Question

Heat

Q5 A vertical flat plate (1.5 m) height and (1 m) width ,with uniform

temperature (120 oC) one face of this plate expressed to the air with the velocity (6

m/s) to the up direction, the second face expressed to the static air ,the temperature

of the air with two side (30oC) . Calculate the heat losses from the plate. The

properties of the air at (75 oC),[ ρ=0.998 kg/m3

.Cp=1.009 kJ/kg.oC, υ =2.076 *10-5

m

2

/s , k= 0.03 W/m. k]

Nu)L=0.664(ReL)

0.5 (Pr)0.33

for laminar flow

Nu)L=[0.036(ReL)

4/5

-836] (Pr)0.33

for turbulent flow

For free convection

Nu)L =0.59 (RaL)

0.25

104

< RaL< 109

Nu)L =0.1 (RaL)

0.33

109

< RaL< 1012

Answer 1