Design, Evaluation and Application of a Fuel Cell Vehicle Julian Gardner, Ron Fifield, Rick Hurt, Yahia Baghzouz, and Robert Boehm Center for Energy Research

Overview Original Configuration Design Considerations Vehicle Electrical Mechanical Fuel Cell Design Considerations Objectives Integration Safety Component Protection

Overview Results Future Work Fuel Cell Integration Application Water Recirculation System Fuel System Power Electrical System Control Electrical System Application Results Design Validation Future Work

Original Configuration Vehicle Electrical Specifications Batteries: Twelve 6V, Deep-cycle, 244 Ah Motor: NEMA rated 72V, 22 hp @ 2820 rpm intermittent duty;11.5 hp @ 4000 rpm normal duty Controller: 400 A, 72V solid-state speed controller

Original Configuration Vehicle Mechanical Specifications Bed Dimensions (LxWxH): 85 in x 62in x 32.25in Weight: 2700 lbs Transmission: 14:1 reduction, power traction in oil bath

Original Configuration Fuel Cell Stack and control electronics located above radiator Radiator gravity fed

Original Configuration Fuel Cell Specifications PEM Fuel Cell Power Output: 2.5 to 5.5 kW Dimensions: 1.5’x2.8’x2.5’ Weight: 95 kg Supply pressure: 1.03 bar Heat rejection: radiator with variable speed fan

Design Considerations Objectives Integration Maintain original outward appearance of the vehicle Integrate fuel cell into vehicle bed Safety Pressure relief and service vents directed up and away from vehicle cab Tanks oriented with heads pointed away from cab

Design Considerations Safety Minimized length of high pressure piping Redundant check valve behind fill nozzle Flexible line length minimized. Component Protection Stack overpressure Stack contamination Water recirculation system freezing

Fuel Cell Integration Unit too tall for efficient integration Accumulator added to FC exhaust system Lowered position of stack relative to radiator Added second cooling coil

Fuel Cell Integration Modified water recirculation system Fuel Cell Fan Cooling Water Hot Vapor, Water, and Air Inlet Air Reservoir Pump Cooling Coil Hot Water Accumulator Hot Vapor Fuel Cell Filters Rejected Heat Exhaust Radiator Overflow

Fuel Cell Integration Fuel system Vehicle bed raised four inches Modified bed frame to accept power converter Fuel system All fittings and tubing selected to meet or exceed working pressures Avoid different brand fittings on same section of tube

Fuel Cell Integration Fuel system Fuel Cell PRV Filter Check Valve Fill Nozzle Isolation Valve Fuel Cell Shutoff Valve Low Pressure Vent 2nd Stage Regulator 1st Stage Regulator Pressure Transducer Cylinder Fill Line Tank 2 Tank 1 High Pressure Relief Vent Fuel Cell Low Pressure Vent Un-pressurized Line Low Pressure Line (15 psi) High Pressure Line (5000 psi)

Fuel Cell Integration Fuel Cell Power Electrical Original 12 6VDC batteries replaced with 6 12VDC batteries Steel box fabricated and installed to house power control elements DC to DC converter integral to FC

Fuel Cell Integration Power from DC to DC converter passed through Zahn Voltage converted from 48 VDC to 72 VDC battery voltage Current back flow into fuel cell prevented through addition of power diode Load sharing refined iteratively

Fuel Cell Integration Fuel Cell Control Electrical Operation on battery power only preserved Fuel cell startup and shutdown sequenced Reduces inrush of electricity into the control electronics

Results Effectiveness of second cooling coil verified by subsequent testing Reservoir temperatures verified using interfacing software Interfacing software used in iterating on power sharing

Results

Application Vehicle Fuel cell Medium to light duty utility use on the premises of the Las Vegas Valley Water District Research platform for future vehicle development Fuel cell Battery assist (charge, power demand)

Future Work Install regenerative braking Replace motor with 3-phase AC motor Speed controller functions as an inverter and a rectifier Reevaluate performance Refine power sharing