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[alan1979]

Hello.

I am trying to calculate how much the temperature of a fluid (styrene) would rise if it sits full in an unisulated 10in sched 40 pipe for up to 10 days during the summer. The reason we do not want to insulate the pipe is the risk of corrosion under insulation due to the pipe being in a flood plane. This pipe has to go under railways so we cannot raise it up too high (rail lines also get flooded). We are assuming it is 100F outside during the day and 80F at night. I'm not sure how to account for the solar radiation heating up the pipe, I've seen references to use 170 F but don't understand how this would be calculated. The pipe would be painted white.

Data:
Outside temp day: To(d) = 100 F
Outside temp night: To(n) = 80 F
Fluid temp: Ti = 75 F
Inside Pipe diam: di = 0.835 ft
Inside radius: ri = 0.4175 ft
Outside Pipe diam: do = 0.8958 ft
Ouside radius: ro = 0.4479 ft
Cross sect area: A = 0.5475 ft

Fluid: Styrene
density: p = 56.559 lb/ft^3
Specific heat: cp = 0.4132 BTU/lb-F

Thermal Conductivity
CS pipe: k(pipe) = 26 BTU/ft-h-F
Styrene: k(styrene) = 0.09245 BTU/ft-h-F
Air: k(air) = 0.0156 BTU/ft-h-F

The equation I was trying to use was to calculate the energy going through the pipe, but I don't think this is correct.

Using a length: L = 1 ft

q = k(pipe)*AL*(Ti-To(d))/(ro-ri) = -58046 BTU/hr !!this value seems way to high!!
AL = 2*3.14*L*rL = 2.716289
RL = (ro-ri)/LN(ro-ri) = 0.43253

Any suggestions/corrections/ideas would be greatly appreciated,

Thanks.