Study on the Performance and Exhaust Emissions of Motorcycle Engine Fuelled with Hydrogen-Gasoline Compound Fuel

Introduction

As global warming and high oil price caught the world’s attention, energy saving and carbon reducing become the major issues around the world. Motorcycle (motorbike, scooter) has been the most popular personal transportation vehicle in Taiwan for the past two decades. More than 50% of the burnt gases from motorcycle exhaust emission are noxious oxidized-carbon, hydrocarbon and nitrogen oxide compounds. Emissions pollution from motorcycle becomes a moving pollutant which is responsible for localized air pollution. Although there have some green techniques been applied to electric vehicle, the disadvantages of electric motorcycle are also reported for its low speed, insufficient torque, short travelling range, time consuming recharged battery and expensive market price. Traditional motorcycles are still on the road and the moving pollutants are still remaining. New energy construction and novel combustion technology are required to develop to save energy and reduce the air pollution.

Many methodologies have been reported to generate hydrogen gas, however, it is a challenge for researchers to safely implement hydrogen gas into transportation vehicle with low cost. Hong, Liauh, Huang, Chao, Hsu, and Lai (2006) developed a Butane-air reformer for hydrogen gas generation in a four-stroke motor engine. Experiments demonstrated that the best thermal efficiency is 28% for half open engine valve and 34% for full open engine valve. Also, the reduction rate of NOx was 95% for half open engine valve at low speed and 50% for full open engine valve at high speed. The best reduction rate was 95% at 3000 rpm (revolution per minute) and butane gas flow rate at 1.05 and 1.40L/min. Chen, Huang, Lin, and Lin (2006) built a low temperature plasma methanol fuel reformer for enriched hydrogen gas generation in a multiple injection nozzles 1800c.c. car engine. 50% hydrogen gas and 50% gasoline mixed compound was applied to idle and 1500 rpm, respectively. In the case of TPS open 10%, exhausted emission, exported power and torque were measured. Experimental results illustrated that torque increased 6%, HC reduced 9%, CO reduced 3% and CO₂ increased 5%.

Hacohen and Sher (1989) applied gasoline-hydrogen mixed fuel to motor engine and reported less 10-15% fuel, 0.6-1.6% CO reduction and 120-2000 ppm HC reduction. However, an increase of 450-880 ppm in NOx was found. Lee, Yi, and Kim (1994) demonstrated that hydrogen gas provides an adequate thermal efficiency when injection valve pressure is 1.0MPa. Compared with gasoline fuel, hydrogen gas exported much higher thermal efficiency at thin inflammation which resulted in fast flame speed and small ignition angle. The emission of NOx by hydrogen gas fuel would 2.3 times of gasoline fuel. Yi, Lee, and Kim (1996) used hydrogen gas as fuel and clarified the performance between direct injection and port injection. Al-Baghdadi (2003) investigated the performance of gasoline with hydrogen-ethanol mixed gas in four-stoke plug ignition engine and reported that combustion was improved, engine power was increased, fuel consumption was reduced and polluted exhaust was decreased when the mass ratio was 0-0.35% and compression ratio was 12. Kim, Lee, and Choi (2005) examined the cyclic variation of injected hydrogen gas engine at different engine rpm, injection timing and ignition timing. Most of major cyclic variation occurred at the beginning stage of combustion.

Cohn, Rabinovich, and Titus (1996) and Cohn, Rabinovich, Titus, and Bromberg (1997) used vehicular micro-plasma reformer to generate the enriched hydrogen gas which is mixed with gasoline fuel for internal combustion engine. Thermal efficiency was improved and exhaust emission was decreased. The application of ternary catalytic converters resulted in extremely low polluted emission. Bromberg, Cohn, Rabinovich, Surma, and Virden (1999) and Bromberg, Cohn, Rabinovich, and Heywood (2001) adopted plasma fuel converter to generate hydrogen gas which cooperated with the original fuel system. The engine still functioned well at a range of very thin mixed fuel. Emission pollutants, such as NOx and HC were effectively reduced and the thermal efficiency of engine was dramatically improved. Shrestha and Karim (1999) used methane mixed with a small amount of hydrogen gas as fuel. Experimental results illustrated that an increase in hydrogen gas flow rate would result in an improvement in the engine performance at thin mixed fuel.