One way to cool chips mounted on the circuit boards ofa computer is to encapsulate the boards in metal framesthat provide efficient pathways for conduction to supporting cold plates. Heat generated by the chips is thendissipated by transfer to water flowing through passages drilled in the plates. Because the plates are madefrom a metal of large thermal conductivity (typicallyaluminium or copper), they may he assumed to be at atemperature, T s , c p . (a) Consider circuit hoards attached to cold plates ofheight H = 75 0 mm and width L = 6 00 mm . eachwith N = 10 holes of diameter D = l 0 mm . Ifoperating conditions maintain plate temperatures of T s , c p = 32 ° C with water flow at m 1 = 0.2 Kg/s perpassage and T m , i = 7 ° C , how much heat may he dissipated by the Circuit boards? (b) To enhance cooling, thereby allowing increased power generation without an attendant increase insystem temperatures, a hybrid cooling scheme maybe used. The scheme involves forced airflow over theencapsulated circuit boards, as well as water flowthrough the cold plates. Consider conditions forwhich N c b = 10 circuit hoards of width W = 35 0 mm are attached to the cold plates and their average surface temperature is T s , c b = 47 ° C when T s , c p = 32 ° C . Ifair is in parallel flow over the plates with u ∞ = 10 m/sand T ∞ = 7 ° C , how much of the heat generated bythe circuit hoards is transferred to the air?
One way to cool chips mounted on the circuit boards ofa computer is to encapsulate the boards in metal framesthat provide efficient pathways for conduction to supporting cold plates. Heat generated by the chips is thendissipated by transfer to water flowing through passages drilled in the plates. Because the plates are madefrom a metal of large thermal conductivity (typicallyaluminium or copper), they may he assumed to be at atemperature, T s , c p . (a) Consider circuit hoards attached to cold plates ofheight H = 75 0 mm and width L = 6 00 mm . eachwith N = 10 holes of diameter D = l 0 mm . Ifoperating conditions maintain plate temperatures of T s , c p = 32 ° C with water flow at m 1 = 0.2 Kg/s perpassage and T m , i = 7 ° C , how much heat may he dissipated by the Circuit boards? (b) To enhance cooling, thereby allowing increased power generation without an attendant increase insystem temperatures, a hybrid cooling scheme maybe used. The scheme involves forced airflow over theencapsulated circuit boards, as well as water flowthrough the cold plates. Consider conditions forwhich N c b = 10 circuit hoards of width W = 35 0 mm are attached to the cold plates and their average surface temperature is T s , c b = 47 ° C when T s , c p = 32 ° C . Ifair is in parallel flow over the plates with u ∞ = 10 m/sand T ∞ = 7 ° C , how much of the heat generated bythe circuit hoards is transferred to the air?
Solution Summary: The author analyzes the heat dissipated from the circuit board. The mass flow rate of water is 0.2kg/s.
One way to cool chips mounted on the circuit boards ofa computer is to encapsulate the boards in metal framesthat provide efficient pathways for conduction to supporting cold plates. Heat generated by the chips is thendissipated by transfer to water flowing through passages drilled in the plates. Because the plates are madefrom a metal of large thermal conductivity (typicallyaluminium or copper), they may he assumed to be at atemperature,
T
s
,
c
p
.
(a) Consider circuit hoards attached to cold plates ofheight
H
=
75
0
mm
and width
L
=
6
00
mm
. eachwith N = 10 holes of diameter
D
=
l
0
mm
. Ifoperating conditions maintain plate temperatures of
T
s
,
c
p
=
32
°
C
with water flow at
m
1
=
0.2
Kg/s
perpassage and
T
m
,
i
=
7
°
C
, how much heat may he dissipated by the Circuit boards?
(b) To enhance cooling, thereby allowing increased power generation without an attendant increase insystem temperatures, a hybrid cooling scheme maybe used. The scheme involves forced airflow over theencapsulated circuit boards, as well as water flowthrough the cold plates. Consider conditions forwhich
N
c
b
=
10
circuit hoards of width
W
=
35
0
mm
are attached to the cold plates and their average surface temperature is
T
s
,
c
b
=
47
°
C
when
T
s
,
c
p
=
32
°
C
. Ifair is in parallel flow over the plates with
u
∞
=
10
m/sand
T
∞
=
7
°
C
, how much of the heat generated bythe circuit hoards is transferred to the air?
on the outer surface of a thin-walled
somm diameter and 6m leng th
steam condensing
eircular tube of's
auniform surface temp. of 108c. water flows through the
tube at a nate of m=0-2s kgls and its inlet and'outlet
temp. are i5 s7c. what is the average convection
Coefficient associated with water flow
maintains
The condenser of a steam power plant consists of AISI 302 Stainless steel tubes, each with outer and inner diameters of 35 mm and 30 mm, respectively. Saturated steam at 0.135 bar condenses on the outer surface of the tube, while water at a mean temperature of 295 K is in fully developed flow through the tube (you can assume that 295 K is the mean temperature in the axial direction of the tube (e.g. along its length) or you may assume that the inlet water temperature is 295 K).
For a water mass flow rate of 0.22 kg/s, what is the outer surface temperature of the tube and the rates of heat transfer and steam condensation per unit tube length? As an approximation you may evaluate the properties of the liquid film at the saturation temperature.
PROBLEM: IVB-46
FROM THE BOOK: ENGINEERING THERMOFLUIDS, M. MASSOUD.
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Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning