Psychrometrics

Humid Air Properties - Psychrometrics
Dynamic Link Library

C++ dynamic-linked library (dll) of functions used for the development of Windows applications.

Any Windows client application that supports C++ function imports can make use of this library by including it in its deployment.

High-precision calculations of thermodynamic and psychrometric properties of humid air based on the latest mathematical models used in the ASHRAE formulation.

MAIN FEATURES

• Royalty free distribution for unlimited Windows applications.

• Full support of .NET, C++, C# framework development environments.

• 64-bit and 32-bit libraries included.

• Performs all the calculations implementing the latest mathematical models used to generate the tables for humid air properties and thermodynamic properties of water in the 2009 ASHRAE Handbook of Fundamentals, namely:

  • Thermodynamic and psychrometric property algorithms from the ASHRAE Research Project 1485.

  • Properties of steam, water and ice from the Industrial Formulation IAPWS-IF97, the Scientific Formulation IAPWS-95, IAPWS Formulation 2008 and IAPWS Formulation 2006. Properties of dry air are from the NIST Reference equation of Lemmon et al.

• Allows for 17 different combinations of thermodynamic properties to be entered as input parameters:

  • Dry-bulb Temperature / Wet-bulb Temperature

  • Dry-bulb Temperature / Dew Point Temperature

  • Dry-bulb Temperature / Relative Humidity

  • Dry-bulb Temperature / Humidity Ratio

  • Dry-bulb Temperature / Specific Enthalpy

  • Dry-bulb Temperature / Specific Volume

  • Wet-bulb Temperature / Dew Point Temperature

  • Wet-bulb Temperature / Relative Humidity

  • Wet-bulb Temperature / Humidity Ratio

  • Dew Point Temperature / Relative Humidity

  • Dew Point Temperature / Specific Enthalpy

  • Dew Point Temperature / Specific Volume

  • Relative Humidity / Humidity Ratio

  • Relative Humidity / Specific Enthalpy

  • Relative Humidity / Specific Volume

  • Humidity Ratio / Specific Enthalpy

  • Humidity Ratio / Specific Volume

• Supports input parameters and calculation results in both the SI (metric) and I-P (English) system of units.

• For each combination of input thermodynamic properties validates the range of input variables.

RANGE OF VALIDITY

The valid range of calculations for thermodynamic and psychrometric properties is defined by the IAPWS (International Association for the Properties of Water and Steam) as shown on Figure 1.

Valid range for Humid Air Properties - Psychrometrics.

SYSTEM OF UNITS

Psychrometric variables in the SI (metric) system of units can be entered and/or the calculation results can be displayed in the following units (w = water, da = dry air):

• Pressure: Pa

• Temperature: K

• Humidity Ratio: kg(w)/kg)(da)

• Relative Humidity: decimal ratio

• Absolute Humidity: kg(w)/m³

• Parts per million: ppm

• Specific Volume: m³/kg

• Density: kg/m³

• Specific Enthalpy: J/kg

• Specific Entropy: J/(kg·K)

• Specific Isobaric Heat Capacity: J/(kg·K)

Psychrometric variables in the I-P (English) system of units can be entered and/or the calculation results can be displayed in the following units (w = water, da = dry air):

• Pressure: psi

• Temperature: °F

• Humidity Ratio: lb(w)/lb(da)

• Relative Humidity: decimal ratio

• Absolute Humidity: lb(w)/ft³

• Parts per million: ppm

• Specific Volume: ft³/lb

• Density: lb/ft³

• Specific Enthalpy: Btu/lb

• Specific Entropy: Btu/(lb·°R)

• Specific Isobaric Heat Capacity: Btu/(lb·°R)