TFS · Thermodynamics · Problem 24PDFSolution in PDF ↓
TFS · Thermodynamics · Problem 24
Problem & Solution
Video Synthesis
- Problem: An air compressor has a compression ratio of 10.
- Key step: But it can be modeled like a process that is constant entropy by changing the ratio of specific heats, k, which is normally taken as 1.4 to another va
- Watch out: So it's a process where it is not constant entropy.
- Result: And that means n turns out to be approximately 1.1 and that's closest to answer choice A.
- ✅ Answer: A
Office Hours
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Student questions asked in live office hours about this problem
OH 91
Q: How do I get to the constant enthalpy formula and replace k with n for polytropic processes? Is this something I need to memorize?
A: Yes, this is a key technique to remember for the exam. For isentropic ideal gas processes, you use k=1.4 in the relationship T₂/T₁ = (P₂/P₁)^((k-1)/k), but in polytropic processes where the gas doesn't behave ideally, you replace k with n (the polytropic exponent) and solve for n using known temperatures and pressures—essentially determining what the actual exponent is for that non-ideal process.