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Zeolite retains heat indefinitely, absorbs 4x more heat than water

extremetech.com

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Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#51

Post by excuse-me »

gte910h wrote: post #44
excuse-me wrote: post #16

Earlier quoted context omitted.

Recharging it isn't that simple We use zeolite as a water scavenger in high vacuum systems, it's tremendously good at grabbing onto water BUT because it's so porous and very low thermal conductivity it's a real pain to heat it enough to get all the water out again. We have a heater resistor at the bottom of a small can of this and the top of the pellets a few cm away is cool enough to touch. You might do better with…

A drum dryer like you use for clothing sounds built to take water out of these things (with grates smaller than the pellets of course).

The stuff is fragile (or at least the 5nm molecular sieve type)- if you shake it too much you make dust which blocks the pores

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#52

Post by rcthompson »

excuse-me wrote: post #16
rcthompson wrote: post #3

Short version of the science: The heat is released via an exothermic chemical reaction between the Zeolite and water. However, unlike the one-time-use chemical-reaction heating pads you can buy in a pharmacy, this reaction is reversible, so you can "recharge" the Zeolite by heating it and removing the water as it is released in order to force the reaction to reverse itself. The reaction goes something like this: Zeol…

Recharging it isn't that simple We use zeolite as a water scavenger in high vacuum systems, it's tremendously good at grabbing onto water BUT because it's so porous and very low thermal conductivity it's a real pain to heat it enough to get all the water out again. We have a heater resistor at the bottom of a small can of this and the top of the pellets a few cm away is cool enough to touch. You might do better with…

Is it such a major problem that it leads to major efficiency losses (measured as joules of output energy over joules of input energy required to "recharge")?

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#53

Post by hexagonal »

ars wrote: post #41
hexagonal wrote: post #20

Earlier quoted context omitted.

The term of art you're looking for is "specific heat". https://en.wikipedia.org/wiki/Specific_heat The relevant number for water at 25C is 4.184 joules per gram. But this isn't a strict apples to apples comparison: if you heat and cool zeolite in a vacuum chamber, it'll have a pathetic specific heat. (Like perlite, another foamed mineral, which has a specific heat of something like 0.1) That's because there's a chemi…

Someone downmodded you because you messed up your units. It's 4.184 joules per gram Kelvin . Meaning it stores that much energy for each dress of heat you add to it. If you take water from near freezing to boiling that's 100 degrees of storage - meaning 418.4 joules per gram - which is much more reasonable. And there is no reason you have to stop at boiling. Storing something at 500 degrees is not impractical, so ass…

Oh gosh, you're right.

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#54

Post by ktizo »

ChuckMcM wrote: post #24
ktizo wrote: post #11

Earlier quoted context omitted.

Why not exactly? Is basically decent heat storage and transfer with fairly low losses and minimal decay. Silos of these seem perfect for solar. Admittedly the big question, if you were going to rely on it, is whether there is enough zeolite globally to scale to the terawatt-hour range.

Not exactly because it doesn't change the design space of CSP, it just offers up a different heat storage mechanism. To put it differently, if heat storage was the only problem with CSP, and there is already a heat storage solution available (liquid salt) then Zeolite isn't solving a known 'problem'. You don't need 'indefinite' heat storage for CSP, you really only need a couple of days worth, and we have that alread…

Was thinking of it more as an urban/industrial thing.

Makes sense if you have to do power storage with this technology to do a lot of it at the street level if you can, rather than on the power generation site, as it gives you multiple redundancy and you have to supply cities with water anyway.

So when you have excess electrical power you dry pellets.

When you want power you give them water vapour which then gives you heat, which can give you motive power from heat engines, and from that electricity from induction generators.

All three of which are needed in a typical urban environment, so you are not having to convert all the way back to electric for a large percentage of the power used.

Now I know that this is not by any stretch the most thermodynamically efficient arrangement, but I suspect that it could be a relatively cheap and very robust approach that could store a hell of a lot of energy in a widely distributed network.

[edit] looked into this a bit, and the temperature rise you tend to be able to achieve from adsorption in zeolite is not going to be enough to do anything much more than direct heating, from what I can find. On reflection, that should have been fairly obvious. Sulk. ;)

http://engineering.ucsb.edu/~yuen/references/ref-2.pdf

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#55

Post by rcthompson »

eigenvector wrote: post #5
rcthompson wrote: post #3

Short version of the science: The heat is released via an exothermic chemical reaction between the Zeolite and water. However, unlike the one-time-use chemical-reaction heating pads you can buy in a pharmacy, this reaction is reversible, so you can "recharge" the Zeolite by heating it and removing the water as it is released in order to force the reaction to reverse itself. The reaction goes something like this: Zeol…

I don't see how this can translate to the title "Zeolite retains heat indefinitely". After the cycle of heating and cooling has been repeated some finite number of times, parasitic heat loss to the environment will eventually remove all of the heat added at the beginning.

When you use water as a heat storage medium, you are storing the heat in the kinetic energy of the water molecules. In common parlance, you are increasing the temperature of the water. Obviously, over time the water's temperature will gradually revert to the ambient temperature, and you will lose all the heat you stored in it.

In contrast, when you store heat in Zeolite, you are not storing it as kinetic energy, you are driving an endothermic chemical reaction that stores the energy in high-energy chemical bonds. After you are done heating the Zeolite to "charge" it, it will return to the ambient temperature, but it still has (lots of) energy stored in the chemical bonds. This energy does not dissipate in the way that the kinetic energy of a high-temperature substance would. The energy can only be released by reversing the chemical reaction, so it is securely stored. You can then transport the Zeolite at ambient temperature to a location in need of heat, and then add water, which reverses the chemical reaction and releases the heat again.

So it doesn't actually store "heat", it takes in heat (i.e. molecular kinetic) energy and stores it in a different form (chemical bond energy).

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#56

Post by jerf »

ars wrote: post #41
hexagonal wrote: post #20

Earlier quoted context omitted.

The term of art you're looking for is "specific heat". https://en.wikipedia.org/wiki/Specific_heat The relevant number for water at 25C is 4.184 joules per gram. But this isn't a strict apples to apples comparison: if you heat and cool zeolite in a vacuum chamber, it'll have a pathetic specific heat. (Like perlite, another foamed mineral, which has a specific heat of something like 0.1) That's because there's a chemi…

Someone downmodded you because you messed up your units. It's 4.184 joules per gram Kelvin . Meaning it stores that much energy for each dress of heat you add to it. If you take water from near freezing to boiling that's 100 degrees of storage - meaning 418.4 joules per gram - which is much more reasonable. And there is no reason you have to stop at boiling. Storing something at 500 degrees is not impractical, so ass…

And that's a big part of my question... given that in the abstract water can store any amount of heat (between absolute 0 and the point at which we can no longer call it "water" due to being a plasma of some form), what exactly does it mean for this material to be able to store 4 times as much?

I'm sure there's an answer, because I'm sure the journalist got that number from somewhere, but I lack the connections to know where to begin finding this information.

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#57

Post by kenrikm »

rcthompson wrote: post #55
eigenvector wrote: post #5

Earlier quoted context omitted.

I don't see how this can translate to the title "Zeolite retains heat indefinitely". After the cycle of heating and cooling has been repeated some finite number of times, parasitic heat loss to the environment will eventually remove all of the heat added at the beginning.

When you use water as a heat storage medium, you are storing the heat in the kinetic energy of the water molecules. In common parlance, you are increasing the temperature of the water. Obviously, over time the water's temperature will gradually revert to the ambient temperature, and you will lose all the heat you stored in it. In contrast, when you store heat in Zeolite, you are not storing it as kinetic energy, you…

So then it could be used to store heat created from a reactor then transported where the heat is needed?

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#58

Post by rsanchez1 »

julian37 wrote: post #27
samstave wrote: post #22

Earlier quoted context omitted.

Can you give me some examples of how this can be used?

The article gives one example: you could charge them with waste heat at plants and factories, then transport them to homes and offices where (I suppose) they could be used for heating and hot water, at some later point in time. Sounds more efficient than teleheating via insulated pipes: http://en.wikipedia.org/wiki/District_heating

This is a great application. It could be particularly useful in the New England states. Manufacturing could store their waste heat in the zeolite, and resell it to homes and businesses who can use it to heat up during the winter. It could be a major disruption to utility companies.

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#59

Post by creamyhorror »

JonnieCache wrote: post #36
mistercow wrote: post #4

>By applying heat to Fraunhofer’s zeolite comes into contact with water, a chemical reaction adsorbs the water and emits heat. Parse Error: Unexpected verb "comes" on line 129.

Also: "adsorbs." EDIT: upon further research, I find that "adsorption" is actually also a thing, but it appears that here they meant the traditional absorption. Adsorbtion definitely isn't a thing. Also it sounds like a baby trying to say "abortion," which is weird. What possesses people to give things such similar names? And while we're at it, mathematicians: stop using variables that rhyme. Bs, Cs, Ds, Es, Ps, Zs,…

I learnt the verb "adsorb" in high school chemistry. Why is adsorption not a thing? (Although it does look like the article meant "absorption" and not "adsorption".)

Quote for those not in the know:

-----

We would use "absorb" for when light is absorbed by a coloured or opaque object, or for when water is soaked into a sponge, or even for when my students manage to "take in" some of what I am telling them. It is an ordinary English word.

"Adsorb" is used for a very specific situation where molecules get stuck onto a surface. It does not occur as a word in ordinary language, outside its scientific meaning. Adsorption is very important, because many chemical reactions can go a lot faster when the reacting molecules are adsorbed at a surface (reactions of hydrogen gas on the surface of nickel, for example), or chemical reactions can be prevented by the presence of a barricading adsorbed layer on the surface (aluminium failing to react with air, for example), or impurities can be removed from a solution by adsorbing them onto a finely divided solid (activated charcoal for decolorizing solutions, or for medicinal use, for example).>>>

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#60

Post by rcthompson »

kenrikm wrote: post #57
rcthompson wrote: post #55

Earlier quoted context omitted.

When you use water as a heat storage medium, you are storing the heat in the kinetic energy of the water molecules. In common parlance, you are increasing the temperature of the water. Obviously, over time the water's temperature will gradually revert to the ambient temperature, and you will lose all the heat you stored in it. In contrast, when you store heat in Zeolite, you are not storing it as kinetic energy, you…

So then it could be used to store heat created from a reactor then transported where the heat is needed?

Yes, that is the general idea.
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