The technical implementation of a retrofit hydrogen PFI system on a passenger car 2011-01-2004

The chicken or the egg dilemma is an often used metaphor to explain the problem where car manufacturers are not eager to produce hydrogen cars since there are no hydrogen fueling stations. Petrochemical companies on the other side, do not want to invest in hydrogen fueling stations for there are no cars to fuel. Many proposals have been made to overcome this predicament, for example starting the implementation of the hydrogen economy with early markets such as public busses that run on hydrogen, because they can use a centralized fueling infrastructure and thereby reduce initial costs. However, another way to address this stalemate is by avoiding the dependency on hydrogen fueling infrastructure. This can be achieved by using flex-fuel vehicles that can run on hydrogen as well as on gasoline and/or compressed natural gas. Such a flex-fuel vehicle, in this case an Opel Combo bi-fuel (gasoline and CNG) with a retrofitted hydrogen port fuel injection system, forms the subject of this experimental study. When this vehicle should run out of hydrogen, it can easily switch to gasoline or CNG operation. Hereby it also eliminates the other major bottleneck for hydrogen vehicles, the range. The low to zero emission benefit of hydrogen operation disappears while running on one of the other fuels, but the threshold for the buyer of a hydrogen vehicle decreases since he is no longer dependent on the presence of hydrogen fueling infrastructure. In this paper special attention will be given to the adaptations to the fuel system which are necessary to facilitate flex-fuel operation, as in combination with the programmable motor management system it forms the backbone of the conversion package. The hydrogen storage tanks, the pressure regulation system and the injectors will be described. Furthermore the engine control strategy and its effects on emissions and performance will be discussed.