Electrochemical and other Processes within a Fuel Cell

Question 1

How is defined the fuel efficiency?

Answer 1

Fuel efficiency (eta) = electrical energy produced/heating value of the fuel

• We always have to specify if it has been calculated with the Lower Heating Value or with the Higher Heating Value.

Normally it’s the low heating value.

Question 2

Define HOR and ORR and say which produces higher losses

Answer 2

HOR: Hydrogen Oxidation Reaction
ORR: Oxygen Reduction Reaction

ORR losses are much higher than HOR losses. The main reason of this is the slow kinetics of the ORR. Besides, in the Oxygen during ORR we need to break a double bond; being this a proccess in which a lot of losses occur.

Question 3

Cell Performance Assessment - Draw the polarization curve explaining each deviation form the theoretical reversible cell voltage

Answer 3

Presentation 1 Slides 100-106

Question 4

Draw the Polarization curve and the power density in a simple graph (same x-axis but different y-axis)

Answer 4

Presentation 1 slide 107

Question 5

Effects of T and p on individual contributions

Answer 5

Individual Losses Table (Urev and losses within a Fuel Cell)