Method for Flushing a Fuel Cell System

Patent metadata

Field	Value
Publication number	US-2018358638-A1
Application number	US-201615777001-A
Country	US
Kind code	A1
Filing date	Oct 28, 2016
Priority date	Nov 19, 2015
Publication date	Dec 13, 2018
Grant date	—

Abstract

A method for flushing a fuel cell system during a power-down cycle includes conveying air by an air conveying device through a cathode space of a fuel cell and releasing the conveyed air through an exhaust air line. An outlet valve is cyclically closed and opened during the power-down cycle, where an opening duration depends on an amount of air that is conveyed and the outlet valve connects an anode discharge line to the exhaust air line. The conveyed air is guided from a delivery side of the air conveying device directly to the exhaust air line at least in part through a system bypass.

First claim

1 .- 9 . (canceled)

10 . A method for flushing a fuel cell system during a power-down cycle, comprising the steps of:
conveying air by an air conveying device through a cathode space of a fuel cell and releasing the conveyed air through an exhaust air line; cyclically closing and opening an outlet valve during the power-down cycle, wherein an opening duration depends on an amount of air that is conveyed and wherein the outlet valve connects an anode discharge line to the exhaust air line; and guiding the conveyed air from a delivery side of the air conveying device directly to the exhaust air line at least in part through a system bypass.

11 . The method according to claim 10 , wherein the opening duration is extended when a larger amount of air is conveyed and wherein the opening duration is reduced when a smaller amount of air is conveyed.

12 . The method according to claim 10 , wherein the air conveying device is operated at a constant speed during the power-down cycle.

13 . The method according to claim 10 further comprising the step of returning exhaust gas from an anode space of the fuel cell to the anode space by a recirculation line and a recirculation conveying device.

14 . The method according to claim 10 , wherein the anode discharge line branches off at a point on an anode side of the fuel cell system that is lowest.

15 . The method according to claim 14 , wherein a water separator is disposed on the anode side of the fuel cell system in a region where the anode discharge line branches off

16 . The method according to claim 10 , wherein the air conveying device is a flow compressor.

17 . The method according to claim 10 , wherein the air conveying device is operatively connected to an exhaust turbine and to an electric motor.

18 . The method according to claim 10 , wherein during normal operation, the fuel cell system provides driving power in a vehicle.

Assignees

• Daimler Ag

Inventors

• Mielke Sascha
• Pastor Nigorra Pere Antoni
• Schmalzriedt Sven
• Usman Muhammed

Classifications

• H01M8/04228

  during shut-down · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M8/04303 Primary

  applied during shut-down · CPC title

• H01M8/04164

  by condensers, gas-liquid separators or filters · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title