1,721,456 research outputs found
Energie rinnovabili: classificazione e caratteristiche
No full textLe fonti rinnovabili rappresentano una via interessante alla produzione di energia ma devono essere valutate in base a precisi indicatori che permettano di definire il loro sfruttamento e la loro convenienza economica. Vengono di seguito elencate le varie forme di energie rinnovabili e per ciascuna di esse viene fornita una valutazione quantitativa nell’ottica di delineare una classificazione generale di ciascuna fonte
Generatori di Vapore a Tubi Elicoidali per Reattori Nucleari Innovativi
No full textNell’ambito degli studi per i reattori nucleari di nuova generazione, il generatore di vapore riveste una importanza fondamentale, anche alla luce delle performance di questi componenti nel recente passato, non sempre ottimali.
In alcuni progetti di nuovi reattori i modelli di generatore di vapore tradizionali sono sostituiti da quelli a singolo attraversamento forzato (once- through), spesso con l’impiego di tubi elicoidali.
Le problematiche di sviluppo, in particolare quelle termoidrauliche, termomeccaniche e di dinamica, sono qui sinteticamente trattate
Produzione di energia elettrica e sviluppo sostenibile
No full textIl prezzo dell’energia elettrica prodotta tramite le diverse fonti dovrebbe essere quantificato lungo l’intera catena produttiva per tenere conto dell’impatto che esse producono sia sull’ambiente che sulla salute umana. Una valutazione di questi aspetti permette di definire in modo coerente il concetto di sviluppo sostenibile
A Critical Overview of Heat Transfer Phenomena through Different Solutions of In-Pool Condensers for Passive Safety Systems
No full text
Optimal implementation of dagger sampling variance-reducing techniques in Monte Carlo reliability analysis
No full textNeutron and/or Photon Response of a TLD-Albedo Personal Dosimeter on an ISO Slab Phantom
No full textBologna, Ital
Investigation on a Double-Pass Tubular Absorber for Application in Solar Towers
No full textThe present study combines the concept of double-pass flows with high-temperature solar receivers, introducing a novel design to reduce heat losses and increase performance. A tubular absorber from the billboard solar tower systems was used to develop the new double-pass (DP) design, working with air as the heat transfer fluid. To assess the effectiveness of such a system, a numerical study was performed using CFD analysis with Star CCM+ commercial software. Several simulations were made based on the thermal models, validated with real data obtained from a solar furnace tested during an experimental campaign in June 2022. The thermo-hydraulic characteristics were analyzed for various solar peak fluxes (50, 100, and 200 kW/m2) and air mass flow rates (30, 40, 50 L/min) to provide a comprehensive comparison between the single pass (SP) and DP absorbers. The computed numerical results suggested that using the DP design instead of SP absorbers under all the test conditions, the average energy and exergy efficiency enhancement are 35% and 55%, respectively, while the pressure drop increases with an average of 62%. As a result, the DP design can be used as an alternative for future solar tower designs, bringing higher heat removal efficiency in air-based solar systems
Gas transfer model to design a ventilator for neonatal total liquid ventilation
Full text linkThe study was aimed to optimize the gas transfer in an innovative ventilator for neonatal Total Liquid Ventilation (TLV) that integrates the pumping and oxygenation functions in a non-volumetric pulsatile device made of parallel flat silicone membranes. A computational approach was adopted to evaluate oxygen (O2) and carbon dioxide (CO2) exchanges between the liquid perfluorocarbon (PFC) and the oxygenating gas, as a function of the geometrical parameter of the device. A 2D semi-empirical model was implemented to this purpose using Comsol Multiphysics to study both the fluid dynamics and the gas exchange in the ventilator. Experimental gas exchanges measured with a preliminary prototype were compared to the simulation outcomes to prove the model reliability. Different device configurations were modeled to identify the optimal design able to guarantee the desired gas transfer. Good agreement between experimental and simulation outcomes was obtained, validating the model. The optimal configuration, able to achieve the desired gas exchange (ΔpCO2 = 16.5 mmHg and ΔpO2 = 69 mmHg), is a device comprising 40 modules, 300 mm in length (total exchange area = 2.28 m(2)). With this configuration gas transfer performance is satisfactory for all the simulated settings, proving good adaptability of the device
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