Michele Gambino

Effect of Ethanol Content on Thermal Efficiency of a Spark-Ignition Light-Duty Engine

The use of bioethanol in the transport sector can contribute to mitigate the greenhouse gas emissions of the vehicles. To achieve this goal, together with a positive energy balance in global productive process of ethanol (well to tank), it is important that adding ethanol to gasoline does not cause a worsening of the efficiency of the internal combustion engine (tank to wheel). In this paper, a research activity on a commercial spark-ignition light-duty engine at the test bench is reported. The aim of the work was to characterize the effect of different bioethanol/gasoline blends on engine behaviour. Blends until 85% of ethanol were tested. Comparative studies of combustion development of gasoline and gasoline/ethanol blends at different concentrations have been made through the analysis of pressure cycles in combustion chamber. Moreover, emissions were collected and analyzed. Emissions downstream of the catalyst, measured with the blends, resulted quite similarly to the gasoline case. Instead, upstream the catalyst a reduction of emissions, proportional to oxygenated content was noted. Moreover, a general carbon dioxide reduction with ethanol blends was achieved due in particular to better engine thermal efficiency.

Low-Polluting, High-Efficiency, Mixed Fuel/ Natural Gas Engine for Transport Application

Mixed fuel (MF) technology was the first way proposed for natural gas (NG) utilization in heavy-duty transportation. The unsolved problems of high levels of unburned hydrocarbons (THC) and the low amount of possible substitution of diesel oil with NG lead to the renouncing of this technology in favour of spark ignited full NG engines. In many situations, mixed fuel could represent the only way to access the environmental benefits connected to NG use in the transport sector. Therefore, a new generation of mixed fuel systems was developed and analysed the effects of intake throttling, catalytic exhaust gases and exhaust gas recycling (EGR). In the present paper, the influence of each component on performance and emissions is evaluated and the results on the regulated test, for a heavy-duty engine, are reported.

LEAN BURN NATURAL GAS ENGINES AS A POSSIBLE POWER UNIT IN URBAN FLEETS OF HEAVY DUTY VEHICLES WITH LOW ENVIRONMENTAL IMPACT

This work aimed to examine the possibility of creating natural gas urban bus fleets by applying lean burn technology. Different engine configurations were tested, keeping in consideration the necessity to ensure suitable performance, and to meet the European regulations. With the target torque and power, the severe European limits were not met only for methane emissions. In addition, the GWI (global warming impact) values were also computed and compared with proposed limits expressly conceived for natural gas engines. The results showed that the NG lean burn engine at the present state of development does not appear able to meet the future requirements of both low NOx emissions and GWI, because of the difficulty of resolving the trade-off between NOx and HC.

Research Into The Use Of A Lean Burn And AStoichiometric Heavy Duty Engine Fuelled With ABlend Of Hydrogen And Natural Gas

Energy sustainability implies the increase of share of renewable sources, as well as the reduction of inefficiencies during generation and distribution. However, a large use of renewable intermittent energy sources, such as solar and wind, in power plants and in small generators distributed could complicate the electrical grid. An important aspect of the impact of electrical networks operating on the distribution system concerns the regulation of voltage. In the case of surplus of electricity decentralized production, energy storage could be a viable solution. In this scenario the production of hydrogen by electrolysis as energy carrier, with oxygen as a byproduct, can become appealing. Hydrogen in urban areas could easily be used in blends with natural gas in urban vehicle fleets. This solution is flexible regarding the amount of hydrogen available and in any case natural gas is the best choice for the internal combustion engine for urban fleets. The use of natural gas in stoichiometric or lean burn engines guarantees a very low level of toxic emissions and zero particulate matter without the need of a trap, even after the vehicle has accumulated a considerable mileage. In particular, only the NOx emissions are harmful, since the emission of hydrocarbons are mainly composed of methane, which is not toxic to human health. In this paper the effect of the addition of hydrogen to natural gas, in the amount of 15% by volume, on the emission of a stoichiometric and a lean burn heavy duty engine was studied. The tests were carried out on the European transient cycle. The results show that with the stoichiometric engine no special attention must be put in the supply change while with the lean burn engine the problem of poor NOx control suggests adjusting the calibration of ignition; with the aim of not compromising the engine emission.

Gaseous Biofuels from Waste: Low Environmental and Toxicological Impact with Maximum Benefit on the Greenhouse Effect

This paper on using gaseous biofuels from waste is from the proceedings of 14th international Conference on Urban Transport and the Environment in the 21st Century, which was held in Malta in 2008. The authors note that biomethane, which can be used in existing natural gas engines, supports vehicles with low environmental and toxicological impact, would be particularly suitable for urban area operation (fleets of cars, buses and trucks), and can satisfy the more stringent regulation limits that are being put in place worldwide. They maintain that on-site biomethane production, through anaerobic digestion or future gasification-methanization plants, will allow the problem of gas distribution to be overcome when a natural gas grid is not widely diffused. The capture and use of biomethane derived from the organic waste matter decomposition process allows a significant reduction of greenhouse gas emissions into the atmosphere. The authors also consider the problems of land use competition, the efficiency of biomass utilization, second generation technologies that leave edible fractions of plants for food use, improvements in hydrogen production by dark fermentation, the direct production of methane/hydrogen mixtures, and the development of gas engines with higher efficiency and further reduced emissions.

Using Natural Gas/Hydrogen Mixture as a Fuel in a 6-Cylinder Stoichiometric Spark Ignition Engine

Hydrogen added to natural gas improves the process of combustion with the possibility to develop engines with higher performance and lower environmental impact. In this chapter, experimental analyses on multi-cylinder heavy duty engines, fuelled with natural gas–hydrogen blends, are reported. Theoretical aspects on engine performance are illustrated and a formula to evaluate the benefit of H2 addition on NG combustion is defined. Experimental data on the effects of air index and exhaust gas recycling on combustion with different NG/H2 blends are discussed followed by an experimental comparison of stoichiometric and lean-burn strategies on the European transient cycle for heavy duty emission certification. Results of the study indicate that a right metering of hydrogen into the natural gas and an optimization of the charge dilution provides not only a reduction in tailpipe CO2 emissions and a more complete combustion process with a lower formation of THC and CO, but also a possible increase in engine efficiency, avoiding abnormal combustion phenomena.

Feasibility of a Dual-Fuel Engine Fuelled with Waste Vegetable Oil and Municipal Organic Fraction for Power Generation in Urban Areas

Biomass, in form of residues and waste, can be used to produce energy with low environmental impact. It is important to use the feedstock close to the places where waste are available, and with the shortest conversion pathway, to maximize the process efficiency. In particular waste vegetable oil and the organic fraction of municipal solid waste represent a good source for fuel production in urban areas. Dual fuel engines could be taken into consideration for an efficient management of these wastes. In fact, the dual fuel technology can achieve overall efficiencies typical of diesel engines with a cleaner exhaust emission. In this paper the feasibility of a cogeneration system fuelled with waste vegetable oil and biogas is discussed and the evaluation of performance and emissions is reported on the base of experimental activities on dual fuel heavy duty engine in comparison with diesel and spark ignition engines. The ratio of biogas potential from MSW and biodiesel potential from waste vegetable oil was estimated and it results suitable for dual fuel fuelling. An electric power installation of 70 kW every 10,000 people could be achieved.