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heat transfert between pipes and ambiant air

heat transfert between pipes and ambiant air

heat transfert between pipes and ambiant air

(OP)
Hi, it is my first partcipation,
 i have to design a seaw water network used for cooling in several heat exchangers, the old network was underground, and we want to make it outside, but i need to calculate the water temperature change due to air temperature which can reach 47 °C,

is the heat transfert is

Q1 : forced convection inside the pipe ( Re, Pr) h = (k/d)*Nu
Q2 : forced convection betwen air and external pipe wall ??? how?
Q3 : conduction against wall pipe (ks(T1-T2)/e)

with q1=q2=q3

is it right and what relation must be used for air coefficient

 

RE: heat transfert between pipes and ambiant air

what the heck is a seaw?

RE: heat transfert between pipes and ambiant air


It's probably a typo from "sea water" by typing w twice.

RE: heat transfert between pipes and ambiant air

(OP)
sorry, i mean sea water,
 thanks  

RE: heat transfert between pipes and ambiant air

Is the piping to be insulated?

RE: heat transfert between pipes and ambiant air

(OP)
no, it's in direct contact with air, sea water is at 25°C and air is estimated at 47 °C, the temperatume must not reach 28.5°C at the inlets of heat exchangers, this is what i want to confirm.

RE: heat transfert between pipes and ambiant air

lomli,
The only way to prevent the heat absorbtion in the pie and overheating the sea water is to insulate the pipe. The Insulation Design Guide I sent you will help you to calculate the insulation thickness, but I would leave it in your case to the insulation contractor to design and install the most suitable insulation and at a cost you may negotiate with them. This way you can ask the contractor to guarantee his work, to ensure the termal isolation of your pipe.
cheers,
gr2vessels

RE: heat transfert between pipes and ambiant air

(OP)
thank you very much gr2vessels

I am agree with you Mr, but if the sea water temperature don't exceed 28.5 °c at the XCHgrs inlets ,I prefer avoid insulating (cost) if I will be sure that it reaches the 28.5 °C, so i will not have choice,

(sorry my english is bad)
thank you      

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