| 1. |
- Belgiorno, Giacomo, et al.
(author)
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Performance and emissions of diesel-gasoline-ethanol blends in a light duty compression ignition engine
- 2018
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In: Fuel. - : Elsevier BV. - 0016-2361. ; 217, s. 78-90
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Journal article (peer-reviewed)abstract
- An approach to reduce CO2 emissions while simultaneously keeping the soot emissions down from compression ignition (CI) engines is to blend in short chained oxygenates into the fuel. In this work, two oxygenated fuel blends consisting of diesel, gasoline and ethanol (EtOH) in the ratio of 68:17:15 and 58:14:30 have been utilized and studied in a single cylinder light duty (LD) CI engine in terms of efficiency and emissions. The reasons of utilizing gasoline in the fuel blend is due to the emulsifying properties it has while increasing the total octane rating of the fuel to be able to run the engine with a higher fraction of premixed flame. When performing the experiments, the control parameters were set as close as possible to the original equipment manufacturer (OEM) EU5 calibration of the multi-cylinder engine to study the possibility of using such blends in close to stock LD CI engines. With the oxygenates, in particular the fuel with the higher concentration of EtOH achieved an indicated net efficiency of ∼51% inf comparison to ∼47% for diesel at 8 bar BMEP. The NOX emissions increased slightly for the double injection strategy at 13 bar BMEP from ∼13.5 g/kW h to ∼14.5 g/kW h when going from diesel fuel to the higher ethanol blend. However utilizing single injection strategy at lower loads reduces the NOX. Highest soot mass measured for diesel was ∼0.46 g/kW h in contrast to ∼0.1 g/kW h for the oxygenates. Also, soot production when running the engine on the ethanol containing fuels was not significantly affected by EGR utilization as in the case of diesel. Considering particle size distribution, the particles are reduced both in terms of mean diameter and quantity. At 1500 rpm and 2 bar BMEP an increase of over ∼300% in THC and CO was measured, however, increasing the speed and load to above 2000 rpm and 8 bar BMEP respectively, made the difference negligible due to high in-cylinder temperatures contributing to better fuel oxidation. Despite having lower cetane numbers, higher combustion stability was observed for the oxygenates fuels.
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| 2. |
- Gren, Louise, et al.
(author)
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Effect of renewable fuels and intake O2 concentration on diesel engine emission characteristics and reactive oxygen species (ROS) formation
- 2020
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In: Atmosphere. - : MDPI AG. - 2073-4433. ; 11:6
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Journal article (peer-reviewed)abstract
- Renewable diesel fuels have the potential to reduce net CO2 emissions, and simultaneously decrease particulate matter (PM) emissions. This study characterized engine-out PM emissions and PM-induced reactive oxygen species (ROS) formation potential. Emissions from a modern heavy-duty diesel engine without external aftertreatment devices, and fueled with petroleum diesel, hydrotreated vegetable oil (HVO) or rapeseed methyl ester (RME) biodiesel were studied. Exhaust gas recirculation (EGR) allowed us to probe the effect of air intake O2 concentration, and thereby combustion temperature, on emissions and ROS formation potential. An increasing level of EGR (decreasing O2 concentration) resulted in a general increase of equivalent black carbon (eBC) emissions and decrease of NOx emissions. At a medium level of EGR (13% intake O2), eBC emissions were reduced for HVO and RME by 30 and 54% respectively compared to petroleum diesel. In general, substantially lower emissions of polycyclic aromatic hydrocarbons (PAHs), including nitro and oxy-PAHs, were observed for RME compared to both HVO and diesel. At low-temperature combustion (LTC, O2 < 10%), CO and hydrocarbon gas emissions increased and an increased fraction of refractory organic carbon and PAHs were found in the particle phase. These altered soot properties have implications for the design of aftertreatment systems and diesel PM measurements with optical techniques. The ROS formation potential per mass of particles increased with increasing engine O2 concentration intake. We hypothesize that this is because soot surface properties evolve with the combustion temperature and become more active as the soot matures into refractory BC, and secondly as the soot surface becomes altered by surface oxidation. At 13% intake O2, the ROS-producing ability was high and of similar magnitude per mass for all fuels. When normalizing by energy output, the lowered emissions for the renewable fuels led to a reduced ROS formation potential.
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| 3. |
- Gren, Louise, et al.
(author)
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Effects of renewable fuel and exhaust aftertreatment on primary and secondary emissions from a modern heavy-duty diesel engine
- 2021
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In: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 156
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Journal article (peer-reviewed)abstract
- Compared to petroleum diesel, renewable diesel fuels and exhaust aftertreatment systems can reduce primary exhaust emissions that are hazardous to human health and the environment. Secondary aerosol emissions which form upon atmospheric processing have, however, been less studied. This study aimed to quantify the impacts of replacing petroleum diesel with renewable fuels (hydrotreated vegetable oil [HVO] and rapeseed methyl ester [RME]) on primary and secondary aerosol emissions from a heavy-duty diesel engine at different stages of an exhaust aftertreatment system. Emission characterization was obtained by combining a battery of physical characterization techniques with chemical characterization using aerosol mass spectrometry. At engine-out measurements, RME and HVO reduced primary particulate matter (PM) emissions (for example equivalent black carbon [eBC]) and secondary aerosol production (studied with an oxidation flow reactor [OFR]) by mass compared to petroleum diesel. The diesel oxidation catalyst (DOC) reduced primary nucleation mode emissions, reduced the effective density of soot mode emissions, and reduced secondary particle production by mass. The DOC + a diesel particulate filter removed >99% of the particle number and eBC emissions. Volatile PM emissions (for example organic aerosol) were found to be distributed between the nucleation mode and soot mode for both primary and secondary emissions, to a degree that depends on both fuel type and aftertreatment. A high mass concentration of condensable species and a low condensation sink in the soot mode led to increased fractions of condensable species present in the nucleation mode. Aging in the OFR led to increases in particle effective density. Motoring the engine (running without combustion) showed that the nucleation mode originated primarily from lubricating oil, and nonvolatile nanoparticle emissions were identified down to 1.2 nm in particle size. In conclusion, replacing petroleum diesel with HVO and RME changes emission characteristics and can help reduce key aerosol emissions of relevance for adverse health and climate impact, especially for diesel engines with no or limited exhaust aftertreatment.
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| 4. |
- Korhonen, Kimmo, et al.
(author)
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Particle emissions from a modern heavy-duty diesel engine as ice nuclei in immersion freezing mode: a laboratory study on fossil and renewable fuels
- 2022
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In: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 22:23, s. 1615-1631
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Journal article (peer-reviewed)abstract
- We studied ice-nucleating abilities of particulate emissions from a modern heavy-duty diesel engine using three different types of fuel. The polydisperse particle emissions were sampled during engine operation and introduced to a continuous-flow diffusion chamber (CFDC) instrument at a constant relative humidity RHwater=110 %, while the temperature was ramped between −43 and −32 ∘C (T scan). The tested fuels were EN 590 compliant low-sulfur fossil diesel, hydrotreated vegetable oil (HVO), and rapeseed methyl ester (RME); all were tested without blending. Sampling was carried out at different stages in the engine exhaust aftertreatment system, with and without simulated atmospheric processing using an oxidation flow reactor. In addition to ice nucleation experiments, we used supportive instrumentation to characterize the emitted particles for their physicochemical properties and presented six parameters. We found that the studied emissions contained no significant concentrations of ice-nucleating particles likely to be of atmospheric relevance. The substitution of fossil diesel with renewable fuels, using different emission aftertreatment systems such as a diesel oxidation catalyst, and photochemical aging of total exhaust had only minor effect on their ice-nucleating abilities.
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| 5. |
- Li, Changle, et al.
(author)
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Transition from HCCI to PPC : The Sensitivity of Combustion Phasing to the Intake Temperature and the Injection Timing with and without EGR
- 2016. - April
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In: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2016-April
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Conference paper (peer-reviewed)abstract
- An experiment was conducted to investigate the effect of charge stratification on the combustion phasing in a single cylinder, heavy duty (HD) compression ignition (CI) engine. To do this the start of injection (SOI) was changed from -180° after top dead centre (ATDC) to near top dead centre (TDC) during which CA50 (the crank angle at which 50% of the fuel energy is released) was kept constant by changing the intake temperature. At each SOI, the response of CA50 to a slight increase or decrease of either intake temperature or SOI were also investigated. Afterwards, the experiment was repeated with a different intake oxygen concentration. The results show that, for the whole SOI period, the required intake temperature to keep constant CA50 has a "spoon" shape with the handle on the -180° side. Depending on the required intake temperature, the whole SOI period is divided into five zones: the injection against intake valve closing zone, the classical Homogeneous Charge Compression Ignition (HCCI) zone, the top-land/crevice effect zone, the stratification effect zone, and the ignition delay effect zone. From the sensitivity study, it is found that a higher intake temperature always leads to an earlier CA50 for the whole SOI period, while an earlier SOI can either result in an earlier or a later CA50, depending on how this variation of SOI affects the mixing process. When SOI is within the last three zones, CA50 is sensitive to the changes of both the intake temperature and SOI. But relatively, the sensitivity of CA50 to SOI is higher. When the exhaust gas recirculation (EGR) is not used, CA50 becomes more sensitive to SOI and less sensitive to the intake temperature. The THC, CO, and NOx emissions increase and the combustion efficiency decreases especially during the top-land/crevice effect zone.
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| 6. |
- Malmborg, Vilhelm, et al.
(author)
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Characteristics of BrC and BC emissions from controlled diffusion flame and diesel engine combustion
- 2021
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In: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 55:7, s. 769-784
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Journal article (peer-reviewed)abstract
- Constraining the climate impact of particulate brown carbon (BrC) will require identification of formation mechanisms and isolation of its different components to allow for source apportionment. For fresh combustion aerosols, the light absorption characteristics and the Absorption Ångstrom Exponent (AAE) are principally controlled by the combustion conditions in which the particles formed and evolved. We investigated the influence of combustion temperatures on the BrC or black carbon (BC) emission characteristics for a miniCAST soot generator (propane fuel) and a modern heavy-duty diesel engine (petroleum diesel and two renewable diesel fuels). Changes in the AAE, mass spectral signatures, and thermal-optical characteristics were studied. We show that changing operating parameters to gradually reduce the combustion temperatures in these two fundamentally different combustion devices result in a regression from BC dominated to BrC dominated particle emissions. The regression toward BrC was associated with: (1) an increasing mass fraction of particulate non-refractory polycyclic aromatic hydrocarbons (PAHs), (2) an increasing fraction of refractory organic carbon, (3) more curved soot nanostructures and shorter fringe lengths, and (4) increased signal from (refractory) large carbon fragments in IR laser-vaporization aerosol mass spectra. Based on these results we argue that fresh BrC dominated combustion aerosols are attributed to primary emissions from low temperature combustion, highlighting the influence of refractory constituents and soot nanostructure. Higher temperatures favor the growth of conjugated polyaromatic structures in the soot, a progression hypothesized to control the evolution from BrC to BC character of the emitted aerosols.
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| 7. |
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| 8. |
- Novakovic, Maja, et al.
(author)
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Analysis of Exhaust PM Composition Emitted from Non-Sooting Volatile Alcohols
- 2017
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Conference paper (other academic/artistic)abstract
- The combustion engine, a well-known source of aerosols, has seen remarkable improvements regarding efficiency and emissions. A drawback of the conventional compression ignition (CI) engine is its requirement for a high cetane number fuel, i.e. diesel which contains long carbon chains forming particulate matter (PM) when combusted in the conventional diesel combustion (CDC) process. A previous study of PM from partially premixed combustion (PPC) and CDC utilizing ethanol and methanol in a Scania D13 engine without emission after treatment systems (EATS) showed that the particle sizes from the alcohol combustion never exceeded 30 nm in diameter. Until now, the characteristics (origin, formation and constituents) of these nano-sized particles formed in the PPC and CDC process were unknown. It has been hypothesized that they originate from lubrication oil and engine wear.
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| 9. |
- Novakovic, Maja, et al.
(author)
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Fresh and Aged Organic Aerosol Emissions from Renewable Diesel-Like Fuels HVO and RME in a Heavy-Duty Compression Ignition Engine
- 2023
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In: Technical paper - WCX SAE World Congress Experience. - 2688-3627 .- 0148-7191. ; :2023-01-0392
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Conference paper (peer-reviewed)abstract
- A modern diesel engine is a reliable and efficient mean of producing power. A way to reduce harmful exhaust and greenhouse gas (GHG) emissions and secure the sources of energy is to develop technology for an efficient diesel engine operation independent of fossil fuels. Renewable diesel fuels are compatible with diesel engines without any major modifications. Rapeseed oil methyl esters (RME) and other fatty acid methyl esters (FAME) are commonly used in low level blends with diesel. Lately, hydrotreated vegetable oil (HVO) produced from vegetable oil and waste fat has found its way into the automotive market, being approved for use in diesel engines by several leading vehicle manufacturers, either in its pure form or in a mixture with the fossil diesel to improve the overall environmental footprint. There is a lack of data on how renewable fuels change the semi-volatile organic fraction of exhaust emissions. In order to characterize and explain the difference in exhaust emissions from fossil diesel, HVO and RME fuels, particulate matter (PM) emissions were sampled at two exhaust positions of an experimental single cylinder Scania D13 heavy-duty (HD) diesel engine: at the exhaust manifold, and after a diesel oxidation catalyst (DOC). Advanced analyzing techniques were used to characterize the composition of the organic PM. Special attention was paid to an operating point at 18% intake oxygen level with constant engine operating conditions where the emission level of nitrogen oxides (NOx) was low, and carbon monoxide (CO) and total hydrocarbon (THC) were relatively low. On-line aerosol mass spectrometry (AMS) suggests that the chemical composition of the organic aerosols (OAs) was similar for HVO and diesel. However, RME both reduced the OA emissions and changed the composition with evidence for fuel signatures in the mass spectra. When the emissions were aged in an oxidation flow reactor to simulate secondary organic aerosol (SOA) formation in the atmosphere, it was found that OA concentration strongly increased for all fuels. However, SOA formation was substantially lower for RME compared to the other fuels. The DOC strongly reduced primary organic emissions in both the gas (THC) and particle phase (OA) and only marginally affected OA composition. The DOC was also effective in reducing secondary organic aerosol formation upon atmospheric aging.
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| 10. |
- Novakovic, Maja, et al.
(author)
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Regulated Emissions and Detailed Particle Characterisation for Diesel and RME Biodiesel Fuel Combustion with Varying EGR in a Heavy-Duty Engine
- 2019
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In: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019:December
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Journal article (peer-reviewed)abstract
- This study investigates particulate matter (PM) and regulated emissions from renewable rapeseed oil methyl ester (RME) biodiesel in pure and blended forms and contrasts that to conventional diesel fuel. Environmental and health concerns are the major motivation for combustion engines research, especially finding sustainable alternatives to fossil fuels and reducing diesel PM emissions. Fatty acid methyl esters (FAME), including RME, are renewable fuels commonly used from low level blends with diesel to full substitution. They strongly reduce the net carbon dioxide emissions. It is largely unknown how the emissions and characteristics of PM get altered by the combined effect of adding biodiesel to diesel and implementing modern engine concepts that reduce nitrogen oxides (NOx) emissions by exhaust gas recirculation (EGR). Therefore, the exhaust from a single-cylinder Scania D13 heavy-duty (HD) diesel engine fuelled with petroleum-based MK1 diesel, RME, and a 20% RME blend (B20), was sampled while the inlet oxygen concentration was stepped from ambient to very low by varying EGR. Regulated gaseous emissions, mass of total black carbon (BC) and organic aerosol (OA), particle size distributions and the soot nanostructure by means of transmission electron microscopy (TEM), were studied. For all EGR levels, RME showed reduced BC emissions (factor 2 for low and 3-4 for higher EGR) and total particulate number count (TPNC) compared with diesel and B20. B20 was closer to diesel than RME in emission levels. RME opens a significant possibility to utilise higher levels of EGR and stay in the region of low NOx, while not producing more soot than with diesel and B20. Adding EGR to 15% inlet O2 did not affect the nanostructure of PM. A difference between the fuels was noticeable: branched agglomerates of diesel and RME were composed of many primary particles, whereas those of B20 were more often “melted” together (necking).
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