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Obamot
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by Obamot » 17/11/15, 12:05

At what altitude is your STP building located?

Photos of the land, the property line?

What is the current water source for your water-water heat pump?

PS: did you not suggest some limits in your own ability to implement your project (when you talk about trades "who already have trouble talking to each other and coordinating actions among themselves")
... sorry, if I try to decrypt a little ... ^^
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lilian07
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by lilian07 » 17/11/15, 14:16

altitude 300m
PAC water source: water-glycol water (it is water that goes underground 1m (horizontal geothermal 500 m2 of soil) closed circuit.

Project limits: Self-construction and possibly the use of a second-hand drill.

When I mentioned the limits of the trades it was to illustrate the difficulty of having passive houses built (like the one cited as an example by Yves35) for our builders who sometimes have poor control over the coordination between the different bodies ... this coordination becomes preponderant in a passive house ...

The parcel :
Image
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Christophe68
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by Christophe68 » 25/11/15, 12:30

Interesting subject in which I have already participated (under the same nickname) on another forum here, if it can help you:
http://forum.apper-solaire.org/viewtopi ... 3&start=45
It would seem that the proposed installation, 2 or 3 200 liter tanks, is largely underestimated.
We will rather speak here of inter-daily storage.
It is useless to isolate the earth below, the insulation on the surface is enough.
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Obamot
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by Obamot » 25/11/15, 14:54

Ok for the "underestimated" capacity (thanks to Izentrop's calculation)

Christophe68 wrote:It is useless to isolate the earth below, the insulation on the surface is enough.

It all depends on how big eXergy you aim ... In addition. not insulating creates a thermal bridge (at -1m you are frost-free, at -10m you are only at + 10 ° C it's not quite the giant foot yet ...) : roll:

Image
Source: Goongan-Geothermal

If you can support this statement with a concrete case? And observations?

RTDC.

PS: failing that, very good insulation seems imperative to me.
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Christophe68
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by Christophe68 » 27/11/15, 14:46

Obamot wrote:If you can support this statement with a concrete case? And observations?

I developed on the link of my previous post (the graphics have disappeared but it is understandable all the same).

There is a large-scale experiment in Canada:
http://www.dlsc.ca/how.htm

The average soil temperature in the Ardèche should be around 12-15 °.
In the case of a horizontal cold source, the earth will cool and the sun will heat it.
You can bias the average temperature by playing on the albedo. Ideally, a black earth in the visible and low emissivity (white in the far infrared) is needed.
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by Obamot » 27/11/15, 20:02

It has nothing to do with it, I was asking for something serious (pfff far infrared at -6 m in winter!). : Shock:

The Canadians we talked about during riverside sons in this forum: a) it is perfectly insulated b) they have a gas back-up plant, in particular for DHW c) they are passive houses.

All this is unusable in this project.

Also, at -6m from the albedo here, sorry. This argument is used in particular for issues of global climate warming, it was used to criticize Désertec, but there it has nothing to do, what is the point!

Finally, if you look at the cold winter months and you note the temperatures, relatively to the depth, it is completely impossible to reach at -6m 12 ° C to 15 ° C, it is rather of the order of 8 ° C to 10 ° C and elsewhere the lower you go, the less the surface temperature plays a role (this is precisely the goal).

And what interest to take then such temperatures in summer, when the situation is not critical and on the contrary we would try to cool the buildings during heat waves. Still not relevant, or I did not understand the argument.

In short, anyway 15 ° C is very insufficient, would it be possible to heat such a building with such a cold bridge below and which will pump the available temperature already not very high ... (admitting not not isolate) it will not already be possible under normal conditions, so there I do not understand the reasoning ...! For me it's totally irrelevant.
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by lilian07 » 27/11/15, 21:23

Hi,
I retain several interesting things, in particular the old discussion and assertion of Christophe. It leaves a glimmer of hope to try to harvest a few Kwh of the summer surplus. I also remember and it is a real plus to simplify the thing well (I remember that I stayed with a cube of 64 m3 of earth (4x4x4) isolated on the 6 faces by 35 cm of insulation.

I had made a brief loss calculation to assess the achievement:
With some approximation I get the following reasonable values:

Diagram :
Image

Total storage energy 2232,00 Kwh
Total loss 503,06 W (delta of 30 ° taken into account)
Daily loss 12,07 Kwh
Theoretical storage time (linear loss to reach earth temperature) 6,16 Months

Now if I don't isolate the most complex side to reach, that of the bottom of the 64 M3 excavation, then it becomes much easier to do because I no longer have to do the total excavation of the 64 m3, just 4 trenches of 4mx4m to 6m deep and to isolate on the 5 faces (side and surface at -1m deep before putting an umbrella (EDPM and finexe type). Possibly small greenhouse above the storage.

I keep the study of plan B with the core drilling system at 1500 euros used. I also studied the possibility of putting a hydraulic auger on the shovel (1000 euros of occasion) ... finally the subject begins to please me.
Good night
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by Obamot » 27/11/15, 22:15

: Shock:

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Christophe68
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by Christophe68 » 30/11/15, 11:46

Obamot wrote:a) it is perfectly isolated


Only on the surface and around it, it is explained on the site.

Obamot wrote: or else I did not understand the argument.


Indeed there is a misunderstanding.
Albedo depends only on the surface of the soil and determines the temperature of the soil on toute depth without distance limit.
Concretely this means that a black soil will be warmer than a white soil (regardless of the depth).

@lilian07
It is interesting as a project, but there is a small calculation error.
The volume thermal capacity of the earth is only half (approximately) of that of water, i.e. 0,6KW / h per m3 and per degree, or for 64 m3 64 * 0.6 * 30 = 1152KW / h.
It is far too little, the project is undersized.
In addition, hysteresis must be taken into account (the earth will heat up in the vicinity of the pipe when injecting calories and cool down when pumping calories).

I don't have access to your diagram, can you put it as an attachment?
The losses will depend on the surface insulation, it is useless to dig the trenches (take inspiration from the site in link on my previous message).

The first thing to do is to check the nature of the soil.
I can dig a meter of clay in 5 minutes with a hand auger, but as soon as there is a pebble things get complicated, and if there is granite it is not even worth it.

The absence of runoff must also be checked.
The presence of a nearby water table would disturb the project by draining calories.
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lilian07
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by lilian07 » 30/11/15, 20:33

Ok considering the error .... I took the heat capacity of the water !!!

Cube storage 64 m3
insulation thickness 0,35 m
Coef insulating conductivity 0,045 W / (mK)
Delta T 30 °

Area transmission coefficient 0,13 W / (m².K)
Insulating thermal resistance 7,78 m².K / W
External surface 132,54 m²
External volume 103,82 m3
Heat loss 16,77 W / K
Energy stored / liter 17,08 Wh


Total storage energy 1093,33 Kwh
Total loss 503,06 W
Daily loss 12,07 Kwh
Theoretical storage time 3,02 Months

It is worrying because I have just arrived at my initial objective ... 10% of 10.000 Kwh .... which is not very good because it has no margin.
We have to find room for maneuver, but how?

Project
Image


Of course I have an umbrella underground to be out of the water.
As Obamot mentions, I am thinking of using the heat pump to be able to pump up to 10 ° which will allow me to obtain by default my objective: COP +1> 2000 Kwh ......

the hysteresis I think about it but as I charge the earth in around 2 months I hope to be able to pump the calories over the same period ....

I hope to be able to go up to 50 ° at the end of the summer to be able to consume up to 10 ° ...... which would be not bad !!!

I'm going to do a thermal auger survey (neighbor) and put some extensions ....

Good night
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