2.4　Fuel Cell Vehicles（FCVs）

Constituents and Some Issues of a FCV

Text（课文）

The same figure which was used for the EV applies here.It can be seen from Figure 2.2 that the high-voltage source is already labeled as either a battery or fuel cell.The constituent elements are therefore，identical to the EV.

One of the problems with the fuel cell is that it is a unidirectional device，that is，it can deliver power output，but unlike a battery or an ultracapacitor，it can not receive any power back.Obviously then，the fuel cell has to be ruled out for any regenerative efforts in a vehicle.This implies that a battery or an ultracapacitor has to be introduced in order to gain a regenerative capability.It is not just for regenerative braking that a storage battery or an ultracapacitor is necessary:such storage elements also serve as mechanism by which the fuel cell can be started.This is important for both series and parallel hybrid vehicles.The battery or ultracapacitor has to be designed to meet such a starting current capability for at least half a minute，if not longer.In addition，based on the typical drive cycle of the vehicle，an assessment has to be made about the regenerative needs of the vehicle during braking and the size of the battery or uhracapacitor should be large enough for the worst case scenario.

The second problem with the fuel cell is its sensitivity in terms of the individual cell voltage.This gives an indication of the health of the fuel cell condition.If the cell voltages show a difference，that can indicate a problem.Fuel cells generally can not handle large transients，hence a battery often helps reduce the size of fuel cell needed and protects it during large transients in the dynamic process.

The fuel cell，not the cell per se but rather the whole module，along with all the peripheral devices like a compressor，water disposal mechanism，and warming system，together lead to a relatively low overall system efficiency.

New words and expressions（单词和短语）

1.New words（单词）

2.Expressions（短语）

Notes to the text（难点解析）

★1.One of the problems with the fuel cell is that it is a unidirectional device，that is，it can deliver power output，but unlike a battery or an ultracapacitor，it can not receive any power back.燃料电池的一个问题是，它是一种单向设备，也就是说，它能输出能量，与蓄电池或超级电容器不同，它不能回收能量。

★2.Fuel cells generally can not handle large transients，hence a battery often helps reduce the size of fuel cell needed and protects it during large transients in the dynamic process.燃料电池不能承受大的瞬变，因此蓄电池有助于减小燃料电池的尺寸，在动态过程中保护它不会剧变。

Exercises（练习）

◆1.Translate the following passages（expressions）into Chinese（英译汉）

（1）The battery or ultracapacitor has to be designed to meet such a starting current capability for at least half a minute，if not longer.

（2）The second problem with the fuel cell is its sensitivity in terms of the individual cell voltage.

（3）high-voltage source

★2.Translate the following passages（expressions）into English（汉译英）

（1）外围设备

（2）水分处理机构

（3）很显然，在汽车上它不能实现再生制动。

Reading material（阅读材料）

The criteria that manufacturers had to take into account to choose the fuel cell most adapted to the light vehicle are numerous；the main ones are the following:

1）technology for which the cost projections are the lowest and in any event of the same order of magnitude as the current cost of the thermal engine；

2）specific mass and volume equivalent to those of a thermal engine；

3）low enough operating temperature to authorize an acceptable start-up time（from 1 to 2 minutes）but high enough to allow a residual heat evacuation mode compatible with the volume available；

4）technology compatible with correct operation in the traditional temperature range（-30℃to＋40℃）；

5）operation with air as a combustive and insensitivity to gases and pollutants included in the air.

Taking these criteria into account led virtually all manufacturers to make the choice of the technology known as PEM.The Canadian manufacturer，Ballard Power Systems，currently equips the majority of the prototypes comprising PEM systems.Nevertheless，whilst the fuel cell is the main component of this new technology，the fuel is at the center of the debate on this subject.If the final fuel is hydrogen，which all agree is the fuel of the future，this gas is not distributed today on the road.Consequently，two major approaches currently clash:

1）whatever the primary fuel selected，hydrogen is manufactured in-station and distributed to users in a form that is to be specified（gas under pressure，liquid，absorbed）；

2）the vehicle carries a hydrocarbon fuel（hydrocarbon or alcohol）and transforms it on-board（reforming）into hydrogen，as and when it is needed.