Axial turbo-expander design for organic Rankine cycle waste-heat recovery with comparative heavy-duty diesel engine drive-cycle performance assessment

Despite the high thermal efficiency achieved by modern heavy-duty diesel engines, over 40% of the energy contained in the fuel is wasted as heat either in the cooling or the exhaust gases. By recovering part of the wasted energy, the overall thermal efficiency of the engine increases and the pollutant emissions are reduced. Organic Rankine cycle (ORC) systems are considered a favourable candidate technology to recover exhaust gas waste heat, because of their simplicity and small backpressure impact on the engine performance and fuel consumption. The recovered energy can be transformed into electricity or directly into mechanical power. In this study, an axial turbine expander for an ORC system was designed and optimized for a heavy-duty diesel engine for which real-world data were available. The impact of the ORC system on the fuel consumption under various operating points was investigated. Compared to an ORC system equipped with a radial turbine expander, the axial design improved fuel consumption by between 2 and 10% at low and high engine speeds. Finally, the benefits of utilising ORC systems for waste heat recovery in heavy-duty trucks is evaluated by performing various drive cycle tests, and it is found that the highest values of fuel consumption were found in the NEDC and the HDUDDS as these cycles generally involve more dynamic driving profiles. However, it was in these cycles that the ORC could recover more energy with an overall fuel consumption reduction of 5 and 4.8%, respectively

Axial Turbo-Expander Design for Organic Rankine Cycle Waste-Heat Recovery With Comparative Heavy-Duty Diesel Engine Drive-Cycle Performance Assessment

Data Availability Statement: The datasets presented in this article are not readily available because of commercial reasons. Requests to access the datasets should be directed to Brunel University [email protected] the high thermal efficiency achieved by modern heavy-duty diesel engines, over 40% of the energy contained in the fuel is wasted as heat either in the cooling or the exhaust gases. By recovering part of the wasted energy, the overall thermal efficiency of the engine increases and the pollutant emissions are reduced. Organic Rankine cycle (ORC) systems are considered a favourable candidate technology to recover exhaust gas waste heat, because of their simplicity and small backpressure impact on the engine performance and fuel consumption. The recovered energy can be transformed into electricity or directly into mechanical power. In this study, an axial turbine expander for an ORC system was designed and optimized for a heavy-duty diesel engine for which real-world data were available. The impact of the ORC system on the fuel consumption under various operating points was investigated. Compared to an ORC system equipped with a radial turbine expander, the axial design improved fuel consumption by between 2 and 10% at low and high engine speeds. Finally, the benefits of utilising ORC systems for waste heat recovery in heavy-duty trucks is evaluated by performing various drive cycle tests, and it is found that the highest values of fuel consumption were found in the NEDC and the HDUDDS as these cycles generally involve more dynamic driving profiles. However, it was in these cycles that the ORC could recover more energy with an overall fuel consumption reduction of 5 and 4.8%, respectively

Clinical evidence continuous medical education: a randomised educational trial of an open access e-learning program for transferring evidence-based information – ICEKUBE (Italian Clinical Evidence Knowledge Utilization Behaviour Evaluation) – study protocol

<p>Abstract</p> <p>Background</p> <p>In an effort to ensure that all physicians have access to valid and reliable evidence on drug effectiveness, the Italian Drug Agency sponsored a free-access e-learning system, based on <it>Clinical Evidence</it>, called ECCE. Doctors have access to an electronic version and related clinical vignettes. Correct answers to the interactive vignettes provide Continuing Medical Education credits. The aims of this trial are to establish whether the e-learning program (ECCE) increases physicians' basic knowledge about common clinical scenarios, and whether ECCE is superior to the passive diffusion of information through the printed version of <it>Clinical Evidence</it>.</p> <p>Design</p> <p>All Italian doctors naïve to ECCE will be randomised to three groups. Group one will have access to ECCE for <it>Clinical Evidence </it>chapters and vignettes lot A and will provide control data for <it>Clinical Evidence </it>chapters and vignettes lot B; group two vice versa; group three will receive the concise printed version of <it>Clinical Evidence</it>. There are in fact two designs: a before and after pragmatic trial utilising a two by two incomplete block design (group one versus group two) and a classical design (group one and two versus group three). The primary outcome will be the retention of <it>Clinical Evidence </it>contents assessed from the scores for clinical vignettes selected from ECCE at least six months after the intervention. To avoid test-retest effects, we will randomly select vignettes out of lot A and lot B, avoiding repetitions. In order to preserve the comparability of lots, we will select vignettes with similar, optimal psychometric characteristics.</p> <p>Trial registration</p> <p>ISRCTN27453314</p

Valutazione della bont&#224; educativa dei casi clinici di ECCE, il programma di formazione a distanza (FAD) basato sulle evidenze destinato ai medici italiani

OBIETTIVO. Valutare la qualit\ue0 dei percorsi clinici di un programma FAD destinato a tutti i medici italiani verificando le loro propriet\ue0 psicometriche. METODI. AIFA ha lanciato un programma nazionale di sostegno dell\u2019informazione indipendente tramite la distribuzione gratuita ai medici di Clinical Evidence (CE). Sulla base dei contenuti di CE \ue8 stato sviluppato un programma FAD all\u2019interno del sistema di Educazione Continua in Medicina (ECM) dal nome ECCE, anch\u2019esso gratuito. I medici hanno accesso a CE online e ai relativi percorsi clinici. Superandoli il medico ottiene i crediti ECM. Nel corso del 2006 \ue8 stata valutata la qualit\ue0 di un campione di venti percorsi, su un totale di 120. La valutazione formale della qualit\ue0 dei 20 casi selezionati \ue8 avvenuta attraverso le seguenti dimensioni psicometriche: Giudizio generale sui percorsi da parte degli utilizzatori (face validity); Valutazione dei contenuti da parte di clinici esperti (content validity); Valutazione della attendibilit\ue0 del test attraverso un criterio di consistenza interna (internal reliability); Difficolt\ue0 degli items; Capacit\ue0 del test di rilevare una modificazione della conoscenza (responsiveness). RISULTATI: Alcune migliaia di utenti hanno partecipato alla valutazione fornendo esiti contrastanti: mentre la face e content validity sono state valutate positivamente dagli utilizzatori e dai clinici esperti, altri parametri come l\u2019internal reliability e la difficolt\ue0 degli items hanno mostrato grande variabilit\ue0 tra i percorsi. Sette casi mostrano un valore di alpha complessivo inferiore a 0.50 (soglia minima di affidabilit\ue0). I casi si sono dimostrati nel complesso medio-facili. Facendo riferimento solo alle proprie conoscenze i partecipanti rispondevano correttamente a circa a met\ue0 delle domande. La lettura delle fonti era associata a un miglioramento della performance (miglioramento prima-dopo statisticamente significativo, p<0.05 per 19/20 percorsi). CONCLUSIONI: L\u2019importante eterogeneit\ue0 tra percorsi dimostrerebbe come differenti casi possono analizzare in maniera molto disomogenea il domino conoscenza evidence-based derivata dai contenuti di CE

A naturally anti-diffusive compressible two phases Kapila model with boundedness preservation coupled to a high order finite volume solver

International audienceThis paper presents a two phases flow model combined with a high order finite volume solver on unstructured mesh. The solver is highly conservative and preserves the sharpness of the interface without any reconstruction. Special care has been taken for boundedness preservation, as a high order scheme does not guaranty the boundedness of the volume fraction. The efficiency of the method is demonstrated with two numerical experiments: the simple advection test and the interaction between the shock and a bubble. Although experiments have been carried out with fine mesh, it is also demonstrated that the method allows satisfactory results to be obtained with coarse mesh

Experimental identification of turbocharger mechanical friction losses

International audienceUnderstanding the friction losses of automotive turbochargers is a key parameter in assessing properly the mechanical efficiency of these machines. Current turbochargers are mostly equipped with oil bearings: two journal bearings and one double-acting axial thrust bearing. In order to know on which element improvement efforts have to be focused, it is important to determine their contribution to the total friction losses. This will also make it possible to calibrate the computation models of friction losses of the bearings separately. Measuring the friction losses of a turbocharger is not easy and existing methods measure only the total losses due to the association of journal and thrust bearings. A novel turbocharger test bench equipped with a highly accurate torquemeter and a magnetic axial load device has been developed. Measuring methodologies have been fine-tuned to measure the total friction losses, the influence of axial load on the thrust bearing, and the mechanical friction losses of the journal bearings alone. The experimental device and measuring methods are detailed in this paper. Experimental results are presented and analysed. The influence of axial load, oil inlet pressure and the distribution of friction power and oil mass flow between thrust bearing and journal bearings are discussed

A naturally anti-diffusive compressible two phases Kapila model with boundedness preservation coupled to a high order finite volume solver

International audienceThis paper presents a two phases flow model combined with a high order finite volume solver on unstructured mesh. The solver is highly conservative and preserves the sharpness of the interface without any reconstruction. Special care has been taken for boundedness preservation, as a high order scheme does not guaranty the boundedness of the volume fraction. The efficiency of the method is demonstrated with two numerical experiments: the simple advection test and the interaction between the shock and a bubble. Although experiments have been carried out with fine mesh, it is also demonstrated that the method allows satisfactory results to be obtained with coarse mesh

Surge detection on an automotive turbocharger during transient phases

International audienceThe surge limit on automotive turbocharger needs to be avoided to prevent operations with pressure and mass flow oscillations. Mild surge is accompanied by noise which is disturbing. Deep surge can cause significant loss of engine power and severe drivability issues. It is necessary to know the stationary limit in order to match a turbocharger with an engine, ensuring enough surge margin. However, this choice does not guarantee surge free operation during transient functioning. In this paper, the surge onset of a compressor while closing a downstream valve is studied. Various tests have been carried out varying the closing time, the position of the initial operating point and the volume of the circuit. The inlet and outlet signals of physical parameters are analyzed with spectral and temporal methods in order to define the instant of the surge occurrenc