Thernal transfer grout or just concrete for thermal tranfer
 

In some cases they use a high thermal transfer grout to surround geothermal ground lines, I am thinking this might be a superior product to use for Hydronic heating or cooling.

Since they go to the trouble to use a high thermal grout to surround geothermal lines would it be worth it to use the grout to surround the lines in the floor heating circuit or a refrigeration cooling circuit ?

I could use opinions on if concrete will be just as good to use as a thermal grout for cooling in my case but I think it would apply equally to heating.

I am making a line imbedded mini refrigeration unit and want it to function well.

I want to hear concrete would be just as good as its easier to get but I would seek out and get the thermal grout if its deemed worthy.

educated guesses or opinions would be helpful as I am winging it.

I looked into thermal grout more thoroughly , its basically just a high silica sand grout with concrete and plasticizers in it.

So i looked at home hardwares advertising for grout , they have 25lb Sanded Floor Grout.


here is the description of home hardware's standard grout:

A Polymer modified, blend of portland cement, specially graded and washed silica sand and organic pigments
Requiring only water for the mix, this rapid curing product will yield, when cured, a hard, dense, non- shrinking, uniform colour joint that produces high compressive strength with improved flexibility and freeze-thaw stability
This non-toxic, non-dusting, iron-free grout is resistant to bacteria, fungus, oils and alkalis

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Which is close enough to a thermal grout as it is made from the same fine grade silica sand.

I also found out that they use thermal grout for hydronic radiant heating as well as for filling around

geothermal lines to increase thermal transfer of the bore hole.

In short its a cheap readily available product that will increase the transfer rates of hot or cold.

I am going to use it with the edition of added concrete powder to increase its structural strength.

So, what do you think the increase in thermal conductivity of your mix would be over a normal sand mix or concrete and what would be the real benefit?

My point is.....there is no real need to get a higher conductivity out of a concrete slab as the dT over the loop is usually appropriate for length of tubing and size of room. Having a higher heat draw out of the tube would only mean, IMO, that a typical 250' loop length would be dropped to (for example) 200'. What would the implication of that for your system? What size area are you trying to heat?

I am making a DIY fish tank cooler from a water jug cooler , for the thermal mass rather then water It will employ cement or common grout with its fine grade silica sand.

the stainless chiller bucket will not be used , just the copper refrigerant tubing that spirals around it.

Its that tubing that will be embedded in concrete and wrapped in layers of thin black poly tubing with concrete or grout in between to insure 100% contact and thermal transfer from one coil to the next.

After its wrapped with 70 feet of tubing ,inside and outside of the copper spiral
I will encase in a few inches of concrete to act as the thermal storage.
then it will be encased in about 6" of ' Great Stuff ' spray insulation.

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to circulate the tank water threw the tubing I will us my Aqua Lifter dosing pump ,which is normally used in conjunction with a float switch for automatic top ups of the main fish tank from a lower water tank.

The Aqua dosing pump is rated at 3GPH , it is going to be controlled by a eBay temperature controller relay with on / off temp settings.

The stock water cooler comes with full control over temperature settings so I have its built temp controller to adjust the chiller itself.

Silica has a very high thermal transfer rate much more then common concrete does

I will post the thermal values later when I look threw my bookmarks , if memory serves me correctly its 3x more effective at thermal transfer as compared to concrete.

PDF file on benefits of thermal grout

Attachment 4974

Interesting. I assume the copper tube will not be in direct contact with the cement. I couldn't tell exactly from your post if it was. I don't know how many feet of tubing there will be but you may not get the 3GPH (H not M?) from a pump that is designed for a lower head loss. Something to check.

The cement will be used for its ability to surround both the copper pipe and the fluid transfer poly tubing , In full the cement will be used as a full contact thermal bridge *and* as the thermal mass to store the cold.

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The pump is rated for a 30 inch head , I will only require about about 8 inches of head ,

Using gravity to my advantage the water will enter from a high point and exit from a low point , causing a slight siphon effect that will reduce the work load of the pump.


I have faith the siphon effect I mentioned will allow the Aqua lifter pump as its called to circulate the water at a constant low rate.

Being the pump is external it is easily swapped out for a larger pump

Do you think the copper will react with the cement or grout , causing oxidation of the copper ?

If that is a problem I will spray paint the copper refrigerant tubing with primer to seal it.

The pump

https://www.youtube.com/watch?v=S2NmQVqwWa0

https://www.youtube.com/watch?v=EoETbDQxgAo

I have seen this kind of reasoning before, here on EcoRenovator.

It is correct if your objective is to build the minimum heat-transfer structure.

However, if it is your intent to build a system with maximum efficiency, then another kind of reasoning is called for...

-AC

The cost to effect number works out well for such a little system like this, also I am thinking it would be best to maximized its efficiency as it runs off electricity.

The pdf file I uploaded brought up cost to effect , there is a effect its the costs of it that you need to think of.

When it dawned on me that the normal fine grade silica grout would suffice I pretty much made up my mind to use common grout over the concrete.


I don't think I will bother with the purpose made thermal grout , unless it is deemed worthy by others ?

The thermal grout comes in thermal grades so there is some improvements to be had if I do upgrade to a quality thermal grout. Not sure if it will be worth it in my projects case

I think now my question is ordinary fine silica grout or the high grade silica thermal grout ..