Example:Oil at 150C flows slowly through a long,thin- walled pipe of 30-mm inner diameter.The pipe is suspended in a room for which the air temperature is 20 C and the convection coefficient at the outer tube surface is 11W/m2.K. Estimate the heat loss per unit length of tube. KNOWN:Oil flowing slowly through a long,thin-walled pipe suspended in a room. FIND:Heat oss pernt of the pipe, SCHEMATIC: Koom air ho=11W/m2 Tm=20℃ 1hinD 1haMD Ppe,D30m -Tm-150℃ ASSUMPTIONS:(1)Steady-state conditions,(2)Tube wall thermal resistance negligible,(3) Fully developed flow,(4)Radiation exchange between pipe and room negligble PROPERTIES:Table 4-5,Unused engine oil (Tm=150C=423K):k=0.133 W/mK. Heat Transfer #9 Su Yongkang School of Mechanical EngineeringHeat Transfer Su Yongkang School of Mechanical Engineering # 9 Example: Oil at 150℃ flows slowly through a long, thin- walled pipe of 30-mm inner diameter. The pipe is suspended in a room for which the air temperature is 20 ℃ and the convection coefficient at the outer tube surface is 11W/m2 .K. Estimate the heat loss per unit length of tube