Exergy Assessment of Recovery Solutions from Dry and Moist Gas Available at Medium Temperature

This article has been published in an open access journal, it's also available at http://www.mdpi.com/1996-1073/5/3/718/pdfThis article belongs to the Special Issue Selected Papers from the 24th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS2011)International audienceThe Agence Nationale de la Recherche (ANR-EESI) ENERGY ReCOvery from Low Temperature heat sources (ENERCO_LT) project is a waste heat recovery project that aims to reduce energy consumption in industrial gas production sites, by producing electrical power from exothermic processes discharges at low and medium temperature. Two promising thermal sources, consisting of: (i) almost dry gas flow at 165 °C and (ii) moist gas flow at 150 °C with a dew point at 60 °C, were then investigated. In this paper, the challenge was to discern suitable recovery solutions facing resource specificities and their thermodynamic constraints, in order to minimize the overall exergy destruction, i.e., to move up the exergy efficiency of the entire system. In this spirit, different designs, including Organic Rankine Cycles (ORCs) and CO2 transcritical cycles, operating as simple and cascade cycles, were investigated. Combined exergy analysis and pinch optimization was performed to identify the potential of various working fluids, by their properties, to overcome the global irreversibility according to the studied resource. Supercritical parameters of various working fluids are investigated too, and seem to bring promising results regarding system performances

Geometry optimization of a heat storage system for concentrated solar power plants (CSP)

In the present study, geometry optimization of a phase change material (PCM) heat storage system is presented. The existing PCM-fins heat exchanger system works at the back side of a solar receiver in order to minimize the effect of the solar radiation fluctuations inside the cavity. As initially designed, the system does not accomplish the expected design purposes and thus optimization is needed. Optimization is usually time-consuming and some algorithms need a starting point, therefore one suitable method is geometrical optimization which aims to find the optimal shape of a system for a given criteria and providing a rough optimal geometry. Here, constructal theory, 'point to volume', is applied to find the optimum shape factor of the elemental volume of the presented PCM-heat exchanger. With this methodology, an optimum ratio of the PCM and fin width and length is found and beyond that the method is extended to 'surface to volume' problem. Results have been numerically validated using a CFD software and demonstrate that it gives a very good approximation of the real optimum which can be used as initial configuration for further optimization through CFD simulation or other optimization methods that require a starting point.The author Aran Solé would like to thank the Societat Economica Barcelonesa Amics del Pais (SEBAP) for the funds that made possible her research stay. The authors would like to thank Jean-Marie Mancaux for his help and Jinqiu Shen for her contribution in the work. The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREA (2014 SGR 123). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). Aran Solé would like to thank Ministerio de Economía y Competitividad de España for Grant Juan de la Cierva, FJCI-2015-440 25741

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

A limit result for a system of particles in random environment

We consider an infinite system of particles in one dimension, each particle performs independant Sinai's random walk in random environment. Considering an instant $t$, large enough, we prove a result in probability showing that the particles are trapped in the neighborhood of well defined points of the lattice depending on the random environment the time $t$ and the starting point of the particles.Comment: 11 page

Family firms types based on beliefs

The purpose of this study was to find an effective way of identifying homogeneous family firm groups, based on the prevailing beliefs of the owning family on ownership, management and intergenerational transmission. We conducted a two-stage cluster analysis, using data from a representative sample of 240 Spanish family firms. The results showed three types of clearly differentiated family firms, each of them with a profile of different beliefs. Our work contributes to the previous literature by integrating the components of involvement and essence approaches and beliefs about these to distinguish homogeneous groups of family firms

Epidémiologie de la toxicomanie dans le canton de Vaud et évaluation des nouveaux projets financés par le canton de Vaud: deuxième phase d'évaluation 1998-2000

[Table des matières] 1. Résumé du rapport. 1.1. Augmenter la prise en charge et la rétention des consommateurs de drogues. 1. 2. Contribuer à la réduction du nombre de consommateurs dépendants. 1.3. Renforcer les activités de prévention primaire et secondaire. 1.4. Recommandations. 1.5. Bilan épidémiologique. 2. Evaluation des centres de traitement ambulatoire et des centres d'accueil, des centres résidentiels : historique, objectifs, fréquentation de la structure, profil des usagers lors de leur admission, activités de la structure, types de prise en charge, collaborations et issue de la prise en charge, enjeux et recommandations. 2.1. Centre St-Martin (CSM) : Centre d'accueil, d'orientation et de traitement. 2.2. Unité ambulatoire spécialisée pour toxicodépendants (UAS). 3.1. Entrée de secours (EdS) : centre d'accueil pour la région Morges-Aubonne. 3.2. Zone Bleue (ZB) : centre d'accueil et de prévention pour toxicomanes à Yverdon. 4. Unité de sevrage : le Calypso. 5. Travail de proximité : travail éducatif de proximité de la Riviera (ACT), Morges-Aubonne (PMA), Aigle/Pays d'Enhaut (APE). 6. Autres projets. 6.1. Le Parachute. 6.2. Trampoline. 6.3. La Mallette. 6. 4. JV Vaud. 6.5. Fleur de Pavé. 7. Les autres recherches. 7.1. Contribution exploratoire à l'évaluation du travail socio-éducatif. 7.2. Exploration de la faisabilité d'une étude "capture-recapture" pour estimer le nombre de consommateurs de drogues dans le canton. 8. Epidémiologie de la toxicomanie dans le canton de Vaud. 8.1. Consommation de drogues illégales. 8.2. Consommation de drogues illégales chez les adolescents de 15 ans. 8.3. Evolution de la consommation de drogues illégales dans la population âgée de 17 à 45 ans. 8.4. Indicateurs de décès, de répression, de traitement. 8.5. Traitements de substitution. 8.6. OPALE, la statistique des institutions psychiatriques vaudoises. 8.7. Enquête nationale des centres à bas seuil UEPP 1993, 1996, 2000. 8.8. Données sur le nombre de seringues mises à disposition dans le canton de Vaud. 8.9. Données sur le VIH et les hépatites pour la Suisse et le canton de Vaud. 8.10. Les consommateurs de drogue dans le système carcéral vaudois

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

Slitless spectrophotometry with forward modelling: principles and application to atmospheric transmission measurement

In the next decade, many optical surveys will aim to tackle the question of dark energy nature, measuring its equation of state parameter at the permil level. This requires trusting the photometric calibration of the survey with a precision never reached so far, controlling many sources of systematic uncertainties. The measurement of the on-site atmospheric transmission for each exposure, or on average for each season or for the full survey, can help reach the permil precision for magnitudes. This work aims at proving the ability to use slitless spectroscopy for standard star spectrophotometry and its use to monitor on-site atmospheric transmission as needed, for example, by the Vera C. Rubin Observatory Legacy Survey of Space and Time supernova cosmology program. We fully deal with the case of a disperser in the filter wheel, which is the configuration chosen in the Rubin Auxiliary Telescope. The theoretical basis of slitless spectrophotometry is at the heart of our forward model approach to extract spectroscopic information from slitless data. We developed a publicly available software called Spectractor (https://github.com/LSSTDESC/Spectractor) that implements each ingredient of the model and finally performs a fit of a spectrogram model directly on image data to get the spectrum. We show on simulations that our model allows us to understand the structure of spectrophotometric exposures. We also demonstrate its use on real data, solving specific issues and illustrating how our procedure allows the improvement of the model describing the data. Finally, we discuss how this approach can be used to directly extract atmospheric transmission parameters from data and thus provide the base for on-site atmosphere monitoring. We show the efficiency of the procedure on simulations and test it on the limited data set available.Comment: 30 pages, 36 figures, submitted to Astronomy and Astrophysic

Prolonged increase of corticosterone secretion by chronic social stress does not necessarily impair immune functions

The influence of a chronic social stress upon immunity was investigated in Wistar rats, submitted for four weeks to two different behavioral situations, balanced in a factorial design: housing with three females and membership rotation. The combination of these two factor led to adrenal enlargement (43.3%), thymus involution (39.5%) and increased basal corticosterone levels, all indices of activation of the hypothalamic-hypophysis-adrenal axis. However, neither natural killer cell activity, splenocyte reactivity to mitogen nor the rate of spontaneous development of antibodies against Mycoplasma pulmonis, a common pathogen of the respiratory tract, were changed in the endocrine activated animals. Analysis of the data on kinetics of stress at 1, 7 and 28 days after the initial mixing of the animals gave the same results. These data question the immunosuppressant activity usually conferred to corticosteroids, at least when adrenal hyperactivity is induced by chronic environmental stressors