💨 Psychrometric Processes
Analyze AHU psychrometric processes: sensible heating/cooling, cooling & dehumidification, adiabatic humidification, and air stream mixing. Compute heat loads, SHR, humidity ratio, and thermodynamic properties.
📝 Configuration
Key Equations:
Psat = 0.6105·exp(17.27T/(T+237.3))
W = 0.622·Pw/(Patm−Pw)
h = 1.006T + W(2501+1.86T) kJ/kgda
SHR = Qsensible/Qtotal
Mixing: Wmix = (ṁ₁W₁+ṁ₂W₂)/(ṁ₁+ṁ₂)
Psat = 0.6105·exp(17.27T/(T+237.3))
W = 0.622·Pw/(Patm−Pw)
h = 1.006T + W(2501+1.86T) kJ/kgda
SHR = Qsensible/Qtotal
Mixing: Wmix = (ṁ₁W₁+ṁ₂W₂)/(ṁ₁+ṁ₂)
📊 Results
Configure inputs and click Analyze to view results.
📘 Methodology
Psychrometric Properties
Moist air properties are computed from dry-bulb temperature and relative humidity using standard correlations: Magnus formula for saturation pressure, and ASHRAE relations for humidity ratio, enthalpy, specific volume, dew point, and wet bulb.
AHU Processes
- Sensible heating/cooling: W constant, RH changes
- Cooling & dehumidification: below dew point, condensate formed
- Adiabatic humidification: follows wet-bulb line (h ≈ const)
- Mixing: properties mix linearly on psychrometric chart
Sensible Heat Ratio
SHR = Qsensible/Qtotal characterizes the process. SHR=1 for pure sensible processes. Cooling coils typically have SHR = 0.6–0.8. The SHR line on the psychrometric chart determines coil selection and sizing.