MCP / PCM: phase change air conditioning!

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 ...
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MCP / PCM: phase change air conditioning!




by Christophe » 13/06/12, 22:39

For passive building air conditioning: phase change materials

Phase change materials (MCPs) have the ability to store heat before releasing it. In times of overheating, the MCP melts and the heat is stored. When the building cools, the MCP solidifies and the stored energy is returned. This new material therefore gives the possibility of increasing thermal inertia and reducing the need for air conditioning. An ecological and economical solution.

Vincent Pessey d'Alcimed, a consulting and decision support company applied to life sciences and chemistry, explains that “PCMs (Phase Change Materials), placed in partitions, melt and absorb thermal energy excess when the outside temperature exceeds their melting temperature (during the day) and solidify by restoring the energy accumulated when the temperature goes down (at night) ”. Energy is therefore stored as latent heat. MCP can be used in passive air conditioning or even in off-season heating.
The objectives
Due to global warming, the energy consumption linked to air conditioning is only increasing, strongly impacting the environment. Limiting the need for air conditioning has become a real challenge. Feedback shows that temperature peaks in a room equipped with PCM can be reduced by 3 to 4 ° C and the electricity consumption linked to air conditioning can drop by 30%. Being able to store energy also avoids having to use thick layers of heavy materials such as concrete and creating high inertia which can lead to overheating during heavy internal loads (computers in offices).

Daniel Quénard, of CSTB, underlines the interest of the PCM in the renovation of tertiary buildings with light structure, in order to reinforce their thermal inertia and improve their summer comfort. If PCMs are ecological, they are also economic: a study carried out in 2007 by the Lyon Thermal Center assesses a return on investment at 8 years, which is interesting in the current context of energy prices and scarcity fossil fuels, especially since the PCMs have a very long lifespan, identical to that of the building.
Integration with building materials
The phase change takes place depending on the materials between 19 and 27 ° C, temperatures corresponding to the limit values ​​respectively fixed for winter and summer comfort. MCPs (paraffin, polymer, fatty acid, etc.) can be incorporated into construction materials (plaster, concrete, certain plastics) and even into a graphite matrix, which has the advantage of having excellent thermal conductivity. Paraffins, chemically stable, are the most common substances.

They can be packaged in microscopic plastic beads (microencapsulation) mixed with plaster or concrete, or else incorporated into the pores of a carrier material (impregnation), which allows them to be added during a renovation. 3 cm of plaster containing 30% of MCP is equivalent to 18 cm of concrete or 23 cm of brick in terms of thermal inertia.
MCPs are indestructible, inert and non-toxic; they do not require maintenance. In addition to the constituent walls of buildings, MCPs can also be integrated into false ceilings. CSTB specifies that a night ventilation system optimizes the release of calories, which makes it possible to regenerate MCP more efficiently.
Research and first experiences

Products are starting to be marketed (around € 50 / m2), such as Micronal® (paraffin in polymer microcapsules) from BASF or Energain® (paraffin / polyethylene composite) from Dupont de Nemours: references exist abroad and in situ experimental monitoring takes place in France. Many other types of materials and forms are also being studied. Another type of MCP with a solid / solid transition is being researched, because moving from one solid phase to another allows more heat to be stored than the solid / liquid phases; the fact that they are permanently solid is interesting for construction, because they are more easily packaged and usable as they are.

CSTB considers that specific points still need to be improved and specific research: better definition of the melting / solidification range, fire behavior, characterization of any secondary products emitted (potential harmfulness), conditioning and durability to cycles merger / solidification. Research is also underway on the coupling of phase change and super-insulating material (VIP) to produce lightweight envelopes with both good insulation and significant thermal inertia. MCP has no doubt a promising future to reduce air conditioning consumption while preserving a good level of comfort for buildings with low inertia.

By Pascale Maes, Journalist


Source: http://www.techniques-ingenieur.fr/actu ... cle_73628/
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by Obamot » 14/06/12, 08:38

At first we find it great, as said for offices in the tertiary sector.

After reflection we can find it tangent, why (?):
- because for it to work optimally it should - as specified - integrate it directly into the concrete. Concrete being a heavy material, it will tend to store heat during the day, which will be very good because it will melt the paraffin;
- then, overnight, the paraffin will solidify to diffuse the stored heat. Yes but there is nobody in the offices at night!
- finally, this implies giving up external insulation. Because if the concrete is perfectly coated, it will not absorb heat, so it will not melt the paraffin ... Result = zero.

It would be more interesting to do this in homes, and to circulate this paraffin in facade elements, the slab of an outdoor parking lot or the median in front of the house (etc), and to store it in the cellar in a container / tank with an exchanger connected to the hot water circulation of the central heating (and of course this would only be optimally operational during mid-season or even a little cool summer, which is already not so bad).
This could come in addition to the Jenni house system, in order to avoid as much as possible consuming the caloric capital of the large tank!
https://www.econologie.com/forums/chauffage- ... 11285.html

In this case, I see a fluid better than paraffin, because if the pipes are blocked, tintin ...

Finally, serious consideration will still have to be given to possible applications. And weigh the pros and cons of implementation scenarios. But the idea is excellent.
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by Rabbit » 14/06/12, 10:19

I find it great. But for recycling, when it is necessary to destroy the
building, how is it going?
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by cortejuan » 06/11/12, 23:19

Hi,

this is a subject that has interested me for a long time. When I installed my first greenhouse in 1980, I had thought of using mineral salts, I had discussed it with the chemistry teachers of my university. without success.

I see that it is starting to take shape but I searched on the web and found only ready-made panels (micronal and energain) and very expensive. You specialists, do you know if these microbeads are available in bulk in order to condition them for uses other than construction?

Another question, the MCP-paraffin being adapted for the building, the phase change is around 20 degrees. I'm looking for a CP around 10 degrees ...

cordially
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by dedeleco » 07/11/12, 00:57

Hi,
There are some by searching well, see the links that I had put elsewhere on econology, like kind paraffins or oils (of olives), with the good molecular weight which fixes the T of fusion, but their price will be between 1 € and 10 € per liter, for around 20 to 100KWh / m3 !!


While the free earth under our feet stores 3 to 10KWh / m3 !!

So the land is also interesting.
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by Alain G » 07/11/12, 07:52

dedeleco wrote:Hi,
There are some by searching well, see the links that I had put elsewhere on econology, like kind paraffins or oils (of olives), with the good molecular weight which fixes the T of fusion, but their price will be between 1 € and 10 € per liter, for around 20 to 100KWh / m3 !!


While the free earth under our feet stores 3 to 10KWh / m3 !!

So the land is also interesting.


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by cortejuan » 07/11/12, 13:33

Hello,

I repeat my question: is there the possibility of finding paraffins of the energain or micronal type in bulk.

Finding massive paraffin is no problem, I'm looking for encapsulated paraffin.

Unless I am given the recipe for making microbeads encapsulated on the corner of my workbench ...

cordially
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by Rabbit » 07/11/12, 14:07

Isn't there a risk in case of fire?

Paraffin, does it risk seeping out of concrete.

cortejuan wrote:Unless I am given the recipe for making microbeads encapsulated on the corner of my workbench ...


Perhaps by spraying the liquid paraffin on top of a tarpaulin in winter using a paint spray gun.
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by Gaston » 07/11/12, 14:19

Rabbit wrote:
cortejuan wrote:Unless I am given the recipe for making microbeads encapsulated on the corner of my workbench ...


Perhaps by spraying the liquid paraffin on top of a tarpaulin in winter using a paint spray gun.
It will (maybe) make beads, but to encapsulate them so that the whole does not become liquid again when the paraffin melts :?:
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by Rabbit » 07/11/12, 22:32

Gaston wrote:but to encapsulate them so that the whole does not become liquid again when the paraffin melts :?:


In a concrete mixer without the plates for pralining? But all this seems very complicated.
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