Wyniki wyszukiwania - BazTech

1

Numerical investigation on low calorific syngas combustion in the opposed-piston engine

Pyszczek R., Mazuro P., Jach A., Teodorczyk A.

Combustion Engines

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2017

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R. 56, nr 2

53--63

EN

The aim of this study was to investigate a possibility of using gaseous fuels of a low calorific value as a fuel for internal combustion engines. Such fuels can come from organic matter decomposition (biogas), oil production (flare gas) or gasification of materials containing carbon (syngas). The utilization of syngas in the barrel type Opposed-Piston (OP) engine arrangement is of particular interest for the authors. A robust design, high mechanical efficiency and relatively easy incorporation of Variable Compression Ratio (VCR) makes the OP engine an ideal candidate for running on a low calorific fuel of various composition. Furthermore, the possibility of online compression ratio adjustment allows for engine the operation in Controlled Auto-Ignition (CAI) mode for high efficiency and low emission. In order to investigate engine operation on low calorific gaseous fuel authors performed 3D CFD numerical simulations of scavenging and combustion processes in the 2-stroke barrel type Opposed-Piston engine with use of the AVL Fire solver. Firstly, engine operation on natural gas with ignition from diesel pilot was analysed as a reference. Then, combustion of syngas in two different modes was investigated – with ignition from diesel pilot and with Controlled Auto-Ignition. Final engine operating points were specified and corresponding emissions were calculated and compared. Results suggest that engine operation on syngas might be limited due to misfire of diesel pilot or excessive heat releas which might lead to knock. A solution proposed by authors for syngas is CAI combustion which can be controlled with application of VCR and with adjustment of air excess ratio. Based on preformed simulations it was shown that low calorific syngas can be used as a fuel for power generation in the Opposed-Piston engine which is currently under development at Warsaw University of Technology.

2

Cycle-by-cycle variability in CAI engine with internal EGR and direct gasoline injection

Hunicz J., Gęca M.

Combustion Engines

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2013

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R. 52, nr 3

855--860

EN

Cycle-by-cycle variability in CAI gasoline engine was studied in terms of indicated mean effective pressure and combustion timing variations. Cyclic variability was analyzed for two different engine loads and different injection timings, applied during negative valve overlap. It was found that fluctuations of combustion course and produced indicated work reveal deterministic oscillations, where engine was operated in close to misfire regime. Moreover, kind of correlation between consecutive cycles was found to be affected by fuel injection strategy

PL

W pracy przedstawiono analizę zmienności cyklicznej procesu roboczego benzynowego silnika CAI (controlled auto-ignition) przeprowadzoną na podstawie średniego ciśnienia indykowanego oraz przebiegu spalania. badania przeprowadzono dla dwóch wartości obciążenia silnika oraz różnych kątów początku wtrysku paliwa w czasie ujemnego współotwarcia zaworów. Uzyskane wyniki wykazały występowanie zdeterminowanych oscylacji przebiegu kątowego spalania oraz ilości pacy generowanej w cyklu roboczym w warunkach pracy silnika w pobliżu granicy wypadania zapłonów. Ponadto zaobserwowano, że rodzaj korelacji pomiędzy kolejnymi cyklami zależny jest od strategii wtrysku.

3

An investigation of supercharged CAI engine with internal gas recirculation and direct gasoline injection

Hunicz J., Gęca M.

Silniki Spalinowe

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2012

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R. 51, nr 3

63-71

EN

Influence of boost pressure on combustion process and exhaust emission in controlled auto-ignition (CAI) engine was studied. The examinations were carried out using single-cylinder engine with fully variable valvetrain and gasoline direct injection. In order to achieve auto-ignition in-cylinder temperature was elevated with the use of internal gas recirculation (EGR) obtained via the negative valve overlap (NVO) technique. Fuel dilution obtained via increase of intake pressure resulted in substantial reduction of cylinder-out nitrogen oxides emission. However application of boosting resulted in excessive advance of auto-ignition timing and increase of pressure rate rise (PRR) at higher engine loads.

PL

W artykule przedstawiono analizę wpływu doładowania silnika o kontrolowanym samozapłonie (CAI) na przebieg procesu spalania oraz emisję toksycznych składników spalin. Obiektem badań był jednocylindrowy silnik wyposażony w całkowicie zmienny układ rozrządu oraz bezpośredni wtrysk benzyny do cylindra. Do dostarczania energii niezbędnej do samozapłonu wykorzystano wewnętrzną recyrkulację spalin uzyskaną dzięki ujemnemu współotwarciu zaworów. Rozrzedzenie ładunku w cylindrze, uzyskane w wyniku doładowania, pozwoliło na znaczne obniżenie emisji tlenków azotu. Doładowanie spowodowało jednak nadmierne wyprzedzenie samozapłonu oraz uzyskiwanie znacznych szybkości narastania ciśnienia w cylindrze przy większych obciążeniach silnika.

4

A study of combining gasoline engine downsizing and controlled auto - ignition combustion

Moxey B., Cairns A., Ganippa A., Zhao H., Bassett M.

Journal of KONES

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2012

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Vol. 19, No. 1

289-300

EN

In recent years European automotive CO2 emissions targets have largely been met through increased diesel sales. However, the distillation of crude oil results in high proportions of both gasoline and diesel fuel and ultimately this has resulted in Europe being "diesel lean" at times. In order to meet future global emissions goals, in the short term it will be necessary to improve the fuel consumption of the gasoline engine and in the longer term source sustainable alternatives to crude oil. The objective of the current work was to investigate the optimum trade-off between the opposing engine operating requirements of gasoline engine downsizing and Controlled Auto-Ignition (CAI) combustion for use in a family-sized passenger car. Experimental fuel consumption and emissions data were produced for four sizes of spark ignition engine, varying from 1 to 2 litres in capacity. The additional benefits of two experimentally developed CAI operating methodologies were evaluated in each engine using drive cycle simulation software. The first CAI mode was based on novel use of combined internal and external EGR to attain higher loads. The second involved the adoption of turbocharging at part-load for yet higher output via so-called lean-boosted CAI. It was concluded that, for such a vehicle, a compromise exists where best fuel economy can be obtained from a moderately downsized CAI-capable engine. Compared to the baseline 2 litre engine, it was possible to obtain fuel economy benefit equivalent to that offered from an aggressively downsized 1 litre unit but using a moderately downsized 1.4 litre CAI engine, without the need for any complex boosted operation or expensive emissions aftertreatment systems. As capacity was reduced below 1.4 litres, the benefit of CAI diminished at an accelerated rate due to progressive failure to capture key higher load sites visited across the European drive cycle.

5

A research into a gasoline HCCI engine

Hunicz J., Niewczas A., Kordos P.

Silniki Spalinowe

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2010

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R. 49, nr 1

3-13

EN

Homogeneous charge compression ignition (HCCI) is nowadays a leading trend in the development of gasoline internal combustion engines. The application of this novel combustion system will allow to comply with future legislations concerning the exhaust emissions including carbon dioxide. This paper presents a design and implementation of a research engine with a direct fuel injection and the capability of HCCI combustion via an internal gas recirculation and a negative valves overlap (NVO). The technical approach used in the engine allowed an autonomous HCCI operation at variable loads and engine speeds without the need of a spark discharge. Experiments were conducted at a wide range of valve timings providing data which allowed an assessment of a volumetric efficiency and exhaust gas recirculation (EGR) rate. Permissible range of air excess coefficient, providing stable and repeatable operation has also been identified. The use of direct gasoline injection benefited in the improvement of the start of the combustion (SOC) and heat release rate control via the injection timing.

PL

Kontrolowany samozapłon mieszanki paliwowo-powietrznej jest obecnie dominującym kierunkiem rozwoju silników benzynowych. Zastosowanie tego nowego systemu spalania pozwoli na spełnienie przyszłych norm emisji toksycznych składników spalin oraz dwutlenku węgla. W artykule przedstawiono konstrukcję silnika badawczego umożliwiającego realizację obiegu roboczego HCCI z wewnętrzną recyrkulacją spalin uzyskaną przez ujemne współotwarcie zaworów. Zastosowane rozwiązania techniczne umożliwiły autonomiczną pracę silnika w trybie HCCI przy zmiennych obciążeniach i prędkościach obrotowych, bez konieczności wspomagania zapłonu wyładowaniem iskrowym. Przeprowadzenie badań w szerokim zakresie zmian faz rozrządu pozwoliło na ocenę możliwości regulacji napełnienia cylindra i współczynnika reszty spalin. Określono także zakres współczynnika nadmiaru powietrza, w którym uzyskiwana jest stabilna i powtarzalna praca silnika. Zastosowanie bezpośredniego wtrysku benzyny do cylindra pozwoliło na rozszerzenie możliwości kontroli chwili samozapłonu i szybkości wywiązywania się ciepła przez regulację kąta początku wtrysku.

6

Experimental research of the gasoline engine operated in spark ignition and controlled auto-ignition combustion modes

Hunicz J., Kordos P., Kozaczewski W., Niewczas A.

Silniki Spalinowe

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2009

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R. 48, SC2

258--263

EN

The paper presents results of the preliminary research of the gasoline engine with capability of controlled auto-ignition (CAI) mode of combustion. The research was conducted on the single cylinder engine with fully variable valve train and direct fuel injection. In order to achieve temperature of the in-cylinder load which allows for gasoline auto ignition, exhaust gas trapping technique was applied. The research engine was run with negative valves overlap and valves lift reduced to less than 3 millimeters. In order to control start of ignition and heat release rate different valves timings were applied. Comparison of the spark ignition and controlled auto ignition operation modes was done with the use of in-cylinder pressure, net heat release and incylinder temperature values. Analysis of the measurement data shows substantial decrease of heat release duration and peak in-cylinder temperature in CAI operation mode.