Project ForgeHeat Transfer
Convection & Radiation
GATE 2013
Medium
For the same pipe described above (water, ṁ=0.01 kg/s, cp=4.18 kJ/kgK, inlet 20°C, diameter 50 mm, length 3 m), if qW=5000 W/m² (constant) and the convection heat transfer coefficient at the pipe outlet is 1000 W/m²K, the temperature in °C at the inner surface of the pipe at the outlet is
- A71
- B76
- C79
- 81
Explanation
Total heat input=qW×πDL=5000×π×0.05×3≈2356.2 W. Bulk temperature rise=Q/(ṁcp)=2356.2/(0.01×4180)=56.37°C, so exit bulk temperature=20+56.37=76.37°C. Wall temperature from qW=h(Tw−Tbulk): Tw=Tbulk+qW/h=76.37+5000/1000=81.37≈81°C.
Source: GATE ME 2013 (Booklet Code A) (2013)
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