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EN
Increasing the sustainability of individual transportation and replacing a part of fossil energy in traffic by renewable energy carriers are worldwide important objectives. Bioalcohols are generally recognized as one of very useful alternatives. The global share of bioethanol used for transportation is continuously increasing. Butanol, a four-carbon alcohol, is considered in the last years as an interesting alternative fuel, both for diesel and for gasoline application. Its advantages for engine operation are: good miscibility with gasoline and diesel fuels, higher calorific value than ethanol, lower hygroscopicity, lower corrosivity and possibility of replacing aviation fuels. In the present work, the emissions of two gasoline vehicles – with older and with newer technology – were investigated in dynamic-, stationary and cold start operation.
EN
The particle number (PN) emissions are increasingly considered in the progressing exhaust gas legislation for onand off- road vehicles. The invisible nanoparticles penetrate like a gas into the living organisms and cause several health hazards. The present paper shows how the PN- and gaseous emissions of a modern GDI (Abbreviations see at the end of this paper) vehicle change, when there is an in-creased lube oil consumption. What are the potentials of a gasoline particle filter to reduce the emissions? The lube oil consumption was simulated by mixing 2% vol. lube oil into the fuel. A non-coated GPF was mounted at tailpipe, so only the filtration effects were indicated. The tests were performed at transient (WLTC) and at stationary (SSC) operating conditions. It has been shown that the increased lube oil consumption significantly increases the PN-emissions and the applied high quality GPF eliminates these emissions very efficiently.
3
EN
The nanoparticles (NP) count concentrations are limited in EU for all Diesel passenger cars since 2013 and for gasoline cars with direct injection (GDI) since 2014. For the particle number (PN) of MPI gasoline cars there are still no legal limitations. In the present paper some results of investigations of nanoparticles from five DI and four MPI gasoline cars are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. Moreover, five variants of “vehicle – GPF” were investigated. The PN-emission level of the investigated GDI cars in WLTC without GPF is in the same range of magnitude very near to the actual limit value of 6.0 × 1012 1/km. With the GPF’s with better filtration quality, it is possible to lower the emissions below the future limit value of 6.0 × 1011 1/km. The modern MPI vehicles also emit a considerable amount of PN, which in some cases can attain the level of Diesel exhaust gas without DPF and can pass over the actual limit value for GDI (6.0 × 1012 1/km). The GPF-technology offers in this respect further potentials to reduce the PN-emissions of traffic.
EN
In the present paper, the results and experiences of testing different PEMS on the chassis dynamometer and on-road are presented. In the first part of work the measuring systems were installed on the same vehicle (Seat Leon 1.4 TSI ST) and the results were compared on the chassis dynamometer in the standard test cycles: NEDC, WLTC and CADC. in the second part of work the nanoparticle emissions of three Diesel cars were measured with PN-PEMS. PN-PEMS showed an excellent correlations with CPC in the tests on chassis dynamometer and it indicated very well the efficiency of DPF in eliminating the nanoparticles in real world driving.
EN
Public concern and complaints regarding ambient air in zones of dense traffic pertains to two compounds of nitrogen, nitrogen dioxide (NO2) and ammonia (NH3); both are toxic and strongly irritant, such that legal limitations are under discussion. This paper contributes to measuring methods as already in part proposed by GRPE subgroup WLTP-DTP (Worldwide Light Duty Test Procedures – Diesel Test Procedures) for NO2. Despite legally lowered NOx emission levels, lumping both, NO2 and NO, levels of NO2 have risen in cities and agglomerations as a result of both, deployed catalytic exhaust after-treatment devices and low sulphur Diesel fuels. In present tests two different combinations of NO2 measuring methods as proposed by WLTP were checked on Diesel cars for practicability in handling and accuracy. These integral, indirect methods (NO2 = NOx – NO) have been found as useful tools for estimate of NO2 and with use of appropriate analyzers a satisfactory accuracy was attained. Furthermore, attention was brought to ammonia (NH3) emitted by gasoline engines with three way catalysts (TWC) which ought not to be ignored while on the other hand SCR systems for Diesel engines are strictly regulated. Emission levels of more recent TWC turned out to be mostly below 20 ppm NH3. Vehicle of older technology exhibited significantly higher levels, about 10 times more. As chemical reactions depend on pressure and temperature (= i.e. flow condition in CVS-tunnel) as well as concentrations, doubts need to be considered on accuracy of results based on chemical reactive substances. Nevertheless, clear tendencies regarding changes of concentrations of NO2 and NH3 along the path-way could not be observed.
EN
The well-balanced use of alternative fuels worldwide is an important objective for the sustainable development of individual transportation. Several countries have set objectives to substitute a part of the energy of traffic by ethanol as the renewable energy source. The global share of Bioethanol used for transportation is continuously increasing. Investigations of limited and unregulated emissions of a flex fuel vehicle with gasoline- thanol blend fuel, have been performed in the present work according to the measuring procedures, which were established in the previous research, in the Swiss Network. The investigated fuel contained ethanol (E), in portions of 10% and 85% by volume. The investigated vehicle represented a newer state of technology and an emission level of Euro 5. The engine works with homogenous GDI concept and with 3-W-catalyst (3WC). Since there is special concern about particle emissions of gasoline cars with direct injection, the nanoparticle counts measurements were systematically performed with Scanning Mobility Particle Sizer (SMPS) at stationary and with Condensation Particle Counter (CPC) at dynamic operation. The non-legislated gaseous emissions were tested with Fourier Transform Infrared Spectroscopy (FTIR), with special focus on NH3, N2O and HCHO (Formaldehyde). The main results to be mentioned are: • the particle counts emissions are generally significantly reduced with Ethanol blend fuels at all operating conditions, • in Worldwide Light-duty Test Cycle (WLTC) there is a clear increase of NH3 with E85 and an insignificant tendency of increasing NH3 with E10, • with all fuels (E0, E10 & E85) there are no emissions of N2O and no increase of HCHO (below 1 ppm) observed, in WLTC warm. The present research did not address the durability aspects and cold startability in extreme conditions.
EN
Alcohol-based fuels are promising substitutes for petrol-based fuels to be used in internal combustion engines. Blending of ethanol with gasoline increases the oxygen content of the fuel, allowing a more complete combustion and hence reducing the emissions of several pollutants, but it is not clear if emissions of genotoxic compounds and therefore, the genotoxic potential of an exhaust are also reduced. The gasoline direct injection technology is quickly replacing traditional port fuel injection technologies due to enhanced fuel efficiency and lower CO2 emissions. However, substantial emissions of soot-like particles have been reported in literature. In this study we compared emissions of a Euro-5 GDI vehicle (1.6 L) when operated with gasoline (EO) and two ethanol/gasoline blends (E10 and E85) under transient conditions and study the effects on particle and emissions of polycyclic aromatic hydrocarbons, including those reported to be genotoxic.
8
Content available Nanoparticle research on four gasoline cars
EN
The invisible nanoparticles (NP) from combustion processes penetrate easily into the human body through the respiratory and olfactory ways and carry numerous harmful health effects potentials. NP count concentrations are limited in EU for Diesel passenger cars since 2013 and for gasoline cars with direct injection (GDI) since 2014. The limit for GDI was temporary extended to 6 x 1012 #/km. Nuclei of metals as well as organics are suspected to significantly contribute especially to the ultrafine particle size fractions, and thus to the particle number concentration. In the present paper, some results of investigations of nanoparticles from four gasoline cars – an older one with MPI and three never with DI – are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. The results show that the older vehicle with MPI emits high particle count concentrations. The size distributions of this vehicle are decisively bimodal with high numbers in nuclei mode. The emissions of the newer vehicles with DI show sometimes no typical uniform shape of particle size distributions and are at lower level, than for the older vehicle. There is no visible nuclei mode and the ultrafine particle concentrations below 10 nm are insignificant. Some of the newer, low-emitting vehicles show at constant speed operation a periodical fluctuation of the NPemissions. Increased NP-emissions at cold start were confirmed.
EN
Starting from Euro 6 not only for diesel but also for gasoline vehicles, with direct injection technology (GDI) a solid particle number emissions limit of 6 × 1011#/km becomes effective. The limit was temporary extended for GDI to 6 x 1012#/km. Nuclei of metals as well as organics are suspected to significantly contribute especially to the ultrafine particle size fractions, and thus to the particle number concentration. In the project GasOMeP (Gasoline Organic & Metal Particulates) metal-nanoparticles (including sub 20 nm) from gasoline cars are investigated for different engine technologies. In the present paper some results of basic investigations of nanoparticles from two gasoline cars – an older one with MPI and a never one with DI – are represented. The measurements were performed at vehicle tailpipe, with varying sampling conditions and with different SMPS-systems, which enabled the mobility scanning in different size ranges. The results show that the older vehicle with MPI emits high particle count concentrations. The size distributions are decisively bimodal with high numbers in nuclei mode. In this case, the particle counting below 10 nm yields important information. The emissions of the newer vehicle with DI show no typical uniform shape of particle size distributions and are at lower level, than for the older vehicle. There is no visible nuclei mode and the ultrafine particle concentrations below 10 nm are insignificant. A sampling with a strongly increased primary dilution has a clear influence on the indicated (higher) particle concentrations.
PL
Począwszy od normy Euro 6 wprowadzone zostanie ograniczenie emisji cząstek stałych do 6 × 1011#/km nie tylko dla pojazdów wyposażonych w silniki ZS, ale także dla pojazdów z silnikami ZI z bezpośrednim wtryskiem paliwa (GDI). Dopuszczalna liczba cząstek stałych emitowanych przez pojazdy wyposażone w silniki GDI była tymczasowo zwiększona do 6 × 1012#/km. Cząstki metali, jak również substancje organiczne prawdopodobnie są powodem emisji bardzo małych cząstek stałych, przyczyniając się do zwiększenia liczby emitowanych cząstek stałych. W projekcie GasOMeP (cząstki organiczne i metalowe z silników benzynowych) badana jest emisja nanocząstek metali (również o średnicy < 20 nm) z samochodów wyposażonych w silniki benzynowe różnych generacji. W artykule przedstawiono wyniki badań emisji nanocząstek z dwóch samochodów wyposażonych w silniki benzynowe – starszy z wtryskiem MPI i nowszy z wtryskiem DI. Spaliny pobierano z układu wylotowego pojazdu przy różnych warunkach pomiarowych i z wykorzystaniem urządzeń do pomiaru emisji cząstek stałych o różnych zakresach pomiarowych. Wyniki badań wskazują, że stężenie cząstek stałych w spalinach starszego pojazdu z wtryskiem MPI jest duże. Rozkłady wielkości mają charakter bimodalny z dużymi wartościami w fazie nukleacji. Wtedy istotny jest pomiar liczby cząstek stałych o średnicy mniejszej niż 10 nm. Emisja z pojazdu z wtryskiem typu DI nie wykazuje typowego jednolitego kształtu rozkładu wymiarowego, również liczba cząstek stałych jest mniejsza niż z pojazdu starszego. Nie zauważono znaczącej emisji cząstek w fazie nukleacji, a stężenia cząstek najmniejszych o średnicy poniżej 10 nm są nieznaczne. Pobór próbki spalin przy zastosowaniu dużego współczynnika rozcieńczenia ma zauważalny wpływ na zwiększenie stężenia cząstek stałych.
EN
Nanoparticle emissions of two 2-stroke scooters were investigated along the exhaust- and CVS-system (Constant Volume Sampling) with closed and with open line (cone). Due to their technology, the scooters produce different kind of aerosol (state of oxidation & SOF-content) and in addition to that they were operated with and without oxidation catalyst. The scooters represent a modern technology with direct injection TSDI* ) (two stroke direct injection) and with carburettor. The tests were performed at two constant speeds of the vehicles (20 km/h & 40 km/h) according to the measuring procedures, which were established in the previous research in the Swiss Scooter Network. The nanoparticulate emissions were measured by means of SMPS (CPC) and NanoMet (abbreviations see at the end of this paper). The most important results are: - the changes of the PSD's of the aerosol along the exhaust and CVS-system are connected to the average gas temperature and PC-concentration, which result after the different dilution steps and cooling down in the connecting pipe, - in the "open" variant of exhaust gas extraction there is a dilution step with unfiltered ambient air directly after tailpipe. This causes a stop of agglomeration, reduction of diffusion loses and increased background NPconcentration. There is also lower post oxidation of CO & HC. In some cases spontaneous condensates due to the temperature drop are supposed, - with the "closed" variant there is a stronger reduction of SMPS PC's along the gas way, than with the open variant. This is to explain with the higher temperatures and concentrations in the closed system, which enable more intense thermophoresis - and diffusion losses, - the NP-concentrations measured with "open" variant are always higher, - most intense oxidation is observed with Peugeot Carb: due to the SAS, rich tuning and a relatively high temperature level there are oxidation effects already without catalyst (temp. approx. 350 centigrade). With catalyst the temperature is in the range of 400centigrade and the oxidation is so intense, that the particles are nearly eliminated. The type of sampling: "open", or "closed" as well as the sampling position in the exhaust installation have significant influence on the measured nanoparticles emission results.
EN
The objectives of the present work are to investigate the regulated and unregulated (particle) emissions of a classical and modern 2-stroke and a typical 4-stroke scooter with different ethanol blend fuels. There is also comparison of two different ethanol fuels: pure ethanol (E) and hydrous ethanol (EH) which contains 3.9% water and is denatured with 1.5% gasoline. Special attention is paid in this research to the hydrous ethanol, since the production costs of hydrous ethanol are much less than those for (dry) ethanol.
PL
W artykule przedstawiono badanie uregulowanych i nieuregulowanych prawnie emisji cząstek dla klasycznego i nowoczesnego skutera 2-suwowego i typowego skutera 4-suwowego zasilanych paliwami o różnym udziale etanolu. Ponadto zamieszczono porównanie dwóch różnych paliw etanolowych: czystego etanolu (E) i wodnego etanolu (EH) zawierającego 3,9% wody i skażonego 1,5-procentowym stężeniem benzyny. Szczególnie skupiono się na badaniach wodnego etanolu, od chwili, gdy koszty produkcji etanolu z dodatkiem wody okazały się mniejszy niż etanolu bez takiego dodatku.
EN
The objectives or the present work are to investigate the regulated and unregulated (particle) emissions or a classical and modern 2-stroke and a typical 4-stroke scooter with different ethanol blend fuels. There is also comparison of two different ethanol fuels: pure ethanol (E) and hydrous ethanol (EH) which contains 3.9% water and is denatured with 1.5% gasoline. Special attention is paid in this research to the hydrous ethanol, since the production costs of hydrous ethanol are much less than those for (dry) ethanol. The vehicles are with carburettor and without catalyst, which represents the most frequent technology in Eastern Asia and offers the information or engine-out emissions. Exhaust emissions measurements have been performed with fuels containing ethanol (E), or hydrous ethanol (EH) in the portion of 5, 10, 15 and 20% by volume. During the test systematical analysis of particle mass (PM) and nanoparticles counts (NP) were carried out. The present investigations did not concern the durability or parts exposed to the chemical influences or ethanol. Also the cold start, particularly in extreme conditions and the lube oil dilution were not addressed.
PL
W artykule przedstawiono badanie uregulowanych i nieuregulowanych prawnie emisji cząstek dla klasycznego i nowoczesnego skutera 2-suwowego i typowego skutera 4-suwowego zasilanych paliwami o różnym udziale etanolu. Ponadto zamieszczono porównanie dwóch różnych paliw etanolowych: czystego etanolu (E) i wodnego etanolu (EH) zawierającego 3,9% wody i skażonego 1,5-procentowym stężeniem benzyny. Szczególnie skupiono się na badaniach wodnego etanolu, od chwili, gdy koszty produkcji etanolu z dodatkiem wody okazały się mniejszy niż etanolu bez takiego dodatku. Pojazdy są wyposażone w gaźnikowy układ zasilania i nie posiadają reaktora katalitycznego, co stanowi najczęstsze rozwiązanie konstrukcyjne w Azji Wschodniej, umożliwiając uzyskanie tym samym informacji o emisji z silnika. Pomiary emisji spalin przeprowadzono na paliwach zawierających etanol (E) lub wodny etanol (EH) o udziale objętościowym odpowiednio 5, 10, 15 i 20%. Podczas pomiaru dokonywano systematycznej analizy masy cząstek stałych i liczby nanocząstek (NP). Obecne prace badawcze nie dotyczyły trwałości elementów poddanych chemicznemu oddziaływaniu etanolu. Ponadto nie uwzględniono tzw. "zimnego startu ", szczególnie w warunkach granicznych oraz rozcieńczenia oleju smarującego.
EN
In order to analyze the processes during the gas exchange in the engine, knowledge of pressure states in both inlet and outlet is required. This pressure measuring is known as "low pressure indication ". In the presented work, three examples of controlling the quality of low pressure measurement are presented. The projects performed during the collaboration with Kistler showed the high demands regarding accuracy, dimensions and lifetime of measuring chains and piezoresistive sensors for low pressure measurement. To gain reliable resultsfor use in simulation tools for calculating and modeling gas exchange phase the sensor and measuring chain must be designed in order to consider all possible influences on the signal such as thermal and mechanical stress, electrical parasitic induction and gas dynamic effects. The increasing demand regarding accuracy and low thermal drift for highly dynamic measurements and the restricted space available in most applications are further challenges. It was shown that: a small inaccuracy of measurement, lower than 10 mbar can be attained, the asymmetric course of the exhaust pulse can clearly be verified, and a protection screen for a sensor exposed to the exhaust blow-off pressure wave can be a tool to optimize between longlife and accuracy.
EN
2- and 3-wheelers with 2-S propulsion are still a very serious source of air pollution worldwide in many urban areas. Therefore, every effort to reduce the emissions of those vehicles is an important contribution to improve the air quality. In the present work detailed investigations of regulated emissions and of particle emissions of 2-stroke scooters with direct injection and with carburator were performed. To demonstrate the emission reduction potentials some possibilities of emission improvements were grouped into steps. These technical measures were: - Higher tier lube oils - Lower oil dosing - Active oxidation catalyst - Supplementary filtration & oxidation devise (WFC) - Special fuel. Particle mass and nanoparticles (number), which are amply present in 2-stroke exhaust gas and which contribute strongly to the toxicity level are still unlimited by the international exhaust gas legislation. They were extensively investigated in the present project series. The Toxicity Equivalence (TEQ) of the emitted particle mass was evaluated by means of PAH analysis and comparison with the standards based on benzo[a]pyrene (EPA method). It was demonstrated, that a strong reduction of particle mass emissions and toxicity is possible by means of a combination of these technical measures. There are also further possibilities of improvements, like total filtration or use of alternative fuels. All those technical measures can be effective in the fleet only if the necessary market conditions will be created, like: incentives for better products, production conformity control, in-use compliance control, public information and others.
EN
Four of these Particulate Reduction Systems (PMS) were tested on a passenger car and one of them on a HDV. Expectation of the research team was that they would reach at least a PM-reduction of 30% under all realistic operating conditions. The standard German filter test procedure for PMS was performed but moreover, the response to various operating conditions was tested including worst case situations. Besides the legislated CO, NOx and PM exhaust-gas emissions, also the particle count and NO2 were measured. The best filtration efficiency with one PMS was indeed 63%. However, under critical but realistic conditions filtration of 3 of 4 PMS was measured substantially lower than the expected 30 %, depending on operating conditions and prior history, and could even completely fail. Scatter between repeated cycles was very large and results were not reproducible. Even worse, with all 4 PMS deposited soot, stored in these systems during light load operation was intermittently blown-off. Due to these stochastic phenomena the behaviour of these systems is hardly predictable. Furthermore the provision of NO2, through catalysis ahead of the filter or in the filter matrix, is inherent in these systems. Some of this secondary NO2 is emitted. Cost/benefit ratio is high compared to full-flow filters and Diesel engines equipped with partial-flow filters are inferior to SI engines regarding global warming potential. Based on these findings it is concluded that the sustainable performance of partial-flow filters is not yet determined.
PL
W artykule przedstawiono wyniki badań czterech systemów redukcji cząstek stałych (PMS - Particulate Reduction Systems) zamontowanych w samochodzie osobowym i ciężarowym. Oczekiwanym efektem badań była 30-procentowa redukcja emisji cząstek stałych w rzeczywistych warunkach ruchu. Badania przeprowadzono według niemieckiej procedury badawczej rozszerzonej o badania filtrów w zmiennych warunkach pracy silników. Wykonano pomiary limitowanych normą związków toksycznych (CO, NOx, PM), a także nielimitowanych - NO2 oraz liczby cząstek stałych. Największa zmierzona sprawność filtracji wynosiła 63%. Jednakże w rzeczywistych warunkach ruchu sprawność filtracji dla trzech, z czterech przebadanych, filtrów wynosiła znacznie mniej niż zakładane 30% i jednocześnie zależała od warunków użytkowania pojazdu. Różnice wyników między poszczególnymi pomiarami były znaczne i nie były reprezentatywne. Wszystkie badane konfiguracje systemów redukcji emisji cząstek stałych pozwalały na efektywną filtrację cząstek stałych na obciążeniach częściowych. Ponadto zmiany w stężeniu NO2 przed filtrem w stosunku do stężenia za filtrem są zgodne z przewidywaniami - występuje niewielka wtórna emisja tego związku za filtrem. Wskaźnik kosztów zastosowania filtra do korzyści ekologicznych jest wyższy dla filtrów o pełnym przepływie spalin w stosunku do filtrów o częściowym przepływie spalin, a jednocześnie większy jest również potencjał globalnego ocieplenia. W wyniku przeprowadzonych badań stwierdzono konieczność dalszych badań w zakresie polepszenia właściwości filtrów o częściowym przepływie spalin.
EN
Limited and non-regulated emissions of scooters were analyzed during several annual research programs of the Swiss Federal Office of Environment (RAFU). Small scooters, which are very much used in the congested centers of several cities, are a remarkable source of air pollution. Therefore every effort to reduce the emissions is an important contribution to improve the air quality in urban centers. In the present work detailed investigations of particle emissions of different 2-stroke scooters with direct injection and with carburettor were performed. The nanoparticulate emissions were measured by means of SMPS, (CPC) and NanoMet. Also the particle mass emission (PM) was measured with the same method as for Diesel engines. Extensive analyses of PM-residuum for SOF/INSOF, PAH and toxicity equivalence (TEQ), were carried out in an international project network. Particle mass emission (PM) of 2-S Scooters consists mostly of SOF. The standard coulometric EC/OC-analysis, as well as the analyzer MEXA 1370 PM overestimate the amount of soot due to the effect of "charring", which provokes the heaviest VOC to stay in the sample during the thermal extraction and to be indicated as EC. A solution for this analytical problem is demonstrated. Wiremash Filter Catalyst (WFC) is en efficient measure to intensify the oxidation of the exhaust gas components and to reduce PM, PC, PAH, TEQ and VOC. The presented WFC needs a further development for durability and product integration. WFC is an efficient aftertreatment measure to substantially lower the toxicity of 2-S exhaust gases.
17
Content available remote Influencing (nano)particle emissions of 2-stroke scooters
EN
Limited and nonlimited emissions of scooters were analysed during several annual research programs of the Swiss Agency of Environment Forests and Landscape (SAEFL, BUWAL)*). Small scooters, which are very much used in the congested centres of several cities are a remarkable source of air pollution. Therefore every effort to reduce the emissions is an important contribution to improve the air quality in urban centres. In the present work detailed investigations of particle emissions of different 2-strokescooters with direct injection and with carburettor were performed. The nanoparticulate emissions with different lube oils and fuels were measured by means of SMPS, (CPC) and NanoMet*). Also the particle mass emission (PM) was measured with the same method as for Diesel engines. It can be stated, that the oil and fuel quality have a considerable influence on the particle emissions, which are mainly oil condensates. The engine technology influences the (nano)particle emissions by: mixture preparation, mixture tuning, oil consumption, postoxidation, quality, condition and temperature of the catalyst. Since the particulate emission of the 2-S consists mainly of lube oil condensates the minimization of oil consumption stays always an important goal
18
Content available remote Addition of CNG and reformer gas to the gasoline fuelled SI-engine
EN
Addition of gaseous fuels to the gasoline fuelled SI-engine offers several potentials of improvements, like: cold start without enrichment, lower engineout emissions, in certain cases better strategy of catalyst heating. In the present work some results of investigations with addition of compressed natural gas CNG and of H[2]-containing reformer gases are presented. Two engines were fuelled with different compositions of H[2]-CO-CO[2]-N[2] mixtures as model gases for methanol-, or gasoline- reformed fuels. The investigations were performed at warm, stationary, part load operation. Due to the presence of hydrogen the reformer gas causes more advantages, than CNG. It lowers the gaseous emission components, shortens the combustion duration, increases the combustion stability and enables much more expanded lean-limits and EGR limits. The passive components of the reformer gas (CO[2], N[2]) have similar influence on NO[x]-reduction as the internal EGR. Due to a very low stoichiometric air requirement the reformer gas enables a dethrottling of the engine at part load and consequently an improvement of efficiency.
PL
Dodatek paliw gazowych do zasilanych benzyną silników ZI powoduje szereg potencjalnych ulepszeń, takich jak: zimny start bez wzbogacania, niższy poziom emisji i w pewnych przypadkach lepszą strategię podgrzewania katalizatora. W pracy przedstawiono pewne rezultaty badań z dodatkami sprężonego gazu ziemnego CNG i gazów reformowanych zawierających H[2]. Dwa silniki byty zasilane różnymi mieszaninami H[2] - CO - CO[2] - N[2] jako gazy modelowe dla metanolowych i benzynowych reformowanych paliw. Badania były prowadzone w warunkach nagrzania, stacjonarnych, z częściowym obciążeniem. Z powodu obecności wodoru gaz reformowany zapewniał więcej korzyści niż CNG. Obniżał on emisję składników gazowych, skracał czas spalania, poprawiał stabilność spalania i umożliwiał znaczne rozszerzenie ograniczeń dla mieszanek ubogich i ograniczeń EGR. Pasywne składniki gazu reformowanego (CO[2], N[2]) posiadały podobny wpływ na redukcję NO[x] jak wewnętrzny EGR. Z powodu bardzo niskiego stechiometrycznego wymagania dla powietrza gaz reformowany umożliwia oddławienie silnika przy częściowych obciążeniach i w konsekwencji prowadzi do poprawy sprawności.
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