Abstract
During recent years, the exacerbation of greenhouse effect in conjunction with thecontinuous increase of world fleet of vehicles and the crude oil prices stirred interesttowards the improvement of vehicle mileage and the reduction of engine-emittedpollutants. It is well known that diesel engines indicate the highest fuel economy andthus, the highest CO2 reduction potential compared to all other thermal engines due to their higher thermal efficiency. However, diesel engine particulate and NOx emissionsare higher compared to modern spark-ignited engines. For this reason, the reduction ofpollutant emissions and specifically, PM and NOx emissions without increase of specificfuel consumption or without improvement of fuel economy is a difficult task whichnecessitates the implementation of immediate and drastic measures. A direct mean for thereduction of diesel-emitted pollutants without simultaneous deterioration of fuel economyis the reformulation of conventional diesel fuel. One promising path for improving thebehavior of diesel oil is the blending with synthetically or biologically renewableoxygenated fuels.However, since the characteristics of the initial conventional fuels affect directly thebehavior of the resulting mixtures, it is of utmost importance the optimization of thechemical composition and properties of the initial conventional fuel. A vast number ofexperimental and theoretical studies has been conducted in the past, which examined theeffect of chemical synthesis and physical and chemical properties of diesel oil on dieselengine exhaust emissions.The most important fuel characteristics examined in these studies was the aromaticcontent and structure, the sulphur content, the hydrocarbon molecular structure, thecetane number, the heating value, the density, the viscosity and the distillationtemperatures. The effects of the aforementioned fuel properties on diesel-emittedpollutants were evaluated in various types of diesel engines (direct and indirect injection)and diesel vehicles under different operating conditions (steady-state and transient). Itwas shown that the effects of fuel properties on pollutant emissions depend on the enginetype and the operating conditions.In addition, it was revealed that it is extremely difficult to distinguish the individualeffects of each fuel property on diesel exhaust emissions since many of them arestatistically interrelated. Moreover, the impact of fuel properties such as compressibilityfactor and surface tension on diesel engine performance characteristics and pollutantemissions has not been thoroughly examined. For this reason, the purpose of the presentstudy is the examination of the effects of fuel chemical composition and properties ondiesel engine performance parameters and pollutant emissions. Towards this aim,theoretical and experimental results from four European research programs in which ourresearch group has participated during the past years in conjunction with correspondingresults obtained from the literature.During the aforementioned research programs, it was examined both theoreticallyand experimentally the influence of fuel aromatic content and structure as well as of thefuel physical properties on various types of diesel engines under diverse operatingconditions. In contrast to other studies, the present study focuses on the investigation ofthe effects of fuel characteristics not only on legislated diesel-emitted pollutants but alsoon fuel injection system, on combustion process and on pollutant formation insidecombustion chamber. In addition, it is investigated the background and the procedure ofvarious statistical approaches, which have been used in the literature to identify possiblecorrelations between fuel properties and exhaust emissions.The conclusions of these statistical evaluations will be compared against statisticalmethods used by our research group to statistically correlate diesel-emitted pollutants andfuel characteristics. The ultimate goal of this review study is the consolidation of existingknowledge in this particular field and the identification of the influence of each one of thecharacteristics of conventional diesel oils on engine performance parameters andpollutant emissions.
Original language | English |
---|---|
Title of host publication | Diesel Fuels |
Subtitle of host publication | Characteristics, Performances and Environmental Impacts |
Publisher | Nova Science Publishers, Inc. |
Pages | 1-59 |
Number of pages | 59 |
ISBN (Print) | 9781626188662 |
Publication status | Published - Mar 2013 |
Externally published | Yes |
Keywords
- Diesel engine
- Fuel
- Performance
- Pollutant emissions