Ethylene heat transfer coefficient 1

[packo]

i found coefficient for conductivity but i need heat transfer coefficient(W/m^2*K) from surface to liquid/gas ethylene
can't find it
please help

 

[25362]

Heat transfer coefficients (HTCs) may refer to conduction, convection and radiation. HTCs depend on (and are estimated from) the thermophysical properties of the fluids in question as well as on the temperatures, velocities, as well as geometrical and other considerations of the vessel or conduit.

As for the thermophysical properties you can find them in

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

just by writing the name of the chemical, selecting "fluid properties". Good luck.

 

[25362]

Ballpark estimates for streams flowing in heat exchangers would be:
for the non-boiling liquid ~1 kW/m[sup]2[/sup]K, for the gas ~0.2 kW/m[sup]2[/sup]K.

 

[packo]

i still can't find heat transfer coefficient for ethylene,i just find for water and for liquids but in general,nothing specificaly,if you know HTC for something similar to liquid and gas of ethylene please help
tnx!

 

[packo]

ethylene is stored in vertical tank

 

[25362]

FWIW, for condensing and boiling, the overall HTC is about 600 W/(m[sup]2[/sup]K). See

http://www.uop.com/objects/59chevronSpr99AICHE.pdf

 

[packo]

one more-if i looking HTC for air (natural convection) ,i know it's in the range 5-100 W/m2K but how can i determine that exactly ?i need table or graph where HTC of air is connected with outside temperature

 

[25362]

Taken from Holman's Heat transfer for natural convection (no wind):

h(laminar) = 1.42([Δ]T/L)[sup]0.25[/sup]
h(turbulent) = 0.95([Δ]T)[sup]0.33[/sup]

laminar: 10[sup]4[/sup]>GrPr>10[sup]9[/sup]
turbulent: GrPr>10[sup]9[/sup]

From this I suppose the overall HTC would be much much much lower than the value quoted from the above link. It would necessarily be lower than the h values estimated above.

 

[thermcool]

why not try experimental approach. Heat transfer coefficient are very much situational dependent and are very sensitive to the surface conditions involved. Normally it is difficult to take into account these surface anomalities using the emperical or estimated values and you will end up with an order of magnitude different values than the real values for your system.

The emperical relations are derived for specific situations that normally differ from one another.