Hydrogen supply method for fuel cell system

Patent metadata

Field	Value
Publication number	US-2019006688-A1
Application number	US-201715813639-A
Country	US
Kind code	A1
Filing date	Nov 15, 2017
Priority date	Jul 3, 2017
Publication date	Jan 3, 2019
Grant date	—

Abstract

A hydrogen supply method for a fuel cell system, for supplying hydrogen according to a state of the fuel cell system when the fuel cell system is started, includes steps of (a) measuring a stop time period which elapses until the fuel cell system is started after the fuel cell system is stopped, (b) determining whether a reaction time period consumed to complete a reaction of residual hydrogen and residual oxygen residing in a fuel cell stack since the fuel system is stopped is not more than the stop time period, and (c) when it is determined in the step (b) that the stop time period is less than the reaction time period, closing a purge valve that is able to discharge gases accommodated in an anode from the anode and supplying at the same time hydrogen to the anode such that an internal pressure of the anode becomes a predetermined first target pressure.

First claim

What is claimed is:

1 . A hydrogen supply method for a fuel cell system, for supplying hydrogen according to a state of the fuel cell system when the fuel cell system is started, the hydrogen supply method comprising steps of:
(a) measuring a stop time period which elapses until the fuel cell system is started after the fuel cell system is stopped; (b) determining whether a reaction time period consumed to complete a reaction of residual hydrogen and residual oxygen residing in a fuel cell stack since the fuel system is stopped is not more than the stop time period; and (c) when it is determined in the step (b) that the stop time period is less than the reaction time period, closing a purge valve that is able to discharge gases accommodated in an anode from the anode and supplying at the same time hydrogen to the anode such that an internal pressure of the anode becomes a predetermined first target pressure.

2 . The hydrogen supply method of claim 1 , wherein the predetermined first target pressure is set such that a concentration of the hydrogen in the anode becomes a predetermined first target concentration.

3 . The hydrogen supply method of claim 1 , further comprising a step of:
(d) before the step (b), measuring the internal pressure of the anode.

4 . The hydrogen supply method of claim 3 , further comprising steps of:
(e) determining whether the internal pressure of the anode measured in the step (d) is less than a predetermined abnormal pressure; and (f) when it is determined in the step (e) that the internal pressure is not less than the predetermined abnormal pressure, opening the purge valve and supplying at the same time hydrogen to the anode such that the internal pressure of the anode becomes a predetermined maximum allowable pressure.

5 . The hydrogen supply method of claim 3 , further comprising:
(g) when it is determined in the step (e) that the internal pressure of the anode is less than the predetermined abnormal pressure, determining whether a cross-over time period, for which residual gases residing in the fuel cell stack cross over through a polymer electrolyte membrane and the anode and the cathode is in pressure equilibrium after the fuel cell system is stopped, is not less than the stop time period; (h) when it is determined in the step (g) that the stop time period is less than the cross-over time period, estimating partial pressures of remaining gases, excluding the hydrogen, of the gases accommodated in the anode with reference to the internal pressure of the anode measured in (d); and (i) closing the purge valve and supplying at the same time an amount of the hydrogen corresponding to the partial pressures of the remaining gases estimated in the step (h) to the anode.

6 . The hydrogen supply method of claim 5 , wherein the step (i) includes:
(i1) setting a second target pressure of the anode with reference to a predetermined second target concentration of the hydrogen accommodated in the anode and the partial pressures of the remaining gases estimated in the step (h); and (i2) closing the purge valve and supplying at the same time the hydrogen to the anode such that the internal pressure of the anode becomes the second target pressure.

7 . The hydrogen supply method of claim 6 , further comprising:
(j) when it is determined in the step (g) that the stop time period is the cross-over time period or more, determining whether a condensation time period, consumed to complete condensation of vapor residing in the anode when the fuel cell system is stopped, is the stop time period or more; (k) when it is determined in the step (j) that the stop time period is less than the condensation time period, estimating the partial pressures of the remaining gases, excluding the hydrogen, of the gases accommodated in the anode; and (l) closing the purge valve and supplying at the same time an amount of the hydrogen corresponding to the partial pressures of the remaining gases estimated in the step (k) to the anode.

8 . The hydrogen supply method of claim 7 , wherein the step (k) includes:
estimating the partial pressures of the remaining gases with reference to the internal pressure of the anode measured in the step (d).

9 . The hydrogen supply method of claim 8 , further comprising:
(m) between the step (j) and the step (k) , estimating an amount of the vapor accommodated in the anode, which has been condensed during the stop time period, wherein the step (k) further includes: estimating the partial pressures of the remaining gases with reference to the internal pressure of the anode measured in the step (d) and the amount of the condensed vapor estimated in the step (m).

10 . The hydrogen supply method of claim 9 , wherein the step (m) includes:
estimating the amount of the condensed vapor with reference to the internal pressure of the anode.

11 . The hydrogen supply method of claim 7 , wherein the step (l) includes:
(l1) setting a third target pressure of the anode with reference to a predetermined third target concentration of the hydrogen accommodated in the anode and the partial pressures of the remaining gases estimated in the step (h); and (l2) closing the purge valve and supplying at the same time the hydrogen to the anode such that the internal pressure of the anode becomes the third target pressure.

12 . The hydrogen supply method of claim 7 , further comprising:
(n) when it is determined in the step (j) that the stop time period is longer than the condensation time period, setting a fourth target pressure of the anode with reference to the internal pressure of the anode measured in the step (d); (o) determining whether the fourth target pressure exceeds a predetermined maximum allowable pressure; and (p) when it is determined in the step (o) that the fourth target pressure is not more than the maximum allowable pressure, closing the purge valve and supplying at the same time hydrogen to the anode such that the internal pressure of the anode becomes the fourth target pressure.

13 . The hydrogen supply method of claim 12 , wherein the fourth target pressure is set such that a concentration of the hydrogen of the anode becomes a predetermined fourth target concentration.

14 . The hydrogen supply method of claim 12 , further comprising:
(q) between the step (j) and the step (n), when it is determined in the step (j) that the stop time period is longer than the condensation time period, determining whether the condensation of the vapor is completed, wherein when it is determined in the step (q) that the condensation of the vapor is completed, the step (n) is performed, and wherein when it is determined in the step (q) that the condensation of the vapor is being performed, the step (k) is performed.

15 . The hydrogen supply method of claim 14 , wherein the step (q) includes:
determining whether the internal pressure of the anode measured in the step (d) is a predetermined condensation end pressure or more.

16 . The hydrogen supply method of claim 12 , further comprising:
when it is determined in the step (o) that the fourth target pressure is less than the maximum allowable pressure, opening the purge valve and supplying at the same time hydrogen to the anode such that the internal pressure of the anode becomes the maximum allowable pressure.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Kim Dae Jong
• Ahn Deuk Kuen
• Lee Hyun Jae

Classifications

• H01M8/222

  Fuel cells in which the fuel is based on compounds containing nitrogen, e.g. hydrazine, ammonia · CPC title

• H01M8/04223

  during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells · CPC title

• H01M8/04365

  of other components of a fuel cell or fuel cell stacks · CPC title

• H01M8/04432 Primary

  Pressure differences, e.g. between anode and cathode · CPC title

• H01M8/04201 Primary

  Reactant storage and supply, e.g. means for feeding, pipes · CPC title