Steam at 120∘C is continuously passed through a 50 -cm long rubber tube of inner and outer radii 1.0 cm and 1.2 cm. The room temperature is 30∘C. Calculate the rate of heat flow through the walls of the tube. Thermal conductivity of rubber = 0.15Js−1m−1∘C−1.
Given
Krubber=0.15J/m−s−∘C
T1=120∘C T2=30∘C
We know for radial conduction in a cylinder
Qt=2π Kl(T2−T1)ln(R2/R1)
=2×3.14×15×10−2×50×10−1×30ln(1.2/1)
= 232.5 = 233 J/s