mordenite and natural clinoptilolite (with different structures, Si/Al ratios and balancing cations), the pure zeolites and their composites (obtained by depositing NaOH onto the molecular sieves) were characterized in their structural and surface properties by using appropriate techniques (N-2 adsorption isotherms at -196 degrees C, XRD and (MAS) NMR). The adsorption of water was performed using a Setaram TG-DSC 111 apparatus. Three successive cycles of hydration (at 20 degrees C)/dehydration (at 150 degrees C) were carried out to check the stability of the system in conditions close to those used in adsorption heat pumps. The measured heats of dehydration vary in the 183-614kJkg(sample)(-1) range for the various samples that present also different water vapor sorption capacities (from approximate to 0.08 to approximate to 0.14 kg(H2O) kg(sample)(-1)). The water adsorption/desorption behavior of the zeolites was mainly related to the porous structure and to the Si/Al ratio, that drive the affinity of zeolite to water. The experimental results showed that the impregnation of the three kinds of nanoporous zeolites with different amounts of sodium hydroxide negatively affects the sorption characteristics of the composites. The blockage of zeolite pores (that limits the access to water molecules), the slight amorphization of the zeolite structure and the formation of carbonates are some of the phenomena identified to influence the water sorption onto NaOH-containing composites. Copyright (c) 2016 John Wile

haleur d'adsorption de la vapeur d'eau sur des matériaux solides : application pour la pompe à chaleur

National @ ING+AJH:SBE:AAUInternational audienceLe défit énergétique imposé par l’épuisement des ressources fossiles d’une part, et l’augmentation de la consommation énergétique d’autre part, favorise de plus en plus l’utilisation de ressources propres et intermittentes telles que l’énergie solaire. En particulier, le stockage à sorption de vapeur d’eau par un matériau composite offre une capacité de stockage de chaleur thermique importante à long terme [1] par rapport aux autres technologies de stockage existantes telles que le stockage par chaleurs sensible, latente ou chimique [2]. Le stockage thermochimique (à sorption d’eau), qui se fait habituellement par le biais de composés à base d’une matrice poreuse et d'un sel hygroscopique, se caractérise par une alliance entre la chimisorption et la physisorption.L’objectif de ce travail consiste à élaborer de nouveaux composites qui permettent de libérer de la chaleur tout en se régénérant dans une gamme de température compatible avec la consigne donnée par les capteurs solaires. L’étape la plus difficile dans le développement de ce matériau est le choix de la matrice poreuse qui va être imprégnée par des hydrates salins. La capacité d'adsorption/désorption d’eau et la chaleur générée correspondante sont les propriétés les plus importantes à estimer pour les adsorbants dans les systèmes de stockage thermochimique. Ces propriétés ont été déterminées pour différentes zéolithes commerciales (CLP , 5A , Na -X et HY ) en utilisant un analyseur thermique TG- DSC 111 de Setaram. Des cycles successifs d'hydratation ( à 20°C ) / déshydratation ( à 150°C ) ont été effectués pour vérifier la cyclabilité du système.Il a été montré que les chaleurs d’adsorption/désorption d’eau mesurées pour les différentes zéolithes sont fonction de la quantité totale d’eau sorbée. La chaleur dégagée par kg de matériau augmente dans l'ordre CLP , 5A , Na-X et H-Y ( 402 , 619 , 658 et 703 kJ.kg-1zéolite respectivement) de façon concomitante avec la capacité de sorption de la vapeur d'eau ( 0,09 , 0,15 , 0,18 , 0,22 et kJ.kg-1H2O respectivement ). Ceci peut être attribué aux fortes interactions des molécules d'eau avec les cations compensateurs de charge [3].En conclusion, on constate que les zéolithes 5A, Na-Y et H-Y sont des candidats prometteurs pour les applications de stockage thermique à long terme en raison de leur très forte chaleur d’adsorption à l'exception de la clinoptilolite qui est une zéolithe naturelle avec une faible teneur en Al (SiO2 / Al2O3 = 9,6) et par conséquent un nombre réduit de cations

Effect of aluminum sulfate addition on the thermal storage performance of mesoporous SBA-15 and MCM-41 materials

SSCI-VIDE+ATARI+AJH:SBE:AAUInternational audienc

Contribution to the study of water vapor adsorption by porous materials: heat pump application

SSCI-VIDE+ATARI+AJA:SBE:AAUNational audienceIntroductionThermally driven adsorption processes like heat pumps or cooling applications are important for saving primary energy. The use of porous adsorbents in the field of seasonal heat storage in building is an attractive solution for the reducing of energy consumption as well as improving thermal comfort [1]. In recent years, there has been significant research progress on microporous adsorbent materials for closed/open systems [2]. Thermochemical heat storage (TCS) is based on the reversible chemical and physical sorption of gases, mostly water vapour, in solids. The water adsorption capacity and heat generated are the most important properties for adsorbents in thermochemical heat storage systems. 2Experimental/methodology In order to understand the adsorption-desorption behaviour of different kinds of commercial nanoporous molecular sieves (with different structures, Si/Al ratios and balancing cations), materials were characterised in their structural, textural and surface properties by using appropriate techniques (N2 isotherms and XRD) and by adsorption of water vapour using Setaram TG-DSC 111 apparatus. Successive cycles of hydration (at 20°C) / dehydration (at 150 °C) were performed to check the cyclability of the system. 2Results and discussion The experimental results obtained for zeolites (MOR, CLP, K-L, 3A, 4A, 5A, Na-X, Na-Y, H-Y, Ca-X and Li-X) and zeolite-type materials like SAPO and AlPO are reported. The measured heats of dehydration (kJ.kg-1sample) vary in the 360-950 kJ.kg-1sample range for the different samples those present also different water vapor sorption capacities (from 0.09 kgH2O.kg-1sample to 0.26 kgH2O.kg-1sample). As example the dehydration enthalpy values determined for zeolites type Linde A (3A, 4A and 5A) follow the order: 4A (about 800 kJ.kg-1sample) > 3A (about 660 kJ.kg-1sample) > 5A (about 614 kJ.kg-1sample). This behaviour can be attributed to the strong interactions of water molecules with the electronegativity [3] of charge-balancing cations of the different zeolites and with the pore size. 4Conclusions A relationship between water adsorption behavior on zeolites, the porous structure, the Si/Al ratio, the zeolite framework and the extraframework monovalent cation which showed the strongest affinity to water, has been established. The knowledge of the structural modifications induced by temperature and of the stability field of these materials is of prime importance to ensure their durability and effectiveness for seasonal heat storage applications. Based on the experimental investigations of the different materials, the kinetics of the adsorption and desorption processes was analyzed.Acknowledgements The authors acknowledge the French Ministry of High Education and Research for the PhD-student fellowship allocated to A. Jabbari-Hichri and the scientific services of IRCELYON for their valuable help in the characterization of the samples.References [1] P. Tatsidjodoung, N. Le Pierrès, L. Luo, Renew . Sust. Energ. Rev., 18 (2013) 327-349.[2] N. Yu, R.Z. Wang, L.W. Wang, Prog. Energ. Combust., 39 (2013) 489-514.[3] E.P. Ng, S. Mintova, Micropor. Mesopor. Mat., 114(2008)1-26

Effect of aluminium sulfate on the thermal storage performance of mesoporous SBA-15 and MCM-41 materials

SSCI-VIDE+ATARI+AAUNational audienceNon

thermochemical heat storage in zeolitic materials

SSCI-VIDE+ATARI+SBE:AAUNational audienceThermally driven adsorption processes like heat pumps or cooling applications are important for saving primary energy. The use of porous adsorbents in the field of seasonal heat storage in building is an attractive solution for the reducing of energy consumption as well as improving thermal comfort [1]. In recent years, there have been significant research progresses on microporous adsorbent materials for closed/open systems [2]. Thermochemical heat storage (TCS) is based on the reversible chemical and physical sorption of gases, mostly water vapor, in solid. The water adsorption capacity and heat generated are the most important properties for adsorbents in such TCS system. This study focuses on the determination of sorption capacity and heats of adsorption/desorption of water vapor for different zeolites (MOR, CLP, K-L, 3A, 4A, 5A, Na-X, Na-Y, H-Y, Ca-X and Li-X) and zeolite-type materials like SAPO and AlPO. The measured heats of dehydration (kJ.kg-1) varied in the 360-950 kJ.kg-1 range for the different samples that present also different water vapor sorption capacities (from 0.09 kgH2O. kg-1 to 0.26 kgH2O.kg-1). This behavior can be attributed to the strong interaction of water molecules with the electronegativity of charge-balancing cations of the different zeolites and with the pore size.Relationships between water adsorption in zeolites, the porous structure, the Si/Al ratio, the zeolite framework and the compensating cation have been established. The knowledge of the structural modifications induced by temperature and of the stability of these materials is of prime importance to ensure their durability and effectiveness for seasonal heat storage applications