Design and development of large fuel cell land-vehicles - those with weights above 20 tons or power above 1 MW - encounter technical challenges not found in smaller vehicles. These challenges derive principally from the effects of large mass, density, and power on heat transfer. The authors are developing two large fuelcell vehicles: (1) a fuel cell-battery hybrid mine loader with weight of 23 tons and maximum power rating of 160 kW and (2) a fuel cell road-switcher locomotive with weight of 109 tons and continuous power rating of 1.2 MW. Both vehicles will employ polymer-exchange fuel cells (PEFC) and reversible metal-hydride storage. Heat dissipation from the compact underground loader requires water cooling of the stacks, traction battery, and hydraulic systems. Operation of the system cooling fan alone requires 19 kW. The hydraulic system, which operates the bucket and steering of the articulated vehicle, requires a peak power in excess of 100 kW. The principal heat-transfer challenge of the locomotive is removal of heat from the 25-tons hydride bed during refueling. Allowed time for refueling with 250 kg of hydrogen is 30 minutes. Since heat removal is rate-limiting, refueling at this rate necessitates removal of heat at the rate of 1.9 MW. This is achieved in a two-step process involving a large water-based heat sink. In contrast, the much easier requirement of discharging the hydrogen from the bed to the fuel cell is accomplished in real-time. Because the time to desorb 250 kg of hydrogen from the bed to the fuel cell stacks can be as long as 30 - 40 hours, waste heat from the fuel cells is sufficient to drive the process in real-time.
Technical challenges of large fuel cell vehicles
Technische Herausforderungen bei Schwerlastfahrzeugen mit Brennstoffzellenantrieb
2005
8 Seiten, 5 Bilder, 4 Quellen
Aufsatz (Konferenz)
Englisch
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