About Humid Air Application
The psychrometrics application calculates 35 thermodynamic properties of humid (moist) air
in SI and English units.
It allows 21 different combinations of input variables to be used for calculations.
Input variables that can be used are:
- Dry bulb temperature
- Wet bulb temperature
- Dew bulb temperature
- Relative humidity
- Humidity ratio
Main features of the application:
- Professional quality, industrial strength software
- Based on the real gas formulation developed by Hyland and Wexler
- Developed in C++ for maximum speed
- Copy and paste calculated results to Excel or other applications
- One year free technical support
The following figure shows the log P-H diagram generated with Steam97 application.
Humid Air Application
The psychrometrics application uses the most accurate formulations of thermodynamic properties of moist air.
Formulations are based on the study performed by Hyland and Wexler, and approved by ASHRAE (American Society
of Heating, Refrigeration and Air-conditioning Engineers) as documented in the 1997 ASHRAE Handbook "Fundamentals".
They presented the equation of state in:
- Formulations for the thermodynamic properties of the saturated phases of H2O from
173.15 K to 473.15 K, W. Hyland and A.Wexler, ASHRAE Transactions, 89(2A) 500-519, 1983.
- Formulations for the thermodynamic properties of dry air from 173.15 K to 473.15 K,
and of saturated moist air from 173.15 K to 372.15 K, at pressures to 5 MPa, R. W.
Hyland and A. Wexler, ASHRAE Transactions, 89(2A) 520-535, 1983.
Humid Air Application Functionality
The HumidAir is a standard win32 application. It is very ease to use, after selection of units (SI or English are supported)
and completed calculation for entered parameters, results are displayed in the output table.
Obtained results can be saved to a file, printed, or copy and pasted (cell, row column or whole table) to Excel or any other application.
Installation of the application requires standard privileges.
Humid (Moist) Air Properties
The following thermodynamic properties can be calculated with Humid Air Application:
|Calculable properties in SI or E units - HumidAir Application v4.2
|| Dry bulb temperature [Tdb]|
|| Wet bulb temperature [Twb]|
|| Dew point temperature [Tdp]|
|| Pressure [P]|
|| Saturation water pressure [Ps]|
|| Saturation pressure at wet bulb temperature [Pwb]|
|| Saturation pressure at dew point temperature [Pdp]|
|| Mole fraction of water [Xw]|
|| Mole fraction of air [Xa]|
|| Weight fraction of water [Ww]|
|| Weight fraction of air [Wa]|
|| Humidity ratio [W]|
|| Saturation humidity ratio [Ws]|
|| Degree of saturation [DS]|
|| Relative humidity [RH]|
|| Specific volume of dry air [Va]|
|| Specific volume of saturated ice [Vi]|
|| Specific volume of saturated water [Vw]|
|| Specific volume of saturated vapor [Vv]|
|| Specific volume of moist air [Vm]|
|| Specific density of dry air [Da]|
|| Specific density of saturated ice [Di]|
|| Specific density of saturated water [Dw]|
|| Specific density of saturated vapor [Dv]|
|| Specific density of moist air [Dm]|
|| Specific enthalpy of dry air [Ha]|
|| Specific enthalpy of saturated ice [Hi]|
|| Specific enthalpy of saturated water [Hw]|
|| Specific enthalpy of saturated vapor [Hv]|
|| Specific enthalpy of moist air [Hm]|
|| Specific entropy of dry air [Sa]|
|| Specific entropy of saturated ice [Si]|
|| Specific entropy of saturated water [Sw]|
|| Specific entropy of saturated vapor [Sv]|
|| Specific entropy of moist air [Sm]|
Range of Validity
The entire set of equations used by the Humid Air application,
is defined by the following temperature and pressure range:
- 173.15 K <= T < = 473.15 K
- 0.000001 MPa <= P < = 5 MPa
Moist Air Properties Limits
The upper limit of the absolute pressure is set at 5 MPa, and the
temperature is restricted to the range -100 to 200°C. However, for any given
absolute pressure, the highest temperature cannot exceed that temperature at
which the saturation vapor pressure equals the absolute pressure.
In other words, moist air properties are valid for any dry-bulb temperatures below or equal to the saturation temperature of water
at the same given absolute pressure, above that limit saturated moist air cannot exist.
In the used formulations for calculation of thermodynamic properties of moist air, the reference state
(zero enthalpy) is set at 0 °C. On some psychrometric charts (especially in the US)
the reference state (zero enthalpy) is set at 0 °F.
As a consequence, enthalpy and entropy values calculated by the library will be
shifted on these charts for the difference between the reference points.
Since for any process calculation only enthalpy difference (in and out of a process)
is important, the reference point doesn't really matter.
If you want to reproduce enthalpy values from such charts, you should find the enthalpy
difference for one point (doesn't matter which one), and then add that value for all
calculated enthalpies. The same applies for entropy values.
1. Humid Air Properties
Fig 1. HumidAir Application
Humid Air Desktop Application
- Download HumidAir Desktop Application version (2.4) - demo
You can also evaluate the HumidAir application online, visit "Psychromatric Calculator" web application.
It uses the same calculation engine as the HumidAir desktop application.
Prices subject to change without notice!
|HumidAir Application version 2.4
||USD 149.95 per copy|
||USD 134.95 per copy|
|21 > licenses
||USD 119.95 per copy|
|Company wide license
Each license also includes the following:
- One year free e-mail technical support
- One year free minor version updates if available (for example 2.5, 2.x up to, but not including version 3.0)
If you have any questions, please don't hesitate to contact sales at:
For quick access to the HumidAir Application, you may purchase and download our product using automated and secure online
ordering system. After ordering, you will receive a notification mail with further instructions, your
password (required during installation) and the retail version download location.
The Registration includes a free subscription program. Each Registered user will be receiving bug
fixes and technical support for the registered version within one year.
Shipping by the postal mail is not available.
How to order
1. Internet ordering
Available ordering options (open an order form to select):
- Credit Card (Visa®, Mastercard®, American Express®, Discover®)
To buy a specific number of licenses for the HumidAir Application click the button:
or to purchase a Company Wide License contact sales at:
2. Bank Direct Payment
If you prefer to pay for the product by "Bank Direct Payment", contact sales at: firstname.lastname@example.org.