HVAC · Psychrometrics · Problem 8PDFSolution in PDF ↓
HVAC · Psychrometrics · Problem 8
Problem & Solution
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Problem: Psychometrics problem 8.
Given: 000 feet above sea level, a one-ton fan coil unit, discharge is 54 degrees dry bulb 52 degrees wet bulb supplier, mai...
Approach: And then we have our FCU overhead supplying air into the room and returning air from the room.
Key formula: equation for total heat transfer, where we want to include both the sensible and the latent, would be 4
Calc: And this is happening at high elevation, so we're going to have to adjust our approach to accommodate for the fact that we're 5...
Calc: The room is 74 degrees and 50% humidity and the supplies 54 degrees dry bulb and 52 degrees wet bulb.
Result: So there's a sensible heat ratio that's not 1.
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Student questions asked in live office hours about this problem
OH 80: HVAC: Psychrometrics #8
Q: When reading the psychrometric chart for air at 54°F DB and 52°F WB, I get an enthalpy of 23.4, which leads to ~520 CFM, but using 23.3 gives ~510 CFM—will the actual PE exam really have answer choices this close when small chart reading errors cause different solutions?
A: You're right that these answers are too close, but since you fully understand the concepts and are within a couple percent, you should mark it correct and move on—there may be a handful of problems like this on the exam, so just do your best and don't lose sleep over it. Remember, practice problems aren't scored; what matters is that you understand the fundamentals.