In a refinery fuel oil is to be cooled from 100°c to 40°c by water at 25°c flowing on the outside of the tube at 0.66 m/s.
the inner diameter is 25 mm and the oil flow rate is 1 kg/s.
water is heated to 45°c.
the tube is made of 0.5% carbon steel of thickness 3 mm.
the inner diameter of the outer pipe is 62.5 mm.
the outside may be considered as insulated.
the properties of oil at 70°c are:
rho = 858 kg/m3
μ = 0.0515 kg/m-s
k = 0.140 w/m-k
cp = 2100 j/kg-k.
determine the overall heat transfer coefficient based on the outside tube area.
for turbulent flow, the following correlation may be used:
nu = 0.023 re0.8 pr0.4