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:
![](https://i.postimg.cc/5Nv9SvBB/ice-Chests.jpg)
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:
![](https://i.postimg.cc/Mpp624kD/freezer.jpg)
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.
![](https://i.ibb.co/ZNSQsTR/power.jpg)