@Gas 4.0
@Gas is a member of Techware’s family of software packages
bringing accurate thermodynamic properties of fluids to many popular
Windows programs.
The gas property functions can be used directly from within
applications including Microsoft Excel, 123 and MathCad.
Addins attach the functions so that you can use them as if they were
built in to the applications.
This version supports 32bit and 64bit applications. New
64bit components include the gas function library (DLL), the Excel Addin and
DeskTop Air. The package also includes 32bit versions of these
components plus the addins for 123 and MathCad.
@Gas
provides thermodynamic properties and transport properties of flue gases
and moist air.
The
@Gas
package includes:
DeskTop Gas, an advanced interactive gas properties
calculator; a dynamic link library (DLL) of gas property functions; and
various addins which link the functions to Windows applications.
The addins allow you to use the functions as if they were builtin
to Microsoft Excel, Lotus 123 for Windows
and
MathSoft Mathcad.
@Gas accounts for the
following gases; nitrogen (N
_{2}), oxygen (O
_{2}), argon (Ar),
carbon dioxide (CO
_{2}), and water vapor (H
_{2}O). These
gases account for 99.997% of the volumetric composition of standard air
and also account for better than 99.9% of most combustion gases.
The thermodynamic functions are calculated for mixtures of all five
gases using an accurate third order virial equation of state.
The general form of the equation of state and the derived
thermodynamic properties can be found in many publications dealing with
gas properties.
The specific
form of the equations, the data correlation and the computational
methodology have been developed by Techware.
The functions have been tested against published data and show
excellent agreement.
A
description
of the
theoretical basis and accuracy is included with the package.
All
types of calculations involving flue gas are greatly simplified with the
@Gas functions.
The functions are extremely useful in predicting the performance of
waste heat boilers, fossil fuel fired steam generators, heat exchangers,
air compressors and gas turbines.
You can design equipment right on your favorite spreadsheet without
having to look up thermodynamic properties from tables or charts.
@Gas is going to change the way you solve many problems involving
moist air and flue gases!
Your results will be more accurate because you won’t have to read
data from charts or interpolate from tables, and you won’t have to make
perfect gas assumptions.
What's New in Version 4.0
 Added 64bit version of Gas property DLL.
 Added 64bit version of DeskTop Gas.
 Converted all help files to compiled HTML format.
 Removed @Gas Help link from all versions of Excel
and 123 menus.
 Updated on Jan 11, 2022 to add missing TGas64.lib file
for those wishing to program in C++.
What's New in Version 3.2
 Removed Help file link from Help Menu for Excel 2007 and
later.
 Corrected a bug in the Expansion Tool on DeskTop Gas
@Gas 3.2 is available as a
free
upgrade to licensed users of @Gas 3.0.
What's New in Version 3.0
@Gas 3.0 has added many new
features over the previous version, @Gas 2.0. These include
the following:
 Extends the temperature range upwards from 1300 °K,(1880
°F) to 2000 °K, (3140 °F) and downwards from 273.16 °K,(32.018
°F) to 180 °K, (135.67 °F).
 Adds transport property functions:
 GasPTWM, which calculates dynamic viscosity given pressure,
temperature and humidity ratio.
 GasPTWK, which calculates thermal conductivity given pressure,
temperature and humidity ratio.
 Includes DeskTop Gas, an
advanced gas property calculator with many improved features over the
previous gas property calculator.
 Adds new unit sets including, EngG using psig for pressure instead of
psia, SIF, which uses the formal SI units, MPa for pressure instead of
bar and °K for temperature, instead of °C, SIK using kPa instead of
bar for pressure, MET using the calorie instead of the joule for
energy and METF using kg/cm^{2} for pressure instead of
bar.
 Improved installation program that allows distribution over the web.
 Dropped support for Quattro Pro and 16bit applications.

 Seamlessly
extends your spreadsheet program's set of builtin functions.
 Equations
based on virial equation of state using second and third order mixing
coefficients.
No perfect gas assumptions.
 Accuracy
fully documented.
 Supports
many combinations of input data.
 Uses
English, SI and metric unit sets.
 Allows
pressures up to 50 bar
(725 psia) and temperatures from 180 °K (135.67 °F) to 2000 °K
(3140 °F).
 Calculates
specific volume, enthalpy, entropy, specific heat, viscosity and
thermal conductivity.
 Calculates
humidity ratio, molecular weight, amount of condensation and dew
point.
 Express
moisture as humidity ratio, mole fraction or mass fraction.
 Express
results on wet or dry basis.
The @Gas package includes various addins which link
the functions to many popular 32bit and 64bit Windows applications.
32bit addins are
included for Microsoft Excel versions for Office 95, Office 97, Office
2000; Office
XP; Office 2007 and Office 2010 (32bit version), Lotus 123
97 and 123 Millennium (Rel 9.0) and MathSoft Mathcad Plus
Versions 6, 7 and 8. A 64bit addin is included for Office 2010,
2013, 2016 and 365
(64bit version.)
No programming is required to use the @Gas functions
with any of these applications. Just follow a few simple steps to load the
addin, and from then on, the functions will be available every time you
start the application. You use the functions just like any of the builtin
functions. The functions can be used in any spreadsheet formula and any
argument to the functions can be a number, a formula or a cell reference.
All of the gas property functions are contained in a Windows Dynamic
Link Library (DLL). The @Gas package includes a 32bit
version of the DLL which supports
applications designed for Windows 95, 98, NT, 2000 and XP. Function prototypes and
LIB files are included in the package to support Microsoft C/C++ compilers. Declaration files are included to facilitate programming
with Microsoft Visual Basic or Microsoft Access.
Go Back to Key Features
The following table lists all of the WinSteam
functions currently available.
Function(Input Arguments) 
Output Value 
GasPTXV(P,T,N2,O2,Ar,CO2,H2O,unit) 
Specific Volume 
GasPVXT((P,V,N2,O2,Ar,CO2,H2O,unit) 
Temperature 
GasTVXP(T,V,N2,O2,Ar,CO2,H2O,unit) 
Pressure 
GasXW(N2,O2,Ar,CO2,H2O,unit) 
Humidity Ratio 
GasPTXW(P,T,N2,O2,Ar,CO2,H2O,unit) 
Saturated Humidity Ratio 
GasPXD(P,N2,O2,Ar,CO2,H2O,unit) 
Dew Point Temperature 
GasPTXH(P,T,N2,O2,Ar,CO2,H2O,unit) 
Specific Enthalpy 
GasPTXHS(P,T,N2,O2,Ar,CO2,H2O,unit) 
Saturated Specific Enthalpy 
GasPHXT(P,H,N2,O2,Ar,CO2,H2O,unit) 
Temperature 
GasPTXS(P,T,N2,O2,Ar,CO2,H2O,unit) 
Specific Entropy 
GasPTXSS(P,T,N2,O2,Ar,CO2,H2O,unit) 
Saturated Specific Entropy 
GasPSXT(P,S,N2,O2,Ar,CO2,H2O,unit) 
Temperature 
GasPTXC(P,T,N2,O2,Ar,CO2,H2O,unit) 
Specific Heat (constant pressure) 
GasPTXM(P,T,N2,O2,Ar,CO2,H2O,unit) 
Dynamic Viscosity 
GasPTXK(P,T,N2,O2,Ar,CO2,H2O,unit) 
Thermal Conductivity 
GasPTXL(P,T,N2,O2,Ar,CO2,H2O,unit) 
Water Condensed 
GasXMW(N2,O2,Ar,CO2,H2O,unit) 
Molecular Weight 
GasWX(N2,O2,Ar,CO2,H2O,unit) 
Water Mole Fraction 
GasVapPT(Pvap,unit) 
Saturation Temperature of Water 
GasVapTP(T,unit) 
Saturation Pressure of Water 
GasCondPTH(P,T,unit) 
Enthalpy of Compressed Liquid Water 
GasCondPTS(P,T,unit) 
Entropy of Compressed Liquid Water 
 Note:
 P = Pressure
 T = Temperature
 H = Enthalpy
 S = Entropy
 V = Specific Volume
 Pvap = Water vapor pressure
 N2,O2,Ar,CO2,H2O
= gas composition
 unit = Unit Set
The unit set argument selects one of the basis unit sets, selects
composition based on either mole fractions or mass fractions, selects
water vapor input as either fraction of mixture or humidity ratio, selects
reference point for enthalpy and entropy as either absolute zero or same
as ASHRAE conditions for dry air, and selects output value as either per
mass wet gas or per mass dry gas.
When calling the functions from 123, the function name is preceded by
the "@" character, eg. @GASPTXH(P,T,N2,O2,Ar,CO2,H2O,unit)
DeskTop Gas Calculator
The @Gas package includes DeskTop Gas, a handy interactive
gas property calculator which runs in its own window. The calculator image
below illustrates some of its features including flexible unit selection
and an intuitive, standard Windows user interface. DeskTop Gas is an ideal
replacement for your gas tables and it calculates the properties at the
exact point you desire so there is no need for interpolation. More
importantly, results from @Gas are more accurate than
looking up gas properties in tables because the model used for @Gas
takes into consideration the effects of compressibility and
mixing.
If you wish to try @Gas you may download
a fully
functioning copy for a 30 day evaluation period. You may also use
this download as a replacement for a lost or damaged copy of @Gas
4.0. If you decide to purchase @Gas
you may use the download and we will provide you with a serial number for
permanent use. Go to our Order page when you are ready to purchase @Gas