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bobo5195 · 04-01-2006, 08:52 AM

Had a little think any you should be able to quantify secondary losses. Send me a PM with an email and i'll give you a paper i handed in for CFD.

Basically heat transfer rate from a vertical plate by convection is

Nu = C*Ra^n

c we will never know but n is between a 1/4 and a 1/3.

Ra = Rayleigh nuber, reynolds number for natural convection

Which is
Ra= Gr*Pr

Gr is grashof number and is a non dimensional number based on the amount of energy added to the system by convection
Gr = g * (1/T) * (T surface - T air) * L^3 / viscosity^2

We can hence say that the heat transfered from the board varies by a certain range and with a few emperical results could possibily work it out.

04-01-2006, 08:52 AM	#5
bobo5195 Cooling Savant Join Date: Aug 2005 Location: uk Posts: 400	Re: Testing under vacuum Had a little think any you should be able to quantify secondary losses. Send me a PM with an email and i'll give you a paper i handed in for CFD. Basically heat transfer rate from a vertical plate by convection is Nu = CRa^n c we will never know but n is between a 1/4 and a 1/3. Ra = Rayleigh nuber, reynolds number for natural convection Which is Ra= GrPr Gr is grashof number and is a non dimensional number based on the amount of energy added to the system by convection Gr = g * (1/T) * (T surface - T air) * L^3 / viscosity^2 We can hence say that the heat transfered from the board varies by a certain range and with a few emperical results could possibily work it out.