Method and apparatus for vaporizing fuel for a reformer fuel cell system

A fuel vaporizing system for use in a fuel cell propulsion system including

• a source of liquid fuel;
• a source of water;
• a source of fluid at an elevated temperature;
• and
• a heat exchanger for vaporizing fuel and water and delivering the resulting vapor to a reformer, said heat exchanger having an inlet for said fluid, an outlet for said fluid spaced therefrom, the inlet being connected to said fluid source, a fluid flow path extending between said fluid inlet and said fluid outlet, and having an upstream end at said fluid inlet and a downstream end at said fluid outlet, a fuel/water inlet and a fuel/water outlet spaced therefrom and connected by a plurality of fuel/water flow paths that are in heat exchange relation with said fluid flow paths, said fuel/water inlet being connected to said fuel and water sources and located adjacent said upstream ends of said fluid flow paths.

A method of vaporizing liquid fuel and water prior to its introduction into a reformer in a fuel cell system, comprising the steps of:

• a) causing a stream of hot fluid to traverse a flow path such that the fluid is at maximum temperature at the beginning of the flow path and at a lower temperature at a location downstream of said beginning;
• b) vaporizing the liquid water and fuel by bringing liquid water and liquid fuel into heat exchange relation with said stream at said beginning and flowing the water and fuel concurrently with said stream and in heat exchange relation therewith to said location;
• and
• c) subsequently flowing the vaporized water and fuel in heat exchange relation and countercurrent with said stream back to said beginning and out of contact with the flow of water and fuel occurring during the performance of step b) to superheat the vaporized water and fuel;
• steps a), b) and c) being performed in a continuous operation.

A fuel cell system including:

• a fuel reservoir for storing a liquid fuel for a fuel cell;
• a fuel cell for consuming a fuel and generating electricity therefrom;
• a fuel reformer for receiving fuel in a vaporized state and connected to the fuel cell for providing a fuel thereto for consumption therein;
• and
• a fuel vaporizer interposed between the fuel reservoir and the fuel reformer for receiving liquid fuel from the fuel reservoir and vaporizing the liquid fuel to the vaporized state for delivery to the fuel reformer, and including a heat exchanger having a hot fluid inlet, a hot fluid outlet and a core interconnecting said inlet and said outlet, said core having alternating hot fluid passages extending between said hot fluid inlet and said hot fluid outlet and in heat exchange relation with liquid/vaporized fuel passages, a fin or fins in said hot fluid passages, said heat exchanger further including a liquid fuel inlet and a vaporized fuel outlet, each said liquid/vaporized fuel passage extending between said liquid fuel inlet and said vaporized fuel outlet and including an undulating spacer to define a plurality of flow ports of relatively small hydraulic diameter, said spacer being formed of a plurality of spacer sections, each separated by a gap.