What Is the Moist Air Psychrometric Enthalpy & Humidity Ratio Calculator (ASHRAE)?
Moist air psychrometric enthalpy quantifies the combined thermal and latent energy per kilogram of dry air.
How Does the Moist Air Psychrometric Enthalpy & Humidity Ratio Calculator (ASHRAE) Work?
First, saturation vapor pressure is derived via Magnus-Tetens. Humidity ratio W is computed, followed by the ASHRAE enthalpy equation h = 1.006·T + W·(2501 + 1.86·T).
Moist Air Psychrometric Enthalpy & Humidity Ratio Calculator (ASHRAE) Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
ASHRAE psychrometric formula derives humidity ratio W from actual water vapor pressure and barometric pressure, then evaluates moist air specific enthalpy.
How to Use the Moist Air Psychrometric Enthalpy & Humidity Ratio Calculator (ASHRAE)
- Enter ambient dry-bulb temperature in °C.
- Provide relative humidity in %.
- Adjust local atmospheric pressure if at elevated altitude.
Step-by-Step Example Calculation
Standard Comfort Air (25°C at 50% RH)
Input Values:
Understanding Your Result
Specific Enthalpy: Total energy content in kJ per kg of dry air.
Humidity Ratio: Absolute moisture mass in grams of water per kg of dry air.
Dew Point: Temperature at which air reaches 100% saturation.
Factors That Affect the Result
- Air temperature and moisture content heavily drive enthalpy; higher altitude reduces barometric pressure and increases humidity ratio.
When Should You Use This Calculator?
- HVAC air conditioning coil load calculations, cooling tower performance, and cleanroom humidity control.
Assumptions & Limitations
- Applies to standard atmospheric air between -40°C and 80°C under ideal gas assumptions.
Frequently Asked Questions
Calculation Accuracy & Reference Note
ASHRAE Fundamentals compliant psychrometric formulation.