Thermodynamic analyses on hybrid sorption cycles for low-grade heat storage and cogeneration of power and refrigeration

International audienceThis paper investigates three ways of coupling a solid/gas sorption refrigeration cycle with a Rankine cycle to create innovative hybrid cycles enabling power and refrigeration cogeneration with intrinsic energy storage. A new methodology has been developed to analyze these hybrid cycles and assess five relevant performance criteria (required heat source temperature, energy efficiency, exergy efficiency, power production ratio, and exergy storage density). Screening of 103 reactive salts implemented in the different hybrid cycle configurations highlights the most favorable configuration and reagent to meet the requirements of various applications. Analyses show that energy and exergy efficiencies can reach 0.61 and 0.40, respectively. Exergy storage density ranges from 142 to 640 kJ/kg NH3 when the heat source temperature is increased from 107 °C to 250 °C

Hybrid thermochemical cycles for low-grade heat storage and conversion into cold and / or power

International audienceIn order to recover low grade heat (available at temperatures under 250 °C) provided for instance by an industrial plant or solar energy, innovative thermodynamic cycles are investigated. These cycles are based on the hybridization of a solid/gas chemical sorption cycle (thermochemical cycle) with a power cycle (Organic Rankine Cycle (ORC)), they enable converting a low grade heat input into cold and / or power while providing an intrinsic energy storage feature. Four hybrid configurations are considered, a thermodynamic analysis allows comparing their performances with those of existing ORC through several criteria: energy and exergy efficiencies, specific exergy output and power production ratio. For each of the five systems, potential applications, advantages and weaknesses are summarized

Microstructure Evolution in an Aluminum Cladded Sheet during Vacuum Brazing

Microstructure evolution of a 3003 sheet cladded with 4004 brazing alloy is investigated during slow heating (1K/min) under secondary vacuum up to isothermal brazing temperature (590°C). Optical and scanning microscopies, EDS chemical analysis and EBSD orientation mapping are used. Experimental results are discussed in the light of thermodynamic calculations using Thermo-Calc. Comparisons show good agreement as long as Mg vaporization does not take place

Hybrid system combining mechanical compression and thermochemical storage of ammonia vapor for cold production

International audienceThis paper studies a hybrid system for cold production consisting of a compression cycle combined with a thermochemical process 10 by sharing the same condenser, evaporator and refrigerant fluid. The aim of this hybridization is to solve mismatch issues between 11 the demand of cold and the source of energy (availability and/or price) with a system as compact as possible. One important side 12 benefit is that the interaction between the compressor and the thermochemical reactor reduces the activation temperature for 13 ammonia desorption in the thermochemical reactor. To study this interaction a quasi-steady simulation model for both storage 14 and de-storage phases has been developed and experimentally validated by means of a small scale (approx. 300 Wh of cold 15 storage) experimental bench with ammonia as refrigerant and barium chloride (BaCl2) as reactant salt. Experiments proved a 35 16 K reduction in the activation temperature of the desorption reaction with respect to desorption without compressor. Model 17 validation by adjusting permeability and thermal conductivity of the reactive composite showed an acceptable agreement between 18 predicted and experimental reaction advancement-time curves. The validated model was used for simulation of the system in a 19 preliminary case study, representative in power (40 kW) and temperature (-25°C) of an industrial cold demand. It is shown that 20 during ammonia de-storage, the hybrid achieves a higher COP than a conventional mechanical vapor compression system. It 21 increases exponentially with the relative share of thermochemical storage in the cold production. 2

Simulation of a solar hybrid absorption/thermochemical refrigerationsystem for a residential application

Further improvement of solar refrigeration systems depends strongly on development of more efficient energy storage systems. A hybrid absorption / thermochemical refrigeration system is proposed in this work, where both subsystems share the same condenser, evaporator and refrigerant fluid, making the overall system more economic and better performing than operating both parts separately. Performance of the system is evaluated by means of a simulation in a sample scenario, consisting of a demand of refrigeration for a single-family residence. The influence of varying the number of solar thermal collectors and the mass of refrigerant fluid available for storage at the thermochemical subsystem is studied

Analyse comparative de cycles hybrides innovants impliquant des procédés à sorption, pour le stockage d'énergie thermique, la production de froid et/ou de travail mécanique

National audienc

Stockage thermochimique inter saisonnier : caractérisation des transferts de masse au sein d'un sel réactif

National audienceCet article présente la caractérisation des transferts de masse au sein d'un sel réactif (cinétique de réaction, perméabilité du lit de sel, …) destiné au stockage thermochimique inter saisonnier, dans le but d'optimiser à la fois la densité énergétique du lit de sel et sa perméabilité (caractéristiques qui ont des évolutions antagonistes). Un modèle et une expérimentation ont donc été réalisées autour du couple SrBr 2 /H 2 O et leurs résultats ont été comparés

Reading and spelling impairments in children and adolescents with infantile myotonic dystrophy

Abstract This study investigated reading and spelling difficulties in subjects with the juvenile form of myotonic dystrophy (MD). Twenty-three consecutive patients with juvenile MD who were referred to a special clinic were assessed for reading and spelling skills (phonological processing, word identification, narrative comprehension (two tasks), information seeking in a document (TV schedule), and spelling). Reading impairments were frequent (63-84% of the subjects being below the level of literacy depending on the tasks), even in subjects without mental retardation (22-66%) despite normal word identification scores. All but two subjects had spelling difficulties. The severity of these learning difficulties was correlated with longer mutation size and maternal transmission, but could not be related to phonological deficit, suggesting that other brain dysfunction might be involved (e.g., attention, working memory, naming speed, executive function). Children with the juvenile form of MD should systematically be assessed for reading and spelling problems, and correlations with basic cognitive functioning explored.

Reponse d'un reacteur solide-gaz soumis a des contraintes de pression et temperature : couplage entre vitesse de reaction et transferts. Application a la pompe a chaleur chimique

CNRS T 56538 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Procédé à sorption solide/gaz pour le transport de chaleur et de froid à longue distance

Networks of thermal energy transportation are classically based on sensible heat transport and thus they are limited to short distances. In order to realize a long-distance transport, thermochemical processes are investigated, and particularly an innovating system that couples two thermochemical dipoles. The advantages of thermochemical processes, the energetic performances and the operating cost of transport are presented. A comparison with sensible heat network is also done.An experimental study of this innovating system is also made in order to understand the main point of the system: autothermal reactorLe transport de froid ou de chaleur sur longues distances constitue un enjeu majeur d un point de vue énergétique, économique (valorisation de rejets thermiques) et environnemental (diminution des émissions de CO2). Jusqu à présent, le transport d énergie est basé sur la chaleur sensible (eau chaude) ou latente (vapeur). En raison de leurs importantes déperditions thermiques, ces réseaux se limitent aux réseaux urbains (<10km). D autres systèmes, basés sur des processus endo/exothermiques, permettent un transport d énergie à plus longue distance. Notre étude s intéresse en particulier aux procédés thermochimiques utilisant des réactions chimiques renversables solide/gaz : le fluide transporté est du gaz à température ambiante.La première partie du manuscrit décrit les potentialités des procédés thermochimiques : températures de fonctionnement et rendements énergétiques. La partie du procédé relative au transport, est étudiée pour comprendre la gestion et de l impact du transport du fluide sur les performances du procédé. Une comparaison avec les réseaux de chaleur sensible est également réalisée. La deuxième partie s intéresse au couplage de deux procédés thermochimiques en cascade thermique. Ce nouveau procédé présente des performances idéales, énergétiques et températures de fonctionnement, supérieures à celles des procédés classiques. Ce système innovant met en jeu un nouveau réacteur : réacteur autotherme. L analyse théorique du fonctionnement cyclique et énergétique de ce réacteur est décrite. Une étude expérimentale est réalisée : la conception, la construction du prototype et les résultats expérimentaux sont détailléesPERPIGNAN-BU Sciences (661362101) / SudocSudocFranceF