Dataset for comparison between single and double pilot injection in diesel-natural gas dual fuel engine.

The present data article is based on the research work which investigates the low-temperature combustion (LTC) in a dual fuel light duty engine. The LTC mode was activated by means of double pilot injection to control the energy release rate in the first combustion stage, thereby minimizing the increase of the rate of pressure and allowing the operation under LTC. This data article presents all the data which supports the choice for double pilot injection vs single pilot injection for that research. In this experimental work the engine was fueled with diesel, in full-diesel (FD) mode, and in dual fuel (DF) mode with natural gas and natural gas - hydrogen mixtures as main fuel. In DF mode the pilot diesel fuel was injected both with a single and a double injection at the same engine speed and torque. The pressure cycle in one of the four cylinders, the intake manifold pressure and the injector current signal were acquired on a crank angle basis for 100 consecutive engine cycles. Analysis of combustion rate, maximum pressure rise and fuel/air flow rate were performed. The data set, which also includes some engine control parameters, the combustion chamber geometry and some injector features, can potentially be reused to numerically model the combustion phenomena and, in particular, to investigate the effect on the ignition phase of combustion in LTC, also considering the variability from cycle to cycle.

Evaluation of emission toxicity of urban bus engines: compressed natural gas and comparison with liquid fuels.

Emissions from a spark-ignition (SI) heavy-duty (HD) urban bus engine with a three-way catalyst (TWC), fuelled with compressed natural gas (CNG), were chemically analyzed and tested for genotoxicity. The results were compared with those obtained in a previous study on an equivalent diesel engine, fuelled with diesel oil (D) and a blend of the same with 20% vegetable oil (B20). Experimental procedures were identical, so that emission levels of the CNG engine were exactly comparable to the ones of the diesel engine. The experimental design was focused on carcinogenic compounds and genotoxic activity of exhausts. The results obtained show that the SI CNG engine emissions, with respect to the diesel engine fuelled with D, were nearly 50 times lower for carcinogenic polycyclic aromatic hydrocarbons (PAHs), 20 times lower for formaldehyde, and more than 30 times lower for particulate matter (PM). A 20-30 fold reduction of genotoxic activity was estimated from tests performed. A very high reduction of nitrogen oxides (NO(X)) was also measured. The impact of diesel powered transport on urban air quality, and the potential benefits deriving from the use of CNG for public transport, are discussed.

Emission comparison of urban bus engine fueled with diesel oil and 'biodiesel' blend.

The chemical and toxicological characteristics of emissions from an urban bus engine fueled with diesel and biodiesel blend were studied. Exhaust gases were produced by a turbocharged EURO 2 heavy-duty diesel engine, operating in steady-state conditions on the European test 13 mode cycle (ECE R49). Regulated and unregulated pollutants, such as carcinogenic polycyclic aromatic hydrocarbons (PAHs) and nitrated derivatives (nitro-PAHs), carbonyl compounds and light aromatic hydrocarbons were quantified. Mutagenicity of the emissions was evaluated by the Salmonella typhimurium/mammalian microsome assay. The effect of the fuels under study on the size distribution of particulate matter (PM) was also evaluated. The use of biodiesel blend seems to result in small reductions of emissions of most of the aromatic and polyaromatic compounds; these differences, however, have no statistical significance at 95% confidence level. Formaldehyde, on the other hand, has a statistically significant increase of 18% with biodiesel blend. In vitro toxicological assays show an overall similar mutagenic potency and genotoxic profile for diesel and biodiesel blend emissions. The electron microscopy analysis indicates that PM for both fuels has the same chemical composition, morphology, shape and granulometric spectrum, with most of the particles in the range 0.06-0.3 microm.