need help with heat transfer project Task The surface temper

need help with heat transfer project Task: The surface temperature of a heater that simulates a circuit board or CPU is equal to about 85°C (the precise value is dependent of the air temperature in the room). You need to design, build, and test a natural convection cooled heat sink that decreases the surface temperature of the heater by 22±1 °C, while keeping the mass of the heat sink as small as possible. The setup to test the capability of your heat sink is available in the Lockheed Martin Lab. You need to design your heat sink for the dimensions of the available heater, 7.62 x 2.54 cm (see one of possible designs in Fig. 1). The sink must be made of aluminum.

Solution :

taking room temp as 25 C

Initial temp is 85

temp reduces by 22 Tf= 85-22 = 63

Heat loss or decrease in temp of heater is taken by heat sink

heat loss in heater is giveb by Q = hA(T-To)

= h A (T-To) where A is 7.62 x 2.54/10000 m2 ; To is oustide temp

this heat will take up by heat sink made of Aluminium

m Cp dT = h A (T-To)

density volume Cp dT = h A (T-To)

densiy of Al is 2830 kg/m3

Cp is 1.005

taking integral from given temp limit that is 85 to 63, equation reduces to

1/T-To dT = hA/(m Cp)

taking integral

log (T-To) = hA/(mCp)

log (Tf-To)-log(Ti-To) = hA/(mCp)

log((Tf-To)/Ti-To)) = hA/(mCp)

0.456 = hA (mCp)

A is 7.62 x 2.54/10000 m2

Cp is 1.005

m is density x volume = 2830 (V)

taking h for given conditions V can be calculated for required heat sink.

need help with heat transfer project Task: The surface temperature of a heater that simulates a circuit board or CPU is equal to about 85°C (the precise value i

need help with heat transfer project Task The surface temper

Solution

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