6 replies to this topic

[venkat]

I need to calculate the superheated steam enthalpy in the pressure range 80 to 150 bar and temperature range 350 to 500 degC. Can anyone give me an equation with good accuracy to cover this range?

thanks

[Art Montemayor]

VenKat:

Why do you have to use an equation? You have a recognized and respected free Database at:

http://webbook.nist.gov/chemistry/fluid/

where you can obtain all the thermodynamic properties of water & steam up to 1,000 bars and 1,001.9 ^oC.

If you want an equation, then simply collect as much data from the NIST database and regress it into an equation. It's that simple. I've done this before to check out other people's persistance in using an equation and found it to be right on the money.

[Zauberberg]

One free software I often use is available at:

http://ww.chempute.com/ftp.htm

Look for WASP, I think it is still available.

[engware]

Hi there:

A copy of good steam tables should do it for you.

You can always interpolate values from steam tables by using a spreadsheet.

Today, you can help yourself by combining different resources and using computer work. You can even plot your values in no time ...

It is much easier to practice engineering today than it used to be 10, 20 and/or 30 years ago ...

Good luck!

Thanks,

Gordan

[JoeWong]

venkat,

I guess you may find equations in IAPWS.

Try read Steam - Condensate Useful Links......you may find some stuff for simple approach. Not need to reinvent the wheel...


JoeWong

[venkat]

Thanks to you guys for replying.

Art Montemayor - NIST link will be useful.
Zauberberg - Chempute is good
engware - Thanks for the suggestion.
Joe Wong - IAPWS site is good.

As Joe Wong pointed out, I did not want to regress the tables to equation and re-invent the wheel. I need to use these properties in a formula in plant DCS system. I could have done it with a two dimensional array model - but as many of you might know - DCS software is not so convenient for longer programming steps. That is why I opted to for this "equation approach" and wanted some proven equations that are fairly accurate in the range given.

[engware]

venkat:

As long as you can move forward and there is some engineering sense of your approach, then it is a win-win situation for everybody.

Thanks,

Gordan