Build a performant DIY portable air conditioner (ICE POWERED)

[YouCanDoIt]

Does this applies to gel ice packs too?

Yes, there is no way around it. Water is very special medium in this energy storage property, but to utilize it, phase change between solid and liquid is needed. It happening at 0degC is luckily a very good temperature for cooling purposes.

This is a good news, or better, it's good that there will be no difference whatever variants of the gel ice packs I chose (apart the build quality). That discussion about variants was giving me big headaches.

You said that I can cool with material at 10degC, 0degC or -10degC equally well providing same cooling effect, just requiring some more surface area and/or airflow if the temperature isn't as low.
Does this means that a colder temperature is not totally useless and still have the desirable advantage to require less surface area and/or airflow?

Well yeah, but the usable temperature range is pretty limited anyway. If you run the cooling medium below 0 degC, the condensing moisture from room air freezes and blocks your system. And as I said above, going much above 10degC stops your system from being a dryer, which is pretty necessary in many conditions (unless you live in Sahara desert). So cooling systems generally run their "cool parts" (those that interface with air) between say 5 .. 10 degC. Sure 5deg instead of 10deg allows using somewhat smaller coil / less airflow / less noisy fan.

Thanks for the excellent explanation. I should put in bold all of your comments because each one is an excellent source for the design.
I understand what you say. So, 5C would be the ideal temperature. Trying to go lower or high than that starts to be risky for the reasons you well explained.
Ok, let see what I get once I place the ice packs in the water.

Sure 5deg instead of 10deg allows using somewhat smaller coil / less airflow / less noisy fan.

Here is where (I suppose) a temperature controller or a manual switch is helpful by reducing the supplied power. It's on my wish list, but let first get the system up and running before thinking to such kind of enhancements.

The annoyance of swapping ice frequently is pretty much inexistent. That cooler, with a 28QT chest (3 days ice retention advertised), 2 frozen gallon jugs and a couple of ice-packs, latest 4 hours. Good for daytime, but not for nighttime.
Mine uses a 52QT chest (6 days ice retention advertised), it is nearly fully insulated and uses gel ice packs in higher quantities. I expect much longer duration and good even for nighttime.

Freezer size or quality of its insulation ("ice retention") is pretty much irrelevant. Cooling power matters. Freezer's compressor is doing your actual cooling work, you are just using the ice packs as thermal energy storage / transport medium.

By all means check the input power rating of your freezer, and I bet it's between 100-300W. Assuming COP of 2, cooling power is thus in range of 200-600W, while usual room air conditioners range between 1500-4000W in cooling power, or so.

Because ice works as storage medium, you will be able to exceed that cooling power, but only temporarily: you can freeze a lot of water over 10 days, and then consume it during 1 day, giving you 10x boost in cooling power; that would equal to a real air conditioner! But then you are out of ice for the next 10 days.

Or you can find the balance of making the amount of ice the freezer is truly capable of, and keep using it at the same rate. But then the cooling capacity is underwhelming, you can't drop the room temperature/humidity by much. But a little bit yes, and maybe that is enough. And the cooling effect of the cold air hitting the skin is very real of course.

Uahh...the situation is much complicated than expected.
I don't know why the guys from which I posted here their projects (and many other similar projects too) consider size and insulation quality important factors.
I've purchased a (relatively cheap) 52QT Vevor box, but there are people using 70QT Coleman extreme boxes. By looking "before" and "after" insulation enhancement, the experiments seem to confirm big improvements:


I have no idea on why such conflicting statements. The best I can do is to take all of them into account and expect the worst which in this case is the fact that quality and size of my Vevor is irrelevant. At least, between of all this, I can still have one truth: when I'll use the Vevor as food cooler, its size and excellent ice retention will make a big difference compared to a lower quality product.

I will check better later, but my fridge is a Samsung, the Metal Graphite Double Door ones that were on sale, I believe, 5-6 years ago. 
I understand what you mean. Some other guys gave me some numbers and trying to cool down a whole room is nearly impossible which is fine because my expectation has always been to just cool a reduced area. It's just that I can't resist to a similar challenge.
There are so many variables to take into account that it would be very hard trying to understand what to expect. The balance you're talking about is another option for sure.
The best I can do is get something up and running and then, once I have some concrete data, see what could be the best next steps.

This is something that I have not considered at all. My freezer is pretty new technology, but apart from this I can't really imagine how this can happen. Freezer's inside temperature rises each time we introduce new food, but this is just how they are designed to work. Do you recommend to pre-cool the ice packs in the fridge?

This is exactly why freezer manual would state the maximum amount of food/liquids you are supposed to freeze per day, it's some quite low value like 0.5 .. 1 kg per 24hrs. The freezer is capable of freezing more, but then other food stuff is in larger risk of spoiling. For your cooling purposes you would significantly exceed this, causing the temperature to rise closer to 0degC.

Pre-cooling of course helps, but not that much. As shown above by others, temperature change stores only small part of energy, most is in the phase change. Even if you pre-cool to +1degC, you ease the work of the freezer only a bit; it still has to do most of the work, pushing energy to turn the liquid into solid. But by all means, do pre-cool if possible.

You saved me from making something very stupid: put inside the freezer as much ice packs as possible!
And given that gel packs shape can be adjusted, I would have probably ended up to fill 90% of the capacity (food included).

The guy uses 2 gallon jugs and a 2 ice-packs and reported no issues:


If I'm not wrong it should be around 8 liters which means eight 1000ml gel ice bags.
I will check later the user manual for the specs you mentioned, but do you think it is safe for any freezer such quantity as a starting point ?

So, even if does not help much, pre-cooling is still recommended.
I will start with something safe and then will post all the numbers (time to freeze, duration, output temp and many other data). From there we can think to way to optimize everything to get the right balance.
Thanks

EDIT: Freezer is a Samsung RT29K5030S8, but from the user manual I can't find anything that mention the maximum amount of food/liquids one should be supposed to freeze per day.
However I found interesting features like "Power Freeze" and "Power Fridge" mode. If and how these special modes can help, I prefer to leave the last word to the experts.

[YouCanDoIt]

The effect of the humidity of the room air cannot be minimized.  It's been a few decades since I did these calculations in MechEng thermodynamics classes, but I do remember the basics of using what's called a 'psychrometric chart'.  Look it up and how to use it.  Once you cool the room air to its dew point (meaning 100% relative humidity), a big portion of the energy required to cool it further is just consumed to condense the humidity out of the air as you cool it further.  For example: if you start with a room with 80°F air at 80% humidity, your efforts to cool it will drop the air temperature and raise the relative humidity until you hit 100% relative humidity at its dew point (73.3°F).  Cooling it further begins condensation and now a significant portion of the energy transfered is condensing water, not just cooling the air further.  So that's kind of an efficiency loss - some of the energy you'd like to use productively (reducing the room temperature) is 'lost' in just making condensed water that you don't value.

If you start with drier air at a very low relative humidity (Arizona for example), you can cool it to a much lower air temperature with the same available energy because you won't be condensing hardly any water from it.

I’ve only had the most glancing of thermodynamics education in school, but I think that the really unintuitive part of it for people is the amount of energy required for a phase change, and that the temperature is not changed during the phase change. (I think that intuitively, people think that the (static) temperature alone determines the phase. They don’t consider pressure or energy.) That is, it isn’t intuitive at all that a huge amount of energy is required to change 0°C ice to 0°C liquid water, or that a huge amount of energy is needed to change 100°C liquid water to 100°C steam.

When I got to the energy for the phase changes of water in school, I already knew that the phase changes required energy, but what surprised me is just how much energy they take. Intuitively, I figured it maybe just needed a little nudge, when in reality, the phase changes require tons more energy than even fairly large changes in temperature (without a phase change).

tooki, a stupid question, but can this high amount of required energy reduced and/or be partially provided by another source (ex: a solar panel) ?

[tooki]

I’ve only had the most glancing of thermodynamics education in school, but I think that the really unintuitive part of it for people is the amount of energy required for a phase change, and that the temperature is not changed during the phase change. (I think that intuitively, people think that the (static) temperature alone determines the phase. They don’t consider pressure or energy.) That is, it isn’t intuitive at all that a huge amount of energy is required to change 0°C ice to 0°C liquid water, or that a huge amount of energy is needed to change 100°C liquid water to 100°C steam.

When I got to the energy for the phase changes of water in school, I already knew that the phase changes required energy, but what surprised me is just how much energy they take. Intuitively, I figured it maybe just needed a little nudge, when in reality, the phase changes require tons more energy than even fairly large changes in temperature (without a phase change).

tooki, a stupid question, but can this high amount of required energy reduced and/or be partially provided by another source (ex: a solar panel) ?

The amount of energy needed to make your ice is dictated by the laws of physics. It is an inescapable fact.

What source of energy you use is up to you, but since you’re using an electrically-powered freezer, then you need electrical power. If you want to install a solar system on your roof, go right ahead — storing cold in the form of ice is one of the few useful ways to store solar electricity (in the summer at least). But to be clear, this means a serious solar installation, not an A4-size panel that can barely charge a USB power bank.

[YouCanDoIt]

I’ve only had the most glancing of thermodynamics education in school, but I think that the really unintuitive part of it for people is the amount of energy required for a phase change, and that the temperature is not changed during the phase change. (I think that intuitively, people think that the (static) temperature alone determines the phase. They don’t consider pressure or energy.) That is, it isn’t intuitive at all that a huge amount of energy is required to change 0°C ice to 0°C liquid water, or that a huge amount of energy is needed to change 100°C liquid water to 100°C steam.

When I got to the energy for the phase changes of water in school, I already knew that the phase changes required energy, but what surprised me is just how much energy they take. Intuitively, I figured it maybe just needed a little nudge, when in reality, the phase changes require tons more energy than even fairly large changes in temperature (without a phase change).

tooki, a stupid question, but can this high amount of required energy reduced and/or be partially provided by another source (ex: a solar panel) ?

The amount of energy needed to make your ice is dictated by the laws of physics. It is an inescapable fact.

What source of energy you use is up to you, but since you’re using an electrically-powered freezer, then you need electrical power. If you want to install a solar system on your roof, go right ahead — storing cold in the form of ice is one of the few useful ways to store solar electricity (in the summer at least). But to be clear, this means a serious solar installation, not an A4-size panel that can barely charge a USB power bank.

I thought multiple times in the last years if this is the right time to do the transition. Do you think it is better to continue to wait (costs, technology status etc) ? I've been tempted a couple of times from such little panels, but I've always gave up due to the very little usefulness.

[Siwastaja]

You seem to be so enthusiastic in engineering this stuff I don't get it why you consider using ice as an energy transport medium at all. Just hack a freezer to work as a cooler directly. For example, make two holes, build some kind of "maze" inside of it and blow air through it. Or get a good old cheap portable room air conditioner, the kind which sucks indoor air and blows it from a flexible hose, and modify it to perform better e.g. by giving it a closed hot side air loop. I have had excellent results with such mods in the past.

[IanB]

I don't get it why you consider using ice as an energy transport medium at all?

Because ice can act as a storage medium. A freezer has a power of a few hundred watts at most, while an air conditioner runs at kilowatts.

So a big amount of ice can accumulate a reservoir of cold over a 24 hour period and release it in a much shorter period of an hour or two.

[Siwastaja]

Because ice can act as a storage medium. A freezer has a power of a few hundred watts at most, while an air conditioner runs at kilowatts.

Yeah - storage is great, but it actually increases the power requirement:

So a big amount of ice can accumulate a reservoir of cold over a 24 hour period and release it in a much shorter period of an hour or two.

Sure, but cooling for an hour or two is useless for summer time household cooling, as you might want to cool for many months non-stop or nearly non-stop. Even here in relatively cold country cooling needs are either there for 2-3 weeks straight, or then on a colder summer not at all. Storing enough ice for such long period is impractical.

Without storage, you just run 24/7. If you add storage (e.g. to utilize cheaper hours or solar self-use), then you need to deliver the same average power over smaller duty cycle, so need more cooling power, not less.

From OP's posts it seems clear his primary purpose doesn't seem to store cheap electricity.

[joeqsmith]

I was expecting something completely different.  Like an actual air conditioner (removing heat).   

[YouCanDoIt]

You seem to be so enthusiastic in engineering this stuff I don't get it why you consider using ice as an energy transport medium at all. Just hack a freezer to work as a cooler directly. For example, make two holes, build some kind of "maze" inside of it and blow air through it. Or get a good old cheap portable room air conditioner, the kind which sucks indoor air and blows it from a flexible hose, and modify it to perform better e.g. by giving it a closed hot side air loop. I have had excellent results with such mods in the past.

You're probably right, but enthusiasm, optimism and a small dose of madness is what is behind DIY.

Your idea is very interesting, but when my family will see a pretty new and expensive fridge ruined in this way, do you authorize me to show them where I got this idea when they will try to kill me?

Just let me repeat some points for people that came here without having read the message for which I opened the thread, especially when they suggests completely different systems:

• I have already purchased the ice chest cooler along with some other stuff and before opening this thread (this is something stated from the beginning)
• The way I designed the project is to have an air cooler and a beverages cooler at the same time and this makes every different system useless (at least with these two goals in mind)
• Cooling down a whole room is not at all my main target. I have gone through such design with the only intention and expectation to cool a reduced area. Cooling down a whole room (which I know is nearly impossible) is more for the fun I get from the challenge than anything else. I understand that this is what the main discussion is focused on due to the complexity and this may give people the false sense that this is the one target I want to achieve.

Thanks

[YouCanDoIt]

I was expecting something completely different.  Like an actual air conditioner (removing heat).

There is a diagram at the beginning of the thread where you can clearly see it isn't even without reading, but thanks for letting me know. I will edit the title to make this even more clear!

[YouCanDoIt]

Because ice can act as a storage medium. A freezer has a power of a few hundred watts at most, while an air conditioner runs at kilowatts.

Yeah - storage is great, but it actually increases the power requirement:

So a big amount of ice can accumulate a reservoir of cold over a 24 hour period and release it in a much shorter period of an hour or two.

Sure, but cooling for an hour or two is useless for summer time household cooling, as you might want to cool for many months non-stop or nearly non-stop. Even here in relatively cold country cooling needs are either there for 2-3 weeks straight, or then on a colder summer not at all. Storing enough ice for such long period is impractical.

Without storage, you just run 24/7. If you add storage (e.g. to utilize cheaper hours or solar self-use), then you need to deliver the same average power over smaller duty cycle, so need more cooling power, not less.

From OP's posts it seems clear his primary purpose doesn't seem to store cheap electricity.

I'm afraid here the thing is subjective and depends from the user conditions. Here I don't have to keep it running 24H and there are intervals where I don't need all the cooling power a similar device can provide. I should also state again that each time I refer to cooling a reduced area (ex: the desk). From now on I will clearly specify when talking about cooling down a whole room (which is not my target, but rather a way to see if I can achieve such goal at least once, just for fun).

Regarding the cooling autonomy, I'm afraid this is also subjective, but I promised my self to stop posting the plenty of sources showing different results and from different people which also includes more than satisfying results. I rather prefer to post my own results for which I can respond to all user questions and provide the data they want to know.

EDIT: Well, I'm interested to store cheap electricity and I even asked more info on this, but from what I have understood it only make sense with a serious solar panels installation on the roof and I have yet to understand pros and cons.

[tooki]

EDIT: Freezer is a Samsung RT29K5030S8, but from the user manual I can't find anything that mention the maximum amount of food/liquids one should be supposed to freeze per day.
However I found interesting features like "Power Freeze" and "Power Fridge" mode. If and how these special modes can help, I prefer to leave the last word to the experts.

It’s not in the manual because appliance companies are lazy and write one manual for ALL the different models.

But googling the name brings up the product page, and on the “specs” tab, it lists the cooling capacity as 3.6kg/24h.

That’s literally useless for cooling a room. Or part of a room.

[tooki]

I’ve only had the most glancing of thermodynamics education in school, but I think that the really unintuitive part of it for people is the amount of energy required for a phase change, and that the temperature is not changed during the phase change. (I think that intuitively, people think that the (static) temperature alone determines the phase. They don’t consider pressure or energy.) That is, it isn’t intuitive at all that a huge amount of energy is required to change 0°C ice to 0°C liquid water, or that a huge amount of energy is needed to change 100°C liquid water to 100°C steam.

When I got to the energy for the phase changes of water in school, I already knew that the phase changes required energy, but what surprised me is just how much energy they take. Intuitively, I figured it maybe just needed a little nudge, when in reality, the phase changes require tons more energy than even fairly large changes in temperature (without a phase change).

tooki, a stupid question, but can this high amount of required energy reduced and/or be partially provided by another source (ex: a solar panel) ?

The amount of energy needed to make your ice is dictated by the laws of physics. It is an inescapable fact.

What source of energy you use is up to you, but since you’re using an electrically-powered freezer, then you need electrical power. If you want to install a solar system on your roof, go right ahead — storing cold in the form of ice is one of the few useful ways to store solar electricity (in the summer at least). But to be clear, this means a serious solar installation, not an A4-size panel that can barely charge a USB power bank.

I thought multiple times in the last years if this is the right time to do the transition. Do you think it is better to continue to wait (costs, technology status etc) ? I've been tempted a couple of times from such little panels, but I've always gave up due to the very little usefulness.

What transition? You can’t transition to 100% solar, because, ya know, nighttime.

As for solar in general, watch Dave’s various videos about the topic, and then talk to a professional solar installer to see whether your house is even suited for solar. Not all are.

[tooki]

I don't get it why you consider using ice as an energy transport medium at all?

Because ice can act as a storage medium. A freezer has a power of a few hundred watts at most, while an air conditioner runs at kilowatts.

So a big amount of ice can accumulate a reservoir of cold over a 24 hour period and release it in a much shorter period of an hour or two.

But that’s not what OP believes. They mistakenly think their household freezer can make enough ice daily to meaningfully chill some are of their room for hours at a time, including overnight.

[tooki]

You seem to be so enthusiastic in engineering this stuff I don't get it why you consider using ice as an energy transport medium at all. Just hack a freezer to work as a cooler directly. For example, make two holes, build some kind of "maze" inside of it and blow air through it. Or get a good old cheap portable room air conditioner, the kind which sucks indoor air and blows it from a flexible hose, and modify it to perform better e.g. by giving it a closed hot side air loop. I have had excellent results with such mods in the past.

You're probably right, but enthusiasm, optimism and a small dose of madness is what is behind DIY.

Your idea is very interesting, but when my family will see a pretty new and expensive fridge ruined in this way, do you authorize me to show them where I got this idea when they will try to kill me?

Just let me repeat some points for people that came here without having read the message for which I opened the thread, especially when they suggests completely different systems:

• I have already purchased the ice chest cooler along with some other stuff and before opening this thread (this is something stated from the beginning)
• The way I designed the project is to have an air cooler and a beverages cooler at the same time and this makes every different system useless (at least with these two goals in mind)
• Cooling down a whole room is not at all my main target. I have gone through such design with the only intention and expectation to cool a reduced area. Cooling down a whole room (which I know is nearly impossible) is more for the fun I get from the challenge than anything else. I understand that this is what the main discussion is focused on due to the complexity and this may give people the false sense that this is the one target I want to achieve.

Thanks

You realize you can buy a real air conditioner for, like, €300? And that it will perform 100x better than anything based on ice?

Also, I don’t think for a second that a fridge modified into an air conditioner could ever be satisfactory for any purpose; the cooling capacity is simply much too small.

I totally get the DIY spirit, but I also feel that one should spend their money on DIYing something that is good enough to actually use. Building something based on wishful thinking and hopes and dreams, but which is far removed from reality, is simply a waste of time, money, and materials because in the end, all you’ve done is made a piece of trash that will end up in the bin because it doesn’t do anything useful.

[Siwastaja]

For the cold feeling from cool air directly hitting skin, this kind of contraption is fine, and for that purpose freezer capacity should be OK. Just don't expect significant room temperature drops, any Youtuber who is claiming stuff like that is lying or misunderstanding what is actually happening.

I also did this kind of stuff as a kid. I used 1.5-liter plastic soda bottles filled with water, I think I had 8 of them in a box where they fit snuggly, and blew air past the bottles. It was nice until I realized I can't just use our freezer for those eight bottles; freezing two per day seemed a practical limit without serious damage to other foodstuff, so every 4 days I could have a few hours of cooling.

[ebastler]

For the cold feeling from cool air directly hitting skin, this kind of contraption is fine, and for that purpose freezer capacity should be OK. Just don't expect significant room temperature drops, any Youtuber who is claiming stuff like that is lying or misunderstanding what is actually happening.

+1. "Cooling just a limited area" is fine as long as the "area" is one's chest, rather than a few square meters of a room.

To that end, just the air draft from a fan goes a long way, without any active cooling. Lower risk of catching a cold or a stiff neck too...

[Kurets]

+1 This thread just feels like comedy. But I think the main problem is that OP ends up in a confict of ideas (or sunk costs) state. Even the revamped goal of cooling a limited area does not really work as air in a room mixes quite rapidly (especially with a fan). So this is just a way of trying to avoid accepting that the idea is not good.