# film coefficient

## film coefficient

[′film ‚kō·i‚fish·ənt]
(thermodynamics)
For a fluid confined in a vessel, the rate of flow of heat out of the fluid, per unit area of vessel wall divided by the difference between the temperature in the interior of the fluid and the temperature at the surface of the wall. Also known as convection coefficient.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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The exterior convective film coefficient ([h.sub.o,meas]) is then calculated as follows:
The balance of these phenomena is simulated rudely by the film coefficient of convention.
Process fluid is continuously pushed from the center of each tube to the wall and back to the center, eliminating thermal gradients and boosting the inside film coefficient. The static mixer elements are furnace-brazed to the pipe walls.
The resulting film coefficient [h.sub.c] = 11 [W [m.sup.-2] [K.sup.-1]] is within the expected limits for natural convection from a solid body to air (28), (29).
I call this the "film coefficient" effect, and it must be experimentally determined.
Where h = film coefficient of the prevailing condition, in this case 1.65 for still air; [A.sub.s] = surface area of the cylinder and hoses; [Delta]T = temperature change.
A modification of Sieder and Tate's correlation (17) is proposed to estimate the film coefficient ([h.sub.i]) at laminar flow (Re [less than] 2100):
(2008) developed a simplified model to compute the film coefficient of a double glazed window cavity with between-pane metallic blinds.
[R.sub.f] = effective surface film resistance, equal to R/3Kr, s Kr = mass transfer coefficient, also called film coefficient, m/s
To examine the reasons for this difference, the project team looked at the simulation results and separated the total product thermal transmittance (as predicted by simulation) into the specimen conductance and room-side and weather-side film coefficients. Unfortunately, the software used to determine total product U-factors via computer simulation (LBNL 2003) does not provide explicit values for the total room-side film coefficient, so the values had be backed out of the results.
Knowing the air temperatures on either side of the specimen and the total heat transfer through the specimen, it becomes simple to calculate the film coefficient on either side of the specimen.

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