About Humid Air Excel Add-In
The psychrometrics Excel Add-In library 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:
- pressure,
- dry bulb temperature,
- wet bulb temperature,
- dew point tempertature,
- relative humidity,
- humidity ratio,
- enthalpy,
- entropy,
- and volume.
The library is fully integrated in Excel, and available functions can be used in the same way as any other Excel function.
Main features of the library:
- Professional quality, industrial strength software;
- Based on the most accurate formulation (Hyland and Wexler);
- Accurate and thoroughly tested;
- Create User Defined Functions (UDF) which use HumidAir functions;
- Call HumidAir functions from VBA (sample is included in the release version);
- Developed in C++ for maximum speed;
- Easy to install and easy to use;
- For installation and use of the library no administrator rights required;
- After installation no computer restart required;
- One year free technical support.
|
The following figure shows a sample spreadsheet included in the download package.
Humid Air Excel Add-In - Sample calculations in Excel
Used Formulations
The psychrometrics library uses the most exact formulations of thermodynamic properties of moist air currently available.
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.
System Requirements
Operating system Windows 2000/XP/Vista/Windows 7.
Excel 97 or better.
User privilages
Installation and use of the library requires
standard user privilages or better.
Psychrometric Properties
The following termodynamic and transport properties can be calculated with Humid Air Excel Add-In:
| Calculable properties in SI or E units - HumidAir Excel Add-In v2.0 |
| 1 |
Dry bulb temperature [Tdb] |
| 2 |
Wet bulb temperature [Twb] |
| 3 |
Dew point temperature [Tdp] |
| 4 |
Pressure [P] |
| 5 |
Saturation water pressure [Ps] |
| 6 |
Saturation pressure at wet bulb temperature [Pwb] |
| 7 |
Saturation pressure at dew point temperature [Pdp] |
| 8 |
Mole fraction of water [Xw] |
| 9 |
Mole fraction of air [Xa] |
| 10 |
Weight fraction of water [Ww] |
| 11 |
Weight fraction of air [Wa] |
| 12 |
Humidity ratio [W] |
| 13 |
Saturation humidity ratio [Ws] |
| 14 |
Degree of saturation [DS] |
| 15 |
Relative humidity [RH] |
| 16 |
Specific volume of dry air [Va] |
| 17 |
Specific volume of saturated ice [Vi] |
| 18 |
Specific volume of saturated water [Vw] |
| 19 |
Specific volume of saturated vapor [Vv] |
| 20 |
Specific volume of moist air [Vm] |
| 21 |
Specific density of dry air [Da] |
| 22 |
Specific density of saturated ice [Di] |
| 23 |
Specific density of saturated water [Dw] |
| 24 |
Specific density of saturated vapor [Dv] |
| 25 |
Specific density of moist air [Dm] |
| 26 |
Specific enthalpy of dry air [Ha] |
| 27 |
Specific enthalpy of saturated ice [Hi] |
| 28 |
Specific enthalpy of saturated water [Hw] |
| 29 |
Specific enthalpy of saturated vapor [Hv] |
| 30 |
Specific enthalpy of moist air [Hm] |
| 31 |
Specific entropy of dry air [Sa] |
| 32 |
Specific entropy of saturated ice [Si] |
| 33 |
Specific entropy of saturated water [Sw] |
| 34 |
Specific entropy of saturated vapor [Sv] |
| 35 |
Specific entropy of moist air [Sm] |
Range of Validity
The entire set of equations used by the Humid Air Excel Add-In library,
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.
|
Reference Point
IMPORTANT:
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.
|
Screenshots
The following screenshots demonstrate how to use the library, it's a 4 step process.
1.(a) Start Excel and press the "Insert Function" toolbar button.
1.(b) Alternatively, start Excel and press the "Insert Function" menu item.
2. Select a HumidAir library (SI or English units).
3. Select a function and press the OK button.
4. Enter input parameters and press the OK button.
NOTE: You don't have to put quotes around the property ID, they are inserted automatically.
That's it, the result will be displayed in the selected cell.
Downloads
The setup program will automatically install the library in Excel.
|
To install the library successfully you must have at least standard user privileges on your computer.
|
Humid Air Excel Add-In library
IMPORTANT:
For the demo version input pressure is fixed to:
- p = 8 bar in SI Units and
- p = 116.029 psi in English Units.
These values will be used for calculation regardless of your input value for pressure.
To further evaluate the library (at pressure p = 1 bar or p = 14.5 psi),
go to our Psychrometric Calculator web application, it uses the same calculation engine.
|
Quick reference documents
Price info
Prices subject to change without notice!
| HumidAir Excel Add-In v2.0 |
| 1-4 licenses |
USD 179.95 per copy |
| 5-20 licenses |
USD 164.95 per copy |
| 21 > licenses |
USD 149.95 per copy |
| Company wide license |
USD 5995.00 |
Note: when purchasing a license you also receive one year subscription for free.
The subscription includes updates and e-mail technical support.
If you have any questions, please don't hesitate to contact our sales:
sales@megawatsoft.com
General Information
For immediate access to the HumidAir Excel Add-In, 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®);
- PayPal.
To buy a specific number of licenses for the
HumidAir Excel Add-In click the button:
or to purchase a
Company Wide License contact sales at:
sales@megawatsoft.com.
2. Bank Direct Payment
If you prefer to pay for the product by "Bank Direct Payment", contact sales at:
sales@megawatsoft.com.