Influence of the type of land on geothermal energy?

[serge]

Hello

I have a proposal for a new mode of heating geothermal system with burial of a network of horizontal sensors (approximately 200 m² of collecting surface) for a single house built in 1990 (approximately 160 m² to be heated) with radiators, without floor heating.
What you need to know is that the nature of the subsoil is special: about 20 cm of soil on the surface, then pure fine sand to a depth of about 2m.
My question is to know if this layer of pure sand is favorable favorable or on the contrary strongly advised against for this type of sensors?
Do studies exist on the favorable effect or not of the nature of the ground, and in particular in sandy ground?
Does anyone have any perspective on this?
Thanks for giving me info.
SERGE.

[bolt]

Hello

it depends if the sand is aquiferous (full of water) or dry:
see the thermal conduction on the red board of this link
http://www.geothermal-energy.ch/fr/2_erdw_dir/2_erdw_tech.htm

bolt

[serge]

Hello

My basement being sand not very wet therefore not aquiferous, the thermal conductivity is low, which would mean that it is not favorable to the installation of a "domestic" geothermal system?
Is it better that I choose another type of CAP?

[Targol]

Hello

Hi Serge, and welcome to the forums Econology.

My basement being sand not very wet therefore not aquiferous, the thermal conductivity is low, which would mean that it is not favorable to the installation of a "domestic" geothermal system?
Is it better that I choose another type of CAP?

Yes and no
In fact, the thermal conductivity of the ground is both a good thing and a bad thing for geothermal energy.
A good thing because it facilitates exchanges between the collection network and the ground.
A bad thing because it also facilitates exchanges between the soil surface and the deeper soil where the collection pipes are buried. This makes us lose the more or less constant temperature side which is interesting in this type of collection.

What I can tell you on the subject comes from JP Oliva's book "La conception bioclimatique". This is the influence of soils on the efficiency of a Canadian well, but given that the principle of this type of device is based on the same bases as horizontal geothermal energy, I think that we can transpose without worries.

(...) the other physical characteristics of the soils have only a secondary influence on the performance of the system (...) Nevertheless, if the choice is possible, soils made up of elements of fine grain size like silt are preferable soil consisting of sand or even rubble.
On the other hand, the texture and the grain size of the materials surrounding the pipeline have a decisive role.

A diagram follows where the author advises placing the conduit in "a conglomerate predominantly clayey or silty, ensuring that this added material adheres completely to the pipeline".

I hope it helps you ...

[Other]

Hello

When it pierces all deep even in the rock or clay soil, it lays a pipe in U in quality plastic, then it fills the hole with fine sand, made circulate in these pipes a mixture water alcohol and it is pumped by a small circulation pump in the evaporator or condenser thermo pump depending on summer or winter.
the water ends up soaking the sand which makes a thermal contact with the pipe and protects it from surface thawing.

The hole piercers prefer that this is Roc they do not need to install a guard pipe
It costs an arm the holes
Andre

[serge]

Hello

If I follow the principles of "Targology" (with all due respect!), Is it true to say that my sandy basement should not undergo large temperature variations during the heating season, given that the low conductivity sand limits exchanges with the surface soil?

What is the ideal depth for burying sensor networks?

Then, does that mean that in theory it would be necessary to increase the exchange surfaces at the level of the collectors to compensate for this low thermal conductivity encountered in sand?

Serge.

[Targol]

Hello

If I follow the principles of "Targology" (with all due respect!),

Excellent, you think i deposit the term at the INPI?

is it true to say that my sandy subsoil should not undergo large temperature variations during the heating season, since the low conductivity of the sand limits the exchanges with the surface soil?

It's exactly that.

What is the ideal depth for burying sensor networks?

Norman's response (to say that all the Bretons are not blocked on this side): the best, the deepest possible. For information, in our climates, we consider that a non-soggy soil remains at constant temperature from 2,50m deep. Now, if your basement is actually dry sand, it should keep you from going as deep. In addition, 2,5m trenches in sand, there is interest to support ....

Then, does that mean that in theory it would be necessary to increase the exchange surfaces at the level of the collectors to compensate for this low thermal conductivity encountered in sand?

In theory, yes, in practice, "I could not say it" as our Belgian friends would say.

[zac]

the cow
we had a great guru, engineers, plumber mechanics, an oceanologist, electronicians and here we are with a targologist; if with all that we can't get the cars to run in the water it means we suck

@+

[Targol]

the cow
we had a great guru, engineers, plumber mechanics, an oceanologist, electronicians and here we are with a targologist; if with all that we can't get the cars to run in the water it means we suck

@+

It is not given to everyone to be Targologue (with a capital "T" if you want Zac ). You need predispositions at the start and a lot of training.