34 research outputs found
Experimental Investigation on Different After-treatment Technologies for the Control of Pollutant Emissions from Automotive Diesel Engines
No full textHigh Speed Direct Injection (HSDI) Diesel engines are nowadays spreading in the global market of passenger cars, thanks to undoubted advantages such as higher efficiency (lower fuel consumption and CO2 emissions), drivability, durability and reliability. Increasing concerns regarding the two main pollutants from Diesel engines, NOx and PM, started a progressive process of tightening of emission limits; Tier 2 (USA) and Euro5b/6 (Europe) emissions regulations will definitively bring down NOx and PM, with also the introduction of new limitations such as, for instance, on PN emissions. Efficient and reliable after-treatment technologies for NOx and PM control are going to be necessary. PN emissions from a modern diesel engine were characterized by means of a Scanning Mobility Particle Sizer (SMPS); in addition, the performance of an Advanced Diesel Oxidation Catalyst (A-DOC), with low temperature NOx trapping capability, and a Diesel Particulate Filter (DPF) were assessed. PN emissions were evaluated under normal engine operating mode, as well as under DPF regeneration mode; unimodal distribution were found at both engine outlet and DOC outlet, without any effects of DOC on the emitted particles; conversely DPF reduction efficiency up to 2 orders of magnitude were observed, thus confirming the potential of DPF to be effective also on these small particles. PN emissions were found to increase during DPF regeneration, but it was shown that both DOC and DPF were effective in reducing PN under similar operating conditions. PN emissions were also evaluated during engine warm-up. A new experimental methodology, able to provide fundamental information about the soot loading process inside the DPF, was adopted to load small lab-size SiC DPF samples; advanced electron microscopy provided highly detailed images of soot deposited onto channel walls. While morphology of deposited soot and its compressibility characteristics were found in agreement with previous studies, it was shown that soot did not penetrate into channel walls, differently from what is reported in literature; conversely, a soot cake layer was taking place immediately. Finally, A-DOC technology was tested over NEDC. Reduction of NOx was found to be significantly high, especially during the urban driving; spontaneous release of stored NOx (without periodic rich regeneration such as for LNTs) was observed at high exhaust temperatures typical of extra-urban driving, highlighting the potential for a combined application with a downstream SCR system. Further tests on a modified A-DOC system without PGM loading revealed that the A-DOC might be the result of a combination of different after-treatment technologies such as LNTs and LNCs with also HC trapping capabilit
Characterization of a New Advanced Diesel Oxidation Catalyst with Low Temperature NOx Storage Capability for LD Diesel
No full textCurrently, two consolidated aftertreatment technologies are available for the reduction of NOx emissions from diesel engines: Urea SCR (Selective Catalytic Reduction) systems and LNT (Lean NOx Trap) systems. Urea SCR technology, which has been widely used for many years at stationary sources, is becoming nowadays an attractive alternative also for light-duty diesel applications. However, SCR systems are much more effective in NOx reduction efficiency at high load operating conditions than light load condition, characterized by lower exhaust gas temperatures. One possible solution to improve the low temperature behavior, is the use of newly developed Advanced Diesel Oxidation Catalysts (A-DOC) which are capable to store NOx at low exhaust temperatures (typical of urban driving conditions) when SCR efficiency is low, and to release the stored NOx at higher temperatures (i.e. during extra-urban driving conditions) where the urea injected is effectively forming ammonia for the subsequent NOx conversion. Experimental tests were therefore carried out in order to assess the performance of an A-DOC when exposed at the emissions coming from a modern Euro 5, 2.0 L displacement turbocharged Common Rail DI Diesel engine for a typical European passenger car: the engine features a DOC and a DPF in close-coupled position, hosted into an on purpose designed dismountable canning, thus allowing an easy switch between different components. The characterization of these newer DOC formulations was performed over NEDC cycles. Moreover, the catalyst were tested both in fresh and hydrothermally aged conditions in order to have a better understanding relative to robustness and durability of these newer catalyst. NOx storage capability, which was found to be impressively high for a fresh A-DOC, significantly decreased after aging, thus leading to a final NOx cumulated emissions figure which equals the engine-out value for the aged A-DOC. Nevertheless, since most of the NOx release from the A-DOC occurs during the EUDC segment, when a downstream SCR would likely have reached appreciable NOx reduction efficiencies, even an aged A-DOC could provide significant benefits in terms of NOx emissions reduction. However, the analysis of the NO/NO2 share downstream of the DPF, which is of crucial importance for SCR efficiency at low temperature, revealed that the overall conversion efficiency for NO over NEDC was negative, while on the contrary the conversion efficiency for NO2 was remarkably high. As a result, the NO2/NOx ratio downstream of the DPF (i.e. at the inlet of a downstream SCR) remained significantly low during the whole EUDC segment, thus hindering the achievement of high NOx conversion efficiencies and the full exploitation of a synergetic combination of the A-DOC with a downstream SCR
Effects of Rapeseed and Jatropha Methyl Ester on Performance and Emissions of a Euro 5 Small Displacement Automotive Diesel Engine
No full textThe effects of using neat and blended (30% vol.) biodiesel,
obtained from Rapeseed Methyl Ester (RME) and Jatropha
Methyl Ester (JME), in a Euro 5 small displacement
passenger car diesel engine have been evaluated in this paper.
The impact of biodiesel usage on engine performance at full
load was analyzed for a specifically adjusted ECU
calibration: the same torque levels measured under Diesel
operation could be obtained, with lower smoke levels, thus
highlighting the potential for maintaining the same level of
performance while achieving substantial emissions benefits.
In addition, the effects of biodiesel blends on brake specific
fuel consumption and on engine-out exhaust emissions (CO2,
CO, HC, NOx and smoke) were also evaluated at 6 different
part load operating conditions, representative of the New
European Driving Cycle. Emissions were also measured at
the DPF outlet, thus providing information about aftertreatment
devices efficiencies with biodiesel. The application
of a specifically adjusted engine calibration showed a rise of
fuel consumption, due to the lower energy content of
biodiesel, at same fuel conversion efficiency and comparable
CO2 emissions. An appreciable increase of CO and HC
emissions at low load could be noticed, along with a
considerable smoke emission reduction.
Finally, soot-NOx trade-off were also analyzed for three
different engine operating points, in order to gather detailed
information about further possible emissions benefits that
could be achieved through a more extensive ECU
recalibration
Performance and emissions of a Euro5 small diesel engine fuelled with biodiesel
No full textThis article describes the effects of using neat biodiesel on a modern small displacement passenger car diesel engine, highlighting the need for a specific adjusted electronic control unit (ECU) calibration for biodiesel. Engine performance were evaluated at full load with a standard ECU calibration as
well as with an ECU calibration specifically adjusted for biodiesel; Break Specific Fuel Consumption (BSFC) and exhaust emissions was then evaluated at seven part load operating conditions, representative of the New European Driving Cycle (NEDC). Tests showed that through recalibration it is possible to obtain the same performance measured under diesel operation, with benefits in
terms of engine-out emissions, especially as far as smoke emissions are concerned. Moreover, particle number and size distribution at engine outlet were also evaluated at part load operating conditions, showing a significant reduction of particle number and mass with biodiesel
Analysis of Performance and Emissions of an Automotive Euro 5 Diesel Engine Fuelled with B30 from RME and JME
No full textThe effects of using a B30 blend of ultra low sulphur diesel and two different Fatty Acid Methyl Esters (FAME) obtained from both Rapeseed Methyl Ester (RME) and Jatropha Methyl Ester (JME) in a Euro 5 small displacement passenger car diesel engine on both full load performance and part load emissions have been evaluated in this paper. In particular the effects on engine torque were firstly analyzed, for both a standard ECU calibration (i.e. without any special tuning for the different fuel characteristics) and for a specifically adjusted ECU calibration obtained by properly increasing the injected fuel quantities to compensate for the lower LHV of the B30: with the latter, the same torque levels measured under diesel operation could be observed with the B30 blend too, with lower smoke levels, thus highlighting the potential for maintaining the same level of performance while achieving substantial emissions benefits. Moreover, the effects of the two different 30% vol. blends on brake specific fuel consumption and on engine-out exhaust emissions (CO2, CO, HC, NOx and smoke) were also evaluated at 6 different part load operating conditions, representative of the New European Driving Cycle. Both standard engine calibration (change of the accelerator pedal position) and specifically adjusted engine calibration (adjustment of the energizing time of main injection) were evaluated for part load operating conditions, highlighting a 4% average rise of fuel consumption, on a mass basis, at same fuel conversion efficiency and CO2 emissions. A noticeable increase of CO and HC emissions at low load could also be noticed, along with a significant NOx emissions decrease when using a specifically adjusted engine calibration, and a considerable smoke emission reductio
Model Based Engine Control Development and Hardware-in-the-Loop Testing for the EcoCAR Advanced Vehicle Competition
No full textImpact of Engine Operating Conditions on Particle Number and Size from a Small Displacement Automotive Diesel Engine
No full textParticulate Matter (PM) particles number and size
distribution emitted from a small displacement automotive
Common-Rail Diesel engine were analyzed in order to
evaluate the impact of different engine operating parameters,
such as engine load, EGR rate and injection pattern during
DPF regeneration.
The engine was equipped with a close coupled aftertreatment
system, featuring a Diesel Oxidation Catalyst (DOC) and a
Diesel Particulate Filter (DPF) integrated in a single canning.
The pollutant emissions were sampled at two locations along
the exhaust system: at the engine outlet and downstream of
the diesel oxidation catalyst, in order to characterize particles
entering the DOC and the DPF respectively.
Particle size distributions were measured by means of a two
stage dilution system coupled with a downstream Scanning
Mobility Particle Sizer (SMPS).
Particles number were found to increase for increasing load
and EGR rates, the latter being the dominant factor, with no
significant impact of the DOC, showing also good correlation
with conventional smoke opacity measurements.
On the other hand, tests performed with post-injections for
DPF regeneration showed dramatic increases (up to one order
of magnitude) in particle numbers for large post-injected
quantities, along with a significant shift towards smaller
values (below 50) of the peak of particle number distribution.
These increases in engine-out peak particles number values
during regeneration were not detectable with standard FSN
measurements, thus suggesting an increased importance of
semivolatile components in the nanoparticles range.
Moreover, under the same operating conditions, noteworthy
reductions of particle numbers across the DOC were
observed, thus providing further evidence of the importance
of semivolatile components during post-injections
