Convection in Partial vacuum
Convection in Partial vacuum
(OP)
There's a polynomial equation for Kinematic viscosity at different temperatures
But what if I we pressure and temperature both are changed, for example in partial vacuum
Is it possible to find viscosity of air at 3pa pressure and 200K temperature?
How to find convective heat transfer coefficient of air at low temperatures and low pressures?
Kindly help
Thank you
But what if I we pressure and temperature both are changed, for example in partial vacuum
Is it possible to find viscosity of air at 3pa pressure and 200K temperature?
How to find convective heat transfer coefficient of air at low temperatures and low pressures?
Kindly help
Thank you





RE: Convection in Partial vacuum
RE: Convection in Partial vacuum
RE: Convection in Partial vacuum
TTFN
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RE: Convection in Partial vacuum
You didn't answer my question. You didn't provide any information about your problem. As IRStuff indicated, it's not just a simple formula.
When you don't write anything but "I want a function" then I come away with "must be a student who doesn't have a real world problem." Prove me wrong.
RE: Convection in Partial vacuum
Sorry for late response, firstly it is not a school assignment, I like heat transfer so I'm trying to learn and understand the subject more
I'm trying to understand the heat coming out from a Thermos flask, after the partial evacuation of gap in between flasks it might come around 5pa or less, so at low pressure the viscosity of gas trapped inside may change, which in turn changes Coefficient of Convective Heat Transfer... I'm trying to determine the connective heat transfer in partial vacuum
RE: Convection in Partial vacuum
RE: Convection in Partial vacuum
RE: Convection in Partial vacuum
TTFN
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RE: Convection in Partial vacuum
http://www.iaeng.org/publication/WCE2010/WCE2010_p...
The values of pressure and temperature you’ve quoted in your OP are lower than those reported in the paper above, but you can clearly see the trend of the convection/radiation heat transfer coefficient ratio.
RE: Convection in Partial vacuum
http://hpce.iitm.ac.in/website/Manuals/Fluent_6.3/...
But how to find viscosity of air when both temp and pressure are changed? The viscosity of air at partial vacuum
RE: Convection in Partial vacuum
C = .0001 * (7.77 + .0063 * SG * 28.964) * t ^ 1.5 / (122.4 + 12.9 * SG * 28.964 + t)
X1 = 2.57 + 1914.5 / t + .0095 * SG * 28.964
Y = 1.11 + .04 * X1
u = C * Exp(X1 * (pg / 62.43) ^ Y) 'centipoise
ulb = u * .000672 'LB/FT-SEC
'where
' SG = specific gravity of gas (ref air)
' t = temperature of gas Rº
' pr = reduced pressure of gas
' tr = reduced temperature of gas
' p = absolute pressure psia
' z = compressibility factor
' pg = MASS density of gas lbm/ft3
' u = viscosity of gas in centipoise
' ulb = viscosity of gas in lbs/ft-sec
I have lost the reference, or it's from one of my books in my hard copy library at my home base.
I decided to do a quick search and found these. I haven't looked at them in detail yet, but they seem to be promising.
http://www.pe.tamu.edu/blasingame/data/0_TAB_Publi...
http://www.pe.tamu.edu/blasingame/data/z_web_Archi..._[Viscosity_of_Natural_Gases_(1970)].pdf
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Convection in Partial vacuum
http://www.bine.info/fileadmin/content/Publikation...
TTFN
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RE: Convection in Partial vacuum
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Convection in Partial vacuum
RE: Convection in Partial vacuum
Not you, the OP.
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