An aguaje oil (considered as viscous fluid) must be pumped between two buildings in a plant
agroindustrial through an AISI 304 stainless steel pipe spread on the ground that has a
22 cm outside diameter and 110 m long. To facilitate pumping, the liquid will be heated to 40 ° C
in order to reduce its viscosity. The oil flow will be 20 Kg / s and the specific heat of
1300 J / Kg K. Determine the temperature drop that the liquid will experience along the pipe
under the following operating conditions:
Ambient air temperature = 10 ° C
Wind speed = 14 m / s
Pipe surface temperature = 37 ° C
If the pipe surface T is maintained at 37oC all over the pipe wall, the temperature drop will be never over 3oC=40-37oC. So, clarify the thermal condition. Anyway, to calculate that you need to set the heat transfer coefficient both inside and outside. Both can be found in the heat transfer textbook.
You must take into account the heat transfer coefficient for forced convection in air. A typical value for this coefficient for a pipe is hc = 200 w/m2K according to the web Engineers Edge.com
With this value it´s possible calculate for 1 m of pipe the quantity of heat lost and estimate the drop of the oil temperature along the pipe.
A more conservative and simple method would be consider that the pipe wall temperature is constant along the 110 m length and calculate the total lost heat , that substructing it from the initial total heat of the oil, will give you the temperature of the oil at the end of the pipe. This temperature will be lower than the real value.
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