Question

a flat plate has thickness 5cm thermal conductivity 1 w/m.k convective heat transfer coefficient on its two flat faces are 10 w/sq.m.k and 20 w/sq.m.k. the overall heat transfer coefficient for the plate is:

Answer 1

UA = (1 / åR) = [1/{(1/h)+(b/k)+(1/h)}]

UA = [1 / {(1/10)+(1/20)+((5 x 10-2)/1)}]

1/UA = (1/10) + (1/20) + (1/50) = ((10+15+2)/100) = 17/100

UA = 100 / 17 = 5.88

Answer 2

Hey friend,

◆ Answer-
h = 5 W/km^2

◆ Explaination-
# Given-
h1 = 10 W/km^2
h2 = 20 W/km^2
k = 1 W/mk
t = 5 cm = 5×10^-2 m

# Solution-
Conductive heat transfer coefficient is-
h3 = k/t
h3 = 1/(5×10^-2)
h3 = 20

Overall heat transfer coefficient for the plate is calculated by -
1/h = 1/h1 + 1/h2 + 1/h3
1/h = 1/10 + 1/20 + 1/20
1/h = 2/20 + 1/20 + 1/20
h = 5 W/km^2

Therefore, Overall heat transfer coefficient for the plate is 5 W/km^2.

Hope this helps you...