2. The cabin air in an empty aircraft on the ground in a tropical country is maintained at a constant 21°C (=T) by air-conditioning when the outside temperature is 35°C (=Ta). The radius of the fuselage is 3.7m (=r), the thermal conductivity of the cabin wall is 0.4 W/m.K (=k)and the heat transfer coefficients are 9 (=h) and 39 (=ha) W/m.K for the air in the cabin and the external atmosphere respectively. Assume that the effects of radiation are negligible. (a) Draw a sketch of the fuselage showing the dimensions, heat transfers, temperatures as well as the values of thermal conductivity and heat transfer coefficients. Identify the types of heat transfer occurring and express them in terms of the appropriate temperatures and constants of proportionality. Identify the relationships between the temperature differences associated with the heat transfers; and, hence show that the heat transfer unit length of fuselage (b) (c) is (Ta-Te) = = 2ar: Aha'k'hc If the air-conditioning unit is 50% efficient and the fuselage is 40m long and its wall thickness is 0.1m, then how much power is required to maintain these conditions? (d) [Answer: 43.3 kW]

Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
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ChapterMA: Math Assessment
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Q2 please
A SIIICUII Cip mcuJung J m
substrate. In a steady state, the chip has an electrical power input of 0.3W. The top
surface of the chip is exposed to a coolant whose temperature is 20°C. The heat transfer
coefficient for convection between the chip and coolant is 150 W/(m².K).
(а)
Draw a sketch of the chip showing the dimensions, an appropriate system
boundary and energy transfers across the boundary.
If the heat transfer by conduction between the chip and substrate is negligible,
determine the surface temperature of the chip.
(b)
[Answer: 86.7°C]
2.
The cabin air in an empty aircraft on the ground in a tropical country is maintained at a
constant 21°C (=T.) by air-conditioning when the outside temperature is 35°C (=Ta).
The radius of the fuselage is 3.7m (=r), the thermal conductivity of the cabin wall is 0.4
W/m.K (=k)and the heat transfer coefficients are 9 (=h) and 39 (=ha) W/m.K for the air
in the cabin and the external atmosphere respectively. Assume that the effects of
radiation are negligible.
(a)
Draw a sketch of the fuselage showing the dimensions, heat transfers,
temperatures as well as the values of thermal conductivity and heat transfer
coefficients.
Identify the types of heat transfer occurring and express them in terms of the
appropriate temperatures and constants of proportionality.
Identify the relationships between the temperature differences associated with
the heat transfers; and, hence show that the heat transfer unit length of fuselage
(b)
(c)
is
(Ta-Tc)
ģ = 2nr :
ha
If the air-conditioning unit is 50% efficient and the fuselage is 40m long and its
wall thickness is 0.1m, then how much power is required to maintain these
conditions?
(d)
[Answer: 43.3 kW]
Transcribed Image Text:A SIIICUII Cip mcuJung J m substrate. In a steady state, the chip has an electrical power input of 0.3W. The top surface of the chip is exposed to a coolant whose temperature is 20°C. The heat transfer coefficient for convection between the chip and coolant is 150 W/(m².K). (а) Draw a sketch of the chip showing the dimensions, an appropriate system boundary and energy transfers across the boundary. If the heat transfer by conduction between the chip and substrate is negligible, determine the surface temperature of the chip. (b) [Answer: 86.7°C] 2. The cabin air in an empty aircraft on the ground in a tropical country is maintained at a constant 21°C (=T.) by air-conditioning when the outside temperature is 35°C (=Ta). The radius of the fuselage is 3.7m (=r), the thermal conductivity of the cabin wall is 0.4 W/m.K (=k)and the heat transfer coefficients are 9 (=h) and 39 (=ha) W/m.K for the air in the cabin and the external atmosphere respectively. Assume that the effects of radiation are negligible. (a) Draw a sketch of the fuselage showing the dimensions, heat transfers, temperatures as well as the values of thermal conductivity and heat transfer coefficients. Identify the types of heat transfer occurring and express them in terms of the appropriate temperatures and constants of proportionality. Identify the relationships between the temperature differences associated with the heat transfers; and, hence show that the heat transfer unit length of fuselage (b) (c) is (Ta-Tc) ģ = 2nr : ha If the air-conditioning unit is 50% efficient and the fuselage is 40m long and its wall thickness is 0.1m, then how much power is required to maintain these conditions? (d) [Answer: 43.3 kW]
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