Superheated Steam Heat Transfer
Superheated Steam Heat Transfer
(OP)
I need to figure out how much superheated steam is needed for my application.
I have 120 psig steam at 400 Deg. F.
I need to transfer 100,000 btu/hr with a maximum drop of 5 Deg. F of the steam.
I can't seem to find a BTU/LB for just the vapor phase of the superheated steam. Any help would be appreciated.
I have 120 psig steam at 400 Deg. F.
I need to transfer 100,000 btu/hr with a maximum drop of 5 Deg. F of the steam.
I can't seem to find a BTU/LB for just the vapor phase of the superheated steam. Any help would be appreciated.





RE: Superheated Steam Heat Transfer
Find a copy of the steam tables. Look up the enthalphy of your superheated steam at the pressure and temperature. Then, look up the enthalphy of superheated steam at an adjacent temperature. You can use those two values to work out the sensible heat.
RE: Superheated Steam Heat Transfer
Not sure if I'm missing something --- with superheated steam, it's all vapor, so you should be able to read the enthalpy value off of a steam table.
Patricia Lougheed
Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.
RE: Superheated Steam Heat Transfer
RE: Superheated Steam Heat Transfer
Have you ever heard of I-N-T-E-R-P-O-L-A-T-I-O-N?
Good luck,
Latexman
RE: Superheated Steam Heat Transfer
1. Go to Archon Engineering web site: www.archoneng.com
2. Order their Steam Program. It only costs $40, and if you're making a living designing steam systems it will pay for itself in about two or three hours. (It does all the i-n-t-e-r-p-o-l-a-t-i-o-n for you!!)
RE: Superheated Steam Heat Transfer
It has a wonderful steam table built in, and is good up to 2700 PSI or so. Great engineering tool.
RMW
RE: Superheated Steam Heat Transfer
For that pressure, enthalpies, Btu/lb, this source gives:
390oF 1128.6
395oF 1130.8
400oF 1133.0
RE: Superheated Steam Heat Transfer
Download steamtab from the link below. This will give you the desired values of saturated steam, superheated steam and water.
http://www.chemicalogic.com/steamtab/companion/default....
Regards,
Believe it or not : Though human body is made up of intricate and subtle mechanism, it is very poor in energy conversion. The maximum efficiency is 20% during cycling. During under water swimming it is just 4%.
RE: Superheated Steam Heat Transfer
390oF 1217.4
395oF 1220.2
400oF 1223.1
405oF 1225.9
For a 5oF drop starting at 400oF the amount of steam would be 100,000/2.9=34,483 lb/h, which could be rounded up to 34,500 lb/h.
RE: Superheated Steam Heat Transfer
RE: Superheated Steam Heat Transfer
Your enthalpy is 1224.62 Btu/lbs and the mass flow rate should be about 81.66 lbs/hr of steam.
Any more questions?
Dracula
RE: Superheated Steam Heat Transfer
The problem is that Joesteam only wants to desuperheat the steam by 5 deg. He is not condensing at all. Therefore only a very small portion of the enthalpy is available to use. This makes the required steam much higher to do the 100,000 BTU/hr duty.
Also, condensing or not, the total heat available per pound of steam would be the difference between the inlet and outlet enthapy. To get the entire 1224.62 BTU per pound out of the steam, you would have to desuperheat it, condense it, and subcool it to 32 deg F, but not freeze it.
Regards,
Speco
RE: Superheated Steam Heat Transfer
Your correct. I misinterpreted the question.
Thanks,
Dracula