Store thermal energy with palm oil? Natural Phase Change Material (PCM)

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Store thermal energy with palm oil? Natural Phase Change Material (PCM)




by Christophe » 08/04/09, 19:29

Economically optimized thermal energy storage!

(This subject follows solar-thermal / solar-thermal-with-storage-capsules-kaplan-t7405.html )

It would be possible to store, at a very low cost and small footprint, thermal energy (low T °: 40-45 ° C) thanks to the latent heat of fusion of ... coconut oil or palm oil , a 100% natural and inexpensive product with a melting temperature between 35 and 45 ° C!

See: http://fr.wikipedia.org/wiki/Acide_dod% ... o%C3%AFque
et http://fr.wikipedia.org/wiki/Huile_de_palme


Edit: following many strong protests (and coming from people who have not made the effort to read the subject) about the use of palm oil whose production methods are detrimental to local biodiversity, 2 points to be specified:

a) palm oil is taken as an example: any natural body whose melting point is between 35 and 45 ° C could be suitable! We seek to find a natural body, to avoid using chemical or synthetic MCPs whose econological cost would be much higher!

b) the oil is not consumed! So if 200 kg of oil used in heat buffer during 30 years can save tens of tons of wood or fuel oil, the environmental balance is surely more than positive, even with palm oil ...


So how much of the 1kg calorie of palm oil (which will be assimilated into an 1er time to lauric acid) can it store? And especially how much water L that corresponds?

I remember that water is one of the best heat transfer fluid but are used in thermal buffer requires significant amounts because it is difficult to use changes of state!

So if we could use "oil-doped" water (and not the other way around) it could, perhaps, be interesting! Let's make a 1st estimate! For the lazy, read the conclusion at the bottom.

How many calories are released in 1 Kg of oil that solidifies?

It's all stupid, just read: according to the table of this page, we have:

Melting point: 41-43 ° C, take 42 ° C
Latent heat: 211,6 (kJ / kg)


(compare: for info with water: melting temperature: 330 kJ / kg but especially evaporation: 2200 kJ / kg)

Each kg liquid oil that solidifies will release 211 kJ at a level of 42 ° C, or 42 ° C is a VERY interesting temperature for:
a) the ECS
b) Low temperature heating

It corresponds to how much energy 211 kJ?

The specific heat of the water is about 1 calorie is 4.18 kJ / kg ° C.

- 1 kg of oil at 42 ° C thus makes it possible to heat 1 L with water of 211 / 4.18 = 50 ° C
- On a "working" temperature delta of a thermal buffer of 20 ° C (between 50 and 30 ° C for example), each L of water therefore stores 20 * 4.18 = 83.6 kJ
- So we could say that 1 kg of oil stores as much energy as 211 / 83.6 = 2,5 L water but the advantage of the oil is that the T ° is 42 ° C, a more interesting temperature that 30 ° C!
- at 42 ° C, each kg of oil stored

Good truce blabla, here is a small comparative practical example: a buffer water buffer 2000L and a hybrid water-oil balloon

Buffer of 2000 L of water at 50 ° C.

It is estimated that the T ° of use is exploitable up to 30 ° C.

We have an energy stored on delta 20 ° C of:

E = 2000 * 4.18 * 20 = 167,2 MJ is 46 kWh or enough to take about 23 showers (assuming the last showers will be 30 ° C).

Hybrid buffer: "palm oil - water" with 500L of palm oil and 1500L of water at 50 ° C

The volume occupied in the house is the same as the other balloon.

The oil is immersed in water in containers or not (that's not the problem yet).

500L of liquid oil = 500 * 0.862 = 431 kg.
1500 L water = 1500 kg

What is the stored energy?

- Latent heat of solidification of the oil: 431 * 211 = 90 940 kJ released (and that is what is important) at 42 ° C!

- Massive heat:
Between 50 and 30 ° C for water: 1500 * 4.18 * 20 = 125 400 kJ
Between 50 and 42 ° C for liquid oil: 431 * 2.27 * 8 = 7800 kJ
Between 42 and 30 ° C for solid oil: 431 * 1,76 * 12 = 9100 kJ

In total:

E = 90.9 + 125.4 + 7.8 + 9.1 = 233.2 MJ is 64 kWh is enough to take 32 showers around ... but in fact much more see below!

The gain does not seem so important that ca? Except that a large part of these calories are at a more exploitable temperature ... so there comes the question:

c) What is the energy gain thanks to the oil between 50 and 42 ° C (or rather between 50 and 41.9 ° C)?

- 1er we have E = 2000 * 4.18 * 8 = 67 MJ = 18.6 kWh
- 2ieme case one has E = 1500 * 4.18 * 8 + 431 * 2.27 * 8 + 431 * 211 = 50.2 + 7.8 + 90.9 = 149 MJ = 41.4 kWh

Conclusion: between 50 and 42 ° C the hybrid flask containing 1 / 4 by volume of palm oil to provide 2.2 times more energy than a buffer tank identical to water!

Well I learn about the wholesale price of palm oil to put in our big heat buffer!

Well it remains full of questions to solve, the 1ere being: what is the optimum% of oil according to the desired T ° of use? If it is around 42 ° C the answer is simple: 100% oil!

Question: how is it that no industrial heating or even university can think of it yet?

Warning: there is a strong difference in density between liquid and solid oil which must be taken into account in the case of an "operational" test: 1007 kg / m3 for the solid and 862 kg / m3 for the liquid.
Last edited by Christophe the 15 / 07 / 10, 23: 14, 6 edited once.
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by elephant » 08/04/09, 19:33

superb calculation, and ....

can we also use it for fries once? : Oops:
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by Christophe » 08/04/09, 19:39

Oh no, the oil would be captive! Like any good thermal buffer that respects itself!

Please check the calculations anyway, because I do not want the (big) tile found yesterday by Remundo on the paddlewheel to happen again ... : Cheesy:
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by fthanron » 08/04/09, 19:53

Here is a track that seems interesting.

In the idea, it would be interesting to compare with other more "local" oils or shea-type butters, no?

Question: how is it that no industrial heating or even university can think of it yet?


Because they do not have an engineer like you on the one hand.
On the other hand, (paranoid mode) some lobbies are not interested in saving energy.

Strongly the first life-size tests!
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by Rulian » 08/04/09, 20:04

Well then your calculations hold up, t assuming to immerse the oil in the fleet buffer (mix or in containers), the off-system heat loss is negligible.

By cons I have a BIG RESERVE!
Your calculations are based on lauric acid and not on palm oil. And I do not see what allows you to consider that the specific and latent heats are about the same between palm oil and lauric acid.

It is a detail more than important! See it wikipedia sheet of palm oil who does not speak much lauric acid.
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by Christophe » 08/04/09, 20:06

Yes it seems very interesting to me too ...

Uh it's local shea?

And do not try it with cow butter, how much is it? 25 or 30 ° C I think? The problem will be the holding in time ... of course!

The ideal would still be to find a natural product (or not too expensive chemical) whose evaporation rate is towards 40 ° C because generally evaporation heat is much more important than that of fusion ...

Some hydrocarbon or alcohol? Ether? (Boiling point: 34,6 ° C)
Methanol it must be not far from that too ...
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by Christophe » 08/04/09, 20:09

Rulian wrote:By cons I have a BIG RESERVE!
Your calculations are based on lauric acid and not on palm oil. And I do not see what allows you to consider that the specific and latent heats are about the same between palm oil and lauric acid.


There will be some difference (starting with the lower melting point for palm oil), probably different heat specific but I think the orders of magnitude are the same and so I do not think it radically changes the results...

Otherwise we will take cophra oil!

It is the main fatty acid in coconut oil (coconut oil), and is believed to have antimicrobial properties.


But maybe I should change the title ... well ...
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by Rulian » 08/04/09, 20:11

The problem with using a latent heat of evaporation is that you end up with a gas on your arms. And to contain and all that, it is more galley than a liquid that is quiet by gravity. And I do not even talk about the huge change in volume with a liquid / gas transition.

PS: I closed the other topic to avoid duplicates.
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by Christophe » 08/04/09, 20:16

No, do not shut down, we were talking about something other than this subject ...

For gas if it is "encapsulated" from the factory, it does not pose a problem of the style a coil in the middle of the solar exchanger between the 2 exchangers ...

Obviously for do-it-yourselfers like us it's something else ... oil is more "accessible"!
Last edited by Christophe the 08 / 04 / 09, 20: 17, 1 edited once.
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by Rulian » 08/04/09, 20:17

I unlock.
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