Author Topic: The correct EPDM rubber cord diamater to insulate internally a pipe  (Read 2057 times)

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Offline YouCanDoItTopic starter

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Hello to all,
I need to thermally insulate the internal of this 12x8mm PU pipe (for a length of around 4-6 cm):


I will use this EPDM rubber cord (which seems to be the best material for such scope):


Common sense tells me that I should buy 8mm diameter just like the same internal diameter off the pipe I want to seal, but I'm wondering if 10mm (next available diameter available for purchase) could provide better insulation.
I don't know tolerance of such material, so the question is obvious: are there chances that a 10mm cord will not fit at all?
I should also specify that this is not a permanent sealing. I will often need to remove the seal by hand, so it is imperative for me some sort of quick and easy "plug-unplug".

Thanks
 

Offline coppercone2

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #1 on: August 04, 2024, 07:34:28 pm »
That might wick up moisture. I don't get what you are trying to do.

You can plug the pipe with a long piece of foam and then stopper the ends with rubber stoppers like chemistry ones, thats what I would consider a temporary solution

I would buy some segments and see which one fits, you can get them in short lengths on amazon most likely. Its going to depend on how strait the pipe is, if there is a bend obviously you need a smaller one and you need to determine which one empirically.
 
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Offline Whales

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #2 on: August 04, 2024, 09:40:37 pm »
I normally fold over and cable-tie PU pipe.  Have not had it fail or leak but I've only tested to a few bar.

What's your usage scenario?
 
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Offline IanB

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #3 on: August 04, 2024, 09:45:43 pm »
I need to thermally insulate the internal of

Is this still about making a home portable air cooler?

If so, you might change the title of this and your other thread to something "Home Portable Air Cooler", so that more people will read it and give you comments.

As to the question here, if this is a water pipe for such an air cooler, you do not need to thermally insulate it at all. Thermal insulation of pipes and ducts is completely unnecessary in such a device.
 
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Offline coppercone2

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #4 on: August 04, 2024, 09:50:36 pm »
that depends if you are getting dripping where you don't want it, on the exterior. On the interior I have NO idea what he means
 
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Offline IanB

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #5 on: August 04, 2024, 11:47:14 pm »
that depends if you are getting dripping where you don't want it, on the exterior. On the interior I have NO idea what he means

If the external pipe is going to an external radiator, as in the example below, then dripping from the pipe is the least of the problems.

 
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Online tooki

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #6 on: August 05, 2024, 08:47:00 am »
that depends if you are getting dripping where you don't want it, on the exterior. On the interior I have NO idea what he means
Indeed.

OP, I think you’re confusing people with nonstandard terminology.

Thermal insulation means something added to prevent heat transfer. For pipes and hoses, this is a layer of thermally insulating material (typically foam or fiberglass) mounted around the outside of the pipe. Nothing happens on the inside because it’s… a pipe, and needs to stay a pipe.

It sounds to me like you simply want some kind of… cork?
 
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Online ebastler

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #7 on: August 05, 2024, 08:55:45 am »
Hello to all,
I need to thermally insulate the internal of this 12x8mm PU pipe (for a length of around 4-6 cm):

Can you please explain what you want to achieve?
  • Do you want to completely block the flow (gas or fluid?) through the pipe? If so, the porous material you suggest will not achieve that.
  • Or do you still want flow, but hope to suppress the transport of thermal energy? That won't work at all via a simple "plug" insert, I'm afraid. You would need a structure with a large surface area and good thermal conductivity, which the gas or fluid passes through and which you actively keep at the desired temperature via an external heating or cooling unit.
 
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Offline YouCanDoItTopic starter

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #8 on: August 05, 2024, 05:15:46 pm »
Hello to all,
I need to thermally insulate the internal of this 12x8mm PU pipe (for a length of around 4-6 cm):

Can you please explain what you want to achieve?
  • Do you want to completely block the flow (gas or fluid?) through the pipe? If so, the porous material you suggest will not achieve that.
  • Or do you still want flow, but hope to suppress the transport of thermal energy? That won't work at all via a simple "plug" insert, I'm afraid. You would need a structure with a large surface area and good thermal conductivity, which the gas or fluid passes through and which you actively keep at the desired temperature via an external heating or cooling unit.

I'm building a DIY air conditioner (more details here) which is based on 2 containers: one ice chest with the only purpose to be a cold reservoir and a styrofoam box where occur all the processing (radiator, blower fan, water pump etc).
The two containers are connected through two 12mm pipes (glued to the holes) and the two pipes are connected to the two connectors of the radiator located inside the styrofoam box.

There are occasions where I want to detach the styrofoam box and use the ice chest as was originally designed for (picnic etc). I'm left with two holes on the lid and I just need to seal such holes in order to restore insulation.
So, what I want to do is simple: plug the EPDM rubber cord inside the pipe area of the lid. Thickness of the lid should be around 3-4 cm, so a 5-6 cm cord should be enough.

EPDM rubber is what seemed to be the right material for this scope. In the winter I will try to see if my air conditioner works even with hot air. I suppose EPDM rubber should work fine even for heat insulation.

that depends if you are getting dripping where you don't want it, on the exterior. On the interior I have NO idea what he means

If the external pipe is going to an external radiator, as in the example below, then dripping from the pipe is the least of the problems.


IanB, yes, I will try to fix title as soon as possible, but now I need to place the order (AE choice day will end up in 5 hours). I will buy 8mm diameter since this is supposed to seal 8mm holes. It's too risky 10mm (even 9mm). If I want a stronger seal I suppose I can later combine the cord with something else (may be some silicone gasket).
Dripping and humidity has nothing to do with the argument of this thread, but is something that I'm trying to see how can be solved in the other thread (I'm thinking to add a secondary system to reduce the room humidity which seems to be an important factor that reduce cooling capability).
 

Offline IanB

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #9 on: August 05, 2024, 05:45:11 pm »
Dripping and humidity has nothing to do with the argument of this thread, but is something that I'm trying to see how can be solved in the other thread (I'm thinking to add a secondary system to reduce the room humidity which seems to be an important factor that reduce cooling capability).

I don't think room humidity is a factor that affects cooling. It is a factor that affects human comfort, but if you care about that you should purchase and use an electrical air conditioning unit of conventional design.
 
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Offline YouCanDoItTopic starter

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #10 on: August 05, 2024, 06:27:25 pm »
Dripping and humidity has nothing to do with the argument of this thread, but is something that I'm trying to see how can be solved in the other thread (I'm thinking to add a secondary system to reduce the room humidity which seems to be an important factor that reduce cooling capability).

I don't think room humidity is a factor that affects cooling. It is a factor that affects human comfort, but if you care about that you should purchase and use an electrical air conditioning unit of conventional design.
I also think the same, but the other guy who built many of such systems said that cooling performs much better in a dry climate especially when trying to cool a whole room. Given that were I live humidity is above 50% most of the time, I think that I should at least investigate, but it would be out of topic here (will try to respond to my other thread as soon as possible).

Regarding this topic, the solution should be pretty easy. Do you think I can go with a 8mm EPDM rubber cord to achieve the goal or you have a better material type and/or diameter recommendation?
I need to thermally insulate the internal of

Is this still about making a home portable air cooler?

If so, you might change the title of this and your other thread to something "Home Portable Air Cooler", so that more people will read it and give you comments.

As to the question here, if this is a water pipe for such an air cooler, you do not need to thermally insulate it at all. Thermal insulation of pipes and ducts is completely unnecessary in such a device.
You're probably right when used as an air conditioner, but when I detach the styrofoam box to just use the ice chest alone (ex: for picnic), two 12mm open holes will ruin for sure insulation.
« Last Edit: August 05, 2024, 06:34:24 pm by YouCanDoIt »
 

Offline IanB

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #11 on: August 05, 2024, 06:52:18 pm »
See the note above from tooki:

I think you’re confusing people with nonstandard terminology.

Thermal insulation means something added to prevent heat transfer. For pipes and hoses, this is a layer of thermally insulating material (typically foam or fiberglass) mounted around the outside of the pipe. Nothing happens on the inside because it’s… a pipe, and needs to stay a pipe.

It sounds to me like you simply want some kind of… cork?

As tooki says, you are looking for a cork, or a bung, to seal the pipe.

You should probably try to match the outside diameter of the bung with the inside diameter of the pipe.

The primary goal is not to insulate, but to prevent air flow. I doubt much heat is going to get through such a small hole otherwise.

 
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Offline YouCanDoItTopic starter

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #12 on: August 05, 2024, 07:42:14 pm »
See the note above from tooki:

I think you’re confusing people with nonstandard terminology.

Thermal insulation means something added to prevent heat transfer. For pipes and hoses, this is a layer of thermally insulating material (typically foam or fiberglass) mounted around the outside of the pipe. Nothing happens on the inside because it’s… a pipe, and needs to stay a pipe.

It sounds to me like you simply want some kind of… cork?

As tooki says, you are looking for a cork, or a bung, to seal the pipe.

You should probably try to match the outside diameter of the bung with the inside diameter of the pipe.

The primary goal is not to insulate, but to prevent air flow. I doubt much heat is going to get through such a small hole otherwise.


What's wrong with my solution?
Quote
EPDM rubber is an ideal insulation for frost control on cold water plumbing. It prevents heat gain and condensation problems on chilled water and refrigerant pipelines and it also prevents heat loss from hot water plumbing, liquid and dual temperature plumbing.

I understand that with my solution the pipe itself is not insulated, just its internal area.

You mean something like this:


I'm not sure on such materials (I suspect EPDM works much better). With a cap alone, the rest of the hole is not filled.
Perhaps I could insert the rubber cord to fill the whole hole and then a cap on on top of it to isolate the exposed side of the pipe?

Blocking air flow should be pretty easy, but I don't think is enough. If it was just a matter of blocking air flow, then an ice chest like this with walls of 4 cm of thickness made of different layers would not have reason to exists. I created a leak on such container, so I believe I should fix the leak by filling the whole depth of the leak.

Ian, I feel like I will get all the parts without any power supplier. I'm unable to estimate the right amperage because I don't know if later I will add other stuff like peltier module, secondary blower motor, temperature controller etc.
I have here a primary switched power supply rated "12V - 5000ma". Do you think is enough for testing until I will know the definitive amperage needed for the whole system?
 

Online tooki

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #13 on: August 05, 2024, 07:56:21 pm »
What's wrong with my solution?
Quote
EPDM rubber is an ideal insulation for frost control on cold water plumbing. It prevents heat gain and condensation problems on chilled water and refrigerant pipelines and it also prevents heat loss from hot water plumbing, liquid and dual temperature plumbing.
Totally irrelevant, since that's talking about insulation, which as I already explained to you, refers to material applied to the outside of a pipe to prevent heat transfer.

EPDM rope will certainly insulate, but you'll have a devil of a time getting it into your tube.

Blocking air flow should be pretty easy, but I don't think is enough. If it was just a matter of blocking air flow, then an ice chest like this with walls of 4 cm of thickness made of different layers would not have reason to exists. I created a leak on such container, so I believe I should fix the leak by filling the whole depth of the leak.
Here's the thing you're forgetting in your thinking: air is a really poor heat transfer medium -- that is, air is a really good thermal insulator. As long as you can keep air from moving (convection) you can prevent heat movement quite effectively. That's literally how insulation (animal fur, fiberglass wool, blankets, foam, etc) works: you trap air in a way that makes it impossible for the air to move, while providing as little solid material as possible through which heat conduction can occur.

The reason for layers in a cooler or whatever is to create multiple isolated air masses that don't mix, to prevent convection. This is what dense animal fur, foam insulation, etc. do on a microscopic scale.

A stopper in your tube will prevent air movement. Heat transfer will also occur through the walls of the tube itself, and plugging the entire tube won't change this very much. Put a second cork in the inside if you want.

« Last Edit: August 05, 2024, 07:58:56 pm by tooki »
 
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Offline YouCanDoItTopic starter

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #14 on: August 07, 2024, 04:16:46 am »
Guys, I placed the order, but without any EPDM rubber. From what you said, seems like there could be issues with it.

What's wrong with my solution?
Quote
EPDM rubber is an ideal insulation for frost control on cold water plumbing. It prevents heat gain and condensation problems on chilled water and refrigerant pipelines and it also prevents heat loss from hot water plumbing, liquid and dual temperature plumbing.
Totally irrelevant, since that's talking about insulation, which as I already explained to you, refers to material applied to the outside of a pipe to prevent heat transfer.
tooki, many thanks for your help, I really appreciate.
You said that the thermal insulation (foam etc) is only applied externally to the pipe to prevent heat transfer and its internal should left as is.
I understand this and in fact my design works in this way.
I'm afraid I didn't provided enough details about my project especially about insulation, pipe positions, dimensions, water flow etc.

Below is a full diagram:


When I want to use the Ice chest as a regular container for food, drinks etc, I just detach the processing unit and the related parts.
This is what I get once I detach the processing unit:



The Ice chest is pretty much the same of the "untouched version" except for the two holes you see on the right along with two 12mm pipes that goes through the holes.
This breaks insulation, the heat penetrate and cold retention reduced. So, what I need is just restore the default insulation.

I'm not sure on what are the best solutions, but I found 3 possible options.

Option 1


Here the whole hole is filled with material that is supposed to be the closest one to the original of the ice chest.
EPDM rope will certainly insulate, but you'll have a devil of a time getting it into your tube.
I'm surprised about this. Internal diameter of the tube is exactly the same of the EPDM rope diameter. I was expecting a smooth insertion given that EPDM is some sort or rubber.

Option 2


This is the same as the previous option except the additional silicone rubber caps. In this way the external area of the pipe is not exposed anymore. To me this seems to be the best solution and most of all, not at all cumbersome.
I'm not sure if there are better materials. You suggested cork, but I'm not sure it would be easy to find such particular dimensions and how compares with EPDM foam. In addition to that, cork is a material that degrades very fast, even more when is cut in small pieces (just like my case).

Option 3


Pneumatic seals. These are designed to work with that tube and connectors shown in the first diagram. Connection and disconnection is very easy. However, apart that they more cumbersome, the internal area of the tube remains open.
 

Online ebastler

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #15 on: August 07, 2024, 06:32:06 am »
You are overthinking this. Compared to the large surface area of your ice box, the two small openings for the tube have negligible cross section. Just plug them in some way to avoid air flow. But don't worry about heat conduction and insulation in that small area.

Your "processing unit" seems a bit over-engineered to me. Why does that heat exchanger need to sit in a styrofoam box? Isn't its whole purpose to give off cold air to the environment? With the relatively small air inlets and outlets, you will need high air velocities and fan speeds -- i.e. the unit will be louder. I would use a slow, large fan (ventilator) blowing at the full cross section of the radiator, and an air outlet with the radiator's full cross section too. Just look at the way radiators are installed in cars.

Also, what is the purpose of the carbon/Hepa filter on the air inlet? You are sucking in air from the room and blowing it out into the room again, so it's not like you are bringing new contaminants into the room. And the filter will obstruct airflow, again driving the need for a more powerful (i.e. noisier) fan.

Finally, what you do need to think about is condensation inside the processing unit. Since the radiator temperature will be close to 0°C, there will be condensation as the incoming air gets cooled down. Expect the radiator to get dripping wet. I think you need a drip tray below it, with a drain tube.
 
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Online tooki

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #16 on: August 07, 2024, 12:45:51 pm »
Guys, I placed the order, but without any EPDM rubber. From what you said, seems like there could be issues with it.


Here the whole hole is filled with material that is supposed to be the closest one to the original of the ice chest.
EPDM rope will certainly insulate, but you'll have a devil of a time getting it into your tube.
I'm surprised about this. Internal diameter of the tube is exactly the same of the EPDM rope diameter. I was expecting a smooth insertion given that EPDM is some sort or rubber.

Option 2
This is the same as the previous option except the additional silicone rubber caps. In this way the external area of the pipe is not exposed anymore. To me this seems to be the best solution and most of all, not at all cumbersome.
I'm not sure if there are better materials. You suggested cork, but I'm not sure it would be easy to find such particular dimensions and how compares with EPDM foam. In addition to that, cork is a material that degrades very fast, even more when is cut in small pieces (just like my case).

Option 3
Pneumatic seals. These are designed to work with that tube and connectors shown in the first diagram. Connection and disconnection is very easy. However, apart that they more cumbersome, the internal area of the tube remains open.
Sorry, perhaps I needed to be clearer: by “cork”, I simply mean a stopper or bung, regardless of material. It doesn’t have to be natural cork. (Though that would be a perfectly valid option; I’m not sure why you think cork degrades quickly. I mean, it can handle literally decades of direct contact with liquids…)


You are truly overthinking this. You’re worrying about some insanely small amount of efficiency loss/gain in a system that’s fundamentally not very good to begin with. (If such ice-based air conditioners made sense we’d use them widely. We don’t. An air conditioner is better when possible.)

You haven’t said how you will be freezing your ice or ice packs, but unless you’re freezing them in an entirely different location, it’s truly pointless, because the heat pulled out of the water to freeze it is discharged into your house (plus some extra heat due to losses and friction in the freezer itself), so you’re raising your house’s temperature by more heat than your “air conditioner” can cool it.
 
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Online ebastler

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #17 on: August 07, 2024, 01:34:14 pm »
If such ice-based air conditioners made sense we’d use them widely. We don’t. An air conditioner is better when possible.

Good point. I'd say the only valid reason for using the ice-based approach is if you want to run this off-grid, from a battery or solar cell. Otherwise, get one of those self-contained air-conditioning units which are based on a heat pump.
 
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Offline SteveThackery

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #18 on: August 07, 2024, 02:01:36 pm »
You haven’t said how you will be freezing your ice or ice packs, but unless you’re freezing them in an entirely different location, it’s truly pointless, because the heat pulled out of the water to freeze it is discharged into your house (plus some extra heat due to losses and friction in the freezer itself), so you’re raising your house’s temperature by more heat than your “air conditioner” can cool it.

Actually that is an excellent point.
 
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Offline IanB

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #19 on: August 07, 2024, 02:19:56 pm »
You haven’t said how you will be freezing your ice or ice packs, but unless you’re freezing them in an entirely different location, it’s truly pointless, because the heat pulled out of the water to freeze it is discharged into your house (plus some extra heat due to losses and friction in the freezer itself), so you’re raising your house’s temperature by more heat than your “air conditioner” can cool it.

Actually that is an excellent point.

Indeed. Same point reinforced here:

https://www.eevblog.com/forum/projects/i-need-to-connect-a-100mm-dryer-flexible-vent-hose-to-a-102mm-pipe/msg5596439/#msg5596439
 
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Offline YouCanDoItTopic starter

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #20 on: August 08, 2024, 03:36:11 am »
You are overthinking this. Compared to the large surface area of your ice box, the two small openings for the tube have negligible cross section. Just plug them in some way to avoid air flow. But don't worry about heat conduction and insulation in that small area.
You are truly overthinking this. You’re worrying about some insanely small amount of efficiency loss/gain in a system that’s fundamentally not very good to begin with. (If such ice-based air conditioners made sense we’d use them widely. We don’t. An air conditioner is better when possible.)
You're probably right. I always tend to overthink while I design and mostly because, once a project is built, I want to avoid to blame myself with something like "this area does not work as expected and it wasn't at all something that makes very little difference".
I had to experience this several times and is not at all a good thing.

I can't really estimate how can negatively affect two 12mm holes vs two 16mm holes, but a 16mm radiator pipe is significantly bigger and the pipes to connect are two. It's a risk, once two 16mm holes are drilled and negative impact is more than expected, I can reduce the holes, but the original and expensive insulating layers of the ice box are definitively lost. In an expensive ice chest like this, two 12mm holes are different from two 16mm holes "repaired" to 12mm.
For this reason I decided to stay on the safe side.
The 12mm to 16mm connector and all the other blue ones you see in the diagram are pneumatic connectors. They are quick release and free from any hassle.
Even with 16mm holes as you say, I still need a 12mm to 12mm connector in order to achieve "detach" functionality.
So, why not just using a 12mm to 16mm connector and obtain less intrusive modifications to the ice chest?

Yes tooki, air conditioners are for sure better when possible, but they can't be all around the home or even on travel. I can guarantee you that ice-based air conditioners are pretty close as long as they are well designed (mostly available on YT aren't). They are portable, free from any cost an they can be used even outdoor to cool specific areas.

Your "processing unit" seems a bit over-engineered to me. Why does that heat exchanger...
Your other observations about the rest of the design are very interesting, but I will reply in my other thread because here would be off-topic.

Guys, I placed the order, but without any EPDM rubber. From what you said, seems like there could be issues with it.


Here the whole hole is filled with material that is supposed to be the closest one to the original of the ice chest.
EPDM rope will certainly insulate, but you'll have a devil of a time getting it into your tube.
I'm surprised about this. Internal diameter of the tube is exactly the same of the EPDM rope diameter. I was expecting a smooth insertion given that EPDM is some sort or rubber.

Option 2
This is the same as the previous option except the additional silicone rubber caps. In this way the external area of the pipe is not exposed anymore. To me this seems to be the best solution and most of all, not at all cumbersome.
I'm not sure if there are better materials. You suggested cork, but I'm not sure it would be easy to find such particular dimensions and how compares with EPDM foam. In addition to that, cork is a material that degrades very fast, even more when is cut in small pieces (just like my case).

Option 3
Pneumatic seals. These are designed to work with that tube and connectors shown in the first diagram. Connection and disconnection is very easy. However, apart that they more cumbersome, the internal area of the tube remains open.
Sorry, perhaps I needed to be clearer: by “cork”, I simply mean a stopper or bung, regardless of material. It doesn’t have to be natural cork. (Though that would be a perfectly valid option; I’m not sure why you think cork degrades quickly. I mean, it can handle literally decades of direct contact with liquids…)
Do not worry. Well, in this case I would say we're talking about the same thing, just different terminology.
I have read about degradation in the google "People also ask" and what I have read is not encouraging at all:
Quote
How long does it take for cork to degrade?
Whole wine corks can take up to three years to fully decompose, even in ideal conditions. But you can significantly speed up this process by shredding or cutting them in smaller pieces.
It also seems to be very hard to find the needed size and length. They are mostly available in standard size (the sizes suitable for bottles).
Sometimes cork breaks and get stuck inside even when used with regular bottles. Keep in mind that in my case the cork size would be 12mm x 40-50mm. I can already see how can easily break with just a couple of insertion and/or removals.
Let me understand...seems to be that it is more a matter on the material I use to fill the holes, rather than the way I do it.
Apart the issues I have just mentioned, what really makes cork better than EPDM foam rubber?

I have not been able to find thermal properties comparisons, but what I found is that cork has a much lower moisture resistance compared to generic rubber and given that moisture is a concrete risk for a system like this, my concerns increase.

You haven’t said how you will be freezing your ice or ice packs, but unless you’re freezing them in an entirely different location, it’s truly pointless, because the heat pulled out of the water to freeze it is discharged into your house (plus some extra heat due to losses and friction in the freezer itself), so you’re raising your house’s temperature by more heat than your “air conditioner” can cool it.
Many thanks, tooki! IanB and some other guys already made me aware of such issue. Fortunately I will use a freezer which is located in another floor of the home.

You haven’t said how you will be freezing your ice or ice packs, but unless you’re freezing them in an entirely different location, it’s truly pointless, because the heat pulled out of the water to freeze it is discharged into your house (plus some extra heat due to losses and friction in the freezer itself), so you’re raising your house’s temperature by more heat than your “air conditioner” can cool it.

Actually that is an excellent point.

Indeed. Same point reinforced here:

https://www.eevblog.com/forum/projects/i-need-to-connect-a-100mm-dryer-flexible-vent-hose-to-a-102mm-pipe/msg5596439/#msg5596439

Great! And I added another reinforcement just at the beginning of the thread. In this way people will not even attempt to build the project if they are in such condition.
 

Online tooki

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #21 on: August 08, 2024, 10:08:04 am »
You're probably right. I always tend to overthink while I design and mostly because, once a project is built, I want to avoid to blame myself with something like "this area does not work as expected and it wasn't at all something that makes very little difference".
I had to experience this several times and is not at all a good thing.
You learn a lot more from failures than from successes — at least if you then figure out why it didn’t work.

But if you’re having project after project fail for unknown reasons, then you need to examine your process for making projects, because that might indicate that you’re trying to do things too far for your current understanding of the subject matter.

I can't really estimate how can negatively affect two 12mm holes vs two 16mm holes, but a 16mm radiator pipe is significantly bigger and the pipes to connect are two. It's a risk, once two 16mm holes are drilled and negative impact is more than expected, I can reduce the holes, but the original and expensive insulating layers of the ice box are definitively lost. In an expensive ice chest like this, two 12mm holes are different from two 16mm holes "repaired" to 12mm.
For this reason I decided to stay on the safe side.
The 12mm to 16mm connector and all the other blue ones you see in the diagram are pneumatic connectors. They are quick release and free from any hassle.
Even with 16mm holes as you say, I still need a 12mm to 12mm connector in order to achieve "detach" functionality.
So, why not just using a 12mm to 16mm connector and obtain less intrusive modifications to the ice chest?
I don’t think any of it matters.

When using it as a cooler for foods and drinks, the main thing is to prevent airflow. Even just closing the tubes with sticky tape on both ends would give surprisingly good insulation.

When using it as an air conditioner, losses from the ice chest simply do not matter, because the losses cool the same space the cooled air is discharged into. The only time when losses would matter is if the ice chest and the “processing unit” were in completely different spaces.


Yes tooki, air conditioners are for sure better when possible, but they can't be all around the home or even on travel. I can guarantee you that ice-based air conditioners are pretty close as long as they are well designed (mostly available on YT aren't). They are portable, free from any cost an they can be used even outdoor to cool specific areas.
They “can’t be all around the home”?!? Uhh… central air conditioning exists, as does “buying more than one air conditioner” (e.g. to put one in each room). In USA, for example, it is common for old houses (built before air conditioning) to have a small air conditioner in each room.

Free from any cost? Since when is the electricity to run the freezer free?

“Used outdoors to cool specific areas”?  :-DD LOL no. They can be used to blow small amounts of cool air directly at a small part of a person. You’re not going to have any effect on an outdoor area.

Sorry, perhaps I needed to be clearer: by “cork”, I simply mean a stopper or bung, regardless of material. It doesn’t have to be natural cork. (Though that would be a perfectly valid option; I’m not sure why you think cork degrades quickly. I mean, it can handle literally decades of direct contact with liquids…)
Do not worry. Well, in this case I would say we're talking about the same thing, just different terminology.
No, I don’t think we are, because the rest of your reply indicates you absolutely did not understand what I am saying.

I have read about degradation in the google "People also ask" and what I have read is not encouraging at all:
Quote
How long does it take for cork to degrade?
Whole wine corks can take up to three years to fully decompose, even in ideal conditions. But you can significantly speed up this process by shredding or cutting them in smaller pieces.
It also seems to be very hard to find the needed size and length. They are mostly available in standard size (the sizes suitable for bottles).
Sometimes cork breaks and get stuck inside even when used with regular bottles.
But again, I never actually recommended using natural cork, though it likely would work.

What I clarified is that by “a cork”, I mean a stopper or bung. That means an object designed to be a removable closure for an opening, especially one that works by friction-fit of a compressible material. But a cap or other closure would be fine too.

What it doesn’t mean is completely filling the entire length of the tube.

As for your decomposition quote: you’ve again located some completely irrelevant piece of information. That wording indicates it’s saying how long to decompose when you want to compost it. It is NOT saying that cork will decompose in 3 years or less while in use as a stopper! You know that there are wine bottles decades old, with their original cork stoppers still keeping the wine inside, right?!?

OK, yep, I googled your quote and indeed it comes from a composting FAQ: https://insteading.com/blog/composting-wine-corks/

 |O  :palm:  |O

Keep in mind that in my case the cork size would be 12mm x 40-50mm. I can already see how can easily break with just a couple of insertion and/or removals.
So you still have not understood why this shape is not necessary.  :palm:

You just need to block airflow. You don’t need to block the entire length of the tube.

Air that cannot move is an excellent insulator. By blocking one end of the tube, you already significantly reduce heat transfer, and by simply blocking both ends, you completely immobilize the air within. The tube is already made of plastic (a relatively poor heat conductor), and it is tiny compared to the overall surface area of the box, so any improvements due to completely filling the tube would be minimal (to the point of being insignificant) at best.

Let me understand...seems to be that it is more a matter on the material I use to fill the holes, rather than the way I do it.
Apart the issues I have just mentioned, what really makes cork better than EPDM foam rubber?

I have not been able to find thermal properties comparisons, but what I found is that cork has a much lower moisture resistance compared to generic rubber and given that moisture is a concrete risk for a system like this, my concerns increase.
Your conclusion (in bold) is literally the exact opposite of what people have been trying to tell you.

1. We are saying that the important thing is to block airflow, regardless of material. To block airflow you don’t need to fill the entire length of the tube.
2. Nobody ever said natural cork is a superior material to EPDM. All I said is that natural cork would probably work fine for a stopper.


And why would the longevity of natural cork even matter? You said the stoppers are only for when you’re using the box as a beverage cooler, which is not normally a long-term thing. So most of the time, the stoppers would be removed because the tubes are in use with your cooling water, or because the box is sitting in winter storage with neither cooling water nor stoppers. Who cares about the long-term moisture resistance of stoppers that are only used for hours at a time, with ample time to dry out in between?


I’m questioning whether to spend any more time on this thread unless you demonstrate an actual effort to understand what people are saying and a willingness to accept it, because the vibe I’m getting is that you’re one of these people who simply want validation of your own ideas (whether they’re correct or not), and basically tune out anything that doesn’t agree, and find completely irrelevant sources to support your misunderstandings of things. You’re seeing what we say and even responding to it, but it isn’t penetrating.

I’ll also make clear that I think DIY ice-based air conditioning is a fundamentally poor type of air conditioning, which only makes sense in certain extremely narrow circumstances. (Like off-grid use, where you might “store” solar energy this way.) Using one in a normal house is just silly. I think you’re making a ton of effort for something that will not give a particularly good result.

A household freezer has only a small fraction the cooling power of even a small compressor-based air conditioner. The amount of ice needed to effectively cool a room is enormous: approximately 3kg of 0°C ice per square meter of floor area per 24h. So even a tiny 10 square meter bedroom would require 30kg of ice per day. That is far, far beyond what a standard home freezer compartment in a fridge can produce. (A large standalone home freezer can do about 25kg/day.)

(Yes, ice is normally kept substantially colder than 0°C, but energetically, that’s more or less irrelevant, as the huge amount of energy needed for the phase change to/from 0°C water <-> 0°C ice far exceeds the energy needed for the e.g. -20°C ice <-> 0°C ice temperature change.)
 
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Offline YouCanDoItTopic starter

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #22 on: August 10, 2024, 04:50:31 am »
You're probably right. I always tend to overthink while I design and mostly because, once a project is built, I want to avoid to blame myself with something like "this area does not work as expected and it wasn't at all something that makes very little difference".
I had to experience this several times and is not at all a good thing.
You learn a lot more from failures than from successes — at least if you then figure out why it didn’t work.

But if you’re having project after project fail for unknown reasons, then you need to examine your process for making projects, because that might indicate that you’re trying to do things too far for your current understanding of the subject matter.

This is the same statement I repeat myself each time I fails in something  :)
That's the harder part! I always try to push things to the limit even without having the correct knowledge to understand if they can work. I'm afraid I will never be able to solve this.

I can't really estimate how can negatively affect two 12mm holes vs two 16mm holes, but a 16mm radiator pipe is significantly bigger and the pipes to connect are two. It's a risk, once two 16mm holes are drilled and negative impact is more than expected, I can reduce the holes, but the original and expensive insulating layers of the ice box are definitively lost. In an expensive ice chest like this, two 12mm holes are different from two 16mm holes "repaired" to 12mm.
For this reason I decided to stay on the safe side.
The 12mm to 16mm connector and all the other blue ones you see in the diagram are pneumatic connectors. They are quick release and free from any hassle.
Even with 16mm holes as you say, I still need a 12mm to 12mm connector in order to achieve "detach" functionality.
So, why not just using a 12mm to 16mm connector and obtain less intrusive modifications to the ice chest?
I don’t think any of it matters.

When using it as a cooler for foods and drinks, the main thing is to prevent airflow. Even just closing the tubes with sticky tape on both ends would give surprisingly good insulation.

When using it as an air conditioner, losses from the ice chest simply do not matter, because the losses cool the same space the cooled air is discharged into. The only time when losses would matter is if the ice chest and the “processing unit” were in completely different spaces.
This is encouraging, it's much easier that I thought!

This is something that I'm trying to better understand. If seen from this point of view, ice chest used in such kind of project would not make sense because we want immediate release of all the available cold into the room.
In the other thread a guy said that the most efficient way to cool down a room would be a big block of ice placed in the center of the room.

From the information I got from the other thread I have divided an air conditioner like this into two different categories:
  • capable to cool down a small room to the desired temperature (which seems to be very hard)
  • capable to only cool down a limited area of the room
From my understanding, an ice chest plays a big role in both the cases because in both the cases released cold should be controlled to ensure no waste and longer duration of the ice:
  • When a room reached the target temperature we want to suspend or slow down the released cold (just like happens with a regular AC) and when this process happens, the ice chest insulation is what guarantee ice preservation
  • When a target area has reached the target temperature or the cold needed to provide fresh air to that area is less than the maximum cold the cooler can provide, then we want to slow down the cooling process to the minimum required for that area rather than trying to cool down the whole room at max power.
I saw people using manual switches to reduce power (see video below). I prefer a temperature controller that reduce power based on the detected temperature. I'm not sure on what of the twos works better, so I am waiting to get a prototype up and running to see what could be the best way to control the release of the cold.

The only scenario where I see (in both the 2 previous points) an ice chest completely useless is when the full cooling power is needed all of the time. I want to hope this is a very rare possibility.

On the other thread some people have done your same observation about the processing unit and my attempt to reduce heat penetration through a styrofoam box. If I have understood well, I should rather facilitate heat penetration by leaving all the parts exposed. I'm trying how I can solve some issue if I go in this way:
  • i don't know how to adapt air filtering. Placed under the radiator the filters will get ruined by the water that drops from condensation that occur on the radiator. Above above the radiator the motor blower will become much less effective. On a closed container I don't have this problem.
  • With everything exposed I have less control on the cold release. For example when the unit is in standby all the parts will become hotter and the heat will easily penetrate inside the chest box. With a styrofoam box I can at least reduce a a good amount this phenomena.
  • If I point the nozzle to a specific area, the cold will be released even in the cooler location due to all the parts exposed and this would be a waste. With a closed and insulated container all the cold air will go straight to the target point.
With the right design I could fix the first issue (ex: I could place the radiator vertically), but the last two issues seem harder.
In the other thread I expressed a couple of minor issues, but I think they should be easily manageable.
I'm delaying the purchase of the box because I'm in doubt. I was sure about the styrofoam box, but now not at all after I've heard your opinions.

Yes tooki, air conditioners are for sure better when possible, but they can't be all around the home or even on travel. I can guarantee you that ice-based air conditioners are pretty close as long as they are well designed (mostly available on YT aren't). They are portable, free from any cost an they can be used even outdoor to cool specific areas.
They “can’t be all around the home”?!? Uhh… central air conditioning exists, as does “buying more than one air conditioner” (e.g. to put one in each room). In USA, for example, it is common for old houses (built before air conditioning) to have a small air conditioner in each room.
I totally agree with you. Central air conditioning or even an air conditioner in each room would work like a charm and in an automated way...if someone does not care about all the money needed for the initial investment and to keep them running.

Yes tooki, air conditioners are for sure better when possible, but they can't be all around the home or even on travel. I can guarantee you that ice-based air conditioners are pretty close as long as they are well designed (mostly available on YT aren't). They are portable, free from any cost an they can be used even outdoor to cool specific areas.
They “can’t be all around the home”?!? Uhh… central air conditioning exists, as does “buying more than one air conditioner” (e.g. to put one in each room). In USA, for example, it is common for old houses (built before air conditioning) to have a small air conditioner in each room.

Free from any cost? Since when is the electricity to run the freezer free?
A freezer is running 24h anyway. We don't have to power it on just to freeze our ice packs. They are designed to freeze inserted food with minimum power usage, especially modern ones (with good energy saving rate).
When I insert new food into my freezer, the motor start spinning for, may be, 5-10 seconds, then return to its previous state.
In the ceiling of the house I still have one (unused) of such big freezers with the "Ocean" logo. It's very big (may be 2 square meters) and such freezers were very common here around 30-40 years ago. I've been tempted multiple times to use it as a dedicated device to prepare ice for my cooler especially because it allows me to completely fill the ice chest box, but...I'm afraid that this is going to be very expensive in terms of power consumption.

“Used outdoors to cool specific areas”?  :-DD LOL no. They can be used to blow small amounts of cool air directly at a small part of a person. You’re not going to have any effect on an outdoor area.
You verified this personally?


On minute "7:58":
"Does it work? Well that's pretty subjective. I'm finding that it will cool an area and if you're in that area, it will cool you!"

Don't take this as an offence, but between someone stating that it doesn't work at all and Mr Fred’s DIY Garage School showing the experiment directly on video with thermal camera and numbers, you agree with me who have more credits.
We can debate about effectiveness of a full outdoor vs semi-outdoor (like the open garage in the video), if can provide some cooling only on night or under shadow and many other things. But it's wrong to say that it only works inside a completely insulated room. At least, on a garage with one wall completely open, 32% humidity and all of the same conditions in video, works pretty well. As Fred said, it is subjective if a cooled area worth or not, but it is wrong to say that an area can't be cooled at all, unless you proof me that Fred faked data and made false statements.
Some people rely exclusively on thermodynamic laws and when they see a video against their statement they get hot. I'm sure is not your case.
It's good to use science as a first checking point, but science can't just calculate everything. Experiments directly in the field play a big role and should be taken into account.

Sorry, perhaps I needed to be clearer: by “cork”, I simply mean a stopper or bung, regardless of material. It doesn’t have to be natural cork. (Though that would be a perfectly valid option; I’m not sure why you think cork degrades quickly. I mean, it can handle literally decades of direct contact with liquids…)
Do not worry. Well, in this case I would say we're talking about the same thing, just different terminology.
No, I don’t think we are, because the rest of your reply indicates you absolutely did not understand what I am saying.
In this case, please accept my apologies. I will try my best from now on...

I have read about degradation in the google "People also ask" and what I have read is not encouraging at all:
Quote
How long does it take for cork to degrade?
Whole wine corks can take up to three years to fully decompose, even in ideal conditions. But you can significantly speed up this process by shredding or cutting them in smaller pieces.
It also seems to be very hard to find the needed size and length. They are mostly available in standard size (the sizes suitable for bottles).
Sometimes cork breaks and get stuck inside even when used with regular bottles.
But again, I never actually recommended using natural cork, though it likely would work.

What I clarified is that by “a cork”, I mean a stopper or bung. That means an object designed to be a removable closure for an opening, especially one that works by friction-fit of a compressible material. But a cap or other closure would be fine too.

What it doesn’t mean is completely filling the entire length of the tube.

As for your decomposition quote: you’ve again located some completely irrelevant piece of information. That wording indicates it’s saying how long to decompose when you want to compost it. It is NOT saying that cork will decompose in 3 years or less while in use as a stopper! You know that there are wine bottles decades old, with their original cork stoppers still keeping the wine inside, right?!?

OK, yep, I googled your quote and indeed it comes from a composting FAQ: https://insteading.com/blog/composting-wine-corks/

 |O  :palm:  |O
What I can say here other than "please accept my apologies"? And the worst thing is that you clearly stated that by “a cork”, you mean a stopper or bung.
You can see how much hot the other discussion has become and how many messages I had to reply. You can imagine how many drafts I have opened in the browser. Given that english is not even my natural language, do you think could be forgivable the fact that I have missed out or forgotten your statement in a scenario like this? Or I have to be considered as someone who only want people that agree with its own statements?

Let imagine for a while that you was really recommending natural cork, my concerns were not unjustified based on what stated on the google FAQ. There was no mention about composting and this is a google fault. You're right, I should have opened the url and read more, but as it has been said multiple times, it doesn't worth to spend much time in investigations for such aspect of the project and I just thought that thrusting google FAQ was more than enough.

To me the pneumatic plugs or the EPDM rubber cord seemed to match the characteristics you described, even more if you say that i don't have to fill the whole length.

Keep in mind that in my case the cork size would be 12mm x 40-50mm. I can already see how can easily break with just a couple of insertion and/or removals.
So you still have not understood why this shape is not necessary.  :palm:

You just need to block airflow. You don’t need to block the entire length of the tube.

Air that cannot move is an excellent insulator. By blocking one end of the tube, you already significantly reduce heat transfer, and by simply blocking both ends, you completely immobilize the air within. The tube is already made of plastic (a relatively poor heat conductor), and it is tiny compared to the overall surface area of the box, so any improvements due to completely filling the tube would be minimal (to the point of being insignificant) at best.

Let me understand...seems to be that it is more a matter on the material I use to fill the holes, rather than the way I do it.
Apart the issues I have just mentioned, what really makes cork better than EPDM foam rubber?

I have not been able to find thermal properties comparisons, but what I found is that cork has a much lower moisture resistance compared to generic rubber and given that moisture is a concrete risk for a system like this, my concerns increase.
Your conclusion (in bold) is literally the exact opposite of what people have been trying to tell you.

1. We are saying that the important thing is to block airflow, regardless of material. To block airflow you don’t need to fill the entire length of the tube.
2. Nobody ever said natural cork is a superior material to EPDM. All I said is that natural cork would probably work fine for a stopper.


And why would the longevity of natural cork even matter? You said the stoppers are only for when you’re using the box as a beverage cooler, which is not normally a long-term thing. So most of the time, the stoppers would be removed because the tubes are in use with your cooling water, or because the box is sitting in winter storage with neither cooling water nor stoppers. Who cares about the long-term moisture resistance of stoppers that are only used for hours at a time, with ample time to dry out in between?
This is what i call a great explanation and what I was waiting for. 5 stars!
Place it as the first response of the thread and we are almost done.

You've basically solved most of my concerns:
  • caps showed in my diagram are useless since the tube is tiny and the heat that can penetrate is insignificant (much better than minimal).
  • by blocking both ends, I completely immobilize the air within (and this is what I want, right?). No need to fill the entire length
Sorry again for my misunderstanding. I really need to be more careful!
To resume:
  • Although I don't need to fill the whole hole, I am not sure that a shorter cork can significantly reduce the risk of breakage. When I said that needed diameter was 12mm I was wrong: the internal diameter of the tube is 8mm! I don't want to be considered as someone who wants validation of its own ideas through every source he can find. In this specific case I don't even involve sources and given the resistance of corks my concerns about possible breakage make sense when the diameter is only 8mm.
  • I have not been able to find cork or any other material with the features you described when I was searching for 12mm. It will be even harder to find 8mm ones.
I totally agree about longevity. It was a concern I had when I checked the google faq. I was not aware it was about composting. So, I just assumed that on such small size I would had to buy a new supply each time I go on a journey and need a beverage cooler. It's not about the paltry cost, it's all about the hassle.
You're totally right about moisture resistance too: it is useless when used as a beverage cooler. Here I'm afraid happened the same event previously described. With all drafts opened and moisture issues discussed on the other thread I must have done some sort of typo (or I simply was tired and sleepy). Sorry!!!

Anyway, I'm afraid that my concerns have very little importance considering how much is difficult to find such custom size, unless I'm willing pay handsomely a specialized company plus dedicated shipping costs with the risks to find out that they get broken. If it was something I could add to an existing AE order I could give it a try, otherwise it doesn't worth.

Unless someone can suggest me an existing product, I'm afraid I will have to fallback into EPDM or pneumatic seals. Preventing air entrance is what I need and they are both excellent airtight sealers.

I’m questioning whether to spend any more time on this thread unless you demonstrate an actual effort to understand what people are saying and a willingness to accept it, because the vibe I’m getting is that you’re one of these people who simply want validation of your own ideas (whether they’re correct or not), and basically tune out anything that doesn’t agree, and find completely irrelevant sources to support your misunderstandings of things. You’re seeing what we say and even responding to it, but it isn’t penetrating.

I’ll also make clear that I think DIY ice-based air conditioning is a fundamentally poor type of air conditioning, which only makes sense in certain extremely narrow circumstances. (Like off-grid use, where you might “store” solar energy this way.) Using one in a normal house is just silly. I think you’re making a ton of effort for something that will not give a particularly good result.

A household freezer has only a small fraction the cooling power of even a small compressor-based air conditioner. The amount of ice needed to effectively cool a room is enormous: approximately 3kg of 0°C ice per square meter of floor area per 24h. So even a tiny 10 square meter bedroom would require 30kg of ice per day. That is far, far beyond what a standard home freezer compartment in a fridge can produce. (A large standalone home freezer can do about 25kg/day.)

(Yes, ice is normally kept substantially colder than 0°C, but energetically, that’s more or less irrelevant, as the huge amount of energy needed for the phase change to/from 0°C water <-> 0°C ice far exceeds the energy needed for the e.g. -20°C ice <-> 0°C ice temperature change.)
Of course my friend and I started this process by recognizing all my faults and unwanted mistakes, some of them generated by the very confusing scenario I had to face. And I ask you and the other people to accept my apologies for the very long thread it has become this due the numerous off-topic. It should have been marked as solved with just a very small amount of messages, but many people started to comment about the design of my cooler instead of the argument for which this thread has been opened and I have been forced to respond. I'm not the kind of person who ignore messages although such behaviour would have been more appropriate.
You have for sure noticed that each time I talk about my ideas, I often use terms like "may be", "not sure", "from what I have understood..." etc with the main purpose to make people aware that my idea can be wrong.

It's not that I want validation of my own ideas even if they are not correct, but I'm specifically looking for people that demonstrate the reasons why they aren't. However, when I have valid arguments against such reasons, I expose them whether interlocutor appreciate or not. I have given a concrete example with the video above. Vice versa, when such reasons are valid and I have no arguments I just close and mark my idea with something like "I need to revise my idea and make it free from the issues people mentioned!".
Please, forget about the sources I found to validate my arguments (ex: the google cork faq). This is not my default behaviour when I check sources and was not even tendentious. It was plain superficiality and too much trust in google when the argument has very low importance combined with the messy scenario I was facing.

When you talk about solar energy, do you refer to the possibility to power the ice-cooler through a solar panel rather than a battery or a regular AC socket? I feel like you're talking about something completely different.

I was aware on the difficulty to cool a room and I started the project with the awareness that cooling a restricted area (it's not the same, but call it "pushing some fresh air against an object", if you prefer) was the maximum I could achieve which it is perfectly fine for me. However you know how human kind are, they always try to achieve what seems to be impossible (and sometime, someone, succeeds).

I'm probably misunderstanding your numbers, but is 3 kg the equivalent of three 1000ml ice pack bags stored at 0C (at least this is what the conversion tools say) ? If such 3 bags are enough to keep cool one square meter for 24 hours it doesn't sound bad. I'll use gel packs and although I don't have them yet available to verify, I would say that if I give the bags the correct shape I should have the space to freeze, more or less, around 10 bags (food included).
I have no idea on the time needed to freeze such packs, but labels say around 8 hours. If this is true and I'm not misunderstanding your numbers, it should be 30 kg per 24H.
In theory the other big freezer I previously talked about should be able to provide enough ice for a whole room, but what about bills if I have the crazy idea to power it on?
I'm probably missing some other not negligible detail. On the other thread they talked about a temperature drop of 5C. So, with a temperature of 32C, with such quantities I can go down to 27C. If I accept such temp it's better for me. If I want to go to 22C, then I will need to double. Hope I'm wrong!

Thanks for the explanation about the heat exchange. There are still some unclear details, but I think I got what matter.

Regarding the current thread, in particular the ice chest sealers, I really don't want to abuse your time. Everything is well explained.
If you want to comment about the rest (and is not mandatory), it would be better on the other thread because here would be off-topic.

Thanks again
 

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #23 on: August 10, 2024, 12:54:02 pm »
Your home freezer does NOT run 24/7. It’s plugged in 24/7, but typically runs for a few minutes per hour to maintain temperature (= compensate for losses). But adding food or water will increase the duty cycle (the % of time that it’s actually running) significantly — after a delay.

Suppose your freezer is mostly full of frozen foods and liquids (as it should be for optimum efficiency). Then you put in a liter bottle of water to freeze. The freezer doesn’t know this right away, because its temperature sensor is somewhere along (or inside) a wall of the freezer, which is still cold. It doesn’t have an infrared camera to see “oh my, we have a hot spot now”. What happens is that the heat in your water bottle moves from the bottle to everything else in the freezer (the frozen items and the small amount of air). The air we can more or less ignore. But you have to understand that the “cold energy” to freeze the newly added bottle comes from the other foods, and their temperature will rise as they absorb the heat from the bottle. Depending on the shape of the bottle, probably around 3h to freeze. During this time, the temperature of the other frozen goods will rise, causing damage to them if they get too warm (even if still below 0). Eventually the temperature sensor will detect that the temperature in the freezer has risen, and will turn on the compressor to cool everything back down.

It most certainly does not mean your freezer compressor runs for “5-10 seconds” and with that, removed all the heat needed to freeze the bottle. The other foods are a reservoir which has to get refilled later. Your freezer compressor will likely need to run for about 2 hours to bring everything back down to temperature.

As I already told you, a LARGE household freezer can only freeze up to about 25kg per day. A standard freezer compartment, far less. And as we have told you, pushing the limits on this also endangers the other foods in the freezer. If you try to freeze many kilos of ice per day in your normal kitchen freezer, day after day, at some point your mom will kill you because of all the frozen food that has been ruined. For example, ice cream will become grainy, as the slow refreezing causes large ice crystals to form in it. Frozen vegetables will get mushier. Meat will lose more juices when cooked. And if it gets too warm, harmful bacteria can grow. (This is why restaurant refrigerators and freezers have far, far more powerful compressors, so that they can maintain safe temperatures even as large amounts of food are added.)

The kg of ice per square meter is the amount needed to cool an insulated house as a whole. You cannot say “I just want to cool this one square meter of the room” in an open room! No more than you can pour a cup of coffee in the ocean and expect a bubble of warmth around you. No more than you can add a handful of salt into your boiling pasta water and expect only the water beneath your hand to get salty. Heat ALWAYS moves (and always from hot to cold), and in air, other effects like convection also mean the room air mixes. So the kg/sqm is what you need to calculate the ice for the whole room.

As for the video: yeah, um, I’m still going to believe me and not an idiot on YouTube who doesn’t show anything useful. All he shows is that the air exiting the thing is cooled substantially. But all it can do is blow cool air onto someone a few cm away. The massive amount of hot air it’s blowing into means it simply cannot cool any meaningful mass of air, because it immediately gets diluted with ambient air. It’s like pissing in the ocean. You aren’t going to meaningfully warm the ocean because it’s just not enough warm liquid. What he doesn’t show, because it would prove the damned thing is useless, is what happens to the overall room temperature at different distances. You’d see that the temperature change falls dramatically.

FYI, this applies the same way to hot air. This is why you can use an electric hair dryer without burning your head. Or a heat gun: you can have a heat gun with 300C air temperature at the nozzle, yet at half a meter away, it’s not even hot enough to hurt (so under about 80C). (And consider that these have FAR more heating power than your ice box AC has cooling power.)



As for your statement that “science can’t just calculate everything” — ummm…  :palm: Yeah, in this case it absolutely can. Thermodynamics isn’t some poorly-understood, experimental fringe of physics, it’s a part that is extremely well understood and characterized. Your lack of knowledge (and the lack of knowledge in that YouTuber you love) is not of equal importance as the knowledge of people who actually know what they’re talking about.


Sorry to have to be so blunt, but you know so little about the topic that you don’t even realize how little you know, and that is giving you misplaced confidence. You also seem unaware of the need to check into things more deeply to gauge their relevance, as shown in your blind trust in a Google FAQ (which are frequently completely wrong, by the way), without even making the effort to see if it’s applicable — and at the same time ignoring common sense. Surely you’ve seen bottles with corks over 3 years old?!? The fact that bottles with corks much older than exist, and I’m sure you knew that already, should have immediately made you think “wait a second, that can’t be right.” But then again you weren’t actually looking for the relevant facts, you were looking for something to agree with your assumptions so you could “prove” me wrong.

Yes, you couch your statements with weasel words like “it may be”, which is fine, but when people demonstrate to you that you are, in fact, mistaken, you really aren’t accepting it. You’re still believing the sources that say what you hope is true, even though they’re wrong or inapplicable.
« Last Edit: August 10, 2024, 12:59:18 pm by tooki »
 
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Offline IanB

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Re: The correct EPDM rubber cord diamater to insulate internally a pipe
« Reply #24 on: August 10, 2024, 04:06:38 pm »
So I found one example of such a cooling unit that seems to have a sensible justification (use in a small airplane cabin without onboard power) and is thoughtfully designed.

In this case the builder specifically directed the stream of cool air directly at the occupants, and also bought big blocks of ice from the convenience store, rather than freezing ice at home.

This is the kind of video that I would be comfortable taking hints from:


 
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