| 1. |
- Belgiorno, Giacomo, et al.
(författare)
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Performance and emissions of diesel-gasoline-ethanol blends in a light duty compression ignition engine
- 2018
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 217, s. 78-90
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 11:6
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 156
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 22:23, s. 1615-1631
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2016-April
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Konferensbidrag (refereegranskat)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.
(författare)
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Characteristics of BrC and BC emissions from controlled diffusion flame and diesel engine combustion
- 2021
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 55:7, s. 769-784
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Analysis of Exhaust PM Composition Emitted from Non-Sooting Volatile Alcohols
- 2017
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)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.
(författare)
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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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Ingår i: Technical paper - WCX SAE World Congress Experience. - 2688-3627 .- 0148-7191. ; :2023-01-0392
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Konferensbidrag (refereegranskat)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.
(författare)
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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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Ingår i: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019:December
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Tidskriftsartikel (refereegranskat)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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| 11. |
- Pucilowski, Mateusz, et al.
(författare)
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Effect of Start of Injection on the Combustion Characteristics in a Heavy-Duty DICI Engine Running on Methanol
- 2017
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2017-March:March
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Tidskriftsartikel (refereegranskat)abstract
- Methanol as an alternative fuel in internal combustion engines has an advantage in decreasing emissions of greenhouse gases and soot. Hence, developing of a high performance internal combustion engine operating with methanol has attracted the attention in industry and academic research community. This paper presents a numerical study of methanol combustion at different start-of-injection (SOI) in a direct injection compression ignition (DICI) engine supported by experimental studies. The aim is to investigate the combustion behavior of methanol with single and double injection at close to top-dead-center (TDC) conditions. The experimental engine is a modified version of a heavy duty D13 Scania engine. URANS simulations are performed for various injection timings with delayed SOI towards TDC, aiming at analyzing the characteristics of partially premixed combustion (PPC). The simulations are based on a relatively detailed chemical kinetic mechanism and a well-stirred reactor (WSR) approach, accelerated using a so-called chemistry coordinate mapping (CCM). The injection of the fuel is treated with Lagrangian Particle Tracking (LPT) method. A baseline case with SOI of -20 after TDC (ATDC) was studied experimentally; this case was chosen to validate the model and a good agreement between the experiments and the simulation is found after adjustment of the initial pressure and temperature condition. In all injection conditions the combustion phasing is kept the same, i.e. with the 50-percentage heat release at the same crank angle (CA50) by adjusting the intake temperature. It is shown that as SOI is delayed the combustion characteristics changes significantly leading to a high maximal pressure-rise-rate (MPRR). The SOIs between -20 and -7 ATDC results in a combustion process governed by auto-ignition with propagating ignition fronts. The MPRR increases with SOI due to the rapid heat release caused by ignition at lean but increasingly richer conditions towards stoichiometry. The diffusion controlled, diesel like combustion (CDC), starts to occur around SOI -3 ATDC. The first portion of injected fuel ignites with a delay at leaner conditions, and then forms a diffusion flame. The amount of fuel consumed in the ignition process is larger than the amount of fuel consumed in the diffusion flame. Thus, contribution to the total heat release from the ignition process is larger and more rapid from that when using diesel or gasoline in the same CDC injection. Such behavior is attributed to a longer ignition delay time, large latent heat value and higher stoichiometric mixture fraction for methanol than hydrocarbon fossil fuels. It is concluded that a single main injection strategy of methanol may not be preferable due to the high MPRR thus other injection strategies, e.g., multiple injections should be used.
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| 12. |
- Pucilowski, Mateusz, et al.
(författare)
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Heat Loss Analysis for Various Piston Geometries in a Heavy-Duty Methanol PPC Engine
- 2018
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Ingår i: SAE 2018 International Powertrains, Fuels and Lubricants Meeting, FFL 2018. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2018-September
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Konferensbidrag (refereegranskat)abstract
- Partially premixed combustion (PPC) in internal combustion engine as a low temperature combustion strategy has shown great potential to achieve high thermodynamic efficiency. Methanol due to its unique properties is considered as a preferable PPC engine fuel. The injection timing to achieve methanol PPC conditions should be set very close to TDC, allowing to utilize spray-bowl interaction to further improve combustion process in terms of emissions and heat losses. In this study CFD simulations are performed to investigate spray-bowl interaction for a number of different piston designs and its impact on the heat transfer and the overall piston performance. The validation case is based on a single cylinder heavy-duty Scania D13 engine with a compression ratio 15. The operation point is set to low load 5.42 IMEPg bar with SOI -3 aTDC. After satisfactory agreement with experiments in terms of combustion phasing, in-cylinder pressure and heat release rate, the effect of piston bowl geometry is investigated by performing several CFD simulations with modified piston bowl geometry while keeping the compression ratio, CA50 and injection conditions the same as the baseline case. The influence of the wall temperature gradient, the near wall effective conductivity and the piston bowl area on the heat transfer is studied. It was observed that the flow structures that re-direct the hot vapor away from the in-cylinder walls will reduce the wall area that actively transfer the heat. The final piston performance comparison showed that piston bowl designs with a reduced area to volume ratio does not guarantee lower heat loss. Therefore, the mixing process as the result of the spray-bowl interaction and the resulting fuel distribution are considered as the main mechanisms to minimize the total heat losses.
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| 13. |
- Shamun, Sam, et al.
(författare)
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Alternative Fuels for Particulate Control in CI Engines
- 2018
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Ingår i: Engine Exhaust Particulates. - Singapore : Springer Singapore. - 9789811332982 - 9789811332999 ; , s. 181-181
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Bokkapitel (refereegranskat)abstract
- It is widely known that diesel combustion in a compression ignition (CI) engine produces and emits a significant amount of particulate matter (PM) which contributes to degradation in both health and environment. The origin of the soot formation depends on several factors, however, the main source of the soot emissions is the combustion of the diesel fuel itself. To circumvent this issue, studies have been conducted to explore and exploit the advantages of fuels with a lower sooting tendency. Around the world, the utilization of oxygenated biodiesels, such as fatty acid methyl esters (FAME), have been increasing to allow the reduction of PM emissions alongside the net CO2. Due to the FAMEs oxygen content, the fuel is oxidized more readily during the combustion process and thus emitting a significantly lower engine out concentration of PM emission than that of commercial diesel fuel. The utilization of the lighter alcohol fuels, methanol and ethanol neat and blended, is a good option to reduce the soot to zero levels. The reduction of soot to near zero levels introduces another advantage; the soot-NOx trade-off diminishes completely when utilizing exhaust gas recycling (EGR). The issue, however, is that the PN emission of nucleation mode particles is high when utilizing such fuels while ignition is hard to achieve with high octane number fuels in a CI engine.
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| 14. |
- Shamun, Sam
(författare)
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Characterization of the Combustion of Light Alcohols in CI Engines : Performance, Combustion Characteristics and Emissions
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Alternative fuels for combustion engines are becoming increasingly popular as society is pushing to phase out fossil energy to reduce CO2 emissions. The compression ignition (CI) engine has a high overall efficiency which makes it a valuable option for the transport fleet, despite the well known NOx and soot pollutants it emits. These two pollutants are emitted due to a combination of high local combustion temperature and low level of premixing prior to the combustion of diesel fuel. Based on previous work, it is well known that high research octane number (RON) fuels, such as gasoline, can be used in an CI engine to increase the premixing thus reducing the engine-out soot emissions, and to a certain extent, also NOx. Apart from reducing the regulated emissions, the automotive industry is also focusing on developing CI engines that run at a higher efficiency and emit less CO2, which can be achieved by using biomass based fuel, either neat or in blends. Methanol and ethanol are two good examples of such fuels. The idea of using light alcohols to run a CI engine did not arise recently; in Sweden, ethanol has been used in this engine type to run city buses since the mid 1980's. However, it is worth mentioning that the research of their use in CI engines has not been extensive. This work aims to investigate the performance, combustion characteristics and emissions of CI engines running on light alcohols, either neat or in blends with diesel, to study the advantages and drawbacks. The purpose is to better understand how the potential of these fuels can be further exploited while simultaneously finding ways to minimize the drawbacks of their use. The light alcohols, and in particular methanol, have a high heat of vaporization in combination with a low heating value. This contributes to a cooler combustion which also causes an extensive enleanment of the charge. The cooler combustion increases the efficiency by reducing the heat losses. The excessive enleanment, on the other hand, increases the total hydrocarbon (THC) and CO emissions. Moreover, the combustion instability increases. The findings of this work suggests that it is possible to counter these drawbacks, by increasing the intake temperature, Tin. This could be achieved by using a turbocharger without extensive intercooling. The higher Tin reduces the premixing period and improves the stability, resulting in increased oxidation of THC and CO. The drawback of this strategy is, however, an increased formation of NOx. For similar intake conditions, methanol combustion resulted in a 50 % reduction of NOx in comparison to iso-octane due to the its charge cooling effect. A double injection strategy can be used to reduce the required Tin, however, this will come at a cost of lower thermal efficiency due to the longer combustion duration. Another viable option to reduce the required Tin is by using a high compression ratio, rc. The resulting increase in NOx can be countered with EGR. However, if rc is too high, operating flexibility is reduced due to restrictions in structural integrity; for example, high lambda alongside high EGR rates will be limited to lower loads. The light alcohols do not produce black carbon soot when combusted, thus significantly lower particulate matter (PM) emissions, which makes them a good alternative to the heavier diesel fuels. On the other hand, the particle number (PN) emission is generally higher than that of conventional gasoline or diesel. It is worth noting that the emitted PN only consist of particles with a diameter 30 nm as measured with a fast particle analyzer. Furthermore, an observation of the emitted PM under a transmission electron microscope, using energy dispersive X-ray, strongly suggested that the origin of the PM was the lubrication oil rather than the combustion products of the light alcohols. The light alcohols have shown some noteworthy results in terms of efficiency and emissions. In this work, a gross indicated efficiency of approx. 53 % was achieved by using a high rc=27 piston and 50 % EGR at 6 bar IMEPg.
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| 15. |
- Shamun, Sam, et al.
(författare)
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Detailed characterization of particulate matter in alcohol exhaust emissions
- 2017
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Ingår i: COMODIA 2017 - 9th International Conference on Modeling and Diagnostics for Advanced Engine Systems. - 2424-2918.
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Konferensbidrag (refereegranskat)abstract
- A way to reduce net CO2 emission and circumvent the high particle emissions from compression ignition (CI) engines, while retaining high efficiency, is by utilizing lighter alcohols in the partially premixed combustion (PPC) process. Methanol and ethanol have a very short carbon chain, and form less soot/particulate matter (PM) during combustion compared to diesel fuel. This study analyzes and compares the characteristics of PM emissions from methanol, ethanol and diesel in terms of soot mass concentration, number concentration and particle size distribution in one cylinder of a six cylinder Scania D13 heavy duty (HD) engine under two operating loads; 6 bar and 10 bar gross mean indicated effective pressure (IMEPG). An electrostatic precipitator (ESP) was used to sample PM on copper grids for transmission electron microscopy (TEM) and energy dispersive X-ray analysis. Also, new and used lubrication oil together with methanol and diesel were analyzed for their sulphur and metal content. Nucleation mode and the majority of accumulation mode particles from methanol and ethanol combustion, showed mainly Ca, S, P and Zn in the energy dispersive X-ray spectrometry (EDX) analysis and were hypothesized to be emitted mainly from the lubrication oil rather than the combustion of the fuel itself. From diesel combustion, the accumulation mode particles were more abundant in comparison with the alcohols and PM/soot emissions measured with the photo-acoustic technique were 3 to 10 times higher than for the alcohols. There were also fewer nucleation mode particles present; although they consisted of the same four abovementioned elements. Utilizing alcohols in CI engines have a great advantage regarding PM, particle number emissions and efficiency. However, the resulting nucleation mode particles need to be reduced to avoid future health concerns.
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| 16. |
- Shamun, Sam, et al.
(författare)
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Exhaust PM Emissions Analysis of Alcohol Fueled Heavy-Duty Engine Utilizing PPC
- 2016
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Ingår i: SAE International Journal of Engines. - : SAE International. - 1946-3936 .- 1946-3944. ; 9:4, s. 2142-2152
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Tidskriftsartikel (refereegranskat)abstract
- The focus has recently been directed towards the engine out soot from Diesel engines. Running an engine in PPC (Partially Premixed Combustion) mode has a proven tendency of reducing these emissions significantly. In addition to combustion strategy, several studies have suggested that using alcohol fuels aid in reducing soot emissions to ultra-low levels. This study analyzes and compares the characteristics of PM emissions from naphtha gasoline PPC, ethanol PPC, methanol PPC and methanol diffusion combustion in terms of soot mass concentration, number concentration and particle size distribution in a single cylinder Scania D13 engine, while varying the intake O2. Intake temperature and injection pressure sweeps were also conducted. The fuels emitting the highest mass concentration of particles (Micro Soot Sensor) were gasoline and methanol followed by ethanol. The two alcohols tested emitted nucleation mode particles only, whereas gasoline emitted accumulation mode particles as well. Regarding soot mass concentration measurements; methanol never exceeded 1.6 mg/m3 while when operating on gasoline this value never descended below 1.6 mg/m3. From this result it can be concluded that the main contributor to PM mass emissions is mainly increasing CMD (Count Mean Diameter) in the accumulation mode size range, but can in diffusion combustion also be caused by a high amount of nucleation mode particles. A probable cause of higher particle number emissions, when running the engine on methanol compared to ethanol, is the corrosiveness of the fuel itself. Except for the ultra-low PM mass emitted from alcohol combustion, it is also possible to alter the EGR concentration with a higher level of freedom without having to consider the NOX - soot tradeoff.
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| 17. |
- Shamun, Sam, et al.
(författare)
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Experimental investigation of methanol compression ignition in a high compression ratio HD engine using a Box-Behnken design
- 2017
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 209, s. 624-633
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Tidskriftsartikel (refereegranskat)abstract
- Methanol is an alternative fuel offering a lower well-to-wheel CO2 emission as well as a higher efficiency, given that the fuel is derived from biomass. In addition to reduced CO2, methanol does not emit soot particles when combusted which is a great advantage when attempting to reduce NOX levels due to the effectively non-existing NOX-soot trade-off. The engine setup used was a Scania D13 engine modified to run on one cylinder, utilizing a high compression piston with a rc of 27:1. This study analyzes the effects of four control parameters on gross indicated efficiency and the indicated specific emissions; CO, THC and NOX. The control parameters chosen in this work was common rail pressure (PRAIL), EGR, λ and CA50, running at 6 bar IMEPG and 1200 rpm. The effects of the control parameters on performance and emissions was analyzed using a surface response method of the Box-Behnken type. Predictive mathematical models were obtained from regression analysis performed on the responses from the experiments. The highest gross indicated efficiency achieved was ∼53%, when a high level of EGR was applied together with the combustion phasing set to its low level at CA50 = 6 CAD ATDC. The control parameters influencing the CO emissions are λ and the interaction between PRAIL and λ, while THC is only controlled by PRAIL and EGR. NOX emissions was, as expected, influenced mainly by EGR and λ, although PRAIL and CA50 also had minor effects. The effect of increased PRAIL, increased THC emissions which in its turn reduced the gross indicated efficiency. Throughout the experiment, THC concentration never decreased below ∼150 ppm due to utilization of high rc in combination with the volatility of methanol. It was also concluded that a rc = 27 is rather high if operation flexibility is required, especially at the higher load range.
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| 18. |
- Shamun, Sam, et al.
(författare)
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Performance and emissions of diesel-biodiesel-ethanol blends in a light duty compression ignition engine
- 2018
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 145, s. 444-452
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Tidskriftsartikel (refereegranskat)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, biodiesel and EtOH in the ratio of 68:17:15 and 58:14:30 has been utilized and studied in a single cylinder light duty (LD) CI engine in terms of efficiency and emissions. The reasons of utilizing biodiesel in the fuel blend is due to the emulsifying properties it has while the origin of the fuel is biomass. 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. The oxygenates, in particular the fuel with the higher concentration of EtOH, showed an net indicated efficiency of ∼52% at high load in comparison to diesel which never exceeded ∼48%. Regarding the emissions, several trends were observed; the soot-NOX trade-off diminished significantly when utilizing the fuel with the highest concentration of EtOH. The charge cooling effect reduces the NOX emissions while the exhaust particles are reduced both in terms of mean diameter and quantity. At lower loads, the THC and CO emissions were higher for the oxygenated blends than for the diesel due to the earlier mentioned charge cooling negatively affecting the combustion process. However, this trend seized at the higher loads when the in-cylinder temperature is higher and oxidation of the fuel is enhanced.
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| 19. |
- Shamun, Sam, et al.
(författare)
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Quantification and Analysis of the Charge Cooling Effect of Methanol in a Compression Ignition Engine Utilizing PPC Strategy
- 2018
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Ingår i: ASME 2018 Internal Combustion Engine Division Fall Technical Conference. - 9780791851982
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Konferensbidrag (refereegranskat)abstract
- The charge cooling effect of methanol was studied and compared to that of iso-octane. The reduction in compression work due to fuel evaporation and the gain in expansion work were evaluated by the means of in-cylinder pressure measurements in a HD CI engine. A single injection strategy was utilized to obtain a longer premixing period to adequately capture the cooling effect. The effect was clear for both tested fuels, however, methanol generally caused the pressure to reduce more than iso-octane near TDC. It was found that the contribution of reduced compression work to the increased net indicated efficiency is negligible. Regarding the expansion work, a slower combustion with higher pressure was obtained for methanol in comparison to that of iso-octane due to the cooling effect of fuel evaporation. As a result from this, a lower heat transfer loss was obtained for methanol, in addition to the significantly lower NOx emissions.
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| 20. |
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| 21. |
- Shen, Mengqin, et al.
(författare)
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Measurement of gasoline exhaust particulate matter emissions with a wide-range EGR in a heavy-duty diesel engine
- 2019
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Ingår i: Technical Paper - WCX SAE World Congress Experience. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019
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Konferensbidrag (refereegranskat)abstract
- A large number of measurement techniques have been developed or adapted from other fields to measure various parameters of engine particulates. With the strict limits given by regulations on pollutant emissions, many advanced combustion strategies have been developed towards cleaner combustion. Exhaust gas recirculation (EGR) is widely applied to suppress nitrogen oxide (NOx) and reduce soot emissions. On the other hand, gasoline starts to be utilized in compression ignition engines due to great potential in soot reduction and high engine efficiency. New engine trends raise the need for good sensitivity and suitable accuracy of the PM measurement techniques to detect particulates with smaller size and low particulate mass emissions. In this work, we present a comparison between different measurement techniques for particulate matter (PM) emissions in a compression ignition engine running on gasoline fuel. A wide-range of EGR was used with lambda varied from 3 down to 1. The compared equipment includes AVL smoke meter, AVL Micro Soot Sensor, Pegasor and Cambustion Differential Mobility Spectrometer (DMS). The goal of this paper is to compare the recorded values and show the sensitivity of the instruments to soot properties altering, in both lean and stoichiometric combustion situations.
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| 22. |
- Shukla, Pravesh Chandra, et al.
(författare)
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Investigation of Particle Number Emission Characteristics in a Heavy-Duty Compression Ignition Engine Fueled with Hydrotreated Vegetable Oil (HVO)
- 2018
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Ingår i: SAE Technical Papers. - : SAE International. - 0148-7191. ; 11:4, s. 495-505
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Tidskriftsartikel (refereegranskat)abstract
- Diesel engines are one of the most important power generating units these days. Increasing greenhouse gas emissions level and the need for energy security has prompted increasing research into alternative fuels for diesel engines. Biodiesel is the most popular amongst the alternatives for diesel fuel as it is biodegradable, renewable and can be produced domestically from vegetable oils. In recent years, hydro-treated vegetable oil (HVO) has also gained popularity due to some of its advantages over biodiesel such as higher cetane number, lower deposit formation, storage stability etc. HVO is a renewable, paraffinic biobased alternative fuel for diesel engines similar to biodiesel. Unlike biodiesel, the production process for HVO involves hydrogen as catalyst instead of methanol which removes oxygen content from vegetable oil. A modified 6-cylinder heavy-duty diesel engine (modified for operation with single cylinder) was used for studying particle number emission characteristics for HVO fuel. The investigation was performed for varying fuel injection pressure at various engine operating loads (6, 8, 10, 12 and 14 bar IMEP). Five rail pressures were chosen from 800 to 2000 bar at a step of 300 bar. The results show that increase in rail pressure tends to increase nucleation mode particle number concentration (quantify the increase) while increase in engine load results in higher total particle number concentration. No significant differences were observed in soot and oxides of nitrogen (NOx) emission for HVO compared to mineral diesel. The fraction of emitted particles in the nucleation mode was observed to increase with increasing fuel injection pressure.
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| 23. |
- Svensson, Erik, et al.
(författare)
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Potential Levels of Soot, NOx, HC and CO for Methanol Combustion
- 2016
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Methanol is today considered a viable green fuel for combustion engines because of its low soot emissions and the possibility of it being produced in a CO2-neutral manner. Methanol as a fuel for combustion engines have attracted interest throughout history and much research was conducted during the oil crisis in the seventies. In the beginning of the eighties the oil prices began to decrease and interest in methanol declined. This paper presents the emission potential of methanol. T-Φ maps were constructed using a 0-D reactor with constant pressure, temperature and equivalence ratio to show the emission characteristics of methanol. These maps were compared with equivalent maps for diesel fuel. The maps were then complemented with engine simulations using a stochastic reactor model (SRM), which predicts end-gas emissions. The SRM was validated using experimental results from a truck engine running in Partially Premixed Combustion (PPC) mode at medium loads. The SRM was able to predict the combustion in terms of pressure trace and rate of heat release. The CO and NOx emissions were matched, however, the HC emissions were underestimated. Finally, the trajectories from the SRM simulations were superimposed on the T-Φ maps to investigate the in engine conditions. The T-Φ map analysis shows that emission of soot are non-existent, formaldehyde can be avoided and that emissions of methane are kept at, compared to diesel combustion, low levels, however CO and NOx levels are similar to diesel combustion. These results were confirmed for engine conditions by the SRM simulations and the engine experiments.
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| 24. |
- Yin, Lianhao, et al.
(författare)
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Sensitivity Analysis of Partially Premixed Combustion (PPC) for Control Purposes
- 2015
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Ingår i: SAE Technical Paper. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Partially Premixed Combustion (PPC) is a promising advanced combustion mode for future engines. In order to investigate the sensitivity of PPC to exhaust gas recirculation (EGR) rate, intake gas temperature, intake gas pressure, and injection timing, these parameters were swept individually at three different loads in a single cylinder diesel engine with gasoline-like fuel.A factor of sensitivity was defined to indicate the combustion's controllability and sensitivity to inlet gas parameters and injection timings. Through analysis of experimental results, a control window of inlet gas parameters and injection timings is obtained at different loads in PPC mode from 5 bar to 10 bar IMEPg load at 1200 rpm.To further study the PPC controllability with injection timing, main injection timing was adjusted to sustain steady combustion phasing subject to perturbation of inlet gas state. Experimental results show that the main injection timing can resist the interference of intake parameters and maintain constant combustion phasing. Injection timing control is a promising approach to maintain high engine efficiency and low emission levels during transient operation.
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| 25. |
- Zincir, Burak, et al.
(författare)
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Investigation of effects of intake temperature on low load limitations of methanol partially premixed combustion
- 2019
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Ingår i: Energy and Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 33:6, s. 5695-5709
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Tidskriftsartikel (refereegranskat)abstract
- Methanol has unique properties as a fuel, and partially premixed combustion has promising results with high engine efficiency and low emissions. Low load studies with methanol partially premixed combustion are scarce, and the effect of intake temperature on low load methanol partially premixed combustion still remains an intriguing question. This study aims to investigate the effect of intake temperature on low load limitations of methanol partially premixed combustion by an experimental study. The engine was operated at 800 rpm under two different loads. The low load condition was performed at 3 bar Indicated mean effective pressure (IMEP), and the idle condition was commenced at 1 bar IMEP. From the results, it was seen that the intake temperature affected engine stability, engine performance, and engine emissions. The combustion stability decreased with the decrease of intake temperature. The ignition delay became longer and the peak cylinder pressure became smaller with lower intake temperature. The combustion efficiency reduced with the decrease of intake temperature from 0.99 to 0.96 at 3 bar IMEP, whereas it decreased from 0.99 to 0.98 at 1 bar IMEP for the single injection case and the split injection case. The thermodynamic efficiency remained constant at 0.43 at 3 bar IMEP, decreased from 0.30 to 0.28 at 1 bar IMEP for the single injection case, and reduced from 0.26 to 0.24 at 1 bar IMEP for the split injection case. The gross indicated efficiency increased from 0.41 to 0.42 at 3 bar IMEP, whereas it reduced from 0.29 to 0.28 and 0.26-0.24 at 1 bar IMEP at single injection and split injection, respectively. Total hydrocarbon emission increased, NOX emission decreased or remained constant, and CO emission remained constant with the decrease in intake temperature. Finally, the combustion phasing study was performed at 1 bar IMEP at constant intake temperature to determine the effect of the start of injection timing on the engine's performance and the emissions under the idle condition.
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