1. Consider two furnaces burning natural gas with 125% theoretical air. For both furnaces, the products that leave at 25 In furnace A, there is liquid water in the products, while in furnace B, the water remains as a vapor in the products. Which furnace has a lower combustion efficiency, based on the HHV of the fuel?

A. A

B. B

C. They are the same

2. Consider combustion of liquid and gaseous ethanol with the stoichiometric amount of air. Both enter the combustion chamber at 25 degrees C. Which will have a lower adiabatic flame temperature?

A. Liquid ethanol

B. Gaseous ethanol

C. Not enough information

D. They will be the same

3. Consider the following stoichiometric combustion of ethane. For a case with 150% theoretical air, how many kmol of air would be required per kmol of fuel?

C₂H₆ + 3.5(O₂ + 3.76N₂) --> 2CO₂ + 3H₂O + 13.16N₂