A novel scheme for dissipating heat from the chips ofa multichip array involves machining coolant channelsin the ceramic substrate to which the chips areattached. The square chips ( L C = 5 mm ) are alignedabove each of the channels, with longitudinal andtransverse pitches of S L = S T = 20 mm . Water flowsthrough the square cross section ( W = 5 mm ) of eachchannel with a mean velocity of u m = 1 m / s . and itsproperties may be approximated as ρ = 1000 k g / m 3 , c p = 4180 K/kg ⋅ K, μ =855×10 -6 kg/s ⋅ m,k = 0.610 W/m ⋅ K and P r = 5 . 8 . Symmetry in the transversedirection dictates the existence of equivalent conditionsfor each substrate section of length L S and width S T . (a) Consider a substrate whose length in the flow direction is L S = 200 mm. thereby providing a total of N L = 10 chips attached in-line above each flow channel. To a good approximation, all the heat dissipated by the chips above a channel may be assumed to be transferred to the water flowing through the channel. If each chip dissipates 5 W. what is the temperature rise of the water passing through the channel? (b) The chip-substrate contact resistance is R i , c n = 0.5 × 10 − 4 m 2 ⋅ K/W , and the three-dimensional conduction resistance for the L S × S T substrate section is R c o n d = 0.120 K/W . If water enters the substrate at 25 ° C and is in hilly developed flow, estimate the temperature T c of the chips and the temperature T s of the substrate channel surface.
A novel scheme for dissipating heat from the chips ofa multichip array involves machining coolant channelsin the ceramic substrate to which the chips areattached. The square chips ( L C = 5 mm ) are alignedabove each of the channels, with longitudinal andtransverse pitches of S L = S T = 20 mm . Water flowsthrough the square cross section ( W = 5 mm ) of eachchannel with a mean velocity of u m = 1 m / s . and itsproperties may be approximated as ρ = 1000 k g / m 3 , c p = 4180 K/kg ⋅ K, μ =855×10 -6 kg/s ⋅ m,k = 0.610 W/m ⋅ K and P r = 5 . 8 . Symmetry in the transversedirection dictates the existence of equivalent conditionsfor each substrate section of length L S and width S T . (a) Consider a substrate whose length in the flow direction is L S = 200 mm. thereby providing a total of N L = 10 chips attached in-line above each flow channel. To a good approximation, all the heat dissipated by the chips above a channel may be assumed to be transferred to the water flowing through the channel. If each chip dissipates 5 W. what is the temperature rise of the water passing through the channel? (b) The chip-substrate contact resistance is R i , c n = 0.5 × 10 − 4 m 2 ⋅ K/W , and the three-dimensional conduction resistance for the L S × S T substrate section is R c o n d = 0.120 K/W . If water enters the substrate at 25 ° C and is in hilly developed flow, estimate the temperature T c of the chips and the temperature T s of the substrate channel surface.
A novel scheme for dissipating heat from the chips ofa multichip array involves machining coolant channelsin the ceramic substrate to which the chips areattached. The square chips (
L
C
=
5
mm
) are alignedabove each of the channels, with longitudinal andtransverse pitches of
S
L
=
S
T
=
20
mm
. Water flowsthrough the square cross section (
W
=
5 mm
) of eachchannel with a mean velocity of
u
m
=
1
m
/
s
. and itsproperties may be approximated as
ρ
=
1000
k
g
/
m
3
,
c
p
=
4180
K/kg
⋅
K,
μ
=855×10
-6
kg/s
⋅
m,k
=
0.610
W/m
⋅
K
and
P
r
=
5
.
8
. Symmetry in the transversedirection dictates the existence of equivalent conditionsfor each substrate section of length
L
S
and width
S
T
.
(a) Consider a substrate whose length in the flow direction is
L
S
=
200
mm. thereby providing a total of
N
L
=
10
chips attached in-line above each flow channel. To a good approximation, all the heat dissipated by the chips above a channel may be assumed to be transferred to the water flowing through the channel. If each chip dissipates 5 W. what is the temperature rise of the water passing through the channel?
(b) The chip-substrate contact resistance is
R
i
,
c
n
=
0.5
×
10
−
4
m
2
⋅
K/W
, and the three-dimensional conduction resistance for the
L
S
×
S
T
substrate section is
R
c
o
n
d
=
0.120
K/W
. If water enters the substrate at
25
°
C
and is in hilly developed flow, estimate the temperature
T
c
of the chips and the temperature
T
s
of the substrate channel surface.
fluid flow
sulphuric
acid with 75% concentation of
density 1650 kg/m³ and viscosity 8.6 m N/m².
is to be pumped for 0.8 km along a 50mm
internal dimeter pipe at the rate of
3 kg/s and the faised vertically 15m by
the
рит р
driven and has
If the pump is electrically
efficiency
an
What the power will be required?
take (E) as
0.046 m us
of 50% what
long. The inlet water temperature is 10 C, and the tube wall temperature is 15 C
water temperature. k 0.585, Pr= 9.4, u= 1.31x10*,p= 992kg/m, CP= 4195 j/kg.
higher than the water temperature all along the length of the tube. What is the exit
%3D
Q5//answer one of the following branches e jall al je yal
A) cast iron pipe (k=75w/m. °C) air flows inside this pipe at 300°C the inner diameter
is 0.06 m, the outer diameter 7cm,it is covered with insulation type glass wool
with thick 4cm. with k= 0.055w/m.°C .the ambient temperature 6 °C by free
V3.
convection with heat transfer coefficient (20w/m2. °C) the heat transfer inside the
pipe is 65 w/m?. °C. length of tube (L-2) determine
1-the heat lost from the hot air 2-the temperature drop across the pipe shell 3-the
temperature drop across the insulation.
344
14.
1256 and
B) Fill the blanks:
of the
1. The thermal resistance of a medium depends on
medium.
2 All
law.
pes of convection are governed by
10000, the flow is
ori (P=880 kJ /m³ ) Flow under head
30 min Pr Pe (L= 3000 m , D= o-3 m) beconse
OF Cooling Viscosity a long the PiPo length
Will Chanje and equal to o.s Pa-s for
ISoo m and . 14Pa.s for the Yemain length
of Pipe Prove that the flow is laminar and
find the f low ra te .
Fox and McDonald's Introduction to Fluid Mechanics
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.