This preview shows pages 1–2. Sign up to view the full content.
PROBLEM 4.68
KNOWN:
Hotfilm flux gage for determining the convection coefficient of an adjoining fluid stream
by measuring the dissipated electric power, P
e
, and the average surface temperature, T
s,f
.
FIND:
Using the finiteelement method of
FEHT
, determine the fraction of the power dissipation that
is conducted into the quartz substrate considering three cases corresponding to convection coefficients
of 500, 1000 and 2000 W/m
2
⋅
K.
S
CHEMATIC:
ASSUMPTIONS:
(1) Steadystate, twodimensional conduction, (2) Constant substrate properties,
(3) Uniform convection coefficient over the hotfilm and substrate surfaces, (4) Uniform power
dissipation over hot film.
ANALYSIS:
The symmetrical section shown in the schematic above (right) is drawn into
FEHT
specifying the substrate material property.
On the upper surface, a convection boundary condition
(T
∞
,h) is specified over the full width W/2.
Additionally, an applied uniform flux
boundary condition is specified for the hotfilm region (w/2).
The remaining surfaces of the two
dimensional system are specified as adiabatic.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '10
 LEE,J.S.
 Heat Transfer

Click to edit the document details