Heat Loss in insulated Pipework

[Howlin]

TL;DR

how to calculate the w/m heat loss in pipework with xmm of insulation

Hi all,

I have a copper pipe which has 15mm of insulation on it. The outside radius of the pipe is 17.2mm and the inside radius is 14.8mm. The insulation will have a conductivity of 0.025.

I found an question which is meant to show an equation for the heat loss in an Insulated Cylinder or Pipe. I have attached an excel document which has this equation in it and the inputs.

When I calculate the heat loss in w/m, I get a figure if 11.27.

I am wondering is the correct, as it doesn't appear to be, I would have thought it to be lower, somewhere in the region of 8 or 9 w/m.

Can anyone tell me if it is right or where I might be going wrong?

 

[anorlunda]

It all depends on these two numbers that you assumed.

 

[Tom.G]

I notice the spread sheet has the Insulation radius smaller Pipe radius.

Are you really trying to insulate the inside of the pipe?

Cheers,
Tom