Dazzled by diesel? The impact on carbon dioxide emissions of the shift to diesels in Europe through 2009

This paper identifies trends in new gasoline and diesel passenger car characteristics in the European Union between 1995 and 2009. By 2009 diesels had captured over 55% of the new vehicle market. While the diesel version of a given car model may have as much as 35% lower fuel use/km and 25% lower CO₂ emissions than its gasoline equivalent, diesel buyers have chosen increasingly large and more powerful cars than the gasoline market. As a result, new diesels bought in 2009 had only 2% lower average CO₂ emissions than new gasoline cars, a smaller advantage than in 1995. A Laspeyres decomposition investigates which factors were important contributors to the observed emission reductions and which factors offset savings in other areas. More than 95% of the reduction in CO₂ emissions per km from new vehicles arose because both diesel and gasoline new vehicle emissions/km fell, and only 5% arose because of the shift from gasoline to diesel technology. Increases in vehicle mass and power for both gasoline and diesel absorbed much of the technological efficiency improvements offered by both technologies. We also observe changes in the gasoline and diesel fleets in eight EU countries and find changes in fuel and emissions intensities consistent with the changes in new vehicles reported. While diesel cars continue to be driven far farther than gasoline cars, we attribute only some of this difference to a “rebound effect”. We conclude that while diesel technology has permitted significant fuel savings, the switch from gasoline to diesel in the new vehicle market contributed little itself to the observed reductions in CO₂ emissions from new vehicles.     

Determination of ecological efficiency in internal combustion engines: The use of biodiesel

This paper evaluates and quantifies the environmental impact from the use of some renewable fuels and fossils fuels in internal combustion engines. The following fuels are evaluated: gasoline blended with anhydrous ethyl alcohol (anhydrous ethanol), conventional diesel fuel, biodiesel in pure form and blended with diesel fuel, and natural gas. For the case of biodiesel, its complete life cycle and the closed carbon cycle (photosynthesis) were considered. The ecological efficiency concept depends on the environmental impact caused by CO₂, SO₂, NO_x and particulate material (PM) emissions. The exhaust gases from internal combustion engines, in the case of the gasoline (blended with alcohol), biodiesel and biodiesel blended with conventional diesel, are the less polluting; on the other hand, the most polluting are those related to conventional diesel. They can cause serious problems to the environment because of their dangerous components for the human, animal and vegetable life. The resultant pollution of each one of the mentioned fuels are analyzed, considering separately CO₂, SO₂, NO_x and particulate material (PM) emissions. As conclusion, it is possible to calculate an environmental factor that represents, qualitatively and quantitative, the emissions in internal combustion engines that are mostly used in urban transport. Biodiesel in pure form (B100) and blended with conventional diesel as fuel for engines pollute less than conventional diesel fuel. The ecological efficiency for pure biodiesel (B100) is 86.75%; for biodiesel blended with conventional diesel fuel (B20, 20% biodiesel and 80% diesel), it is 78.79%. Finally, the ecological efficiency for conventional diesel, when used in engines, is 77.34%; for gasoline, it is 82.52%, and for natural gas, it is 91.95%. All these figures considered a thermal efficiency of 30% for the internal combustion engine.     

Plug-in hybrid fuel cell vehicles market penetration scenarios

The main objective of this research is to analyze the impact of the market share increase of hydrogen based road vehicles in terms of energy consumption and CO₂, on today's Portuguese light-duty fleet. Actual yearly values of energy consumption and emissions were estimated using COPERT software: 167112 TJ of fossil fuel energy, 12213 kton of CO₂ emission and 141 kton of CO, 20 kton of HC, 46 kton of NO_x and 3 kton of PM. These values represent 20–40% of countries total emissions. Additionally to base fleet, three scenarios of introduction of 10–30% fuel cell vehicles including plug-in hybrids configurations were analysed. Considering the scenarios of increasing hydrogen based vehicles penetration, up to 10% life cycle energy consumption reduction can be obtained if hydrogen from centralized natural gas reforming is considered. Full life cycle CO₂ emissions can also be reduced up to 20% in these scenarios, while local pollutants reach up to 85% reductions. For the purpose of estimating road vehicle technologies energy consumption and CO₂ emissions in a full life cycle perspective, fuel cell, conventional full hybrids and hybrid plug-in technologies were considered with diesel, gasoline, hydrogen and biofuel blends. Energy consumption values were estimated in a real road driving cycle and with ADVISOR software. Materials cradle-to-grave life cycle was estimated using GREET database adapted to Europe electric mix. The main conclusions on CO₂ full life cycle analysis is that light-duty vehicles using fuel cell propulsion technology are highly dependent on hydrogen production pathway. The worst scenario for the current Portuguese and European electric mix is hydrogen produced from on-site electrolysis (in the refuelling stations). In this case full life cycle CO₂ is 270 g/km against 190 g/km for conventional Diesel vehicle, for a typical 150,000 km useful life.     

Modeling the CO2 emissions from battery electric vehicles given the power generation mixes of different countries

With the number of vehicles on the world’s roads expected to grow to 2.9 billion by 2050, steps must be taken to reduce the CO₂ emissions from transport. Battery electric vehicles (BEVs) can help achieve this. This study aimed to determine the CO₂ emissions stemming from BEV operation in different countries and to compare those CO₂ emissions to the emissions from similar vehicles based on internal combustion engines (ICEs). This study selected four ICE-based vehicles, and modeled BEVs based on the specifications of each of these vehicles. The modeled BEVs were run through a simulation to determine their energy consumption. Their energy consumption was combined with data on the CO₂ intensity of the power generation mix in different countries to reveal the emissions resulting from BEV operation. The CO₂ emissions from the BEVs were compared to the CO₂ emissions for their ICE-based counterparts. Amongst the results, it was shown that for China and India, and other countries with a similarly high CO₂ intensity, unless power generation becomes dramatically less CO₂ intensive, BEVs will not be able to deliver a meaningful decrease in CO₂ emissions and an increase in the penetration of BEVs could actually lead to higher CO₂ emissions.     

Electric and plug-in hybrid vehicles influence on CO2 and water vapour emissions

The main objective of this research is to quantify the impact of introducing electric vehicles and plug-in hybrid vehicles, including fuel cell on conventional fleets. The impact is estimated in terms of local pollutants, HC, CO, NO_x, PM, and in terms of CO₂ and water vapour global emissions. The specific fleet of Portugal, roughly 6 million light-duty vehicles (30% diesel, 70% gasoline) is considered, and the mobility indicator of the fleet, 90 thousand million p × km, is kept constant throughout the analysis. Probability density functions for energy consumption and emissions are derived for conventional, electric and plug-in hybrid vehicles, in charge depleting and charge sustaining modes. The Monte Carlo method is used to obtain average distribution estimates for discounting values of “old vehicles” that are removed from the fleet, and to add average distribution estimates for the “new vehicles” entering the fleet. Considering the actual Portuguese fleet as the reference case, local pollutant emissions decrease by a factor of 10-53%, for 50% fleet replacement. A potential 23% decrease of CO₂ is foreseen, and a potential 31% increase of H₂O emissions is forecasted. Life cycle water vapour emissions tend to rise and are, typically, 2-4 times higher than CO₂ values at the upstream stage, due to its release in the cooling towers of thermal power plants. It is interesting to note that considering 1 MJ of energy required at vehicle wheels, in an overall life cycle context, both fuel cell and electric modes have nearly twice as much H₂O emissions than internal combustion vehicles. CO₂ emissions tend to decrease with electric drive vehicles penetration due to the higher fleet life cycle efficiency.     

Cost and CO2 aspects of future vehicle options in Europe under new energy policy scenarios

New electrified vehicle concepts are about to enter the market in Europe. The expected gains in environmental performance for these new vehicle types are associated with higher technology costs. In parallel, the fuel efficiency of internal combustion engine vehicles and hybrids is continuously improved, which in turn advances their environmental performance but also leads to additional technology costs versus today’s vehicles. The present study compares the well-to-wheel CO₂ emissions, costs and CO₂ abatement costs of generic European cars, including a gasoline vehicle, diesel vehicle, gasoline hybrid, diesel hybrid, plug in hybrid and battery electric vehicle. The predictive comparison is done for the snapshots 2010, 2020 and 2030 under a new energy policy scenario for Europe. The results of the study show clearly that the electrification of vehicles offer significant possibilities to reduce specific CO₂ emissions in road transport, when supported by adequate policies to decarbonise the electricity generation. Additional technology costs for electrified vehicle types are an issue in the beginning, but can go down to enable payback periods of less than 5 years and very competitive CO₂ abatement costs, provided that market barriers can be overcome through targeted policy support that mainly addresses their initial cost penalty.     

Influence of fuel type,dilution and equivalence ratio on the emission reduction from the auto-ignition in an Homogeneous Charge Compression Ignition engine

One technology that seems to be promising for automobile pollution reduction is the Homogeneous Charge Compression Ignition (HCCI). This technology still faces auto-ignition and emission-control problems. This paper focuses on the emission problem, since it is incumbent to realize engines that pollute less. For this purpose, this paper presents results concerning the measurement of the emissions of CO, NO_x, CO₂, O₂ and hydrocarbons. HCCI conditions are used, with equivalence ratios between 0.26 and 0.54, inlet temperatures of 70 °C and 120 °C and compression ratios of 10.2 and 13.5, with different fuel types: gasoline, gasoline surrogate, diesel, diesel surrogate and mixtures of n-heptane/toluene. The effect of dilution is considered for gasoline, while the effect of the equivalence ratio is considered for all the fuels. No significant amount of NO_x has been measured. It appeared that the CO, O₂ and hydrocarbon emissions were reduced by decreasing the toluene content of the fuel and by decreasing the dilution. The opposite holds for CO₂. The reduction of the hydrocarbon emission appears to compete with the reduction of the CO₂ emission. Diesel seemed to produce less CO and hydrocarbons than gasoline when auto-ignited. An example of emission reduction control is presented in this paper.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Modeling the prospects of plug-in hybrid electric vehicles to reduce CO2 emissions

This study models the CO₂ emissions from electric (EV) and plug-in hybrid electric vehicles (PHEV), and compares the results to published values for the CO₂ emissions from conventional vehicles based on internal combustion engines (ICE). PHEVs require fewer batteries than EVs which can make them lighter and more efficient than EVs. PHEVs can also operate their onboard ICEs more efficiently than can conventional vehicles. From this, it was theorized that PHEVs may be able to emit less CO₂ than both conventional vehicles and EVs given certain power generation mixes of varying CO₂ intensities. Amongst the results it was shown that with a highly CO₂ intensive power generation mix, such as in China, PHEVs had the potential to be responsible for fewer tank to wheel CO₂ emissions over their entire range than both a similar electric and conventional vehicle. The results also showed that unless highly CO₂ intensive countries pursue a major decarbonization of their power generation, they will not be able to fully take advantage of the ability of EVs and PHEVs to reduce the CO₂ emissions from automotive transport.     

Suitability analysis of advanced diesel combustion concepts for emissions and noise control

During the last years, the preservation of the atmospheric environment has played an increasingly important role in society. The Diesel engine can be considered an environmentally friendly engine because of its low consumption and the subsequent carbon dioxide (CO₂) emissions reduction. However, in the near future it will face strong restrictive emission standards, which demand that the current nitrogen oxides (NO_x) and soot emissions are halved. To comply with these restrictions new combustion concepts are emerging, such as PCCI (premixed charge compression ignition), in which the fuel burns in premixed conditions. Combustion noise is thus deteriorated and consequently end-users could be reluctant to drive vehicles powered with Diesel engines and their potential for environment preservation could be missed. In this paper, Diesel combustion is addressed through the analysis of performance, emissions and combustion noise in order to evaluate the suitability of PCCI engines for automotive applications. The results show that PCCI combustion offers great possibilities to fulfill future emission restrictions, but the engine noise is strongly deteriorated. The great sensitivity of users to this factor requires vehicle manufacturers to focus their efforts on the optimization of passive solutions for implementing the PCCI concept in passenger car and light-duty engines, even with the subsequent increase in the cost of vehicle. This aspect is less restrictive in heavy-duty engines, since the great benefits in emissions reduction compensate the deterioration of engine noise.     

Inserting renewable fuels and technologies for transport in Mexico City Metropolitan Area

This article describes three future scenarios for the potential reduction of CO₂ emissions and associated costs when biogenic ethanol blends and oxygenates are substituted for gasoline, and hybrid, flex fuel and fuel cell technologies are introduced in passenger automobiles (including pickups and sport-utility vehicles (SUVs)) in the densely populated Mexico City Metropolitan Area (MCMA), analyzed up to the year 2030. A reference (REF) scenario is constructed in which most automobiles are driven by internal combustion engines (ICE) fuelled by gasoline. In the first alternative scenario (ALT1), hybrid electric-ICE gasoline-fuelled cars are introduced in 2006. In the same year, ethyl tertiary butyl ether (ETBE) is introduced as a replacement for methyl tertiary butyl ether (MTBE) oxygenate for gasoline. In the second alternative scenario (ALT2), in addition to the changes introduced in ALT1, flex fuel ICE technology fuelled by E85 is introduced in 2008 and electric motor vehicles driven by direct ethanol fuel cells (DEFC) fuelled by E100 in 2013. A comparison between the reference and alternate scenarios shows that while the total number of vehicles is the same in each scenario, energy consumption decreases by 9% (ALT1) and 17% (ALT2), the total non-biogenic CO₂ emissions drop by 15% (ALT1) and 34% (ALT2), CO₂ mitigation cost is 140.14 $US1997/ton CO₂ (ALT2), and ALT1 has savings and is considered a “no regrets” scenario.     

Emissions reductions using hydrogen from plasmatron fuel converters

Improvements in internal combustion engine and aftertreatment technologies are needed to meet future environmental quality goals. Systems using recently developed compact plasmatron fuel converters in conjunction with state-of-the-art engines and aftertreatment catalysts could provide new opportunities for obtaining substantial emissions reductions. Plasmatron fuel converters provide a rapid response, compact means to transform a wide range of hydrocarbon fuels (including gasoline, natural gas and diesel fuel) into hydrogen-rich gas. Hydrogen-rich gas can be used as an additive to provide NO_x reductions of more than 80% in spark ignition gasoline engine vehicles by enabling very lean operation or heavy exhaust engine recirculation. It may also be employed for cold start hydrocarbon reduction. If certain requirements are met, it may also be possible to achieve higher spark ignition engine efficiencies (e.g., up to 95% of those of diesel engines). These requirements include the attainment of ultra lean, high compression ratio, open throttle operation using only a modest amount of hydrogen addition. For diesel engines, use of compact plasmatron reformers to produce hydrogen-rich gas for the regeneration of NO_x absorber/adsorbers and particulate traps for diesel engine exhaust aftertreatment could provide significant advantages. Recent tests of conversion of diesel fuel to hydrogen-rich gas using a low current plasmatron fuel converter with non-equilibrium plasma features are described.     

CO2 benefit from the increasing percentage of diesel passenger cars. Case of Ireland

The decrease of CO₂ emissions is one way to minimize climate changes. An efficient way to decrease these emissions is the replacement of gasoline passenger cars (PCs) by diesel ones, which emit less CO₂. Most of the member countries of the European Union (EU) have high percentages of new diesel PC registrations; however, this percentage remains less than 17% in Ireland. The benefit on CO₂ emitted from new PCs is studied in the case of an increased diesel penetration in Ireland, after several scenarios using the current and estimated future PC sales and estimated fuel consumption. The results show that, in the case of new PCs, a CO₂ benefit of more than 2.9% can be achieved, if a diesel penetration higher than 30% occurs in the case of the current fleet. If this penetration reaches 50%, this benefit will be higher than 7.4%. Future total CO₂ emissions from new PCs can be partially controlled by the introduction of diesel PC or the replacement of heavy PCs by lighter ones. Future fuel consumption of gasoline and diesel PCs and the percentage of diesel penetration are the key factors for this control.     

Long-term implications of alternative light-duty vehicle technologies for global greenhouse gas emissions and primary energy demands

This study assesses global light-duty vehicle (LDV) transport in the upcoming century, and the implications of vehicle technology advancement and fuel-switching on greenhouse gas emissions and primary energy demands. Five different vehicle technology scenarios are analyzed with and without a CO₂ emissions mitigation policy using the GCAM integrated assessment model: a reference internal combustion engine vehicle scenario, an advanced internal combustion engine vehicle scenario, and three alternative fuel vehicle scenarios in which all LDVs are switched to natural gas, electricity, or hydrogen by 2050. The emissions mitigation policy is a global CO₂ emissions price pathway that achieves 450 ppmv CO₂ at the end of the century with reference vehicle technologies. The scenarios demonstrate considerable emissions mitigation potential from LDV technology; with and without emissions pricing, global CO₂ concentrations in 2095 are reduced about 10 ppmv by advanced ICEV technologies and natural gas vehicles, and 25 ppmv by electric or hydrogen vehicles. All technological advances in vehicles are important for reducing the oil demands of LDV transport and their corresponding CO₂ emissions. Among advanced and alternative vehicle technologies, electricity- and hydrogen-powered vehicles are especially valuable for reducing whole-system emissions and total primary energy.     

Investigation of a hydrogen-assisted combustion system for a light-duty diesel vehicle

Two sets of experiments were conducted to investigate the effects of adding gaseous hydrogen to the intake of compression–ignition (CI) engines fueled with 20% bio-derived/80% petroleum-derived diesel fuel (B20). A 1.3 L, 53 kW CI engine coupled to an eddy-current engine dynamometer was tested first. Data were collected on engine operating parameters, fuel consumption, concentration of total oxides of nitrogen (NO_x) in the exhaust, and exhaust temperature. Eight steady-state operating points were tested with hydrogen flow rates equivalent to 0%, 5%, and 10% of the total fuel energy. In a second set of experiments, the stock gasoline engine of a 2005 Chevrolet Equinox was replaced with a 1.3 L, 66 kW CI engine, and urban drive cycles were run on a chassis dynamometer. The drive cycles were repeated with 0%, 5% and 10% of the fuel energy coming from the fumigated hydrogen. In both experiments, the addition of hydrogen did not result in discernable differences in engine efficiency. In the vehicle testing, there were no noticeable differences in drivability. There were modest reductions in NO_x emissions and increases in exhaust temperature with hydrogen addition. This investigation demonstrates that fumigating relatively small amounts of hydrogen into the intake of a modern diesel engine results in only modest changes in combustion efficiency and emissions with no detrimental effects on vehicle performance or drivability. This strategy can be used to partially offset the use of petroleum-based fuels in light-duty transportation vehicles.     

Impact of energy supply infrastructure in life cycle analysis of hydrogen and electric systems applied to the Portuguese transportation sector

Hydrogen and electric vehicle technologies are being considered as possible solutions to mitigate environmental burdens and fossil fuel dependency. Life cycle analysis (LCA) of energy use and emissions has been used with alternative vehicle technologies to assess the Well-to-Wheel (WTW) fuel cycle or the Cradle-to-Grave (CTG) cycle of a vehicle's materials. Fuel infrastructures, however, have thus far been neglected. This study presents an approach to evaluate energy use and CO₂ emissions associated with the construction, maintenance and decommissioning of energy supply infrastructures using the Portuguese transportation system as a case study. Five light-duty vehicle technologies are considered: conventional gasoline and diesel (ICE), pure electric (EV), fuel cell hybrid (FCHEV) and fuel cell plug-in hybrid (FC-PHEV). With regard to hydrogen supply, two pathways are analysed: centralised steam methane reforming (SMR) and on-site electrolysis conversion. Fast, normal and home options are considered for electric chargers. We conclude that energy supply infrastructures for FC vehicles are the most intensive with 0.03–0.53 MJ_eq/MJ emitting 0.7–27.3 g CO_2eq/MJ of final fuel. While fossil fuel infrastructures may be considered negligible (presenting values below 2.5%), alternative technologies are not negligible when their overall LCA contribution is considered. EV and FCHEV using electrolysis report the highest infrastructure impact from emissions with approximately 8.4% and 8.3%, respectively. Overall contributions including uncertainty do not go beyond 12%.     

An integral evaluation of dieselisation policies for households’ cars

Reducing energy consumption and CO₂ emissions in the transport sector is a priority for Great Britain and other European countries as part of their agreements made in the Kyoto protocol and the Voluntary Agreement. To achieve these goals, it has been proposed to increase the market share of diesel vehicles which are more efficient than petrol ones. Based on partial approaches, previous research concluded that increasing the share of diesel vehicles will decrease CO₂ emissions (see 1 and 18; Zervas, 2006). Unlike these approaches, I use an integral approach based on discrete choice models to analyse diesel vehicle penetration in a broader context of transport in Great Britain. I provide for the first time, empirical evidence which is in line with Bonilla's (2009) argument that only improvements in vehicle efficiency will not be enough to achieve their goals of mitigation of energy consumption and CO₂ emissions. The model shows the technical limitations that the penetration of diesel vehicles faces and that a combination of improvements in public transportation and taxes on fuel prices is the most effective policy combination to reduce the total amount of energy consumption and CO₂ emissions among the analysed dieselisation polices.     

Natural gas as an alternative to crude oil in automotive fuel chains well-to-wheel analysis and transition strategy development

Road transport produces significant amounts of CO₂ by using crude oil as primary energy source. A reduction of CO₂ emissions can be achieved by implementing alternative fuel chains. This article studies CO₂ emissions and energy efficiencies by means of a well to wheel analysis of alternative automotive fuel chains, using natural gas (NG) as an alternative primary energy source to replace crude oil. The results indicate that NG-based hydrogen applied in fuel cell vehicles (FCVs) lead to largest CO₂ emission reductions (up to 40% compared to current practice). However, large implementation barriers for this option are foreseen, both technically and in terms of network change. Two different transition strategies are discussed to gradually make the transition to these preferred fuel chains. Important transition technologies that are the backbone of these routes are traditional engine technology fuelled by compressed NG and a FCV fuelled by gasoline. The first is preferred in terms of carbon emissions. The results furthermore indicate that an innovation in the conventional chain, the diesel hybrid vehicle, is more efficient than many NG-based chains. This option scores well in terms of carbon emissions and implementation barriers and is a very strong option for the future.     

Development of variable timing fuel injection cam for effective abatement of diesel engine emissions

Fossil fuel run diesel engines are being favored in light, medium and heavy duty applications as they exhibit higher fuel conversion efficiencies. Direct injection diesels are still facing challenges to obtain trade-off between oxides of nitrogen and particulate emissions. There are sophisticated strategies such as common rail direct injection, particulate filters with associated sensors and actuators but limited to expensive comfort vehicles. In the present experimental study, a mechanically operated simple component, variable timing fuel injection cam, is designed for a 510 cc automotive type naturally aspirated, water-cooled, direct injection diesel engine. Modifications in the fuel injection cam and gear train are carried out to suit the existing engine configuration. Variable speed tests are carried out for testing the efficacy of component on both engine and chassis dynamometers for performance and emissions. It is observed that the engine which is already retarded could further be retarded with variable timing fuel injection cam. Significant reductions in NO_x and smoke emission levels are achieved. Combined effect of VIC with 7% EGR could reduce CO by about 88%, HC + NO_x by 37% and PM emissions by 90%. The Engine incorporated with the designed component and EGR, successfully satisfied the existing emission norms with improved power and specific fuel consumption.     

Effects of low pressure exhaust gas recirculation on regulated and unregulated gaseous emissions during NEDC in a light-duty diesel engine

Regulated and unregulated gaseous emissions with high pressure and low pressure EGR (exhaust gas recirculation) system were tested in a 4-cylinder, light-duty diesel EURO IV engine typically used in European vehicles. Four different engine calibrations with the low pressure EGR system were studied. Regulated emissions of NO_X, CO, HC and CO₂ were measured for each configuration. Unburned Hydrocarbon Speciation, HCHO (formaldehyde), HCOOH (formic acid) and N₂O (nitrous oxide) were also measured in order to determine the MIR (maximum incremental reactivity) of the gaseous emissions. Pollutants were measured without the DOC (diesel oxidation catalyst) to gather data about raw emissions. When the low pressure EGR system was used, decreases in NO_X, N₂O and fuel consumption were observed and significant increases HC, CO and unregulated emissions; this is the result of a lower intake manifold temperature, which provides a higher gas density which modifies the combustion process. The potential of tropospheric ozone production was higher in all cases when the low pressure EGR was used.