HVAC · Practice-Exam-2 · Problem 19PDFSolution in PDF ↓
HVAC · Practice-Exam-2 · Problem 19
Problem & Solution
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Problem: How much power is required to ice and tropically compress a hundred pounds per minute of air at atmospheric pressure and 80 degrees to a 150 psi.
Approach: It's going to be valid to use this equation T2 over T1 equals P2 over P1 raised to the K-1 over K.
Key step: How much power is required to ice and tropically compress a hundred pounds per minute of air at atmospheric pressure and 80 degrees to a 150 psi.
Watch out: And since this is a difference, we don't have to worry about using absolute temperature units.
Result: 12,207 B2 per minute turns out that one horsepower equals 42.4 B2 per minute.
✅ Answer: C
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Student questions asked in live office hours about this problem
OH 124 · July 6, 2026
Q: When should the constant-entropy process relationships be used for compressor problems?
A: Use those relationships when the problem states or implies an isentropic process, constant entropy, ideal behavior, or reversible adiabatic compression. The different isentropic relations connect pressure, temperature, and specific volume, and the specific form depends on which properties are known and what the problem asks for.