Question

2. Compute the maximum efficiency and the maximum work that can be extracted, when 1 mole of hydrogen reacts with oxygen to produce water vapor in the following devices –

a. Carnot Engine, operating between 327oC and 27oC

b. A Fuel Cell operating at 25oC (standard conditions)

Available Information: Standard Enthalpy of formation of water vapor is -242 kJ/Mol and the standard Free Energy of formation of water vapor is -229 kJ/Mol.

Answer 1

Electrical efficiency_max = Electricity produced / Higher heating value = 229 kJ/mol / 242 kJ/mol = 94.6%