HVAC · Thermodynamics · Problem 14PDFSolution in PDF ↓
HVAC · Thermodynamics · Problem 14
Problem & Solution
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Problem: Thermo-14, a Carnot heat pump operates between 20 and 70 degrees.
Approach: So the Carnot cycle turns out to be the most efficient possible cycle because the individual processes that make up the cycle a...
Key formula: formula for a Carnot heat pump as compared to a Carnot refrigerator
Result: So the Carnot cycle turns out to be the most efficient possible cycle because the individual processes that make up the cycle are reversible, or is...
Note: And we won't show the derivation here, but through a series of analysis we can show that the COP-4 a Carnot cycle depends only ...
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Student questions asked in live office hours about this problem
OH 106: HVAC: Thermo Module #14
Q: Why must we use absolute temperature (Rankine or Kelvin) in the Carnot heat pump COP equation instead of Fahrenheit or Celsius?
A: Because the COP equation is based on ratios of temperatures, and these ratios are only proportional to absolute temperatures—not arbitrary scales like Fahrenheit or Celsius which have arbitrary reference points (water's freezing/boiling points). If you used Fahrenheit versus Celsius, you'd get different COP values for the same physical system, which is impossible; absolute temperatures ensure the answer is consistent regardless of which absolute scale you choose.