Psychrometrics: Dew-point temp from Relative Humidity

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SUMMARY

The discussion focuses on calculating the dew-point temperature from a given air/water vapor mixture at 26°C and 45% relative humidity (RH). The key equations referenced include Tdp = Tsat when pg = pv and RH = pv/pg. The participant utilized a psychrometric chart to derive the humidity ratio, volume per kg of dry air, enthalpy, and saturation temperature (Tsat). The conversation emphasizes the importance of understanding these concepts for solving practice problems related to the Fundamentals of Engineering (FE) exam.

PREREQUISITES
  • Understanding of psychrometric charts
  • Knowledge of relative humidity and its calculations
  • Familiarity with the concepts of saturation temperature (Tsat)
  • Basic thermodynamics principles related to air/water vapor mixtures
NEXT STEPS
  • Study the psychrometric chart for practical applications in HVAC systems
  • Learn how to calculate dew-point temperature using the formula provided on Wikipedia
  • Explore the relationship between humidity ratio and enthalpy in thermodynamic processes
  • Review the Fundamentals of Engineering (FE) exam reference materials for relevant equations
USEFUL FOR

Engineering students, HVAC professionals, and anyone preparing for the FE exam who seeks to understand the relationship between relative humidity and dew-point temperature calculations.

mojomike
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Homework Statement



Air/Water vapor mixture, at 26C and 45%RH.
What is the Dew-point temperature


Homework Equations



Tdp = Tsat when pg=pv
RH = pv/pg


The Attempt at a Solution



From the psychrometric chart I can get the Humidity ratio, volume per kg dry air, Enthalpy, and Tsat.

I hope what I've collected here can count toward an "attempt" at a solution. This is not homework. It is a practice problem for the FE exam. This was never covered in my thermo class. I'm sure it is simple, but it is escaping me now. thanks for any help you can provide.
 
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There is a fairly complicated equation on wikipedia for dew point. http://en.wikipedia.org/wiki/Dew_point

If you have all the variables you can just plug and chug. I don't know if that formula is in your FE reference book or not though.
 

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