Question

1. In a combustion process we need to have a flame temperature between 2250 and 2300 C with an air excess between 5 and 15 %.   The candidates are Acetylene (C2H2) and Butane (C4H10). What is your choice of fuel? How much excess air is needed in order to accomplish this objective? Please justify your answer.

2. With respect to the above problem, One Engineer Propones burning Butane only with Oxygen (not with air). He thinks that in this way the flame temperature would increase. Is that right? In that case, what would be the flame temperature in this case?

Answer 1

Q1

a)

choose Acetylene, since adiabatic flame value is much higher

for butane, we will not achieve this temperature, since plenty of CO2, H"O will be produced. Those species will absorb heat and will not allow Temperature increase

choose the least amount of air excess, to increase T, then, choose 5%

b)

Yes, it will

recall that "air" has only 20% O2, and 80% N2

that 80% of air --> _Nitrogen, will absorb heat from the reaction, will not allow T increase due to these "loss" of heat

therefore, the Tdrops