Flowing Water Though Copper As a Refrigerant

The process need is unclear, and varies through the posting. Some offers:

1. Refrigeration is done every day. By passing a stream through a refrigerator, the outcoming material would achieve a temperature close to the setting of the refrigerator subject to the heat rejection capacity of that unit. The outcome is a stream of chilled water.

2. Water from a stream flowing across a radiator - why would one do this? Where is the source of coolth, or is the stream the source of coolth for the radiator circuit? If the latter, the minimum temperature of the coolant circuit would approach that of the open stream and it might be better to divert the stream through the coolant circuit insteadm, thereby saving on equipment.

3. The minimum temperature one might achieve with a evaporative cooling tower is the wet-bulb temperature of the air passing through it. Beware the operation of cooling towers, as there are risks to minimise, particularly with the baterium legionella pneumophilia, and water treatment issues with blowdown frequency, total dissolved solids concentrations and effluent handling to be managed.

Are any of those actually answers? I'm trying to achieve cooling to refrigerator-type levels by using regular stream temperature running water. Are there any possibilities anyone can think of? Short of creating electrical (hydro) energy to power a normal fridge.

I'm sure you could bring the fridge down close to the temperature of the stream water, but why?

By the time you run the piping, hook up a pump, power up the fan to circulate the air..................you could just get an efficient fridge and plug it into the wall.

There is no plug into the wall. Thats why this is under the sustainable engineering header :-) I was just exploring the possibility of having a small amount of running water, being a heatsink, or powering a small device to create real refrigeration c.4 degrees C. We'll see...

The answers in this forum are only as good as the questions. So here are some. For the intended process:

• What are the input streams, flowrates, temperatures and pressures?
• What is/are the desired output stream(s), flowrates, temperatures and pressures?
• What fluids are available?
• What power is available?

Only then can recommendations be made w.r.t. materials-of-construction, equipment sizing, etc.

Designing mechanical solutions, and then looking around for a problem that they fit, just ain't the way it's done.

• Say 1/l/second.
• Anything (refrigeration temps c. 4deg C.)
• Water
• Nothing
• Cheers!

As you describe it, you can make the inside of the box approach the stream temperature, but never reach it due to heats leaks from the air into your water pipe.

Are you in search of a free lunch?

There's always the way Dan Boone and friends did it - put the stuff in the fridge directly into the creek. Then you have a nearly unlimited heat sink. You could try it, but you may need way too many coils flowing with the chilled water to achieve what you are attempting to do. Be aware that many environmental enforcement agencies look unkindly on diverting the flow of streams. You need permits for this. People have been fined for decorative paddle wheels like mills commonly had at one time.

Or if you live where I do, you can use the back porch, from late November to late March as a freezer, or whenever you are sure the bear has gone to hibernation.

#1 shade the "box" where the water flows through

#2 support cheesecloth in a "wire" framework over and extending into the box

#3 the wick effect and evaporation will allow you to approach wet-bulb temperature only, nothing below that, as long as you provide for air flow through the cheesecloth, and at the end of the box, direct the water through the "radiator", and the air through the outside of the "radiator".

This is how my folks used to store butter and milk back in their early farming days during the Great Depression - in West Texas (hot outside temps and pretty arid conditions as to humidity on most sunny days). It did work very well. Large ranches used to store their hanging beef (for use in feeding personnel) in "cold rooms" using only a flow of well water around the edges of open half-walls, with the openings covered in cheesecloth. By the way, there were no houseflies in West Texas back in the old days of ranching's heyday. The flies came with the towns.

Leave the equipment to one side for the moment, Effendi. What are you trying to do?

I think what you're looking for is something like a 'vortex tube' cooling system, a method of separating the warm and cool molecules within a fluid, then using the cooler portion to provide a means of refrigeration. It has been done with compressed air. I haven't heard of just using cool water from a stream.

Here's the Wiki link: Vortex_tube

Yes, that's interesting too. I wonder if a version could be created for a room temperature, or slightly cool liquid? i.e. cold water out one side and warm out the other? This would be a fantastic way to create a static cooling device - with little to no moving parts. Could a reasonably high flow rate, or head, be used as the kinetic energy required?

No. Vortex tubes require a compressible fluid.

vortex tubes require a pressurised gas only, e.g. air? , according to the info available?

pressurized gas = compressible fluid

Yep! Swamp Coolers used out west in the hills. Still need water flowing from pump to unit or stream of water hight in elevation then cooler.

Is this an application for a motor-driven Stirling Engine with the engine being used as a heat pump, perhaps?

better still, but undeveloped for domestic application?? http://en.wikipedia.org/wiki/Thermoacoustic_refrigeration

The evaporative cooler adds moisture to the existing air inside the passenger compartment/cabin. The cooling you feel is partly moisture evaporating from your skin as well as the cooling effect of the air taking on the water vapor.

Using a heat exchanger will not humidify the existing air so, the only cooling effect will be the result of temperature difference between cooling water and the cabin air and the amount of heat you can remove from the cabin air using this method. So, using the maximum area available for heat exchange won't get you much in the way of cooling.
Sorry, apples and oranges don't make lemonade.

Water doesn't make for a good refrigeration fluid, as it boils at high temperatures. What one needs for refrigeration is a process fluid that boils at temperatures below the intended temperature setpoint. Ammonia, carbon dioxide, various halo-carbon molecules - the choice is pretty broad these days, even with the Montreal Protocol to consider.

The source of power is immaterial, just so long as there is some; if one wants to pump anything uphill, it will need a push.

The Eienstein refridgerator (absorption) would be a good start. No moving parts, and claims it can last for 100 years! http://en.wikipedia.org/wiki/Einstein_fridge

The key being to work out how best to provide heat to run it.... A hydro driven stirling engine driven off the flywheel to create heat (for the evaporator) and harvest the cold side of the heat exchange too? Stirling engines, of various style (alpha, beta, etc etc) can operate at over 80% efficiency, as I'm sure you're aware.

I thought those little car cooler boxes use thermoelectric cooling. The inside using the Peltier effect to transfer heat the aluminum fins. Which the fan dissipates the heat.

"My question is; could this type of thing be done"

How we get to copper pipe and a stream? If the stream is colder then 4° C then it could cool the inside to that temperature. Of course if the stream is much colder the 4° C then it isn't flowing it's frozen. And that being the case just stick the box outside.

Good point.

Should have had a cup o joe before expounding.

Stream; copper pipe.....wrong conclusion.

Sorry.

Or could use a swamp cooler...

I think the OP thinks these are new ideas under the sun!

'...Absorptive refrigeration can also be used to air-condition buildings using the waste heat from a gas turbine or water heater....'

..

Anyone who can run an absorptive refrigeration air-conditioning system off the waste heat from their water heater......should really consider better insulation.

Yes! helpful answer. I had found this in my travels also, the intermittant absorption system, using NH3 + H2O as a coolant in a closed loop. http://www.motherearthnews.com/do-it-yourself/alternative-refrigerator-zmaz75sozgoe.aspx

Possibly the easiest/best solution is working out a way to make c.200W from the stream and powering a convetional refridgerator. Seems like the water will have to power something, as opposed to a very basic, almost static system. Cheers.

"and would this cool the inside of the fridge noticeably?"

It might, but your practical answer is likely No.

4 C is below the year round average temperature of most groundwater sources- they would typically be more in the 10 C + range. The best you can hope for is with a counter current exchanger which still will not give you 100% efficiency, so this could possibly work with water taken from a partly frozen stream but little else. You will also have to consider scaling and bacterial fouling potential (not to mention minnows plugging ng the pump??).

So if you do build this, the transfer efficiency will depend on the size and design of your heat exchanger, the placement in the fridge and mechanism for circulating air through it, the temperature will still be at LEAST equal to the stream temperature and the performance is also likely to degrade over time. If it's for a cabin with no electricity or propane it may be better than nothing, but probably not for anything else.

So...you want to make a cooling tower out of your refrigerator...that's really easy enough...

I don't think you will get to where you want to be as far as temperature unless you have a meltwater source. That source would make it do-able...but I wouldn't keep any dairy in there!

As far as the economic aspect, pumping the water will consume energy unless you have some head to help you out with that, essentially creating a gravity fed system.

This would take a bit of doing and your cost/benefit would probably take you several years down the road before you saw any savings.

I am looking for a "swamp" solution here. The less tech the better really. Consider the potential of 100m of head on the stream, assume the stream is only 10-15 degrees C on average, and I could realistically harvest about 1 litre/second from it (it's small, but reliable). In reality, best to drive a brushless motor and create 200w or so of 12v power?

If you have 100 meters head potential, this is a mountain solution not a swamp solution!

Forgive me if this is covered by one of the named systems, above, but I think you are talking about an evaporative cooler of the type that you have the finned tubes, spray water and fan air on them, the water wetting them and the moving air forcing evaporation and cooling the tubes. You could get to a lower temperature than the incoming water if the air was dry, but not to refrigeration level. It only works when the equilibrium between the humidity of the air and temperature are in range, if the air is hot it will warm the tubes at the same time as cooling them.

I mentioned this method in a previous post somewhere, but it is applicable here also.An African gentleman has a patent on a very simple cooler.It consists of an unglazed pottery container,placed inside of another larger unglazed pottery container.

The gap in between is filled with wet sand. the sand is kept wet as necessary. Evaporation can cool the inside to 40 below ambient with sufficient air flow and low humidity.

His device could be hung from a rope, and made to swing by anyone passing by,which increased air flow.(And of course, what kid could resist giving it a push.)

To upscale this for your use, get yourself some cement tiles of suitable sizes.They can be very large,and since they are unglazed, they should say damp enough to produce the chilling effect.

Remember, however, the temperature can never get below the dew point of the atmosphere.

Not as cold as you want it, but it could extend usable life of perishable foodstuff.

This is the correct answer. See, even woody woodpecker is smarter than the person who asked this really dumb question.

Pay your electric bill!

Why is it a dumb question there, Einstein? I'm asking about cretaing refrigeration from natural/sustainable/low energy systems. It IS possible and there have been some great and helpful responses. This is not one of them.

Part of the reason is that an earlier posting has declared that there is no power available.

So one is looking for something that will evaporate below 4degC.

it does simplify the engineering. I like the solar cooker/ space radiator idea : heat from the cooker during the day would be more than adequate to drive the absorption cooling of the Einstein-Svilard unit (butane - water - ammonia)where butane is the refrigerant, water the absorber, and ammonia is the pressure equalizer in the device. Since the unit is completely sealed, with the "right" materials there is little to no chance the thing would ever fail and leak fumes. The coefficient of performance (COP) is not bad on these, a little better than simple ammonia-water systems I do believe.

What about those little RV Propane refrigerators? Why no just go that route?

because it's unsustainable, long term.

The universe is unsustainable, long term; this bloke says so.

How long does the forum have to wait until there are some usable numbers on this thing, FFS?

Maybe it is just the picture.....,

but the look on that 'bloke's' face, suggests his ideas about even his current surroundings might not be that well correlated with reality....,

much less any ideas he might have about the ultimate fate of the universe....

.

.

I'll reserve judgement until I read something he has written, or listen to him speak (though to be fair I should probably avoid looking at him speak, at least at first).

but thinking again... I wonder if you could remove the propane (heating) component of a gas/propane (absorption) fridge, and add a heat source driven by a solar panel? the trouble is finding an efficient way of creating heat from solar without converting to electric. big losses.

Here is a link to some low tech, low energy refrigeration options:

http://www.provident-living-today.com/Alternative-Refrigeration.html

And here is a link to a little premade absorption refrigerator:

http://www.ohgizmo.com/2008/12/10/fridge-cools-with-fire-for-real/

I believe that the little box that keeps food cool when it is plugged in the 12 volt battery supply of an automobile operates on the Peltier effect which creates a heat flux between the junction of two different types of materials when current passes through the junction.

you're right. although compact (the desired thing for a small cooler box), they're inefficient. not a problem in a car really, as you're already being pretty darn inefficient just by being in it! it's a problem when you have to charge a battery to run one though. see the current they draw on the youtube vids of peltior fridges.

Depends on the temperature of the water. Water is NEVER as cool as it seems. What seems like 'ice cold' water to wash your hands and face in is probably 60 deg F (15 C). That is well outside of the food storage range. If you have 34 deg F (1 C) water, then yes, good for fresh food storage, not frozen products. It would take a much larger coil (Radiator) than a compression refrigeration system uses. The car cooler's use Peilter effect thermo-electric heat pumps, not just a heat exchanger. Much info on them is available. -- JHF

If you have free flowing water, (a stream) find an old Pelton wheel or make one, and you will have free power as long as the water flows.

43 posts now, and we're not very close to working up a spec for this thing, are we?

There is no truth in the rumour that this one could go on further than the notorious Bath Breaking Thread.

Why would this be something to post anonymously?

The absorption type refrigerators also contain hydrogen gas, as well as ammonia.The percentages of each gas is critical to maintain proper function, because the percentage determines the pressure of each gas and thus the boiling point.

After carefully considering the thermodynamics of domestic refrigeration I have been using the system described below for a few years now. I'm not going to say that it is cost effective but only that it is a carbon free approach, quiet, and will probably work for years to come. The design may seem a bit outrageous but give it a read.

The first step was to build a custom cooling unit comprised of a series and parallel set of Peltier modules (4 modules total). The ones I selected were about an inch and a half square and consume about 50 watts each (12VDC, Melcor brand but I think they have been bought). The heat exchange unit is liquid to liquid and was made of milled aluminum stock. A simple controller provides a 24 VDC square wave at 300 Hz when on. This is placed inside the top of an existing refrigerator. Single Peltier module designs with air/air heat exchangers require fans and are a bit lame when it comes to serious refrigeration.

There are two cooling modes dependent on the seasons. I use well water (at about 55 degrees Fahrenheit) for the off-winter months. For the winter circuit I have a 3/4 inch copper tube that has fins about 2 inches by 2 inched square. This is located in the attic and out of sight. These are normally used by sane people for hot water baseboard heating. In the winter I run a 50-50 solution of water and propylene glycol through this pipe. I use 2" PVC pipe running from the top of the exterior aluminum heat exchanger. There are two runs to make use of the thermo siphon principle. The cooler and denser water will descend from the attic and displace the warmer less dense water in the top of the heat exchanger. There is very little power consumed during the winter as the controller gates the interior heat within the refrigerator to the top of the heat exchanger. The Peltier devices aren't that efficient and most of the heat pumped to the top that rises is from this inefficiency.

During the off-winter months I just route the 55 degree water through the top of the heat exchanger unit.

The attic loop is also used during the summer months for a different purpose. First the well water goes through an air/liquid heat exchanger (with fan) that provides about a 1500 BTU equivalent freon based air conditioner. The A/C controller has a normally closed solenoid that opens until the exit temperature is equal to the A/C set point of 72 degrees. The 72 degree water then goes to the attic loop. You can get all of the hot water you need this way by sizing it according to your needs. Nice thing is there are no rooftop solar water panels.

I used MELabs PicBasic Pro to create the firmware needed for both the refrigerator and A/C controllers.

I have a 1000 watt photovoltaic system to provide the power. The battery storage system is 24VDC (4 6VDC flooded acid) which directly powers the refrigerator. A 3000 watt sine inverter also provides 120VAC. Not many watts from this system are needed for the refrigerator or A/C unit.

I was incredulous of your description at first. Especially when I read,

'...24 VDC square wave at 300 Hz...'

.

Intent on discovering corroborating evidence of intentional deception, I read the remainder very closely, looking for little errors that can sometimes be found when someone is writing of something that they have dreamed about, but not actually done.....

.

But what you wrote all looks pretty sound, and I think the comment about 300Hz square wave DC was probably just something like a typo. I found it an interesting read.

.

Having 55F well water is a huge resource for cooling. You are lucky to have it.

.

What kind of flow rates of well water do you use at maximum cooling load? What are you using to pump the well water? Is it on all the time/ intermittent/ variable? What kind of power would you estimate?

.

Also, where does the water flow to? If it goes back to the well, do you have any problem with the cooling water supply heating up in the summer?

.

Something to consider... if you are not already doing this...Solar panels often have much better output/higher efficiency at reduced temperature....since you are already using the well water for cooling, it might be worthwhile to pump cool well water over the front or through heat exchangers on the back of your solar panels during the portion of the day when they are hottest.

.

Another thing you might be interested in are heat pipes. Very high heat transfer rates are possible as well the possibility of functioning as a thermal diode in some application. If you know or are willing to learn to braze, they are pretty easy to construct. Heat pipes often have a big advantage over natural convection or thermosyphons in both heat transfer rates (for a given weight or size) as well as reliably starting with much lower delta T.

.

Thanks for sharing.

Since others opened the door to using electricity to drive the cooling, why not use cryoacoustic refrigeration? Not sure where to buy these, and so far, they are being looked at just for food storage, but these can achieve pretty low temperatures, not sure the lower limit, w/o heat load, but low.

If you are fortunate, you can figure out where to buy one, because I cannot.

Get one of these and a car alternator with a built-in voltage regulator and a 12 volt fridge out of a motor home.
Mount the alternator on top! Cut out the other side of the housing with a sawsall so the water flows through and spins the squirrel cage.
Put the air handler squirrel cage in the fastest part of the creek and anchor it down.
If the creek doesn't have a lot of flow you'll have to get a 50' roll of 1 1/2" black poly irrigation pipe and run it upstream until you get about 5 feet higher than the cage. Put a 3' sand filter on the upper end and put a 1" reducer on the bottom end to make the water shoot out faster and aim it at the fins on the squirrel cage to spin it.
Old Datsun B-210 alternators start making power at 250 rpm's.

You'll need to have the fridge as close as possible to the alternator (with the poly pipe system you can put the squirrel cage/alternator anywhere you want) or you can run the fridge off a dump truck battery (12 volt) and just charge the battery with the alternator. Fridge once cooled down should cycle off and on depending on the weather but the alternator will charge all the time and the built-in voltage regulator will take care of it. Fuse the line going to the fridge with an automotive fuse 5 amps bigger than the fridge requires to run.

If you can't find a 12 volt fridge, go to wallyworld in the auto section and buy a DC to AC converter like the boom box kids use and hook it up between the battery or alternator and the fridge and plug the fridge into it.
Or just put the beer in the creek!