[CO2]

Hello everyone..

i dont have any knowlege about chemistry thats why i am here because i need your help..

i want to make a heat exchanger with flexible copper tubes instead of buying one..the simple one that cold water flows in the pipes with a pump and the hot air goes through the pipes and it get a little bit cooler..

now the most cooler the water is in the copper tubes the better results i have, thats why i wanted to do it with liquid nitrogen, as i know the liquid nitrogen stays liquid if it is under presure in the botle and i make some plans to buy or build a bottle with a litle exit hole at the bottom of it and there i wanted to connect the heat exchanger pipes and then connect it to the top of the bottle again and make it work..

i did more research about it and i ask at the local chemistry and they told me that it is possible but the liquid nitrogen will stuck in the cooper tubes and its not going to work and if it works it will not cool the pipes..

and i come here to find out any way that i can keep very cold the water or some other liquid instead of change it every few hours or add ice on it or use it with a chiller..

thank you i hope i explain it simple for you to understand because i dont know anything about chemisrty and this forum looks very helpful

any help will be accepted

good day..

 

[Arkcon]

Hello everyone..

i dont have any knowlege about chemistry thats why i am here because i need your help..

That's why we all come here.  Nobody knows everything, so we're all here to learn from each other.

i want to make a heat exchanger with flexible copper tubes instead of buying one..the simple one that cold water flows in the pipes with a pump and the hot air goes through the pipes and it get a little bit cooler..

That is a simple and clear plan.

now the most cooler the water is in the copper tubes the better results i have, thats why i wanted to do it with liquid nitrogen

Aw man, to this point it was a cogent and rational discussion, and now its just gotten weird.  OK, fine, you want to use cryogenic liquids with minimal knowledge and training.  Lets work with that.

as i know the liquid nitrogen stays liquid if it is under presure in the botle and i make some plans to buy or build a bottle with a litle exit hole at the bottom of it and there i wanted to connect the heat exchanger pipes and then connect it to the top of the bottle again and make it work..

Not really following you here.  I'm guessing you make a liquid nitrogen dewar and recirculate the liquid nitrogen through the copper coil in a closed loop.  And the pressure will keep it liquid, no matter how much heat it absorbs?  Urm ... that doesn't work.

i did more research about it and i ask at the local chemistry and they told me that it is possible but the liquid nitrogen will stuck in the cooper tubes and its not going to work and if it works it will not cool the pipes..

Yes.

and i come here to find out any way that i can keep very cold the water or some other liquid instead of change it every few hours or add ice on it or use it with a chiller..

You want to pump ice cooled water through copper coils as a coolant, to use the copper coils to cool air?  Yes, that will work.

thank you i hope i explain it simple for you to understand because i dont know anything about chemisrty and this forum looks very helpful

any help will be accepted

good day..

[CO2]

i dont know how to do all this quote thing to make my self more easy for you to understand i will try it this way..

the reason i explain above that i have no knowledge about chemistry is not because i am afraid of people here point me with their finger, it is because there is a chance of people find out my question weird like you did at your 3rd quote..
  Nevermind as you can see here i am trying to achieve my plant (not this one with the liquid nitrogen) anything that can makes the water verry cold in a tank so i can pump it in the tubes and do "my job"
  the main question was not IF i can make this work by using liquid chemical materials
  the main question is how can i make this work with liquid chemical materials (or not liquid)and what materials should i need..

Arkcon do you know some chemical materials that can make the water very cold and work for my plan? if yes can you tell them to me, and how i use them?

kind regards CO2 

[Borek]

Anything that is colder than 0°C will immediately block water flow. That puts a limit on the temperature of the cooling system, doesn't it?

[CO2]

Anything that is colder than 0°C will immediately block water flow. That puts a limit on the temperature of the cooling system, doesn't it?

Yes if you say so.. i didnt know that

so what can i use to keep the water around 0°C

[Borek]

Anything that is colder than 0°C will immediately block water flow. That puts a limit on the temperature of the cooling system, doesn't it?

Yes if you say so.. i didnt know that

You didn't know water freezes?

so what can i use to keep the water around 0°C

Ice comes to mind.

[CO2]

Anything that is colder than 0°C will immediately block water flow. That puts a limit on the temperature of the cooling system, doesn't it?

Yes if you say so.. i didnt know that

You didn't know water freezes?

so what can i use to keep the water around 0°C

Ice comes to mind.

Dude if you read above i dont want to use ice because i have to chance it every 2 hours..

[MOTOBALL]

You sound like you want to cool your PC motherboard for intensive high-speed graphics applications---correct ??

It sounds familiar because my son was into that also, and we had a discussion similar to your proposition above.  I did not want possible water leaks from his upstairs bedroom using a home-made water-cooled system.  I'm pretty sure that he bought a system on-line.

FORGET LIQ. NITROGEN !!!!! (from a retired career chemist, who has used it extensively).

[CO2]

no i dont want to cool my pc the heat exchanger will be 300mm x 300mm with big pipes not for a pc computer the cost of liq nitrogen bottles and everything is more expensive than a pc heat exchanger i want to cool the greenhouse

[CO2]

summer sun heat is not good for ice in a greenhouse

[Borek]

summer sun heat is not good for ice in a greenhouse

It won't be good for the liquid nitrogen either.

No matter what the cooling agent is, it won't work forever - you need something that is cheap, easy to replace and has a huge heat capacity, preferably using latent heat (helps keep the temperature constant). I can't think of anything better than ice that fits.

Problem with things like liquid nitrogen or solid CO₂, or various ice/salt mixtures (all of which get to low temperatures) is they will all freeze the water inside of the tubing, and whole system will stop to work. Using just ice makes this a rather unlikely scenario (although not impossible).

[CO2]

how about glucose in the water?

[Borek]

how about glucose in the water?

No idea what you refer to. Freezing point depression? That will help if you were using just the ice, not in other cases. I wouldn't use glucose though, as you will soon end with some bacterial growth, any inorganic salt should be better (although it will speed up possible corrosion).

[CO2]

how about glucose in the water?

No idea what you refer to. Freezing point depression? That will help if you were using just the ice, not in other cases. I wouldn't use glucose though, as you will soon end with some bacterial growth, any inorganic salt should be better (although it will speed up possible corrosion).

hmm i understand..if i use glucose and change the water once a week it will be beter instead of using ice?

[Borek]

hmm i understand..if i use glucose and change the water once a week it will be beter instead of using ice?

No idea what you mean by that, and I am afraid you misunderstood what I wrote.

Glucose is not a cooling agent. All it can do is to lower the freezing point of water, so that it won't freeze in the heat exchanger blocking it (assuming heat exchanger is filled with a water/ice mixture, which won't be ever colder than 0°C).

Sorry to say that, but I feel like you are trying to run without knowing how to walk.

Do you understand how the cooling systems work? They either transfer heat from one place to another (that's how the refrigerator works, it is warm on the back because that's the heat that was removed from the inside), or they consume the heat (that's how ice packs work in the unplugged touristic fridges). In the first case system stops to work once it gets unplugged, in the second case system stops to work once the reaction consuming heat stops (for example ice in the ice pack melts). Liquid nitrogen system would fit the second type - and it will work till the nitrogen boils out (which won't take long, liquid nitrogen has a low temperature, but it doesn't have a large heat capacity). Both systems can (and have to be) described by the heat balance equations, telling you how much heat they can absorb per time unit, how long they can work, what are their limitations. Doesn't look to me like you took any of these into consideration.

You plan to use some cooling system to not let your greenhouse overheat in the Sun, yes? Have you tried to estimate what amount of heat you need to remove from the greenhouse per time unit? Will the 300 mm × 300 mm heat exchanger be large enough?