The prospects of plasmatron on-board fuel reforming vehicles

Improvements in fuel economy and emissions are on-going areas of development in the automotive industry. The reasons for this are economic from the standpoint of the end user and consumer, and forced by Government regulations instituted for political reasons as well as foreign Policy. The two main areas of research are new propulsion system concepts such as electric's, hybrids, and fuel cells; and improvements to conventional engine technology. The author has examined many of these new propulsion system concepts and found that they all share technical promise, but lack competitive economics to the conventional internal combustion engine. Given that current gasoline internal combustion engines only transform 20 to 30 percent of the chemical energy in fuel to useful propulsion energy, there is a far more realistic opportunity to realize substantial gains with advancing this existing technology. Conventional spark ignition (SI) engines spend most of their time operating at a throttled condition for part power operation while losing significant energy to simply pumping air into the cylinders. Engine designers would like to obtain the benefits from simply metering the fuel flow into the engine rather than the airflow (as in diesel engines) which eliminates these pumping losses. The current issue with diesel engines for light duty vehicles is the additional cost, and particulate & NOx emissions. The main reason why an SI engine cannot run in these lean (caused by reduced throttling of air, while instead controlling fuel flow) conditions is the reduced flame speed stability. One way that has proven to increase the lean limit of combustion is hydrogen addition. In addition to reducing throttling losses, lean operation results in improved indicated fuel conversion efficiency (efficiency of the compression and combustion strokes only) This research has developed a preliminary model of life cycle cost benefits of an on-board fuel reforming device (a plasmatron), which creates a supply of Hydrogen from a fuel-air mixture. Several plasmatron engine system configurations are evaluated including lean, higher compression ratio, and turbo charged plasmatron engines. The turbo charged plasmatron engines, which allow the overall engine displacement to be reduced, provide the highest possible improvements in Specific Fuel Consumption (SFC), but are currently in need of additional feasibility testing. The SFC improvements obtainable with the plasmatron are of a potentially high economic and practical attractiveness when compared to hybrid, fuel cell, and conventional vehicles. Advised by: Professor John B. Heywood, Sun Jae Professor qf Mechanical Engineering