Energy Balance for a Direct Carbon Molten Carbonate Fuel Cell Available to Purchase

A novel fuel cell design uses porous bed electrodes. Liquid electrolyte, with fuel and oxidizer entrained, is circulated through the electrodes. An energy balance has been done for the cell and auxiliaries. The design calls for the CO-CO₂ mixture leaving the anode to be burned to supply an O₂-N₂-CO₂ mixture to the cathode. Two heat exchangers are employed: an air preheater cooling the exhaust and a waste heat exchanger cooling the gases entering the cathode. Results show that CO/CO₂ ratio is the most important parameter for determining performance. For other conditions ideal, plant efficiency varies from ∼90% for pure CO₂ to ∼20% for pure CO. If decoupled from CO/CO₂ ratio, the main effect of increasing cell temperature is to increase heat transfer rate in the air preheater. This is also the main effect of increasing excess air. Decreasing internal cell efficiency lowers power output and increases waste heat rejection.