1,721,141 research outputs found
Larianimazione cardio-polmonare nei piccoli animali, moderni orientamenti di terapia
No full textVengono descritte le cause, la diagnosi e la terapia dell'arresto cardio-pomonare nei piccoli animali, con particolare attenzione alla sequenza delle manovre di supporto alle funzioni vitali ed ai dosaggi dei farmaci della rianimazion
Correlations to evaluate subcooled flow boiling critical heat flux in fusion reactor components
No full textSu di un caso di emopericardio osservato nel cane
No full textViene descritto un caso di emopericardio in un cane, la diagnosi clinica e radiologica, la terapia medica e la pericardiocentesi
Studio teorico e campagna sperimentale finalizzati ad incrementare le prestazioni di scambiatori di calore in acqua stagnante in ebollizione a bassi flussi termici
No full textStudi analitici e sperimentali sull’ebollizione in piscina a bassi flussi termici, in corrispondenza di superfici inclinate, sono stati condotti nel passato da alcuni autori, ma la comprensione dei complessi fenomeni termofluidodinamici connessi è ancora lontana dall’essere pienamente raggiunta. Il presente lavoro, oltre che riportare sommariamente lo stato dell’arte teorico e sperimentale sulla problematica in questione, riporta i risultati del lavoro svolto per definire una procedura di ottimizzazione del progetto di scambiatori di calore immersi in piscina, nonchè una campagna sperimentale finalizzata alla verifica di detta procedura. La attività sperimentale sarà svolta utilizzando un circuito sperimentale, in fase di allestimento presso il Dipartimento di Ingegneria Nucleare e Conversioni di Energia dell’Università di Roma “La Sapienza”, nell’ambito del programma di ricerca POOLTHY (Pool Thermal-Hydraulics in Passive Heat Removal Systems) della Comunità Europea. L’attività comprende, tra l’altro, lo studio degli aspetti fluidodinamici (transitorio di avviamento, stabilità) legati all’innesco della circolazione naturale nel circuito di trasferimento del calore in piscina, aspetto particolarmente importante nelle applicazioni in cui si ha necessità di caratterizzare il sistema di scambio termico come passivo
Condensation inside tubes in the presence of high non-condensable concentrations and in transient conditions
No full textThe general aim of the separate-effects test program COTINCO is to investigate basic physical phenomena involved in nuclear power plant containment thermal-hydraulics.
The main objectives of the COTINCO experiment are:
• to investigate physical phenomena involved in condensation of steam inside tubes;
• to study the possibility of improving condensation heat transfer even with high concentration of non-condensable (the whole range of gas concentration, from 0 to 100 %, will be examined);
• to study the influence of geometry (namely, the tube axis slope) on the heat transfer rate, in presence of high concentration of non-condensable;
• to study the effectiveness of devices for venting the condensation tubes;
• to develop models and heat transfer correlations for the given conditions;
• to produce a data base for modelling condensation with high percentage of non-condensable.
The COTINCO test facility consists of a single tube test section with a variable lay-out, crossed internally by steam and air and in communication with external atmosphere, and externally cooled by water. In the paper, the main characteristics of the experimental facility are described, and the experimental test matrix is discussed
An experimental loop to study natural circulation and pool boiling in transient conditions, with an immersed heat exchanger with inclined tubes
No full textIn the framework of the European research program POOLTHY (Pool Thermal-Hydraulics in Passive Heat Removal Systems), the Department of Nuclear Engineering and Energy Conversion (DINCE) of the University of Rome “La Sapienza” provides a theoretical and experimental contribution to analyze thermal-hydraulic aspects of heat removal through boiling in pools, of relevance for passive-type heat removal systems. This contribution includes the study, the design and the construction of an experimental facility (QUSCOCS) and the implementation of an experimental campaign. In particular, the heat removal system foreseen in the MARS nuclear plant (designed by DINCE) has been adopted as reference system for the design of the QUSCOCS test section. The experimental facility will be utilized to optimize the full-scale design of the MARS passive-type decay heat removal system, and to obtain reliable experimental data related to natural circulation in transient conditions
Requirements of high heat flux for fusion reactors components. Revised models and correlations to predict critical heat flux in subcooled flow boiling
No full textThe present paper provide an analysis of available experimental data on critical heat flux (CHF) of subcooled flow boiling in water, in the ranges of interest of fusion reactors thermal-hydraulic conditions, i.e. high inlet subcooling and velocity, and small channel diameter and lenght. The aim of the study was to identify a new correlation based on a structure representing the relation of heat balance and using a non-linear regression analysis of the available data-set. The reference data-set covers a wide range of operating conditions in the frame of present interest (0.1 < p < 5.5 MPa; 0.3 < D < 15 mm; 10 < L < 30 cm; 2000 < G < 40000 kg/m2ùs; 90 < DTsub,i < 230 K).
In a previous study several correlations were analysed with a reduced data-set respect the present one, and others correlations were recently analyzed by Celata et al., Nariai et al. and Caira et al. Three correlations for critical heat flux, providing a consistent prediction of most of the data-set, were selected, namely Macbeth, Macbeth-Thompson and Gunther correlations.
A new correlation, based on the same structure of above and providing a sensible improvement in predictions (an RMS of 15.8% on the entire data-set of 544 points was obtained) was identified and analyzed with respect to various parameters influencing the CHF phenomenon
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