| 1. |
- Lundgren, Marcus, et al.
(författare)
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Optical study on combustion transition from HCCI to PPC with gasoline compression ignition in a HD engine
- 2016. - April
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Ingår i: SAE 2016 World Congress and Exhibition. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. ; 2016-April
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Konferensbidrag (refereegranskat)abstract
- The partially premixed combustion (PPC) concept has shown high efficiency with low soot emissions. However, the in-cylinder phenomena are still to be explained and evaluated for further progress in the research. This work studies the start of combustion process during a transition from homogenous charge compression ignition (HCCI) to PPC. The process is visualized using a heavy-duty, non-swirling engine modified for optical access. High speed video was used to capture the natural luminosity of the combustion. The fuel used was PRF87. Single and double injection strategies were used at a load kept to the moderate level of 7.5 bar IMEPg. Single injections were swept from early HCCI to retarded PPC conditions whilst running a cycle to cycle temperature sweep, to capture the effect of injection timing and temperature differences simultaneously. Results show that retarded injections show less cycle-to-cycle variation due to temperature variations. Advanced in-bowl injections show a stochastic behavior in the location of the first combustion, due to large variations in local fuel rich zones. For the double injection case the main injection cools the bulk temperature and hence delays the start of combustion before igniting in the fuel rich zones.
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| 2. |
- Wang, Zhenkan, et al.
(författare)
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Simultaneous 36 kHz PLIF/chemiluminescence imaging of fuel, CH2O and combustion in a PPC engine
- 2019
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 37:4, s. 4751-4758
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Tidskriftsartikel (refereegranskat)abstract
- The requirements on high efficiency and low emissions of internal combustion engines (ICEs) raise the research focus on advanced combustion concepts, e.g., premixed-charge compression ignition (PCCI), partially premixed compression ignition (PPCI), reactivity controlled compression ignition (RCCI), partially premixed combustion (PPC), gasoline compression ignition (GCI) etc. In the present study, an optically accessible engine is operated in PPC mode, featuring compression ignition of a diluted, stratified charge of gasoline-like fuel injected directly into the cylinder. A high-speed, high-power burst-mode laser system in combination with a high-speed CMOS camera is employed for diagnostics of the autoignition process which is critical for the combustion phasing and efficiency of the engine. To the authors' best knowledge, this work demonstrates for the first time the application of the burst-system for simultaneous fuel tracer planar laser induced fluorescence (PLIF) and chemiluminescence imaging in an optical engine, at 36 kHz repetition rate. In addition, high-speed formaldehyde PLIF and chemiluminescence imaging are employed for investigation of autoignition events with a high temporal resolution (5 frames/CAD). The development of autoignition together with fuel or CH2O distribution are simultaneously visualized using a large number of consecutive images. Prior to the onset of combustion the majority of both fuel and CH2O are located in the recirculation zone, where the first autoignition also occurs. The ability to record, in excess of 100 PLIF images, in a single cycle brings unique possibilities to follow the in-cylinder processes without the averaging effects caused by cycle-to-cycle variations.
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| 3. |
- Andersson, Hans, 1962-
(författare)
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Organisering för individualitet : transparenta och opaka aspekter i utvecklingsprocesser
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The doctoral dissertation 'Organising for individuality - transparent and opaque aspects of development processes' deals with the relationship between a company's ability to develop new products and its ability to change the way it organises its product development activities. The dissertation is based on a real time study of two product development and two organizational change processes at Orrefors Kosta Boda AB.The company has a tradition of innovative product development based on a high degree of individuality. In this study, individuality refers to situations where differences between individuals' (i.e. designers') distinctive features are important for a company's success and not to individuals talents or capabilities per se.In studying and analysing the product deveopment processes an (opaque) underlying thought structure appears in terms of a tension between 'a separating and a unifying logic of effectiveness'. The two logics of effectiveness constituted underlying assumptions and answers to the question of how to be an innovative and commercially successful company in the high quality glass industry.The product development was conducted in an "inescapable" tension of separating and unifying, indicating that the separating and unifying logics of effectiveness should - in the context of product development - be viewed as a 'neccessary relation of incompatibility' rather than mutually exclusive.In spite of two attempts to change the organising of the product development in the company, the measures taken did not alter any fundamental conditions of the product development within the company, and therefore not the problems the change initiatives were designed to address.In the literature on product development and innovation scholars require research with an approach that links structural conditions to action and interaction. Using Archer's (1995) morphogenetic perspective to relate product development to organizational change, this dissertation is an attempt to do this.
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| 4. |
- Andersson, Öivind, et al.
(författare)
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Crank Angle Resolved HC Detection Using LIF in the Exhausts of Small Two-Stroke Engines Running at High Engine Speed
- 1996
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Ingår i: SAE Transactions, Journal of Engines. - 0096-736X. ; 105:961927
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Tidskriftsartikel (refereegranskat)abstract
- In order to separate the HC-emissions from two-stroke engines into short-circuit losses and emissions due to incomplete combustion, Laser Induced Fluorescence (LIF) measurements were performed on the exhaust gases just outside the exhaust ports of two engines of different designs. The difference between the two engines was the design of the transfer channels. One engine had "finger" transfer channels and one had "cup handle" transfer channels. Apart from that they were similar. The engine with "finger" transfer channels was earlier known to give more short-circuiting losses than the other engine, and that behavior was confirmed by these measurements. Generally, the results show that the emission of hydrocarbons has two peaks, one just after exhaust port opening and one late in the scavenging phase. The spectral information shows differences between the two peaks and it can be concluded that the latter peak is due to short-circuiting and the earlier due to incomplete combustion. The flow outside the exhaust port was measured with Laser Doppler Velocimetry (LDV). These measurements confirm the occurrence of two emission peaks.
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| 5. |
- Andersson, Öivind
(författare)
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Development and Application of Laser Techniques for Studying Fuel Dynamics and NO Formation in Engines
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Development and application of some laser techniques for the study of engine combustion are presented. The investigations mainly cover two aspects: fuel dynamics and formation of NO. Fuel dynamics is one of the most central problems in engine design since many performance parameters are affected by it; emission formation, efficiency, drivability etc. The studies include cycle-resolved measurements of short-circuiting losses in two-stroke engines, mixture stratification in a direct-injection gasoline engine, and mixture formation in DI diesel engines. NO is one of the most harmful pollutants from combustion and is subject to tightening emission regulations. Absolute NO concentrations were determined in a near-production spark ignition engine, and a two-photon detection scheme was evaluated for use in practical applications. Furthermore, an alternative fuel for diesel engines, DME, was investigated with respect to optical properties and fuel properties when used in DI diesel engines. One of the major advantages of using laser diagnostics in this context is their unique capability of providing simultaneous multi-point information in two dimensions, e.g. on species concentrations. They also feature superior spatial and temporal resolution and are, almost always, non-intrusive. The use of probe sampling to determine species concentrations yields lower resolution in space and time and inevitably disturbs flows and temperature fields.
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| 6. |
- Andersson, Öivind, et al.
(författare)
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Laser-Rayleigh Imaging of DME Sprays in an Optically Accessible DI Diesel Truck Engine
- 2001
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Ingår i: SAE Technical Paper 2001-01-0915. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
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Konferensbidrag (refereegranskat)abstract
- Laser-Rayleigh imaging has been employed to measure the relative fuel concentration in the gaseous jet region of DME sprays. The measurements were performed in an optically accessible diesel truck engine equipped with a common rail injection system. A one-hole nozzle was used to guarantee that the recorded pressure history was associated with the heat release in the imaged spray. To compensate for the low compression ratio in the modified engine the inlet air was preheated. Spray development was studied for two levels of preheating, from the start of injection to the point where all fuel was consumed. The results indicate that there is a strong correlation between the amount of unburned fuel present in the cylinder and the rate of heat release at a given time. The combustion can not be described as purely premixed or purely mixing-controlled at any time, but always has an element of both. After all fuel appears to have vanished there is still an extended period of heat release. This indicates a rich combustion yielding combustible products.
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| 7. |
- Andersson, Öivind, et al.
(författare)
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Quantitative Imaging of Equivalence Ratios in DME Sprays Using a Chemically Preheated Combustion Vessel
- 2000
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Ingår i: SAE technical paper series, paper 2000-01-5785. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
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Konferensbidrag (refereegranskat)abstract
- Dimethyl Ether (DME) has proved to be a promising fuel for diesel engines. It virtually eliminates particulate emissions and reduces the formation of nitrogenous oxides, without negatively affecting engine efficiency. Obtaining a deeper understanding of the mechanisms behind these properties is thus highly desirable. Various authors have suggested that the low NO emissions associated with DME are an effect of the mixing conditions, which are thought to differ from those of diesel sprays. To examine this, laser-Rayleigh imaging was employed for quantitative measurement of the local equivalence ratios in DME sprays. The quantitative images were analyzed using a statistical approach, in which probability distributions of ϕ -values for burning and for non-reacting sprays were compared. It was concluded that the diffusion flame is established in the stoichiometeric or slightly lean regions of the spray. Measurements were performed in an isochoric combustion vessel chemically preheated by igniting a lean mixture of CO and oxygen-enriched air. A multizone combustion model was used to analyze the DME combustion and the effects of preheating on the vessel atmosphere. The benefits and drawbacks of this set-up are discussed.
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| 8. |
- Andersson, Öivind, et al.
(författare)
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The greenhouse gas emissions of an electrified vehicle combined with renewable fuels: Life cycle assessment and policy implications
- 2021
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619. ; 289, s. 116621-116621
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Tidskriftsartikel (refereegranskat)abstract
- A life cycle assessment is presented for a current vehicle’s greenhouse gas impact when using a combination of electrification and renewable fuels. Three degrees of electrification are considered: a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a battery-electric vehicle. These are combined with fuels with various degrees of renewable content, representing a fossil fuel, a first-generation biofuel and a second-generation biofuel. For charging, the 2020 European electricity mix is used and compared with an electricity mix of low greenhouse-gas intensity. Renewable fuels are found to have a greater potential to reduce the life-cycle greenhouse gas emissions than a low carbon electricity mix. The results are discussed in terms of the supply potential for renewable fuels on the fleet level. It is found that plug-in hybrid vehicles may enable the automotive sector to reach more ambitious climate goals than battery-electric vehicles. An assessment is also made of how the life cycle greenhouse gas emissions compare with the emissions as measured by current policy instruments. The discrepancies indicate that current climate policy instruments are inadequate for minimizing the automotive sector’s climate impact and suggestions for improvements are made.
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