The impact of transportation sector in terms of fossil fuel consumption and environmental effects is an important topic for the world research community: hydrogen seems to be an energy carrier that could give good alternative to fossil fuels, with the provision that it is produced from renewable energy sources. In order to stimulate the hydrogen economy and to build a bridge towards hydrogen technology, it could be useful to boost its use in blends with natural gas as fuel for internal combustion engines. This way it is possible to gain a know-how on such technology and to create units in fuel stations for hydrogen production and distribution for internal combustion engines or fuel cell vehicles. Hydrogen has a laminar combustion speed about eight times greater than natural gas providing a reduction of combustion duration also when mixed with natural gas in small concentrations: as a consequence, the efficiency of natural gas internal combustion engines increases using natural gas-hydrogen blends (HCNG in the following) as fuel. HCNG blends assure also a reduction of total pollutant emissions: in fact, hydrogen increases combustion stability reducing cyclic variation and unburned hydrocarbon emissions (HC). The increase of combustion stability also allows running the engine with diluted charge without increasing HC emissions. HCNG mixtures contribute to reduce CO2 emissions due to the increased H/C ratio of the fuel and the increase of engine efficiency. An increase in NOx emissions is expected in HCNG fuelled engines due to higher temperatures reached into the cylinder; this adverse effect could be balanced using exhaust gas recirculation retaining a stoichiometric air-fuel ratio and so assuring a good efficiency of the three way catalytic converter. The aim of the present work is to evaluate the impact of HCNG blends on exhaust emissions, fuel consumption and performance of a natural gas vehicle. A passenger car has been tested on a chassis dynamometer according to the European emission regulations: it was fuelled alternatively with natural gas and HCNG mixtures allowing evaluating the effect of hydrogen on pollutant emissions and fuel consumption. Engine performance has been evaluated by means of acceleration test on the chassis dynamometer. The HCNG blends tested in this work have a low hydrogen concentration in order to appreciate the effects of hydrogen in the mixtures without engine setup modifications.
The impact of natural gas-hydrogen blends on internal combustion engines performances and emissions
Mariani A;Prati MV
2009
Abstract
The impact of transportation sector in terms of fossil fuel consumption and environmental effects is an important topic for the world research community: hydrogen seems to be an energy carrier that could give good alternative to fossil fuels, with the provision that it is produced from renewable energy sources. In order to stimulate the hydrogen economy and to build a bridge towards hydrogen technology, it could be useful to boost its use in blends with natural gas as fuel for internal combustion engines. This way it is possible to gain a know-how on such technology and to create units in fuel stations for hydrogen production and distribution for internal combustion engines or fuel cell vehicles. Hydrogen has a laminar combustion speed about eight times greater than natural gas providing a reduction of combustion duration also when mixed with natural gas in small concentrations: as a consequence, the efficiency of natural gas internal combustion engines increases using natural gas-hydrogen blends (HCNG in the following) as fuel. HCNG blends assure also a reduction of total pollutant emissions: in fact, hydrogen increases combustion stability reducing cyclic variation and unburned hydrocarbon emissions (HC). The increase of combustion stability also allows running the engine with diluted charge without increasing HC emissions. HCNG mixtures contribute to reduce CO2 emissions due to the increased H/C ratio of the fuel and the increase of engine efficiency. An increase in NOx emissions is expected in HCNG fuelled engines due to higher temperatures reached into the cylinder; this adverse effect could be balanced using exhaust gas recirculation retaining a stoichiometric air-fuel ratio and so assuring a good efficiency of the three way catalytic converter. The aim of the present work is to evaluate the impact of HCNG blends on exhaust emissions, fuel consumption and performance of a natural gas vehicle. A passenger car has been tested on a chassis dynamometer according to the European emission regulations: it was fuelled alternatively with natural gas and HCNG mixtures allowing evaluating the effect of hydrogen on pollutant emissions and fuel consumption. Engine performance has been evaluated by means of acceleration test on the chassis dynamometer. The HCNG blends tested in this work have a low hydrogen concentration in order to appreciate the effects of hydrogen in the mixtures without engine setup modifications.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
