superheated steam as ideal gas
superheated steam as ideal gas
(OP)
I want to know that whether superheated steam can be treated as ideal gas. If yes then why pressure of steam not increases with temperature as by ideal gas equation pressure is directly proportional to temperature. I am talking of steam in superheater of boiler. Please guide me.
Regards
Pradeep
Regards
Pradeep





RE: superheated steam as ideal gas
There are published equations of state for steam, use one of them.
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P.E. Metallurgy, Plymouth Tube
RE: superheated steam as ideal gas
As EdStainless pointed out above, use the tables.
RE: superheated steam as ideal gas
If you place steam in an insulated cylinder and reduce the volume of the cylinder ( by compressing with a piston)both the pressure and temperature will increase, and you will also need to add work by compressing the piston. But this is a different situation than steam flow through a superheater and absorbing heat from the fluegases.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: superheated steam as ideal gas
The results were as follows:
At P= 4000psia and T=1200 dF, v= 0.247 cu.ft./lbm (close to the 0.25 cuft/lbm isometric line)
At P=40psia and T=1200 dF, v=24.71 (closer to the 20 than the 40 cuft/lbm isometric lines).
At P =4000psia and T= 800dF, v= 0.188 (not good probably due to being in the vicinity of the critical point; the 0.188 value was close to the isometric line of 0.10cuft/lbm)
At P=40 psia and T=400dF, v= 12.80 (which was close to the10 cuft/lbm isometric line);
At P=1 psia and T=100 dF which is nearly on the saturated vapor line, v=333.31. The saturated vapor temp. at 1.0psia is 101.74 dF and the "v" value is 333.6 cuft/lbm.
The values compared favorably to my Mollier diagram in several but not all cases. You'll have to try other combinations of pressures, temperatures and specific volumes within the superheat region because in some section of the superheated region, there will be significant errors.
RE: superheated steam as ideal gas
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: superheated steam as ideal gas