Shut-down procedure for hydrogen-air fuel cell system

一种燃料电池系统(100)可通过下列程序关停：断开主负载(148)、切断气流(139)并以可使燃料电池气体在各电池之间达到平衡的方式控制进入系统的燃料流(141)(包括切断该燃料流)及自系统排出的气流，此时，平衡气体组成包含至少0.0001％氢气(以体积计)(且较佳以体积计介于1.0％和小于4.0％氢气之间)且其余为氮气及其他可能的对该燃料电池呈惰性且无害的气体，所有氧气已通过在电池内与氢气反应而被消耗。在整个关停期间使该等电池内一直保持此气体组成，例如通过添加氢气以补充任何在关停期间因与泄漏于电池中的空气反应而消耗掉的氢气。此关停程序实质上不会引起电池性能的任何损失。 A fuel cell system is shut down by disconnecting the primary load, shutting off the air flow, and controlling the fuel flow into the system (including shutting off the fuel flow) and the gas flow out of the system in a manner that results in the fuel cell gases coming to equilibrium across the cells at a gas composition of at least 0.0001% hydrogen (by volume), and preferably between 1.0% and less than 4.0% hydrogen, by volume, with a balance of nitrogen and possibly other gases inert and harmless to the fuel cell, all the oxygen having been consumed by reacting with the hydrogen within the cell. That gas composition is maintained within the cells throughout shut-down, such as by adding hydrogen to replace any that is consumed by reaction with air leaking into the cells during the period of shut-down. This shut-down procedure causes virtually no cell performance losses.