HVAC · Practice-Exam-2 · Problem 77PDFSolution in PDF ↓
HVAC · Practice-Exam-2 · Problem 77
Problem & Solution
Video Synthesis
Topic: Practice Exam #2 — How much air is required to burn 25 pounds of methane with 30% excess air?
Method: So before you have excess air, when the reaction is stoichiometric, which is to say there's just enough air to burn all the fuel and have there be no fuel and no air left over.
Key values: 25 pounds of methane with 30, 17.3 pounds of air per pound of fuel
Reference: reference handbook
✅ Answer: D
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Student questions asked in live office hours about this problem
OH 124 · July 6, 2026
Q: Where should you look in the NCEES handbook for the combustion information needed for a methane problem?
A: Dan recommended searching for the combustion reactions for common fuel constituents and starting with the methane, CH4, reaction in that table. The table gives the oxygen reaction, and nitrogen from air must be carried through as a nonreacting bystander when volume or mass fractions require it.