inter seasonal storage solar thermal

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lilian07
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thermal buffer underground




by lilian07 » 15/11/15, 14:15

Hello,
New on the forum I plan to switch to solar thermal which is the only alternative from my point of view (simple, self-construction possible, good COP> 100 efficiency, allows to reach the greatest number ...) when combined with a technique of inter-seasonal storage (if this is possible even with low storage yields) this system becomes the holy grail considering that the buffering technique is simple.
I naturally come to the buffering technique, as it is understood that capture is under control today. I have read the whole debate about the herakles roller tunnel, Christophe's installation (70 m3 of water), the surface drilling system (10 to 20m) in swarm proposed by dedeleco and the system deep drilling proposed by Christophe.
I think there is what it takes to experiment with something.

I launch my proposal which is a little at the crossroads of his ways I wait for your opinion and criticism because it is not an ideal I hear but a simple experiment.
I therefore plan to achieve a thermal buffer with very little means and especially with the waste of the energy industry.
I propose the recovery of a cylindrical metal tank with a capacity of 1 to 3 m3 to bury it at deep 5m (sliced ​​or single hole of excavator) this uninsulated recovery tank (the right corner) will be used as Thermal vector recharging the surrounding land in the summer and as a source of heat recovery in the winter.
Balloon water is injected and recovered by conventional PER. Study variant bury 2,3 200 flask with a non-insulated heat vector balloon and may be an insulated balloon (DHW recovery) allowing for a warmer energy buffer for DHW or heating .
Sizing was not calculated for multi-balloon cases
But I'm interested in the simple metal balloon case (without insulation) serving as a heat transfer vector in the earth (as well as a roller tunnel) and heat recovery.
I just know that my 200litre single-balloon vector allows me to transfer a lot of heat into a midrange with a delta of 15 °.
Thank you for your opinions.
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Obamot
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by Obamot » 15/11/15, 14:35

1) your project is interesting.

2) it is not possible to answer you until you know what type of dwelling it is (but as you say you would like to switch to thermodynamic solar recovery, it suggests that is the existing ...) nor answer until we know how high the existing building is.

3) if yes, what about the type of thermal insulation of the building? ITI, ITE or what do I know? This is obviously very important since it would allow to measure the sizes of eXergie to size any installation (even if it is too recent for my training, it would need someone sharp to get to do it or so go to empiricism with GROS may crash.)

4) but I tell you straight away that even with the right answers on all these points, it is unlikely to work as well as you think. The sizes of eXergie plays on very small parameters, you have to have a lot more under your feet. We'll have to adapt the idea. For example, if the temperature is stable around -12m, you have to go down to -30m to gain 1 ° C every -30m [...] this to say that at the depth you give, you have to imperatively a perfect thermal insulation to this tank. There is no question of creating sufficient thermal inertia here, between the tank and the surrounding earth in contact, the temperature will be pumped by the earth long before being able to recover the stored energy ... example, it is already necessary to wait 2 years at -350m before the "system" stabilizes ...! And then there are the corrosion problems, the fact that having several small tanks instead of a large one is not a good idea in terms of losses, etc ...

5) it works for a passive house, but the tank (thermal buffer) must be INSIDE the habitat, as here: heating-insulation / heating-solar-building-with-thermal-buffer-in-switzerland-t11285.html and even inside it must be isolated!

6) in all cases, with a good passivation of habitat (ITE 300mm), it is not forbidden to think that you do not need such an installation, must see .... (and if you think you are able to make such an installation yourself, you will be all the better able to review all the insulation, which requires a less complex knowledge.)

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by lilian07 » 15/11/15, 19:06

Thank you Obamot for responding so quickly.
As for the house is a house already built old building ardéchoise 1850 (Rhone Alps at the latitude of Montélimar, altitude 350m) which includes a geothermal heat pump 19 Kw water / water buried horizontal sensor. Power Consumption 15000 CAP Kwh for heating on 4 apartments of 100 m2. Internal insulation 100mm on wall and 200 mm in ceiling. Floor heating base temperature. South-facing greenhouse (polycarbonate / aluminum pool enclosure) of 50 m2 attached to the house.
What I seek above all is to experiment at lower cost (storage tank recovery) but this famous thermal storage capacity (very controversial) to 5m depth or other (earth mass clay and possibility of my excavator on 6m tire of deep).
I am aware that a sizing requires a goal and I am well acquainted with the simple theoretical calculations of diffusivity, conductivity and mass capacity. Let's say I'm looking for the 5000 Kwh storage (I do not have a thermal panel but I will size my system without buffer and build a buffer in parallel to increase the thermal phase shift in time).
I thought beforehand simply to use a thermal balloon without insulation to make use of vector / recuperator of hot water. a single hole 5 / 6 m and I put the balloon as a probe with its PER circuit back / sheathed. According to the calculation of the diffusivity it is admitted empirically that the earth diffuses the thermal wave of one meter per month, I can thus estimate that a phase shift of 4 month will diffuse the spherical wave on 4m around my probe. Still empirically I estimate a quantity of heat of about (268 m3 storage volume of the sphere around the probe). The specific heat of the earth is sufficient to contain my 5000 Kwh. Until then I know by empiricism (surplus) that the amount of my heat must be in this sphere. Where all is complicated is to recover this heat mass (we must agree on the real subject that begins now).
If I want to stay simple I use my probe as a source and it should reverse the process (I pump calories) but the calculations become complex and the only experiment that costs me not much until then (a balloon recover and 10m from PER) takes over. I get 1%, 10% or 50% of my calories ??? if I get 10% of the calories then my system is already largely viable given the robustness and extreme ease of implementation.
I am well aware that from this point everyone breaks their teeth that's why I want to explore at no cost to find or not a possible way.
I already thought about the optimization principle
1er simple optimization stage: excavate 4 sliced ​​(in 4m square) of 0.3 x 5m from deep around the probe to put styrofoil-type insulation to trap calories (can perhaps raise the temperature higher )
2eme stage of optimization: completely evacuate the volume of earth necessary for the storage (calculation heat mass) then isolate (paradox there one could not isolate more the building one insulates the ground, to meditate ...) on the 6 faces of a cube of 4m of 6m deep side to plunge my probe (tank) and be able to recover the calories more easily.
3eme stage of optimization: placing several probes as required by the technique described by dedeleco but in less technical and shallower.
I would like to come back to your Obamot analysis: "4) ... it is imperative that the tank has perfect thermal insulation. No question of arriving to create a sufficient thermal inertia here, between the tank and the earth around in contact, the temperature will be pumped by the ground well before being able to recover stored energy ...! And then there are the problems of corrosion, the fact that having several small tanks instead of a large is not a good idea question wastage, etc ...
My principle is to transfer the calories to the ground to make it just this storage capacity simple and infinite if I bury an insulated balloon so I have a problem of feasibility because I will have to have a pool of water stored at - 5m (if you're right then my project stops there because it is better to put his swimming pool inside his house (see storage 70 m3 ...)
The problems of corrosion are easily surmountable (dry land ... or stainless steel ball ...) if the earth must pump all my calories then the calories go too fast and the theory of diffusivity underground no longer holds (1m / month) even less than that of the pebble tunnel ... and I come back to my point of optimization 2 (still workable) isolated the earth rather than buried a pool ....

This is a first approach that is simple, I expect any form of criticism that may allow advanced.
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by Obamot » 15/11/15, 20:16

I will be even less optimistic. In general it is not good to come to ask advice while the quantities are already made ...

Without personal offense it is very badly barred, there are already erroneous previous choices that can not be corrected by the project thus pinned. Choice in the plural (why an ITI whereas in this way we deprive ourselves to use the thermal inertia of the walls, which thanks to an ITE would cover this mass to benefit from its contribution instead of having to fight against this cold inertia which works against the goal ... There was already a way to store heat for the night cycle ... Why the choice of PAC when they have a poor COP precisely when we need to they to heat themselves, since with the cold the COP collapses ... Why not a stove made mass hand for this type of buildings ... Why finally an ITI that will make the walls unhealthy, create pockets of humidity and risk of destroying the building more one heats ... by disintegration of the walls and invasion of molds / mushrooms)

A priori seeing such a project, I would say that fighting cold bridges in such a construction is insoluble, and almost at the end of the work you will not see any difference. You have such an unfavorable eXergy value that it is not compatible with your project.

Not only would it be good to see everything again, but in the right order and it would be necessary to begin by accepting the mistakes made. I am amazed that no one has warned you against this combination of wrong choices.

Sorry if I see it like this, it must be a bit hard to read, but there is not really a choice.
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by Ahmed » 15/11/15, 22:14

Unfortunately, there is no need to be surprised, so this type of case is common.
A new build near my house has the same basic errors. As I was surprised by the choice of an air / water cap with the future neighbor, he replied that his house was "well insulated" ...!
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by Did67 » 16/11/15, 09:14

I had, there is 3 or 4 anbs, initiated a reflection to know how one could store the fatal heat of a cogeneration group of an anaerobic digestion station, to supply greenhouses.

The idea was comparable: we had, at times, lost heat.

It could be sent, inexpensively, into the deep layers of the soil, to collect it in winter and heat a greenhouse. Greenhouse which could be built directly on the storage site, in order to value the "losses" upwards, above the underground buffer ...

I never advanced because: a) I had something else to do! ; b) I did not find anyone able to calculate all the parameters: effusivity, surface of exchangers to put in place, efficiency (heat recovered / injected heat), etc ...

It is to say the least complex. And that already depends on the nature of the soil, its humidity, etc.

A simple remark: why bury a tank if the buffer is the soil? So much to bury coils, like a big heating floor working in one direction - injecting calories - in the summer and in the other - recovering calories - in the winter?
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by Obamot » 16/11/15, 09:58

Did67 wrote:A simple remark: why bury a cistern if the buffer is the soil? So much to bury coils, like a big heating floor working in one direction - injecting calories - in the summer and in the other - recovering calories - in the winter?

Because of the law of mass ....
Such a system with a heat transfer fluid should not function as a "battery" but as an exchanger.

Your coils would look like you do in a heated floor, but the thermal inertia of the concrete plays in favor of the system, the earth is too much and the pile could not even load, if you count still the losses intrinsic to the cold bridges, you can mark a pity ...

On the other hand by drilling at -350m it becomes possible ... But the cost of drilling is 20'000 € + boiler ECS and sensors on the roof apart: so think carefully ... Completely redone an ITE c ' is not so expensive to do yourself (5'000 6'000.- first price for 150 m2 insulation 200mm LDV, including under-roofing and purchase a small scaffolding). Add the price of the cladding if you want one, but you can plaster on an ad hoc coating anchored to the panels of compressed LDV (thanks to polyester lattices and all sorts of tricks)!

A borehole does not begin to bear fruit until 2 years (necessary time for the balance of the system). At this depth we can store without problem and have an exchange system that continuously provides 23 ° C 24 ° C and ECS apart, but before it is democratized, it will only be worth to heat historical monuments that we can not heat otherwise (if the will of the administration is to have an energy supply 100% EnR ...) and in my humble opinion.
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by lilian07 » 16/11/15, 11:04

Ok thank you for the analysis Ahmed and Obamot and thank you for setting the record on time about the adage that the best calories are the ones you do not consume (I master the field of ITI but my house is not a straw / wood house, BBC or troglodyte ... unfortunately, I specify that I have nothing against this type of house elsewhere they fascinate me ...) .
I specify the situation:
Existing house (exposed stone) in protected site (ZPPAUP) impossible to isolate from the outside.
Renovation classic rock wool 150mm + 200mm + insulation under slab + vaulted cellar on the ground + water / water CAP 19 KW horizontal sensor + large south opening + south greenhouse shelter + North insulation lining + small north opening.
I did almost the maximum with the local constraints and the budget as low as reasonably achievable:
Result: 4 zones heated by the only PAC water.eau without energy programming optimization (autonomous tenant): 18000 Kwh of electrical energy consumed on average over 5 years for heating only (2750 euros / year nuclear per year) for 450m2 of surface to be heated (1200 m3 of volume).
I think it's not so bad 700 heating euros per year all automatic.
I know this is not the ideal but it is not far from being a good result given the constraints.
Sorry for not being able to specify before the inventory what is fundamental.
I come back to the subject:
I'm going on an experiment in the first place concerning 95% of the users "the metric or the measurements are already done ....postulate: a poorly insulated French park, external insulation at prices "in depreciable" and a price of the fossil / nuclear kWh ... excessively low, it is the economy that governs this world and I do not want to debate the top, the subject is too large and complex).
I do not seek in any place the grail, just doing tests before building a passive house. I have for this a great playground (my house sieve poorly isolated and a clay clay virgin ...)
I will refocus the subject: inter seasonal 5000 Kwh buffer (1 / 3 my consumption) the debate begins on the inter seasonal stamping, I site my previous post: "Where everything is complicated is to recover the heat mass underground (we must agree on the real subject that begins here)" ....
Thanks again for your criticisms because they check the sad state of our real estate stock and our choices of society, but we are all responsible...
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by lilian07 » 16/11/15, 11:29

Did67 thank you,
The debate is refocusing. The purpose of using a small uninsulated buffer as a source and vector is its price and ease of implementation (it is a nuclear waste waste HS electric hot water tank available for free (let's give it or Right corner)
200l = about 2m2 radiating / capturing surface ... it is possible to inject 1000 of Kwh / day (metal / earth conductivity) with a delta of 15 ° without any problem between the water injected and the return to the solar or other sensors. ..I do not have yet optimize the source (can be a balloon of 50litre enough to see but less current ...)

My problem is to recover this energy in this imaginary earth sphere of 4 m of radius (250 m3, empirical Earth diffusivity 1m / month) around the source at 6m of deep.

Of course, the operation is very easy to do (a bucket shot of 60 cm ... 30 minutes of excavation) and I send my probe and my temperature sensors. For this operation I want to gather the maximum of information .... I even plan to perform tests by putting a functional electric balloon to heat it with its electrical resistance and to make measurements (conductivity, effusiveness ... ) .....
Kind regards.
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by Obamot » 16/11/15, 11:34

Well, there is not so much to squirm, does a drill!

And the deepest possible with a boiler as a thermal buffer (direct recovery when there is sunshine ....)

Why? Because you already have PAC water-water, and so you would leave with a very interesting exchange temperature by connecting it to your circuit no ?!

If you don't want to and you stay stuck on your project, you still have to know a basic thing: the problem is that it's not so much "we who decide"that the configuration of the data of the problem which is imposed on us, and therefore it is not totally us who choose the solutions to solve this type of problems, it is the solutions which are imposed on us according to the constraints that the 'we have ...! Every engineer knows that.

So if you continue (but I seriously invite you to go to a drilling average depth) there is the project http://www.dlsc.ca/borehole.htm

But I will contact them directly by asking them questions, they are perfectly aware of the constraints, but you will notice that their system buried in the ground is completely isolated and severely!

I have never believed personally (they have a gas central ...) for the good and simple reason that the EPFZ can only happen there and with new constructions passivated! And the Federal Polytechnic School of Zurich, it is not sleeves, they are at the origin of Solar Impulse (the solar plane) it is one of the most visible technological poles in the world.

And then we come back to drilling at medium depth:

Contacts / links:
http://www.largeur.com/?p=4167
http://www.fcl.ethz.ch/person/prof-dr-h ... eibundgut/
http://www.fcl.ethz.ch/module/low-exergy/

For me it's the man of the situation to solve your equation. But he there's something that crumples me, if your facades are protected, your roof will be just as good, so you want to put where your thermodynamic solar collectors to heat the water? Since they can not be on the roof, excluded!

Anyway, my position does not change from what I said above (size of eXergy far too unfavorable for shallow buried storage with a non-passivated house) there will only be "one-off" results. For listed buildings, perhaps a chance in the future with a totally transparent insulation based on an airgel >>> but you have to make it weightlessness : Mrgreen:

It is not that it is not possible to discuss it, it is that we are not touching the ground compared to the reality on the ground ... It is as if we were saying that we are going to produce 'electricity using a home trainer placed in a bus to move it, it will take a long time to pedal for it to make its first turn of the wheel ... and at the slightest climb it will start running more safely back that it will not advance ... but we can always discuss it and start the debate from a point "P" : Lol:

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