Heat a large structure

Heating, insulation, ventilation, VMC, cooling ... short thermal comfort. Insulation, wood energy, heat pumps but also electricity, gas or oil, VMC ... Help in choosing and implementation, problem solving, optimization, tips and tricks ...
dedeleco
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by dedeleco » 12/04/10, 13:40

Totally agree on the figures which further show that energy is not very expensive !!
Many houses, even modern ones (some with monomur on econology for example ask questions) consume double 4 tonnes of pellets per year !!
So at 10000KWh per tonne of fuel = 2 tonnes of pellets and 70KWh per tonne of water heated from 20 to 80 ° C (already the max) you need for 6 months of reserve at 4 tonnes of pellets 2x143m3 = 286m3, a very nice pool !!

It is certain that solar thermal collectors give energy especially in autumn and spring (real practical information on the possible values ​​are very important) and that a reserve of 3 months is sufficient with these good solar collectors, or 143m3 is sufficient.
It is a beautiful pool and therefore using available and unused underground soil with drilling seems very tempting, but the volume of soil required doubles or triples with the water that soaks it. In this case the price is that of drilling and exchanger pipes between 6 to 3 meters deep.
I think this remains possible since there is no longer any energy consumption in perpetuity on a house unchanged apart from the sensors on the roof or in the garden if it is large.
It all depends on the volume of usable soil underground and the price of drilling or excavation.
I think that the price of drilling varies enormously according to the tricks of realization and industrially with tricks one must be able to reduce the price.
The market of millions of houses is huge but less than oil, especially if its price soars !!
The ideal would be a light and small diameter drilling robot (drill which advances by drilling and evacuating the waste with the tube in water) that would allow drilling with curves and lowering the price.
By tinkering very very strongly we must be able to mount and develop such a mini robot driller !! A modified drill and small motors may suffice.

Commercial augers used for soil surveys before foundations can suffice in sandy clay soil at a not too high rental or purchase price.
The tanks for 143m3 seem very bulky and very expensive, although possible in a beautiful buried swimming pool on large grounds with rainwater.
There are swimming pools from 14 to 20m3 in summer for less than 1000 € and therefore with 10000 € we can have such a reserve of 10 swimming pools, to bury and isolate (we rent small excavators to dig in sandy clay soil ??).
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by bernardd » 13/04/10, 21:02

dedeleco wrote:Many houses, even modern ones (some with monomur on econology for example ask questions) consume double 4 tonnes of pellets per year !!


We didn't talk about living space: the advantage of a ton of fuel is that it's easy to calculate :-)


dedeleco wrote:So at 10000KWh per tonne of fuel = 2 tonnes of pellets and 70KWh per tonne of water heated from 20 to 80 ° C (already the max) you need for 6 months of reserve at 4 tonnes of pellets 2x143m3 = 286m3, a very nice pool !!


for example 6m x 24m by 2m deep! It makes people aware of the "size" of energy. But let's avoid the bath at 80 ° C ...

We immediately see the importance of reducing the need for energy: the mere fact of installing solar thermal collectors can reduce the need for fossil heating by half.

Then, it remains to be stored for the longest period without sun, with a collector surface allowing the heating + the filling in heat of the reserve. Less than 3 months is enough then, except perhaps in certain areas of the north?

This is why 8 stainless steel tanks on pallets, stackable (2mx2mx2m) for 10 days of autonomy, I think it is feasible and profitable.

if not, there remains the oil storage, which from what I heard, can go up to 400 ° C. But the heat losses increase, and I have no idea of ​​safety (toxicity, fire?) Nor of the behavior over time.

dedeleco wrote:It is certain that solar thermal collectors give energy especially in autumn and spring (real practical information on the possible values ​​are very important) and that a reserve of 3 months is sufficient with these good solar collectors, or 143m3 is sufficient.


The efficiency of 60% is a minimum with vacuum sensors, and we can base ourselves on the real monthly statistics of photovoltaic solar, taking into account an efficiency of 60% instead of 14%.

dedeleco wrote:I think that the price of drilling varies enormously according to the tricks of realization and industrially with tricks one must be able to reduce the price.


I looked at this problem: today, I can not find anything less than 40 € / m of drilling, even of small diameter. However, for this to be "general public", it would have to be less than 10 € / m.

I have tried with different solutions and the "mass production" drilling is not easy. I think we should look at the side of small quarry drills, but I could not go further for the moment.

However, this will allow you to get to the temperature of the soil, 15 °, but you cannot store at 80 ° c because the losses will be too great. This responds well to the problem of Canadian wells or air conditioning, but I do not see a great effect on the storage of hot water of solar origin.

If anyone has any ideas :-)
Last edited by bernardd the 13 / 04 / 10, 21: 08, 1 edited once.
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Ahmed
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by Ahmed » 13/04/10, 21:08

@ Patric:
The case of a large structure for occasional use is very different from a living space.
The problem of insulation does not seem too critical to me because of a relatively small surface relative to the volume: the usual solutions are more than enough.
For heating, I think that the solution of a large buffer storage is quite unrealistic in this particular case.

Rather than trying to heat air which will tend to stratify, wouldn't it be better to use suspended radiant heaters, using gas?
Advantages: reasonable investment, low consumption, practically no inertia (therefore very simple management of start-up: no need to send staff two hours before), no stratification, comfort for spectators et sportsmen (it is possible to heat differently according to the zones), less expensive insulation ...
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by bernardd » 13/04/10, 21:16

He said it was a one-time use? How often?

Otherwise, using gas to reach a temperature of 15 ° C, which he specifically requested, seems to me a real waste, since it is exactly the temperature of the floor under the room.

So by storing enough solar hot water for the sanitary facilities (showers!), A circulation of underground water must suffice.

Is the room directly on the ground? Is it easy to make trenches with HDPE pipes under the room or in land around the room?
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by Ahmed » 13/04/10, 22:12

The use of this kind of equipment is necessarily intermittent.
... using gas to reach a temperature of 15 ° c, which he specifically asked for, seems to me a real waste ...

This is why reaching 15 ° is not necessary with IR, what is especially requested is a minimum of thermal comfort ...
I know this solution lacks "glamor" and I deplore it too!
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bernardd
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by bernardd » 13/04/10, 22:20

Ahmed wrote:This is why reaching 15 ° is not necessary with IR, what is especially requested is a minimum of thermal comfort ...


To do sports ? between 10 and 15 ° it's perfect for running or basketball ... as long as it doesn't rain :-) Frankly I don't see the point of gas here.

Another solution: swimming pool in the basement, gym above on the mezzanine, and solar collectors on the roof: there is a large water reserve and everyone wins :-)
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dedeleco
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thoughts and error on my part




by dedeleco » 14/04/10, 03:11

Basically we agree, it is not easy and you have to be creative, make the impossible, even unimaginable, possible !!
6m x 24m by 2m deep! It makes people aware of the "size" of energy. But let's avoid the bath at 80 ° C

The energy of a typical winter house heats 1/4 of an Olympic swimming pool!
today, I can't find anything for less than 40 € / m of drilling, even of small diameter. However, for this to be "general public", it would have to be less than 10 € / m.

In large quantities, the price is limited by that of the hour of work for the most part, unless you do it with your hands, or in China, Indonesia or India !!
For an alluvial clay-sandy soil not too hard, drilling is done very quickly for 5cm in diameter with a motor auger we arrive at 6m deep in half an hour as I saw for a geological determination of soil quality ( if too hard, it is solid and good and we stop). So on not rocky ground (but with some limestone stones) you must be able to drill at less than 10 € per meter with auger used by soil analysis geologists.
On solid rock, it's different, with diamond, it's slow and therefore expensive! Then only the insulated tanks remain.
Many houses are on soft ground and even too soft by drought with cracks !!!
Heating with gas to have almost the temperature of the ground is rather strange and puzzling !!

However, this will allow you to get to the temperature of the soil, 15 °, but you cannot store at 80 ° c because the losses will be too great. This responds well to the problem of Canadian wells or air conditioning, but I do not see a great effect on the storage of hot water of solar origin.

The guiding principle is to use the fact that heat takes time to diffuse through a wall that grows like the square of the thickness and therefore from 3m of earth the diffusion time approaches 6 months !! So over a time less than this diffusion time, the heat remains concentrated on the volume where it is deposited plus the one on which it diffuses outwards, almost without loss on this total volume !!
So the losses are low in the diffusion volume if the heated volume is large compared to the diffusion volume, 3m on all sides in 6 months.
Finally we can heat the earth as on a volcano to 400 ° C except for the serious problem on the foundations which do not support the movements of the ground by drought or heat and the water vapor which goes away, with its waste heat . But the earth once dried (like a brick) can heat up to 400 ° C.
The soil can be heated as long as the water does not go too much into the vapor state (40 ° C) so that the soil remains at 25 to 30 ° C as on the surface in full summer heat, for an average of 25 ° C instead of 13 ° C.
The foundations are the most fragile point, because they assume the perfectly rigid floor, on which the house rests with confidence!

So if the temperature of the soil in depth rises from 13 ° C (more or less) to 25 ° C in average temperature on a large volume, then a Canadian well with water exchanger will be enough to heat the house properly.
Also a simpler solar collector giving water in summer at 40 ° C can be enough to heat a larger volume of soil in summer.

Isolating a tank in the very long term is more complex than homogeneous earth because it is heterogeneous, water isolated by polystyrene. Polystyrene has a very high diffusion length per hour because it is very light with a low density and therefore a low specific heat, even if it has a low conductivity !! This means that I wrote an error, the shelf life in a tank is believed to be the inverse of the thickness of light insulation (polystyrene) as soon as the duration exceeds the diffusivity time in the polystyrene, ie 100 to 200 hours approximately for a meter of thickness to be compared at 500h to 2000h for the 1m thick earth (wetland rock) (this time always grows like the square of the thickness!) !!!!
So if you want to insulate a balloon, without putting 3 to 5 m of insulation, with a large time constant you must make a multilayer of low conductivity (light insulation) alternated with a layer with high thermal capacity (metal,) of so as to obtain overall the minimum thermal diffusivity much lower than that of the earth by blocking the heat losses by their slow storage in the intermediate layers with high thermal capacity, therefore heavy to store the losses of the light insulation !!
This balloon solution is not conventional and greatly increases their empty weight by the mass of layers with high thermal capacity.
But so with this method we can multiply the diffusion time by 10 or 100 for the same thickness and keep the heat over more than 1000h by storing a significant part in the layers with high thermal capacity inserted in the insulation. !!
Conceptually the homogeneous earth is simpler more than 3m is enough.
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bernardd
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by bernardd » 14/04/10, 09:00

dedeleco wrote:Basically we agree, it is not easy and you have to be creative, make the impossible, even unimaginable, possible !!


Ah, finally someone who is not afraid to think : Mrgreen: In fact, this forum it brings together several, everywhere else, it's quite rare.

dedeleco wrote:In large quantities, the price is limited by that of the hour of work for the most part, unless you do it with your hands, or in China, Indonesia or India !!


This is why we need a system that goes through all terrains, without the need for adjustment, and inexpensive compared to current drills: it optimizes them for 10m and 50mm in diameter, while all the drills sold are for 100m and 200mm at least. We can then put several in parallel.

dedeleco wrote:On solid rock, it's different, with diamond, it's slow and therefore expensive!


No, for concrete, modern perforators do not need diamonds because they add a hammer at high frequency, which drills do not. I don't know why, is this historic, or is it a problem of filtering the vibration by the length of the rod?

For other terrains, pressurized water is needed, possibly with foam, which also solves the problem of dust evacuation.

dedeleco wrote:This balloon solution is not conventional and greatly increases their empty weight by the mass of layers with high thermal capacity.


The design of the insulation is complex, easy to make mistakes. In particular, many forget that conventional insulation only delays the heat output.

For this problem, we can think of not insulating the balloons, but the central room in which we put them. So we can use standard stainless steel balloons.

On the other hand, after your explanation, we can think of simply using a wall of earth around this room, with the addition of simple insulation on the radiation.

I also think that vacuum insulation, which was the first known all the same, is little used while vacuuming has become relatively simple (diaphragm vacuum pumps, type http://www.knf.fr ).
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Napo dwarf
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by Napo dwarf » 14/04/10, 11:43

Hello,

on another forum speaking of inter seasonal storage by roller tunnel I saw a project that might interest you

http://www.capenergies.fr/fichiers/evenements/seminaire%20capenergies%20derbi/07%20jautardCEFIIM%204-04-07%20ARBOIS.pdf
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by fthanron » 14/04/10, 13:20

Maybe to see on the side of air solar panels http://solarwall.com/fr/produits.php for a relatively minimal investment ... and random performance.

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