| 摘要 |
A fuel cell system 10 comprises a fuel cell 12 with an anode (62, fig 2) to which fuel gas is supplied and a cathode (60, fig 2) to which an oxygenic gas is supplied, and a recirculation unit 30, 34 in which at least some exit gas 28 from the anode can be re-supplied to the anode. The system also includes a control unit to control the recirculation unit 30, 34, the control unit being operated on the basis of the fuel utilisation of the fuel gas supplied to the anode and/or on the basis of an oxygen-to-carbon ratio (O/C) of the fuel gas supplied to the anode. The fuel utilisation is stated to be the ratio of the quantity of gas converted within the anode (62, fig 2) to the quantity of gas supplied overall to the anode, while the oxygen-to-carbon ratio (O/C) is stated to be the ratio of the sum of free and bound oxygen to the sum of free and bound carbon of a fuel gas supplied to the anode. The fuel utilisation and/or the oxygen-to-carbon ratio can be determined from (i) the temperature (Tan) prevailing in the anodic region of the fuel cell 12 (fig 3), (ii) an absolute moisture value (aH) to be assigned to the fuel gas supplied to the anodic region (fig 4), and/or on the basis of an electric current (I) available at the fuel cell 12 (fig 5). Control of the recirculation unit 30, 34 may additionally be effected using the composition of the fuel gas supplied to the anodic region of the fuel cell 12. |
