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Hot air at 80°C is blown over a 2-m by> on0 4-m flat surface at 30°C. If the average? convection heat transfer coefficient varies between 20 W/m2 °C and 100 W/m °C, draw a relation between the rate of heat transfer from the air to the 80°C Air 30°C plate.(nm kW) and the convection heat transfer coefficient

1 Answer

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Step-by-step explanation:

The given data is as follows.


T_(air) = 80 ^(o)C,
T_(surface) = 30 ^(o)C

Area of the flat plate is 2 × 4 = 8
m^(2).

Average convection heat transfer coefficient
(h_(avg)) =
((20 + 100) W/m^(2) ^(o)C)/(2) =
60 W/m^(2) ^(o)C}.

Hence, formula to calculate heat transfer through convection from air to the water is given as follows.

q =
h_(avg) * A_(surface) * (T_(air) - T_(surface))

=
60 W/m^(2) ^(o)C} * 8 m^(2) * [(80 - 30)]^(o)C

= 24000 W

or, = 24 kW

Hence, the direction of heat flow is from air to the surface.

Thus, we can conclude that transfer of heat is 24 kW.

User Jin Lim
by
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