Steam Quality vs Pressure
Steam Quality vs Pressure
(OP)
Hi All
After conducted a throttling experiment with water and noting the results. I would like to verify if it they make sense. What I noticed as that when the pressure inside the sealed vessel increased from say 1 to 7 bar in 1 bar increments the quality factor of the steam remained fairly constant. It was around 0.96 or 96% and when it decreased from 7 bar to 1 bar the quality factor also remained fairly constant but was slightly higher around 0.97. Any Ideads
After conducted a throttling experiment with water and noting the results. I would like to verify if it they make sense. What I noticed as that when the pressure inside the sealed vessel increased from say 1 to 7 bar in 1 bar increments the quality factor of the steam remained fairly constant. It was around 0.96 or 96% and when it decreased from 7 bar to 1 bar the quality factor also remained fairly constant but was slightly higher around 0.97. Any Ideads





RE: Steam Quality vs Pressure
Were you producing steam at various pressures? What did you measure and where/at which point?
Dejan IVANOVIC
Process Engineer, MSChE
RE: Steam Quality vs Pressure
RE: Steam Quality vs Pressure
Good luck,
Latexman
Technically, the glass is always full - 1/2 air and 1/2 water.
RE: Steam Quality vs Pressure
I am not sure if I am calculation the enthalapies correctly, for example if the pressure inside (p1) the vessel is 8 bar, I use the hl (enthalapy of saturated liquid to be 721.02 kJ/Kg at P1), and the enthalapy of vaporization to be hfg ( 2047.28 kJ/KG at P1), lastly the enthalpy of the gas at the exit is hg (2636.29 kJ/KG at T2) these are taken from the tables and used to caculate the quality of the steam.
RE: Steam Quality vs Pressure
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RE: Steam Quality vs Pressure
http://www.engineeringtoolbox.com/wet-steam-qualit...
Dejan IVANOVIC
Process Engineer, MSChE
RE: Steam Quality vs Pressure
TTFN
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[IMG http://tinyurl.com/7ofakss]
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx
RE: Steam Quality vs Pressure
If the experiments were performed at non-equilibrium conditions, then any value for steam quality is possible, I guess.
Dejan IVANOVIC
Process Engineer, MSChE
RE: Steam Quality vs Pressure
http://www.plantservices.com/articles/2003/378/?st...
RE: Steam Quality vs Pressure
If I trap a quantity of saturated steam at a given pressure and temperature, then I can get a decent measure of quality every couple of minutes. A plot of those quality measurements would make sense. If I take the readings every second, the plot gets far jaggy-er and the trend may very well appear to be towards increasing quality even though at steady state that would be impossible.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Steam Quality vs Pressure
RE: Steam Quality vs Pressure
Did you mean "the quality factor of the steam" or the vapor fraction of the steam? They are two entirely different physical characteristics.
Good luck,
Latexman
Technically, the glass is always full - 1/2 air and 1/2 water.
RE: Steam Quality vs Pressure
IMHO, the table you brought to show the irrelevance of % vol of liquid droplets in wet steam, should be accompanied by the pressure at which the reported three-decimals % vol/vol were estimated. Dou you agree?
RE: Steam Quality vs Pressure
Dejan IVANOVIC
Process Engineer, MSChE
RE: Steam Quality vs Pressure
RE: Steam Quality vs Pressure
Vapor fraction is usually used in the situation where a known quantity (batch) or flow rate (steady-state) of liquid is partially vaporized or condensed, but the majority of the time it's used when vaporizing. For example, a vapor fraction of 0.4 could mean that an initial mass of 100 lbs. of water was heated to yield 40 lbs of steam and 60 lbs of water, or 100 lbs/hr of water was heated to yield 40 lbs/hr of steam and 60 lbs/hr of water.
Steam quality is used only where a flow rate (steady-state) of vapor and liquid is partially condensed or vaporized, but the majority of the time it's used when condensing. For example, coming out of a boiler the steam is usually saturated and very high "quality", say 98+ % vapor. The < 2% water in the stream is usually due to imperfect mechanical separation of water droplets that is entrained in the mostly vapor stream. As this steam flows downstream in the piping there is heat loss to the surroundings and some of the vapor condenses to liquid. As such, the quality decreases to, say, 96%, 94%, or further.
There may be industries where the usage of the two terms are different than I described. That would not be surprising to me.
Good luck,
Latexman
Technically, the glass is always full - 1/2 air and 1/2 water.
RE: Steam Quality vs Pressure
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist