Project ForgeHeat Transfer
Conduction
GATE 2018
Hard
A pipe wall (radius 1m) at 200°C is covered by 0.1m insulation (k=0.05 W/m·K). Ambient air is 20°C, h=10 W/m²·K. At steady state, the outer insulation surface temperature (°C) is (rounded off to second decimal place)
28.19 °C(± 0.4 accepted)
Explanation
R_cond=ln(1.1/1)/(2π×0.05)=0.3034, R_conv=1/(2π×1.1×10)=0.01447. Q/L=(200−20)/(0.3034+0.01447)=566.3 W/m. Ts=20+566.3×0.01447=28.19°C.
Source: GATE CH 2018 (2018)
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