Assessment on the consequences of injection strategies on combustion process and particle size distributions in Euro VI medium-duty diesel engine

Ducted fuel injection (DFI) is a novel combustion strategy that has been shown to significantly attenuate soot formation in diesel engines. While previous studies have used optical diagnostics and optical filter smoke number methods to show that DFI reduces in-cylinder soot formation and engine-out soot emissions, respectively, this is the first study to measure solid particle number (PN) emissions in addition to particle mass (PM). Furthermore, this study quantitatively evaluates the use of transient particle instruments for measuring particles from skip-fired operation in an optical single cylinder research engine (SCRE). Engine-out PN was measured using an engine exhaust particle sizer following a catalytic stripper, and PM was measured using a photoacoustic analyzer. The study improves on earlier preliminary emissions studies by clearly showing that DFI reduces overall PM by 76%–79% and PN for particles larger than 23 nm by 77% relative to conventional diesel combustion at a 1200-rpm, 13.3-bar gross indicated mean effective pressure operating condition. The degree of engine-out PM reduction with DFI was similar across both particulate measurement instruments used in the work. Through the use of bimodal distribution fitting, DFI was also shown to reduce the geometric mean diameter of accumulation mode particles by 26%, similar to the effects of increased injection pressure in conventional diesel combustion systems. This work clearly shows the significant solid particulate matter reductions enabled by DFI while also demonstrating that engine-out PN can be accurately measured from an optical SCRE operating in a skip-fired mode. Based on these results, it is believed that DFI has the potential to enable fuel savings when implemented in multi-cylinder engines, both by lowering the required frequency of active diesel particulate filter regeneration, and by reducing the backpressure imposed by exhaust filtration systems.

Section: Resultsmentioning

confidence: 98%

Solid particulate mass and number from ducted fuel injection in an optically accessible diesel engine in skip-fired operation

Wilmer

Nilsen

Biles

et al. 2021

“…This regeneration process consists of increasing the temperature of the exhaust gas and is controlled by the electronic control unit (ECU) in order to burn off and remove the particulate matter (PM) and soot depositions collected in the after treatment system of gasoline and diesel engines. 9,10 When saturation conditions are detected by the ECU, active regeneration strategies as per example post injection and separate diesel injection are performed. 11 These strategies lead to higher pollutant emissions levels and deposits due to the additional fuel mass required to cause this regeneration.…”

Section: Introductionmentioning

confidence: 99%

Impacts of the exhaust gas recirculation (EGR) combined with the regeneration mode in a compression ignition diesel engine operating at cold conditions

Galindo

Dolz

Monsalve‐Serrano

et al. 2021

Internal combustion engines working at cold conditions lead to the production of excessive pollutant emissions levels. The use of the exhaust gas recirculation could be necessary to reduce the nitrogen oxides emissions, even at these conditions. This paper evaluates the impact of using the high-pressure exhaust gas recirculation strategy while the diesel particulate filter is under active regeneration mode on a Euro 6 turbocharged diesel engine running at low ambient temperature (−7°C). This strategy is evaluated under 40 h of operation, 20 of them using the two systems in combination. The results show that the activation of the high-pressure exhaust gas recirculation during the particulate filter regeneration process leads to a 50% nitrogen oxides emissions reduction with respect to a reference case without exhaust gas recirculation. Moreover, the modification of some engine parameters compared to the base calibration, as the exhaust gas recirculation rate, the main fuel injection timing and the post injection quantity, allows to optimize this strategy by reducing the carbon monoxide emissions up to 60%. Regarding the hydrocarbons emissions and fuel consumption, a small advantage could be observed using this strategy. However, the activation of the high-pressure exhaust gas recirculation at low temperatures can produce fouling deposits and condensation on the engine components (valve, cooler, intake manifold, etc.) and can contribute to reach saturation conditions on the particulate filter. For these reasons, the regeneration efficiency is followed during the experiments through the filter status, concluding that the use of low high-pressure exhaust gas recirculation rates in combination with the regeneration mode also allows to clean the soot particles of the particulate filter. These soot depositions are visualized and presented at the end of this work with a brief analysis of the soot characteristics and a quantitative estimation of the total soot volume produced during the experimental campaign.

“…Different outlooks suggest that the passenger cars energy vectors will change significantly in the next years. 1 While internal combustion engines will be still dominant 2 and be improved regarding its fuel injection 3–5 and combustion system design, 6,7 alternative concepts as plug-in hybrids electric vehicles (PHEV) and battery electric vehicles (BEV) 8 will increase their market share consistently 9 due to their benefits in fuel consumption improvements 10,11 and emission reductions. 12 This modification is a consequence of the different mandates, that require an effective reduction on the total tank-to-wheel CO 2 emissions, 13 which cannot be accomplished by the conventional ICE propelled vehicles.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of kinetic mechanisms for battery thermal runaway prediction in lithium-ion batteries

García

Monsalve‐Serrano

Sari

et al. 2021

Self Cite

The urgent need for reducing the carbon dioxide emissions has led to the powertrain electrification at different levels such as hybridization or pure electric vehicles. Despite the benefits in terms of local pollution reduction and lower carbon dioxide footprint that may be achieved with this technology, new hazards have been introduced. Among them, the combustion of the battery pack due to abuse conditions, also known as thermal runaway, is one of the biggest concerns. It can lead to the vehicle combustion under unnoticed failure conditions, threating the driver security. In this sense, different investigations have been carried out with the aim of providing a proper description of the reactions that lead to this phenomenon. Reaction mechanisms have been proposed in the literature for lithium-ion battery considering the most common battery chemistries. Nonetheless, their application leads to different results, which may hinder their utilization in modeling critical operating conditions for thermal runaway. This investigation proposes a detailed assessment of the most common reaction mechanisms, comparing their capability on reproducing the different reaction paths that lead to thermal runaway conditions to explore and depict state of the art of thermal runaway modeling. Additionally, a detailed analysis is performed to define the differences in terms of decomposition and formation reactions for each one of them. The results of this investigation demonstrate that the mechanism proposed by Kriston provides the best results trade-off considering different investigations in differential scanning calorimeter and accelerated rate calorimeter. In addition, it was found that some mechanisms have been adjusted to perform similar to the experimental results, even in the case of not having a physical meaning.