heat gain from friction

[heyjaehey]

Hi, I have a random question. I have posted 2 post about pipe insulation and this question is related to those posts.

This concept might be something that I am totally pulling out of my butt but I would like to get some expert's input.

Let say i have 5" pipeline for oil transfer. Pump power to transport this oil over 50 km is about 1700 kw. Given 0.6 pump efficiency, I have about 1000 kw goes into pipe. Friction generates heat. 1 Btu/C = approx. 1 kw. With this given, based on 5" diameter pipe, i get about 0.33 BTU/hr-ft2-ft/ft of thermal conductivity. I am proposing to use polyurethane insulation which has K value of about 0.02. 0.33 vs 0.02? come one. This basically tells me it probablly doesn't even need insulation due to the heat generated by friction. I know it is not right since it looks like it is too good to be true. But I am trying to find out what I am missing here.

Thanks!!

 

[heyjaehey]

oops. flowrate is about 2100 m3/day

 

[rconner]

This is probably a stupid question (as I am not an experienced oil piper), but what specifically with regard to whatever your application is is the designer's intent of the insulation to begin with (lets say irrespective of your question about any off-setting flow friction heat generated as the oil normally flows through the pipe)? [The reason I ask the question is that if e.g. the purpose was to hypothetically say keep oil warm/viscosity down, and someone took your advice to not insulate, what would happen the first time the thing was shut-down for whatever reason in a cold climate, and maybe even for relatively brief periods?

 

[BigInch]

What's the discharge pressure,
pump discharge temperature,
pump discharge elevation,
pipeline outlet pressure,
pipeline outlet elevation,
ambient temperature,
and the cP, SG at both temperatures?





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"Pumping accounts for 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[MortenA]

It is true that the work spend for pressure drop leads to a similar amount of energy being converted to heat in the liquid. But i haven't seen an example where this was something significant say that your pump adds a total of 1700 kW to the pipe (1000 for dP and the rest inefficiency) then that's less than 1 kW pr m3 of oil - that wouldn't lead to a large temperature increase i think. But i guess you noticed this yourself when you posted post no. 2?

Best regards

Morten