1,721,175 research outputs found
Modello analogico per la determinazione delle procedure operative di un evaporatore concentratore semicontinuo
No full text
On the effects of leakages in Sliding Rotary Vane Expanders
Full text linkRotary Vane Expanders (RVE) are very suitable prime movers for ORC-based power units in on-the-road transportation sector. RVEs suffer volumetric efficiency deficits due to leakages which limit the overall expander efficiency and can vanish their intrinsic benefits with respect to the other prime movers. Making reference to a 2 kW Sliding RVE type (SRVE), the paper presents a theoretical and experimental contribution which goes deep into the effect of leakages inside the machine and aims to quantify their amount and effects on the expander performances. The results showed that the volumetric losses increase the mass flow rate aspirated by the machine if the intake pressure is kept constant. This increase favors a greater recovery from the hot source (up to 50%) but part of it bypasses the vanes, producing a volumetric loss. An interesting feature is that part of this additional mass is exchanged among vanes and this produces a beneficial effect on the indicated power (16.6% increase with respect the ideal case). The resulting knowledge further supported the effectiveness of dual intake expander technology which allows to theoretically reduce the leakages between adjacent vane up to 60–70% ensuring an improvement of expander efficiency
Development and experimental assessment of a Low Speed Sliding Rotary Vane Pump for heavy duty engine cooling systems
No full textRilievo e rappresentazione 3D di un sito archeologico nell’ambito del progetto Urban a Trieste
Full text linkLa Soprintendenza per i Beni Ambientali, Architettonici,
Archeologici, Artistici e Storici della Regione Friuli Venezia Giulia sta gestendo dal 2000, nell’ambito del Programma di Iniziativa
Comunitaria Urban -Progetto Tergeste, diversi scavi, il cui obiettivo generale è quello di acquisire, elaborare ed archiviare i dati relativi al patrimonio storico-archeologico della Città Vecchia di Trieste, al fine di predisporre gli strumenti per la tutela e la valorizzazione di tale patrimonio. Il Dipartimento di Ingegneria Civile dell’Università di Trieste è già stato coinvolto nel 2000 dalla Soprintendenza per un primo rilievo fotogrammetrico di due colonne romane del I sec. a.C.
Nel 2007, assieme al gruppo di Trieste, è stato coinvolto anche il
Laboratorio A.S.T.R.O. della Sede di Topografia e Fotogrammetria del Dipartimento di Ingegneria Civile dell’Università di Pisa, per la
realizzazione di un rilievo dell’area, che nel frattempo ha subito
ulteriori scavi e rinvenimenti, tramite laser a scansione terrestre. Nel presente lavoro vengono descritte le diverse fasi del lavoro di rilievo ed analizzate le diverse modalità con cui è possibile dare una rappresentazione al rilievo stesso. Questa differenziazione dei
prodotti tiene conto soprattutto delle diverse esigenze dei soggetti
che poi devono operare decisioni ed interventi sul bene rilevato. Se il formato digitale per la visualizzazione e la navigazione
tridimensionale risulta idoneo in alcune applicazioni, per altre risulta insoddisfacente e la classica rappresentazione cartacea in forma di tavole a grande scala resta la rappresentazione di maggior praticità. In questi casi, quindi, il rilievo laser è un mezzo per la realizzazione delle immagini ortorettificate, ma la rappresentazione rimane quella tradizionale
Editorial for the Special Issue on “Multidisciplinary Insights on Bone Healing (Volume II)”
Full text linkAs the population ages and differences among sexes and age groups become more pronounced, the research on bone healing and damage mechanisms continues to advance, with evaluation conducted in both pre-clinical and clinical settings [...
Experimental validation of a new modeling for the design optimization of a sliding vane rotary expander operating in an orc-based power unit
Full text linkSliding Rotary Vane Expanders (SVRE) are often employed in Organic Rankine Cycle (ORC)-based power units for Waste Heat Recovery (WHR) in Internal Combustion Engine (ICE) due to their operating flexibility, robustness, and low manufacturing cost. In spite of the interest toward these promising machines, in literature, there is a lack of knowledge referable to the design and the optimization of SVRE: these machines are often rearranged reversing the operational behavior when they operate as compressors, resulting in low efficiencies and difficulty to manage off-design conditions, which are typical in ORC-based power units for WHR in ICE. In this paper, the authors presented a new model of the machine, which, thanks to some specific simplifications, can be used recursively to optimize the design. The model was characterized by a good level of physical representation and also by an acceptable computational time. Despite its simplicity, the model integrated a good capability to reproduce volumetric and mechanical efficiencies. The validation of the model was done using a wide experimental campaign conducted on a 1.5 kW SVRE operated on an ORC-based power unit fed by the exhaust gases of a 3 L supercharged diesel engine. Once validated, a design optimization was run, allowing to find the best solution between two “extreme” designs: a “disk-shaped”—increasing the external diameter of the machine and reducing axial length—and by a “finger-shaped” machine. The predictions of this new model were finally compared with a more complex numerical model, showing good agreement and opening the way to its use as a model-based control tool
Experimentally Based Methodology to Evaluate Fuel Saving and CO2Reduction of Electrical Engine Cooling Pump during Real Driving
No full textEngine thermal management (ETM) is a promising technology that allows the reduction of harmful emissions and fuel consumption when the internal combustion engine (ICE) is started from a cold state. The key technology for ETM is the decoupling of the cooling pump from the crankshaft and the actuation of the pump independently. In this article, an electric engine cooling pump has been designed through a novel experimentally based procedure and operated on a vehicle equipped with an advanced turbocharged gasoline engine, particularly interesting for its hybridization potential. In the first phase, a dedicated experimental campaign was conducted off board on an engine identical to the one equipped in the vehicle to assess the characteristics of the cooling circuit and the reference pump performances. The experimental data have been used to design an electric pump with a best efficiency point (BEP) located in a region more representative of the real operating conditions faced by the vehicle during real driving. Once prototyped, the electric pump has been compared to the reference mechanical one on a real driving mission profile whose parameters have been experimentally evaluated. The comparison was made in the same operating conditions of flow rate and the pressure head acting on the revolution speed of the prototype to focus the attention on the effect of the different design choices made possible by the electric actuation. The procedure can evaluate the pump-related fuel consumption, whatever the real vehicle speed profile and the actuation of the pump. The results show that in a driving cycle with urban, extra-urban, and highway phases, the electric pump absorbs 66% less power compared to the mechanical one, which translates into a 0.55 gCO2/km specific emission reduction. This demonstrates the validity of the novel design procedure together with the benefits of the electric actuation
A definitive model of a small-scale concentrated solar power hybrid plant using air as heat transfer fluid with a thermal storage section and ORC plants for energy recovery
No full textThe aim of this work was to propose a small-scale Concentrated Solar Power plant using conventional technologies, in order to improve their flexibility and performances, and reinforce their competitiveness compared to traditional systems. Additionally, this study analyzed the possibility of providing continuity of energy production through an optimized hybrid system, which considered thermal energy storage from a gaseous Heat Transfer Fluid, air. It also considered the possibility of recovering part of the energy of the thermodynamic cycle through an Organic Rankine Cycle system with appropriate dimensions. The final outcomes were a 170 kW CSP plant with about 805 MWh of annual electricity production with a global solar capacity of 32.5%, about 900 kWh of thermal storage daily capacity, and an ORC recovery section of 54.2 kW with a specific production of 260 MWh/y
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