Question

A 6cm OD, 2cm thick copper hollow sphere [k=386W/m.C] is uniformly heated at the inner surface at a rate of 150W/m2. The outside surface is cooled with air at 20C with a heat transfer coefficient of 10W/m2.oC. Calculate the temperature of the outer surface

Answer 1

Answer:

The outside surface temperature=21.66 C.

Explanation:

Given that

Outer diameter=6 cm

Inner diameter=2 cm

$Heat\ flux\ at\ inner\ surface\q=150\frac{W}{m^2}$

Outside temperature=20 C

$Outside\ heat\ transfer\ coefficient=10\frac{W}{m^2-K}$

To find the outside temperature

Heat out from sphere=Heat absorb by surrounding

$q\times A_i=hA_o\Delta T$

$q\times d_i^2=hd_o^2(T_o-20)$

Now by putting the values

$150\times 2_i^2=10\times 6_o^2(T_o-20)$

$So\ T_o=21.66C$

So the outside surface temperature=21.66 C.