Characterization and Control of Multi-Cylinder Partially Premixed Combustion

In the last decade diesel combustion has developed in a new direction. Research has been carried out trying to prolong the ignition delay and enhance fuel/air premixing to avoid diffusion combustion as well as lowering the combustion temperature through use of EGR. One of these new combustion concepts is Partially Premixed Combustion (PPC). PPC is aimed to provide combustion with low smoke and NOx without sacrificing fuel consumption. This thesis presents the development of a multi-cylinder PPC concept. It reaches from the basic characterization of this new combustion strategy to the demands on hardware, control and fuels for a realizable PPC solution. In summary it contains a thorough PPC characterization where the results suggest that high EGR, early injection PPC strategies are to prefer over late injection approaches or smokeless rich diesel combustion. Further, a strong connection between mixing period, defined as the period between end of injection and start of combustion, and PPC has been ascertained. Based on this knowledge a combustion controller with feedback control of mixing period was derived. The operating range of multi-cylinder diesel PPC was then evaluated. The study showed that the PPC load range was limited covering only 25% of the operating region for conventional combustion. In order to reach higher loads for PPC the EGR system was rebuilt to a low pressure system. This system improves EGR/air mixing and cooling and enables high EGR and boost pressure simultaneously. Additionally, gasoline fuels were introduced to extend the ignition delay and mitigate soot formation. An extensive fuel comparison was carried out to find the most suitable fuel for PPC operation. With the improved set-up the operating range was reevaluated. By combining the use of a low pressure EGR system and standard gasoline the operating region of PPC has been extended to cover 50% of the engine nominal operating region. The final part of this thesis is dedicated to a novel method of cylinder individual efficiency estimation based on the cylinder pressure trace. With this method, control strategies aiming directly at fuel consumption optimization can be developed. An extremum seeking control algorithm was applied. The results show that the controller manages to find the maximum brake torque region both with and without external excitation. Finally, the estimation error in accumulated fuel consumption from the experiments is around 1% which shows the potential of using the absolute value of the efficiency estimation in other control concepts

Actuator Comparison and Coordination for Integrated Vehicle Dynamics Control

The purpose of this Master's Thesis was to compare and coordinate active chassis systems in a search for new ways of controlling two driving situations; side wind exposure and split friction braking. These situations were to be mastered by three active systems; active steering, brakes and suspension. Examples of how to use the systems were presented for each driving situation. The results from the investigation were then used when designing controllers for the applications. Matlab/Simulink was the key tool for evaluation of the control strategies but tests were also carried out in a real vehicle

Бюллетень новых поступлений за сентябрь 2015 года

I slutet av maj 2014 hölls för åttonde gången direktval till Europaparlamentet och väljare i 28 medlemsstater gick till valurnorna. Trenden med stadigt sjunkande valdeltagande stannade av och närmare 43 procent av väljarna röstade. Som Mark Franklin visade i en Sieps-publikation inför valet förklaras trenden med sjunkande valdeltagande till stor del av att EU har utvidgats och att de medlemsstater som tillkommit har haft ett lägre valdeltagande än de som har varit medlemmar en tid. Därför är den brutna trenden kanske inte så förvånande. Valkampanjen bedrevs i en kontext där den ekonomiska krisen alltjämt påverkade EU starkt. Även om eurozonen gradvis har stabiliserats, är effekterna av krisen alltjämt tydliga. Resultatet återspeglar en reaktion hos väljarna som vi känner igen från tidigare Europaparlamentsval, där större partier, i synnerhet i regeringsställning, gör sämre ifrån sig än vid nationella val. Konsekvensen den här gången blev att den politiska “mitten” tappade och flankerna i det framväxande europeiska partisystemet växte. De EU-kritiska partierna fick stor uppmärksamhet under valrörelsen och valresultaten kan delvis tolkas som en protest mot EU, även om det finns skillnader mellan medlemsstaterna och vilka uttryck kritiken tar sig. De politiska majoritetsförhållandena och utvecklingen inom partigrupperna analyseras i den här publikationen av Magnus Blomgren. I Sverige var valkampanjen intensiv och det påföljande riksdagsvalet hade sannolikt en roll i det. Två nya partier, Feministiskt initiativ och Sverigedemokraterna, lyckades vinna mandat medan Piratpartiet inte lyckades upprepa succén från 2009 och tappade sina mandat. Det svenska resultatet analyseras här av Linda Berg. Texterna i den här publikationen utgörs främst av bearbetningar av bidrag vid seminariet Valet är över – vad händer nu? som arrangerades i Stockholm den 28 maj. Det är min förhoppning att Sieps därmed ska kunna bidra till fördjupad förståelse för Europaparlamentsval och parlamentets funktionssätt. Jörgen Hettne Tillförordnad direktö

Model Predictive Control of Partially Premixed Combustion

Partially premixed combustion is a compression ignited combustion strategy where high exhaust gas recirculation (EGR) levels in combination with early or late injection timing result in a prolonged ignition delay yielding a more premixed charge than with conventional diesel combustion. With this concept it is possible to get low smoke and NOx emissions simultaneously. Accurate control of injection timing and injection duration is however necessary in order to achieve this favorable mode of combustion. This chapter presents a method for controlled PPC operation. The approach is to control the time between end of injection and start of combustion which if positive yields sufficient premixing. Model Predictive Control was used to control the engine which was modeled using System Identification. The results show that it is possible to assure PPC operation in the presence of both speed/load transients and EGR disturbances

Extending the Operating Region of Multi-Cylinder Partially Premixed Combustion using High Octane Number Fuel

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 to extend the ignition delay so that air and fuel mix prior to combustion to a larger extent than with conventional diesel combustion. This paper investigates the operating region of single injection PPC for three different fuels; Diesel, low octane gasoline with similar characteristics as diesel and higher octane standard gasoline. Limits in emissions are defined and the highest load that fulfills these requirements is determined. The investigation shows the benefits of using high octane number fuel for Multi-Cylinder PPC. With high octane fuel the ignition delay is made longer and the operating region of single injection PPC can be extended significantly. Experiments are carried out on a multi-cylinder heavy-duty engine at low, medium and high speed

Cylinder Individual Efficiency Estimation for Online Fuel Consumption Optimization

Engine efficiency is often controlled in an indirect way through combustion timing control. This requires a priori knowledge of where to phase the combustion jiff different operating points and conditions. With cylinder individual efficiency estimation, control strategies aiming directly at fuel consumption optimization can be developed. This paper presents a method to estimate indicated efficiency using the cylinder pressure trace as input. The proposed method is based on a heat release calculation that takes heat losses into account implicitly using an estimated, CAD resolved polytropic exponent. Experimental results from a multi-cylinder engine show that with this approach, the estimated efficiency error is within 5% for all operating points tested. The final part of the paper is a discussion of how to use the efficiency estimation for feedback control. Different control concepts are presented as well as suggestions on how to handle the non-linear connection between combustion timing and indicated efficiency

EU-skeptikernas frammarsch : valet till Europaparlamentet 2014

I slutet av maj 2014 hölls för åttonde gången direktval till Europaparlamentet och väljare i 28 medlemsstater gick till valurnorna. Trenden med stadigt sjunkande valdeltagande stannade av och närmare 43 procent av väljarna röstade. Som Mark Franklin visade i en Sieps-publikation inför valet förklaras trenden med sjunkande valdeltagande till stor del av att EU har utvidgats och att de medlemsstater som tillkommit har haft ett lägre valdeltagande än de som har varit medlemmar en tid. Därför är den brutna trenden kanske inte så förvånande. Valkampanjen bedrevs i en kontext där den ekonomiska krisen alltjämt påverkade EU starkt. Även om eurozonen gradvis har stabiliserats, är effekterna av krisen alltjämt tydliga. Resultatet återspeglar en reaktion hos väljarna som vi känner igen från tidigare Europaparlamentsval, där större partier, i synnerhet i regeringsställning, gör sämre ifrån sig än vid nationella val. Konsekvensen den här gången blev att den politiska “mitten” tappade och flankerna i det framväxande europeiska partisystemet växte. De EU-kritiska partierna fick stor uppmärksamhet under valrörelsen och valresultaten kan delvis tolkas som en protest mot EU, även om det finns skillnader mellan medlemsstaterna och vilka uttryck kritiken tar sig. De politiska majoritetsförhållandena och utvecklingen inom partigrupperna analyseras i den här publikationen av Magnus Blomgren. I Sverige var valkampanjen intensiv och det påföljande riksdagsvalet hade sannolikt en roll i det. Två nya partier, Feministiskt initiativ och Sverigedemokraterna, lyckades vinna mandat medan Piratpartiet inte lyckades upprepa succén från 2009 och tappade sina mandat. Det svenska resultatet analyseras här av Linda Berg. Texterna i den här publikationen utgörs främst av bearbetningar av bidrag vid seminariet Valet är över – vad händer nu? som arrangerades i Stockholm den 28 maj. Det är min förhoppning att Sieps därmed ska kunna bidra till fördjupad förståelse för Europaparlamentsval och parlamentets funktionssätt. Jörgen Hettne Tillförordnad direktö

Investigation and Comparison of Multi Cylinder Partially Premixed Combustion Characteristics for Diesel and Gasoline Fuels

Partially Premixed Combustion is a concept able to combine low smoke and NOx emissions with high combustion controllability and efficiency. It is of interest to be able to utilize PPC in a large operating region in order to meet the Euro VI emission legislation without relying on NOx aftertreatment. This paper investigates the differences in PPC characteristics for three fuels; Diesel Swedish Mk 1, Low Octane Gasoline (70 Octane) and US Standard Gasoline (87 Octane). Engine operating conditions, combustion characteristics, emissions and efficiency are in focus. The experiments were carried out at a range of operating points on a Volvo MD13 which is a six-cylinder heavy-duty engine. At each operating point three combinations of EGR level and λ-value were evaluated. 1. High EGR/High λ, 2. High EGR/Reduced λ, and 3. Reduced EGR/High λ. Further, for all these three conditions, four combustion timings were tested reaching from advanced combustion timing at 3 CAD ATDC to retarded combustion timing at 9 CAD ATDC. The indicated load and the combustion timing were controlled cylinder individually by a feedback controller

Steady state fuel consumption optimization through feedback control of estimated cylinder individual efficiency

Engine efficiency is often controlled in an indirectway through combustion timing control. This requires a prioriknowledge of where to phase the combustion for differentoperating points and conditions. With cylinder individual efficiencyestimation, control strategies aiming directly at fuelconsumption optimization can be developed. It has previouslybeen shown that indicated efficiency can be estimated using thecylinder pressure trace. This paper presents a method to usethe estimated efficiency as a feedback variable in an extremumseeking control strategy for online steady state fuel consumptionoptimization. The experimental results show that the controllermanages to find the maximum brake torque region at the givenoperating point both with and without external excitation