High thermal conductivity backfill
High thermal conductivity backfill
(OP)
Greetings in a section I don't normally follow.
I've looked through the search functions etc and haven't quite found what I'm looking for.
My subject is actually the reverse of cable issues - what I have is a very cold (-160 to -110C) fluid inside a highly insulated pipe, buried some 1.5m deep.
The vendors have done some calcualtions and think that to avoid freezing around the pipe (or actually between them as I have two pipes approx. 1m apart) I need soil with thermal properties of around 2W/m/k. With dryish soil around 0.5-0.8, I wold like to guarantee this higher thermal conductivity at all times for 1m around the pipes (30in diameter).
This seems quite similar to "engineered" o "thermal" backfill used for cable backfill where the issue, as you will know, is also transmission of heat, but in the other direction...
I would like any info, data or links to suppliers who could supply this or whether there is a cheaper "fix" which would suffice as I've got a lot of backfill to supply and don't need super duper backfill, just stuff that's good enough.
Any info gratefully received and if you want more info please ask.
I've looked through the search functions etc and haven't quite found what I'm looking for.
My subject is actually the reverse of cable issues - what I have is a very cold (-160 to -110C) fluid inside a highly insulated pipe, buried some 1.5m deep.
The vendors have done some calcualtions and think that to avoid freezing around the pipe (or actually between them as I have two pipes approx. 1m apart) I need soil with thermal properties of around 2W/m/k. With dryish soil around 0.5-0.8, I wold like to guarantee this higher thermal conductivity at all times for 1m around the pipes (30in diameter).
This seems quite similar to "engineered" o "thermal" backfill used for cable backfill where the issue, as you will know, is also transmission of heat, but in the other direction...
I would like any info, data or links to suppliers who could supply this or whether there is a cheaper "fix" which would suffice as I've got a lot of backfill to supply and don't need super duper backfill, just stuff that's good enough.
Any info gratefully received and if you want more info please ask.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.






RE: High thermal conductivity backfill
RE: High thermal conductivity backfill
The insulation vendor has done some calcs and because we have two in close proximity (don't ask) they are predicting close to zero C after some time if we don't have soil of relatively high thermal conductivity - approx. 2W/m/K, which is the inverse of electrical cable conductivity from what I can gather.
Therefore although the heat flow is in the other direction these seemed to be similar to special high thermal conductivity backfill used for cables and I'm just searching to find some experience of it and any contacts / companies / papers / websites which can help me.
If this isn't the right forum then please advise, but it came up a few times when I searched for this topic here.
Thanks
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: High thermal conductivity backfill
RE: High thermal conductivity backfill
thanks for input, but reduction of insulation is not an option and heat input would cause a problem, not solve my current one.
The insulation is very good, but not perfect and therefore there is some small heat transfer from the soil onto the pipe. My issue is that the calculations show that without a relatively high thermal conductivity, over time this could get to or close to freezing.
Therefore my current query is about knowledge and experience of using high thermal conductivity back fill.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: High thermal conductivity backfill
RE: High thermal conductivity backfill
The first question that arose is: Is that really a problem? Honestly I don't know.
If it is :
You could circulate a fluid through the soil to constantly ''feed'' some heat to the system.
Reversely, you could make sure no water will be present around pipes, so that no swell will occur upon freezing.
If the project would be in a remote area i would say just freeze it. But since there are buildings nerby, I don't know.
Charles
Ingenieur Minier. QuTbec, Canada.
RE: High thermal conductivity backfill
RE: High thermal conductivity backfill
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: High thermal conductivity backfill