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Using alternative fuels like Natural Gas (NG) has shown good potentials on heavy duty engines. Heavy duty NG engines can be operated either lean or stoichiometric diluted with EGR. Extending Dilution limit has been identified as a beneficial strategy for increasing efficiency and decreasing emissions. However dilution limit is limited in these types of engines because of the lower burnings rate of
The behavior of Ethanol and seven fuels in the boiling point range of gasoline but with an Octane Number spanning from 69 to 99 was investigated in Partially Premixed Combustion. A load sweep was performed from 5 to 18 bar gross IMEP at 1300 rpm. The engine used in the experiments was a single cylinder Scania D12. To allow high load operations and achieve sufficient mixing, the compression ratio w
It is tractable to increase the torque for an HCCI engine and one way is to add a turbocharger. Operating in HCCI mode requires accurate control of the combustion phasing, CA50. The higher the engine torque, the narrower the CA50 window becomes where HCCI operation is maintained. As the CA50 varies stochastically between cycles this requires improved CA50 control for turbo HCCI engines. The main f
By using a turbo the operating range of the HCCI engine can be increased, but at the expense of increased controller complexity. The dynamics the turbo introduces in the intake and the exhaust manifolds, have a large impact on the in-cylinder mixture temperature, pressure and finally the combustion phasing. To compensate for this and to maintain desired combustion phasing, precise control of the n
For diesel engines the major exhaust problem is particulate matter and NOx emissions. To reduce NOx, exhaust gas recirculation (EGR) is often used. The behavior of the EGR-level will therefore influence the emissions and it is therefore valuable to keep track of the EGR-level. Especially during transients it is difficult to predict how the EGR-level varies. In this paper the CO2-level in the intak
Partially Premixed Combustion (PPC) is a combustion concept by which it is possible to get low smoke and NOx emissions simultaneously. PPC requires high EGR levels and injection timings sufficiently early or late to extend the ignition delay so that air and fuel mix extensively prior to combustion. This paper investigates the operating region of single injection diesel PPC in a multi cylinder heav
A diesel engine developed for an international market must be able to run on different fuels considering the diesel fuel qualities and the increasing selection of biofuels in the world. This leads to the question of how different fuels perform relative to a standard diesel fuel when not changing the hardware settings. In this study five fuels (Japanese diesel, MK3, EN590 with 10% RME, EN590 with 3
Natural gas and hydrogen enriched natural gas has been tested as fuels together with diesel oil and RME in a single cylinder Scania research engine. The gas was introduced as port injection while the diesel was introduced as early direct injection. Because the gas was premixed with air before combustion and the diesel was injected early in the compression stroke, the engine ran close to HCCI mode.
In HCCI you do not have the same control of the combustion like in SI and Diesel engines. Controlling the start of a combustion event is a difficult task and requires feedback from previous cycles. This feedback can be retrieved from ion current measurements. By applying a voltage over the spark gap, ions will lead a current and a signal that represents the combustion in the cylinder will be retri
Utilization of an ethanol driven, combustion-based power generator promises high-efficiency combustion in diesel-like engines and avoids problems connected to shrinking supplies of fossil fuels since fuels like ethanol or dimethyl ether can be produced from renewable resources. Fuel injection into such generator through a piezoelectric micro mass flow controller (MMFC) features low power consumpti
A piezoelectric micro mass flow controller (MMFC) for liquid fuel injection into a mini-HCCI-motor for power generation is introduced. Piezoelectric actuation ensures negligible power consumption for fuel injection allowing self-sustaining operation. A pressurized fuel tank is connected to the MMFC which is designed like a normally-closed, on-/off-operating valve. Integrated piezoresistors are use
This work has focused on studying the in-cylinder pressure fluctuations caused by rapid HCCI combustion and determine what they consist of. Inhomogeneous autoignition sets up pressure waves traversing the combustion chamber. These pressure waves induce high gas velocities which causes increased heat transfer to the walls or in worst case engine damage. In order to study the pressure fluctuations a
In vivo dosimetry of IMRT from Copenhagen University Hospital
An estimation model which uses the gross heat release data and the fuel energy to estimate the total amount of emissions and unburned Hydro Carbon (HC) is developed. Gross heat release data is calculated from a self-tuned heat release method which uses in-cylinder pressure data for computing the energy released during combustion. The method takes all heat and mass losses into account. The method e
Popular Abstract in Swedish Traditionellt sett har man tänkt sig att gradvisa förändringar i yttre miljöfaktorer leder till lika gradvisa ekosystemförändringar, men vi vet nu att ekosystem som utsätts för mänsklig påverkan eller klimatförändringar kan reagera kraftigt och abrupt genom att ett ekologiskt tröskelvärde överskrids varvid en förändring sker från en stabil ekologisk situation till en anRegime shifts in lake ecosystems can occur in response to both abrupt and continuous climate change, and the imprints they leave in palaeolimnological records allow us to investigate and better understand patterns and processes governing ecological changes on geological time scales. This thesis aims at investigating palaeolimnological records of regime shifts in lakes during the Holocene to explor
OBJECTIVE: To assess the reliability of knee extensor and flexor muscle strength measurements in persons with late effects of polio. DESIGN: A test-retest reliability study. SUBJECTS: Thirty men and women (mean age 63 (standard deviation 6.4) years) with verified late effects of polio. METHODS: Knee extensor and flexor muscle strength in both lower limbs were measured twice 7 days apart using a Bi
Popular Abstract in Swedish Prosodi och intonation är viktiga delar i det mänskliga talet. I system för text-till-talomvandling och automatisk taligenkänning måste prosodiska modeller inkluderas för att uppnå acceptabla resultat. Denna avhandling bidrar till modelleringen av svensk prosodi ur lexikalt och akustiskt perspektiv. Tre aspekter av lexikal modellering av prosodi studeras. Vi skisserar Prosody and intonation are very important ingredients of human speech. In speech technology, text-to-speech (TTS) and automatic speech recognition (ASR) systems must incorporate prosodic models in order to reach acceptable performances. We contribute to the modelling of Swedish prosody in a speech technology context from lexical and acoustic angles. Three aspects of lexical prosodic modelling are
Sammanfattning Examensarbete i nationaleknomi vid Lunds universitet, kandidatuppsats, HT 2015 Seminariedatum: 2016.01.26 Författare: Henrik Bäckström Handeledare: Dag Rydorff Titel: Tjänar man på att investera sitt studielån? En undersökning av investeringsmöjligheter med lån från tre studiemedelssystem sedan 1981. Nyckelord: CSN, investering med belånat kapital, passiv placeringsstrategi.
