Heat transfer to/from burried oil pipleline

[friedmanroy]

Hello
Please, your help:

I have real problem of heat tranfer of oil line, I have to solve:
Gasoline flows through a steel pipe line that is burried in the ground. I need to know the exit temp of gasoline in the exit from the pipe.
I know:
Properties of Gasoline
Cp = 2.22 Kj/Kg K
Density = 740 kg/m³
k : 0.15 W/mK
Viscosity= 0.88 cSt (0.88X 10^-6 m²/sec)
µ = 6.512·10^-4 kg/m s
Flowrate = 500 m³/hour=100 kg/sec
V (velocity)=0.76 m/Sec
T inlet of the Gasoline to the pipe = 13 deg C
T of ground= 16 deg C

Pipe properties:
Material : Carbon Steel
Outside Diameter: 20 inch= 0.508 m
Inside Diameter: 19 inch=0.4826 m
k=54 W/mK
Density=7833 kg/m³ (of the carbon steel)
Length of pipeline=2730 meter

How do I solve this?
1) Find Pr number for gasoline:
Pr=µ Cp/k
Pr=(6.512·10^-4·2220/0.15)=9.63
Re= (0.76 ·0.4826/0.88·10^-6)=416,790
Nu=0.029 Re^0.8 Pr ^0.43=2406
Nu=h·D/k
h=Nu k/D = 2400 ·0.15 /0.4826 = 750 W/m²K ( is that for the Gasoline only?)

Now, I think I have to use the follwing, but I am not sure how:
U=(1/h_i+ r_i/k ln(r_o/r_i)+(r_i/r_o·1/h_o)^-1

How do I calculate the the conduction of the ground/soil ? (lets assume that k= 0.5 W/mK for the soil)
Is the method diffrent if the soil(ground) is hotter or colder than the inlet temp of Gasoline?
Please help me find the outlet temp of Gasoline...

Thanks alot
Roy

 

[BigInch]

Don't waste any time with this one.
He's posted 3 times already.