Help needed: Water cooling problem

[Acme]

A chiller is designed to cool water that flows into and out of it through pipes; thus, is different from a refrigerator. swamp cooler = evaporative cooler. I mentioned both.

Well Ed, you run the pipes into the refrigerator/freezer where you make loops before running it back out.

[EdEarl]

Well Ed, you run the pipes into the refrigerator/freezer where you make loops before running it back out.

That is possible, but if I need chilled water, I will probably need more than such a refrigerator can provide. Ronald might be able to use that method; although, I suspect making high efficiency heat transfer would be difficult.

[Acme]

That is possible, but if I need chilled water, I will probably need more than such a refrigerator can provide. Ronald might be able to use that method; although, I suspect making high efficiency heat transfer would be difficult.

Well Ed, it's exactly how home refrigerators chill the water for in-door dispensing.

[michel123456]

Also, underground cooling works fine at the beginning, then slowly the earth change temperature. Unless you have a source of cold, like underground running water.

 

I was also wondering how to increase the available surface for growing the lettuces. one way is to use vertical planting as used for strawberries. The other way round is to plant underground kind of lettuces, called endives in France, chicons in Belgium, http://en.wikipedia.org/wiki/Chicory#Cultivated. Considered as gastronomic delight, and good selling price.

[Ronald Lao]

Aha! Finally understand the multiquote thingamajig!

 

 

 

I think you're missing an important issue. A peltier operated at low power won't do very much cooling. They are useful when you don't need much cooling, because they can be scaled down, while other devices can't. But even something with the capacity of a small refrigerator, a peltier is not going to be the cheapest option.

Okay Swansont, I'll shelve the Peltier option for now, since you might be right that it could be more costly startup for me due to the lossy operation.

 

These are called absorption refrigerators and they can be powered by a variety of heat sources including solar. They are common in recreational vehicles in the US and typically powered by both AC and propane gas.
Dometic is an international supplier of these refrigerators. >> Dometic

Thanks for this link acme. I'll need to check this out some more. Even a small unit costing 1,200 USD might be just a tad expensive for me to consider, but I'm not giving up hope that I might be able to rig something up myself. I'll have to rummage through the DIY world of absorption refs in the next couple of weeks though. Great input!

 

 

It seems root-chilling is quite important in the tropics for good yields and avoiding certain problems in temperate-climate plants. This article called Chilling The Root Zone by Dr Atomic Leow Chuan Tse goes into the details. He has also written a book called A Guide To Hydroponics published by Singapore Science Center that's probably worth acquiring as he will understand your needs and potential problems in your part of the world. It might be worth checking out other literature he's done as well.

Yes StringJunky, root chilling is a major concern if you want to be in commercial. I can make the difference between profit and "Let's pack it up". I read up on the link and I'll try to look for the book as well. This lead of yours is simply one of the best input I have gotten so far that is science backed. Majorify of the information I find in the internet seems to be hearsay and trends. Thanks again man!

 

I'll try to give an update as I move forward to in this project so you guys will know how things worked out.

[Acme]

...

Thanks for this link acme. I'll need to check this out some more. Even a small unit costing 1,200 USD might be just a tad expensive for me to consider, but I'm not giving up hope that I might be able to rig something up myself. I'll have to rummage through the DIY world of absorption refs in the next couple of weeks though. Great input! ...

You're welcome Ronald. Maybe you can find a used unit either working or in need of some repair for less than a new one. You can also find Dometic manuals online in PDF form with schematics and troubleshooting info.

[CasualKilla]

Hi Ronald

 

I have an idea solution that may work.

 

You can use a "radiation cooler" like the one shown below. The water radiates heat to the colder effective night-sky / space temperature. The example below will only work at night, in the day it will actually heat up the water (since it will become a solar collector), but if you use some kind of selective transmitter ( ie reflects / absorbs solar radiation, but is transparent to the lower temperature black body radiation emitted by the water pipes) you can even get cooling during daytime. You can also place the pipes inside a vacuum container to remove the convection heat transfer, and theoretically you can can get the water to freeze with a large enough cooler!!! WOW MUCH AMAZ, SUCH SCIENCE.

 

 

Sorry I don't have any calculations for you, but hopefully someone can take this idea and roll with it.

 

EDIT: Theoretically the water can even circulate by natural convection if the source of warm water is higher than the cool water outlet, but depending on the friction in the pipes, a pump may be needed.

Edited March 19, 2015 by CasualKilla

[imatfaal]

Hi Ronald

 

I have an idea solution that may work.

 

You can use a "radiation cooler" like the one shown below. The water radiates heat to the colder effective night / space temperature. The example below will only work at night, in the day it will actually heat up the water (since it will become a solar collector), but if you use some kind of selective transmitter ( ie reflects / absorbs solar radiation, but is transparent to the lower temperature black body radiation emitted by the water pipes) you can even get cooling during daytime. You can also place the pipes inside a vacuum container to remove the convection heat transfer, and theoretically you can can get the water to freeze with a large enough cooler!!! WOW MUCH AMAZ, SUCH SCIENCE.

 

Sorry I don't have any calculations for you, but hopefully someone can take this idea and roll with it.

 

EDIT: Theoretically the water can even circulate by natural convection if the source of warm water is higher than the cool water outlet, but depending on the friction in the pipes, a pump may be needed.

Even the nighttime temperature in the Phillapines rarely drops below 24 deg C. so almost 23hours a day it will be heating water above desired temperature rather than cooling.

 

Not sure a passive separation of hot and cold is gonna work like you suggest with differences in transmission is gonna work - if it does why do we all pay for refrigerators?

[EdEarl]

Even the nighttime temperature in the Phillapines rarely drops below 24 deg C. so almost 23hours a day it will be heating water above desired temperature rather than cooling.

 

Not sure a passive separation of hot and cold is gonna work like you suggest with differences in transmission is gonna work - if it does why do we all pay for refrigerators?

Radiative cooling works by radiating into the night sky from a black body, which can be glazed to protect from ambient air temps. See: http://en.wikipedia.org/wiki/Radiative_cooling.

See also: http://www.ceen.unomaha.edu/solar/documents/SOL_29.pdf

 

It would be necessary to store the "cool" for use during the day, perhaps in a large insulated water tank. Due to increasing CO2, which retains infrared radiation, radiative cooling is more limited than it was a few decades ago.

Edited March 19, 2015 by EdEarl

[imatfaal]

I had assume conduction would so overwhelm radiation that it would be a bust - but your link Ed seems to show this is not that case

[CasualKilla]

Even the nighttime temperature in the Phillapines rarely drops below 24 deg C. so almost 23hours a day it will be heating water above desired temperature rather than cooling.

 

Not sure a passive separation of hot and cold is gonna work like you suggest with differences in transmission is gonna work - if it does why do we all pay for refrigerators?

I am not sure what the effective night SKY temperature is in the Philippines, but generally it varies from -5 to 15 degrees Celsius for most places (at night). Note radiation heat transfer occurs with the effective SKY temperature, and NOT the ambient air temperature. When the temperature of the cooler drops below the ambient air, there will be convection heat transfer into the water, however the will still be radiation heat transfer out of the water and there are several ways to reduce the convection.

 

@Ronald, I suggest you read this paper by one of my lectures where he creates a model of a passive radiation cooler if you are interested in this idea.

 

http://www.erc.uct.ac.za/jesa/volume16/16-2jesa-dobson.pdf

 

The main limiting factor of these coolers is the dew point, which is normally around 10 Celsius, but depends on humidity. The temperature of the surface will not drop below the dew point temperature because of the latent heat of evaporation of the water on the surface.

 

Since you are planning to cool the water to about 24 Celsius, I don't think you will have any problems at all.

I had assume conduction would so overwhelm radiation that it would be a bust - but your link Ed seems to show this is not that case

Conduction? Do you mean convection?

Edited March 19, 2015 by CasualKilla

[EdEarl]

I am not sure what the effective night SKY temperature is in the Philippines, but generally it varies from -5 to 15 degrees Celsius for most places (at night). Note radiation heat transfer occurs with the effective SKY temperature, and NOT the ambient air temperature. When the temperature of the cooler drops below the ambient air, there will be convection heat transfer into the water, however the will still be radiation heat transfer out of the water and there are several ways to reduce the convection.

 

@Ronald, I suggest you read this paper by one of my lectures where he creates a model of a passive radiation cooler if you are interested in this idea.

 

http://www.erc.uct.ac.za/jesa/volume16/16-2jesa-dobson.pdf

 

The main limiting factor of these coolers is the dew point, which is normally around 10 Celsius, but depends on humidity. The temperature of the surface will not drop below the dew point temperature because of the latent heat of evaporation of the water on the surface.

 

Since you are planning to cool the water to about 24 Celsius, I don't think you will have any problems at all.

Conduction? Do you mean convection?

Radiative cooling depends on the night sky temperature, not the air temperature, which is about 3K. That's radiating into space, past the atmosphere.

Edited March 19, 2015 by EdEarl

[CasualKilla]

Radiative cooling depends on the night sky temperature, not the air temperature, which is about 3K. That's radiating into space, past the atmosphere.

It not not riadting with the ambiat air, correct, but the effective sky temperature is no where near 3k, if that was the case we would have the earth freezing solid at night. If you model the surface with witch the radiation occurs as a single infinite surface with an emmisivity of 1 It is more like -5 to 15 degrees C.

[EdEarl]

It not not riadting with the ambiat air, correct, but the effective sky temperature is no where near 3k, if that was the case we would have the earth freezing solid at night. If you model the surface with witch the radiation occurs as a single infinite surface with an emmisivity of 1 It is more like -5 to 15 degrees C.

From LEO the night sky is about 3K. From Earth the atmosphere, especially CO2 and methane, reduce the amount of radiation that escapes the Earth, because they partly reflect infrared back towards the Earth. IDK how to calculate the effects.

[CasualKilla]

From LEO the night sky is about 3K. From Earth the atmosphere, especially CO2 and methane, reduce the amount of radiation that escapes the Earth, because they partly reflect infrared back towards the Earth. IDK how to calculate the effects.

We don't calculate the effects, that would be a very, very difficult problem, something that probably cannot be solved without some serious computation power. But, we can use an energy balance to determine the "effective" sky temperature with which radiation occurs.

[Ronald Lao]

Radiative cooling works by radiating into the night sky from a black body, which can be glazed to protect from ambient air temps. See: http://en.wikipedia.org/wiki/Radiative_cooling.

See also: http://www.ceen.unomaha.edu/solar/documents/SOL_29.pdf

 

It would be necessary to store the "cool" for use during the day, perhaps in a large insulated water tank. Due to increasing CO2, which retains infrared radiation, radiative cooling is more limited than it was a few decades ago.

 

Wow... this is a cool info literally. It's the first time I've seen this. I do have my doubts on it's effectivity from where I live. I seldom see a clear night sky. I'll probalby see one right after a big storm but most days it's cloudy and such in the evening. But still, it was great info to know.

[EdEarl]

I just found this reference to solar cooling, which sounds very interesting.

http://www.sciencedaily.com/releases/2015/04/150402081756.htm

[Knuckleballerr]

I'm not sure of your resource or budget limitations, but I'm thinking about a closed loop system which will run to a radiator with a high rpm fan blowing on it (sort of like 1/2 of an air conditioner). If you mist water across the radiator for the fan to blow through, you might be able to drop the temps down significantly.

[THX-1138]

I have no idea if it would work, but could a separate system help drop the temperature through spray cooling?

How about using a Ranque-Hilsch vortex tube?