291 research outputs found
Experimental Validation of the Innovative Thermal Energy Storage Based on an Integrated System "Storage Tank/Steam Generator"
Abstract In the past years, an innovative thermal energy storage system at high temperature (up to 550C) for CSP plants was proposed by ENEA and Ansaldo Nucleare: a single storage tank integrated with a steam generator immersed in the heat storage medium. The idea is based on the exploitation of the thermophysical characteristics of the heat storage medium (a binary mixture of salts of NaNO3 at 60% and KNO3 at 40%) in order to maintain over time, in the single tank, a thermal stratification of the fluid. The thermal stratification is able to trigger, in the immersed steam generator, the natural circulation, shell side and downwards, of the hot molten salt cooled down by the water that flows upwards tube side, thus heating up and producing superheated steam. The advantages of such a system are: - efficient performances; - simple implementation; - compactness: - modularity; - and, overall, contained costs: only one storage tank instead of the two tanks and only one heat exchanger instead of the three exchangers of the classic configuration; reduced quantity of salt; minimization of piping, valves and other components. The technical feasibility of the proposed system, together with the stability over time of the stratification in temperature of the storage medium, have been already verified and assessed. This report has the aim of presenting the experimental results obtained by ENEA in the Casaccia Research Centre (Rome, Italy), with a small scale test section consisting of a 300 kWth steam generator inserted in a 8 m3 storage tank with molten salt at high temperature. The reported results relate to the behaviour of the system in steady state conditions, and show its promising performances
An innovative concept of a thermal energy storage system based on a single tank configuration using stratifying molten salts as both heat storage medium and heat transfer fluid, and with an integrated steam generator
Abstract The proposed innovative thermal energy storage system is based on a single tank containing a mixture of nitrate salts (60% NaNO3 and 40% KNO3 in weight; this mixture gradually changes from solid to liquid in the temperature range between about 220 °C and 240 °C, becoming completely melted above this temperature), with an integrated steam generator directly contained inside it. The system is operated exploiting the thermal stratification of the salts mixture in the temperature range between 550 °C (hot temperature) and 290 °C (cold temperature). The experimental work conducted at ENEA has revealed that the thermal stratification of the molten salts mixture can be maintained quite constant for several hours and the presence of the integrated steam generator actively guarantees and maintains the stratification during the operation time, avoiding mixing of the stratified layers. The single-tank system with stratification of the molten salts and an integrated steam generator is an important improvement in terms of efficiency, reliability and cost reduction, with respect to the two-tank thermal energy storage system. This report has the aim of giving an overview of this new technology but, given the fact that the experimental activities are still ongoing, the description of the system remains at a qualitative level. The complete set of experimental results will be presented in the future when the Projects that are framework of this research will have been completed
CFD Model of a Molten Salt Tank with Integrated Steam Generator
Abstract For each solar technology the dispatchable CSP plant scheme that maximizes the solar to electrical energy conversion and minimizes the costs associated to such transformation is searched. In recent years double tank TES systems are evolving towards more simple configurations of a single tank [1] , [2] , [3] , also known as thermocline tank TES systems and, even going beyond, there are already thermocline tanks in process of development where the steam generator (SG) is integrated into the storage tank (European project OPTS). A prototype with integrated SG has been erected for testing purpose in the Casaccia Research Centre of ENEA (Italy) [4] . The model presented in this paper reproduces the experimental data of such prototype using the CFD commercial code STAR-CCM + [5] . Unlike very few published until now [6] . The simulated system account for molten salts behavior, not only for the bulk molten salts, but also for the circulation of the molten salts inside the SG (with three steam coils). The molten salts move by induced natural convection and the steam temperatures and pressures are up to ∼500° C/40 bar. Temperature gauges situated in the bulk and the molten salts mass flow inside the SG are the main variables considered for validating the model. From the numerical point of view is a transient simulation and the model is 2D-axisymmetric. The required features of the system mesh and the physical models used are presented in this work
Double ionization of helium by proton impact: A generalized-Sturmian approach
We present ab initio calculations for the double ionization of helium by fast proton impact, using the generalized-Sturmian-functions methodology and within a perturbative treatment of the projectile-target interaction. The cross-section information is extracted from the asymptotic behavior of the numerical three-body function that describes the emission process. Our goal is to provide benchmark first-order Born fully differential cross sections with which one may investigate the suitability of transition matrices calculated using approximate analytic-type solutions for the double continuum (the choice of effective charges or effective momenta to partially account for the internal target interactions being, to some extent, arbitrary). We also provide fully differential cross sections for the low-ejection-energy regime, which is beyond the suitable range of such perturbative methods. We find, however, that the effective momentum approach allows one to get at least a rough characterization of the most dominant physical process involved. We also compare our calculations with the only available relative experimental set, showing an agreement in shape that can be well understood within the given momentum transfer regime.Fil: Ambrosio, Marcelo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio(i); ArgentinaFil: Mitnik, Dario Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio(i); ArgentinaFil: Ancarani, L. U.. Université de Lorraine; Francia. Centre National de la Recherche Scientifique; FranciaFil: Gasaneo, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Gaggioli, Enzo Leopoldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentin
Riesgos asociados al transporte de mercancias peligrosas: el caso de los líquidos inflamables y sustancias corrosivas
La logística aplicada al transporte de carga resulta un factor de relevancia a la hora de evaluar los distintos procesos y requerimientos a los que debe someterse la mercancía. Dichos procesos se agudizan en función de la complejidad y características específicas que posee el producto a transportar, debiéndose considerar la totalidad de la cadena económica del bien.
El objetivo del presente trabajo es presentar una discusión sobre las realidades del transporte multimodal de mercancías peligrosas en Argentina desde su origen hasta la carga en las aeronaves y presentar el caso específico del transporte de Líquidos Inflamables (ONU 3) y Sustancias Corrosivas (ONU 8).
En ese sentido, y si bien existe un marco de referencia que reglamenta los procesos y la logística para el transporte multimodal de este tipo de carga, se presentarán una serie de casos reales que demuestran la complejidad de los procesos y externalidades negativas frecuentemente inciden sobre el producto o embalaje, restándole efectividad o dejándolo inutilizable.
Los resultados obtenidos indican que, si bien la reglamentación de aplicación es compleja y abarca un amplio espectro de los procesos, aún faltan cuestiones a ser consideradas y reanalizadas para lograr la optimización del transporte de mercancías peligrosas.Facultad de Ingenierí
Riesgos asociados al transporte de mercancias peligrosas: el caso de los líquidos inflamables y sustancias corrosivas
La logística aplicada al transporte de carga resulta un factor de relevancia a la hora de evaluar los distintos procesos y requerimientos a los que debe someterse la mercancía. Dichos procesos se agudizan en función de la complejidad y características específicas que posee el producto a transportar, debiéndose considerar la totalidad de la cadena económica del bien.
El objetivo del presente trabajo es presentar una discusión sobre las realidades del transporte multimodal de mercancías peligrosas en Argentina desde su origen hasta la carga en las aeronaves y presentar el caso específico del transporte de Líquidos Inflamables (ONU 3) y Sustancias Corrosivas (ONU 8).
En ese sentido, y si bien existe un marco de referencia que reglamenta los procesos y la logística para el transporte multimodal de este tipo de carga, se presentarán una serie de casos reales que demuestran la complejidad de los procesos y externalidades negativas frecuentemente inciden sobre el producto o embalaje, restándole efectividad o dejándolo inutilizable.
Los resultados obtenidos indican que, si bien la reglamentación de aplicación es compleja y abarca un amplio espectro de los procesos, aún faltan cuestiones a ser consideradas y reanalizadas para lograr la optimización del transporte de mercancías peligrosas.Facultad de Ingenierí
Riesgos asociados al transporte de mercancias peligrosas: el caso de los líquidos inflamables y sustancias corrosivas
La logística aplicada al transporte de carga resulta un factor de relevancia a la hora de evaluar los distintos procesos y requerimientos a los que debe someterse la mercancía. Dichos procesos se agudizan en función de la complejidad y características específicas que posee el producto a transportar, debiéndose considerar la totalidad de la cadena económica del bien.
El objetivo del presente trabajo es presentar una discusión sobre las realidades del transporte multimodal de mercancías peligrosas en Argentina desde su origen hasta la carga en las aeronaves y presentar el caso específico del transporte de Líquidos Inflamables (ONU 3) y Sustancias Corrosivas (ONU 8).
En ese sentido, y si bien existe un marco de referencia que reglamenta los procesos y la logística para el transporte multimodal de este tipo de carga, se presentarán una serie de casos reales que demuestran la complejidad de los procesos y externalidades negativas frecuentemente inciden sobre el producto o embalaje, restándole efectividad o dejándolo inutilizable.
Los resultados obtenidos indican que, si bien la reglamentación de aplicación es compleja y abarca un amplio espectro de los procesos, aún faltan cuestiones a ser consideradas y reanalizadas para lograr la optimización del transporte de mercancías peligrosas.Facultad de Ingenierí
Autophagy prevents early proinflammatory responses and neutrophil recruitment during Mycobacterium tuberculosis infection without affecting pathogen burden in macrophages
The immune response to Mycobacterium tuberculosis infection determines tuberculosis disease outcomes, yet we have an incomplete understanding of what immune factors contribute to a protective immune response. Neutrophilic inflammation has been associated with poor disease prognosis in humans and in animal models during M. tuberculosis infection and, therefore, must be tightly regulated. ATG5 is an essential autophagy protein that is required in innate immune cells to control neutrophil-dominated inflammation and promote survival during M. tuberculosis infection; however, the mechanistic basis for how ATG5 regulates neutrophil recruitment is unknown. To interrogate what innate immune cells require ATG5 to control neutrophil recruitment during M. tuberculosis infection, we used different mouse strains that conditionally delete Atg5 in specific cell types. We found that ATG5 is required in CD11c+ cells (lung macrophages and dendritic cells) to control the production of proinflammatory cytokines and chemokines during M. tuberculosis infection, which would otherwise promote neutrophil recruitment. This role for ATG5 is autophagy dependent, but independent of mitophagy, LC3-associated phagocytosis, and inflammasome activation, which are the most well-characterized ways that autophagy proteins regulate inflammation. In addition to the increased proinflammatory cytokine production from macrophages during M. tuberculosis infection, loss of ATG5 in innate immune cells also results in an early induction of TH17 responses. Despite prior published in vitro cell culture experiments supporting a role for autophagy in controlling M. tuberculosis replication in macrophages, the effects of autophagy on inflammatory responses occur without changes in M. tuberculosis burden in macrophages. These findings reveal new roles for autophagy proteins in lung resident macrophages and dendritic cells that are required to suppress inflammatory responses that are associated with poor control of M. tuberculosis infection
Sleep dysfunctions influence decision making in undemented Parkinson's disease patients: a study in a virtual supermarket
In the early-middle stages of Parkinson's disease (PD), polysomnographic studies show early alterations of the structure of the sleep, which may explain frequent symptoms reported by patients, such as daytime drowsiness, loss of attention and concentration, feeling of tiredness. The aim of this study was to verify if there is a correlation between the sleep dysfunction and decision making ability. We used a Virtual Reality version of the Multiple Errand Test (VMET), developed using the NeuroVR free software (http://www.neurovr2.org), to evaluate decision-making ability in 12 PD not-demented patients and 14 controls. Five of our not-demented 12 PD patients showed abnormalities in the polysomnographic recordings associated to significant differences in the VMET performance
Identification of 4-amino-thieno[2,3-d]pyrimidines as QcrB inhibitors in Mycobacterium tuberculosis
Antibiotic resistance is a global crisis that threatens our ability to treat bacterial infections, such as tuberculosis, caused b
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