Using a small river for home cooling?

[JeroenH]

A friend of mine lives next to a small river which he plans to use for the generation of some electricity. Experimental at first, but maybe something larger if it works out ok. Would it be possible to use such a river for summer cooling also? The water is quite cold, even in the summer. We have never measured the exact temperature, but I think it's about 10 degrees celcius in the summer, maybe even a bit lower.

I would say a small pump could drive a cooling liquid (water with an anti-freeze additive) through a closed loop which has a few heat-exchange coils on the bottom of the river and some kind of radiator inside the house. Or maybe an open loop which takes water directly from the river. A fan could push air through the radiator, thus cooling a room. The electrical requirements should be modest, the river is about 10 meters from his house, there's only about a 2 meter height difference and I think the pump and the fan don't use much energy.

Is this feasable? And if it works, would for instance the refrigirator benefit from a radiator near its radiator on the back?

[Ungrounded Lightning Rod]

[1.] I would say a small pump could drive a cooling liquid (water with an anti-freeze additive) through a closed loop which has a few heat-exchange coils on the bottom of the river and some kind of radiator inside the house.

[2.] Or maybe an open loop which takes water directly from the river.

I'd opt for 2 unless the area is prone to freezing - or even if it is, but only seasonally.  (You can empty out the lines before the freezin' season.)  Use a drinking-water safe plumbing.

1 Risks dumping antifreeze in the river if there's a leak - which can happen due to your underwater structure being hit by a rock or a boater or something.  So I'd only consider something like that if you're talking, say, a desert where it gets 'way hot in the day and may freeze the same night.  And then I'd still use drinking-water safe plumbing and a drinking-water-safe antifreeze (which could raise the cost significantly but would protect the river in case of leaks and thus you in case of environmentalists).

Such antifreezes don't have an anti-corrosion additive, and neither does river water.  So stick a sacrificial anode in the system (electrically connected to the copper and near it) where there must be copper, another buried next to the river and hooked to your metal if you put metal in the river, and use PVC or other plastic for getting to and from the river.  (Plastic is proably a good idea for the bulk of the runs anyhow to keep the water cool.)

A fan could push air through the radiator, thus cooling a room.

Do you have a forced-air furnace?  Put a radiator in it where you'd put the evaporator of an air-conditioner.  (You might consider using one of those for the job if your cooling load is light, or several if it's not.  They're intended for refrigerants that suck more heat so you may need more of 'em.)  Use a stock air-conditioner-controlling thermostat, but hook up your pump where the compressor relay would go.  All done.  B-)

(Don't forget to install a drip pan and drain to keep the condensation out of your furnace and off your floor - and catch any leaks in your radiator.)

[Ungrounded Lightning Rod]

Oh, yes.  Don't forget a trash filter if you use an open system, to keep from fouling your lines and pump.

[wooferhound]

If you've got flowing water you could use the flow to pump the water. 10 degrees C is 50 degrees F, might not exactly work as good as an air conditioner but it would be a nice cool breeze anyway.

[hiker]

build a water wheel and install a pump on it---plus your  homebuilt alt....

[tecker]

   A small cooling tower. Bring the river water in and have the river water spray  water over a tank with the cooling coils under water this will remove some additional heat . Overflow to a  basin that returns to the river. A couple of washing machines or dishwashers could give up thier pumps .Plan on draindown in winter. Seach for HVAC block diagram .

[JeroenH]

Good tips people!

The house has nothing installed yet in the way of cooling equipment, and only a few small gas furnaces for heat. So we would have to construct a radiator ourselves (old car radiator?).

I think we will build a test setup first with a length of buried gardenhose feeding a radiator we will get from a car junk yard. Then we'll see of some cooling power can be had from such a setup.

[tecker]

  Plan ahead the water could be used for other things also a garden. sterling cycle gen, magnetite slues etc.

[Dan M]

Here are a few numbers:

If you pump water through your radiator at 10 gpm, and the water leaving the house is 10 deg F warmer than when it entered the house, you get about 48,000 BTU/hr.

Someone please check my math!

Air conditioners rated in "BTU's" are actually BTU/hr.  So you can compare this directly to the cooling capacity of an air conditioner unit.

The numbers above are linear with respect to delta T and flow rate, so if you have a higher or lower flow rate or delta T you can adjust the 48,000 BTU/hr number accordingly.

This is based on water weighing 8 lbs per gallon which isn't exactly right but it ought to be close enough.

You need a heat exchanger for the house designed to operate at a low delta T.  These can get pretty big (several coils thick).

Here's something I've wanted to try:

Find an old central air unit (only the part that goes outside).  All you neeed are the coils and the fan.  Get one that has coils that don't leak (maybe had a bad compressor).  HAVE A PROFESSIONAL RECLAIM THE REFRIGERANT.  Refrigerant molecules are so "slippery" (don't ask, this is what a chemist told me once) that they can leak from a hermetically sealed (air tight) container.  A unit that won't hold refrigerant might still hold water.  If you place the unit somewhere in the house and pump water through the coils the fan will circulate the air over the coils.  These fans are usually 240V, but you might be able to get a different fan.  You could even get a line voltage cooling thermostat (about $30) that will turn on the fan and pump.  Depending on the humidity where you live, you may need a drip pan under the unit with a way to get rid of the condensate.

It might be worth a try.

-Dan M

[Dan M]

One other comment:

Car radiators are designed to shed a lot of BTU's per hr but they rely on a very high temperature difference.

If you find a source for cheap car radiators, get a few of them and stack them face-to-face and plumb them in series.

Blow your air through the "stack" in the opposite direction that the water is flowing.

You may still need a way to get rid of the condensate unless you live in a desert.

Good Luck,

-Dan M

[finnsawyer]

Unless the house is a mansion you probably only need about 10-15,000 btu per hour of cooling.  Heat pumps use radiators too. so you might look into using one of them or a truck radiator.  

[kirk]

If you made a wall with a watertight space for the water to flow through -- like 2 sheets of metal connected with a space so they don't bulge from the pressure-- then a fan and its energy demand is avoided. The key is large. Small heat exchangers are used in our homes and the small size is compensated for by lots of energetic movement through the heat exchanger. That of course costs money and is noisy.

[Vince]

wooferhound

10 degrees C is 50 degrees F, might not exactly work as good as an air conditioner but it would be a nice cool breeze anyway.

There's plenty of 'cold' in 50 degree water. It's the entire basis of a geothermal heat pump. Pretty efficient as well. And in this application, without the great expense of having to drill and pump from deep wells.

Just a thought.

[devoncloud]

First, your idea to run cold water through a radiator would work fine.  Every Navy ship on the ocean uses a cooling system exactly like that.  The key is to have a radiator with a good surface area with many coils and ensure that your fan can only pull air throught the coils of the radiater since (of course)your air will come from wherever offers the least amount of resistance.  The ships were always a very nice temperature except during the Gulf War.  The Gulf in that area is very shallow, so the sea temp was in the eighties somewhere while the outside temp was in the hundreds and it was miserable.  

Do not use antifreeze.  Make the system where you can easily remove it from the stream in the winter so it will not freeze.  YOu will kill all sorts of things if you have an accident and simply using the water right from the stream would work great.  Rather than recycle the water, use a radiator that has not been used with any toxic chemicals and simply pump water from the stream straight into the radiator and then back into the stream via an exit line.  As long as the equipment you are using is void of anything that will compromise the water quality by adding toxins, there is no need to use coils in the stream to cool a system.  Simply run off the stream water.  There are all sorts of pumps that would great for that kind of use for cheap.

Devon

[TrotFox]

Here at work they use 56 degree process cooling water to cool the building as well.  Should be just fine with an efficient exchanger!

If you use a car radiator make sure it's not lead-soldered like the old ones were.  Newer designs should be environmentally safe but I think you could do better with a purpose built multi-pass design in the house.  Car units aren't exactly compact.  :]

Just some thoughts...

Trot, the fox who don't know nuthin 'bout nuthin'...

[Ungrounded Lightning Rod]

The house has nothing installed yet in the way of cooling equipment, and only a few small gas furnaces for heat. So we would have to construct a radiator ourselves (old car radiator?).

I think we will build a test setup first with a length of buried gardenhose feeding a radiator we will get from a car junk yard. Then we'll see of some cooling power can be had from such a setup.

Car radiators are full of lots of toxic stuff (copper, lead, ethylene glycol, rust inhibitors).  So if you MUST experiment with one be careful where you dump the water.

[Ungrounded Lightning Rod]

Here at work they use 56 degree process cooling water to cool the building as well.  Should be just fine with an efficient exchanger!

Speaking of efficient heat exchangers:

If you do stack radiators, put them in series for water flow as well, with the water and air going through the stack in the opposite order.

This forms a "counter-current heat exchanger" and can end up with the air and water nearly swapping temperatures.  (Then you don't have to pump nearly as much water as with a single cross-current system such as a single auto radiator.)

If you design your own, build that in layers, too.

A stack of spiral coils of copper pipe ought to work well even without fins - that's what they use on the cold side of dehumidifiers.  Better yet, rotate such a stack 90 degrees and put it in a horizontal run of air duct.  It will drip at the bottom, which is convenient for collecting and discarding any condensation.

Don't heat-shock the fish when you dump the used water back into the river.  Run it into a little lagoon and let that drain into the river rather than injecting it into a fast flow.

[Ungrounded Lightning Rod]

build a water wheel and install a pump on it---plus your  homebuilt alt...

If you've got water with a significant flow and head, but the high end is below (even FAR below) your house, use a hydraulic ram.  You can build one out of a few plumbing parts, rubber from an old tractor tire or inner tube, steel strap, some nuts and bolts, and a little welding.  Essentially no maintainence and even easier and cheaper to build than a water mill or wheel.

You can share the headwater pickup/cleanup and tailwater return facility between the ram and a mill/generator, but you'll need to run a separate pipe for each ("ram pipe" for the ram, "penstock" for the mill) from the inlet to the device.  The ram wants to be low so use a wheel design that wants to be low, too, and you can put 'em in the same facility.  Of course you can dig a trench for both at one shot.  (The ram wants a long straight pipe, the mill is less picky though straight helps.)

A ram is like a transformer for water, taking in a relatively large amount of water at a low pressure and delivering a smaller amount at higher pressure, dumping the excess water at a low point.  You adjust it for the amount of water it takes in, and it self-adjusts for the pressure-flow tradeoff at the output (with some feedback into the input adjustment so that's not quite pure).  At low output flows it can generate a hysterical pressure and pump a dribble of water up a mountain.

(Actually it's an EXACT analogy of a switching power supply with a fixed on-time, configured for voltage-boost.  Inductor -> ram pipe full of water.  Capacitor ->a ir trapped in the "pressure dome" - a foot or so of pipe capped on top and a "sniffter hole" to insure it always has air.  Diode -> one-way valve.  Switching transistor & driving oscilator -> spring-loaded "clack" valve.)

I was just rereading an old home-power book from the hippie/comune/whole-earth-catalog era that has an excelent home-brewable design.  If anybody's interested I'll dig it out and post the reference, and maybe a text description of the design.

The copyright would be expired by now if it weren't for Disney's lobbiests, but thanks to them it's not.  So I can't just post it, illos and all, without getting permission.  But the design should be unemcumbered - at least for home-brewers.

If you build one, run a penstock pipe for a mill/genny at the same time and cap it.  That way if you want to put in a mill later you don't have to dig up the scenery again.

[Ungrounded Lightning Rod]

Should have done a search before posting.  Here's an online article on a similar (maybe even simpler) design.

The exit gate valve is not required but handy to keep all the water from running out if you ever need to take the ram out of service.  For that purpose a manual valve works fine and may be cheaper.

The article doesn't mention two things:

 - The ram tube (the pipe from the source to the ram), or the last part of it, should be dead straight, or as straight as possible, for best operation.

 - If paralleling two pumps for more volume or backup, each should have its own ram pipe from the source, though they can share the delivery pipe.

Here's another design.  This one uses a springless clack valve adjusted by adding or removing weights (washers).  It ought to last more than a century, with a rubber replacment every couple decades.

More articles can be found by google search on something like:  "hydraulic ram" snifter pipe valve.

[Ungrounded Lightning Rod]

"Ram Pipe" -> "Drive Pipe"

The original design was apparently a VITA project.  But there are several slightly simplified versions of it now on the web.

In the VITA version you also homebrew the check valve, similar to the clack valve but simpler, rather than buying one.  This further reduces your cost and avoids a part with limited availability.  It also uses more common plumbing fittings.

[devoncloud]

you can also use a swamp cooler.  Swam coolers are usually used in dry climates instead of refridgerated air because of the energy savings.  They work by passing water over pads of straw or other matterial.  The pads are in a box or cylindrical shape around a fan that then sucks air through the pads and then into your home.  The effect of pulling the air through the water-damped pads has a cooling effect when the water is evaporated into the air.  Why this works in dry areas is because low humidity readily accepts more humidity while high areas of humidity does not provide much cooling effect due to the air already beeing saturated.  This is when a cooler surface area of your pad is needed and why refridgerated air is needed.

By using your stream with very cool water, this would act exactly the same as a refridgerated air unit.  The temperature of the water will probably not be as cool as a refridgerated air unit, but will undoubtedly be able to cool enough to make your cabin very livable.  I suspect that you could cool your place off to be as cool as a refridgerated unit would but you may have to run the unit a bit longer is all.  

If you use a swamp cooler, one modification will need to be made.  Swamp coolers recycle the water as it runs through the pads and drips off the bottom into a reservoir.  A pump then is used to bring that water back up to be re-used through the pads.  This would not be a good thing to do in your case.  Since the water temperature is the main cause of cooling in this use, it would be better to simply exit the water that has already gone through the pads by the use of a hose and utilize this water to irrigate your garden or send it back to the stream as long as all matterials that were used are environmentally friendly.  I would think that using a swamp cooler in this way would basically be an easy way of not having to engineer much.  YOu would simply need a small pump to pump water from the stream and through your pads, and then gravity would take care of taking the water through an exit hose and back to the stream (or your garden).  

[Wolvenar]

I have a friend that does EXACTLY this , I cant get his to post anything he does hes a privacy freak  very paranoid person.. anyhow pont is I cannot stress enough the benifits of stacking the radiator or coils , We found that its much much easier and efficient, water can carry a LOT of heat , but the exchange is slow, so the more times the air passes the water the more heat it will take .

Stack the radiator so the cold water in is on the very last radiator the air touches , farthest from input, and run the water in series back through the radiators toward the radiator that the incoming air first touches, pretty self explanitory why.

 We have noticed for reasons I am completely clueless about. We did some monitoring and made a couple graphs, and the closer the air temps are to the river water temps the farther the exit water temp is from the air temps in house. so say river temp is 60 and house temp is 85 the exit water temp is 82 to 83,

 but if water is 65 the and house is 85 the exit water temp is 79 to 80,

It defies my grasp of logic ( which is known to be flawed A LOT.)

Can anyone fill me in on why ?

We have tried many ways to get the river to move the water but none have worked for us, this incline is way to much and river way to calm so we did a combo of rams, and electric pump , that way the pump doesnt need to be so large, and more efficient. Its probably worth experimenting combining ways to move the water. We gave up when it worked well but plan to keep trying someday in future

Oh yeah we used the water directly from the river , one less heat exhange and inefficiety to mess with.

Have fun keep us posted plz

Cory

[Ungrounded Lightning Rod]

We have noticed for reasons I am completely clueless about. We did some monitoring and made a couple graphs, and the closer the air temps are to the river water temps the farther the exit water temp is from the air temps in house. so say river temp is 60 and house temp is 85 the exit water temp is 82 to 83, but if water is 65 the and house is 85 the exit water temp is 79 to 80

Yes, that's odd.  I'd look at your flow to see if something is clogging up.

We have tried many ways to get the river to move the water but none have worked for us, this incline is way to much and river way to calm so we did a combo of rams, and electric pump , that way the pump doesnt need to be so large, and more efficient.

A ram should do it all by itself if you have enough water flow and head.  It will raise pressure to pretty much any level at the cost of flow.  (That's why you need a tank with an overflow - use a sealed system and you'll be running the pressure relief valve all the time or break the plumbing.)  You should only need the combo if your flow times head is so low that to get enough flow for your cooler you need to stop at a holding tank partway up the hill and go the rest of the way with a pump.

Are you over 30 feet above the outlet?  Maybe you're sucking a vacuum in your radiators.

[Wolvenar]

Oh yes the lift is well over 30 feet,, and the only real power we can gain from the river is from the current, we really only use the ram to get the electric pump primed, after that I am not sure the ram truly does any good. The ram could move the water completely through the system for a limited time after the electric pump is off, but at too slow of rate and it eventualy will stop.

There should be no clogs in it, it's just always had that weirdness with the temps, I dunno if somehow there is something that I am missing , or is that just how its supposed to happen?

One day we are going to try an old car radiator blade underwater where the stream narrows to go under a bridge, see if it can move the water up that hill.

I  have my doubts

[devoncloud]

It may just be me, but all of this radiator stuff is way too much engineering for the worst outcome... a swamp cooler would create the most heat transfer possible since the air travels directly through the cold water (in this case the actual cooling agent).  If you wish to add more surface area for the wind to travel through to gain more cooling effect, it could be done very easily by just stacking an extra pad per side on the cooler.  This is a heck of alot less expensive than throwing in more metal radiators.  You could also buy (or simply take a used one off someone's hands)a used swamp cooler for this purpose as well saving tons of money since the water resivoir is what usually goes out on swamp coolers first, and in this case, you would not be utilizing the resivoir anyway since you are going to want the water that has been used already to exit the system rather than be reused since it is a at a higher temperature.

When you can do all of this with a swamp cooler unit, save money, save time, gain efficiency, and gain a cooler home than using water inside metal radiators, then why use metal radiators?

Using them means water must first cool metal, which in turn cools air and in the meantime due to heat transfer the temperature raises again and the water must cool the metal down again.  This means the water has to work twice as hard to cool the air than if you were using a swamp cooler.  With a swamp cooler, the water only cools down the air.

Besides making the water work harder to accomplish the same task, adding radiators slows down heat transfer as well.  water (if given a good surface area) cools air more efficiently than metal does.  

Radiators is more expensive, and much more engineering since you will need to monitor your water flow to make sure that it is strong enough to keep the radiators cool enough to make a difference in the home (a task that sometimes proves easier said than done).  with a swamp cooler, all you need to do is make sure your pads are wet, your fan is pulling air through the pads, and your used water has a home to go to after it is used.  Your flow of water does not even need to be that strong.  Simple, deffinitely more effective, a fraction of the cost.

Devon

* a wise man never plays leapfrog with a Unicorn

[devoncloud]

Oh, by the way, in case you have not heard of a swamp cooler, they are used in dry areas (desert)such as Arizona, new Mexico, very west texas (El Paso).... IF you would like to go this route I could definitely get some friends to get a used one for you that would serve your purpose for nothing more than the cost to ship it and whatever the cost of the unit (if any).  The blower motors are the same as regular air conditioner motors, so if that needs to be replaced, you can do that where you are located.  Given that most in this forum like to do things cheaply, replacing the motor for a more energy efficient one is something you would probably want to look into anyway.

Devon

*  if at first you don't succeed then skydiving is not for you.

[TomW]

devon;

All your comments on a swamp cooler are true and valid. But, did you consider the fact that if you live in a humid climate they do not work very well?

In that situation the heat exchangers are the better option and will have the added benefit of removing some of the moisture from the 80%+ humidity we see here in the air.

Just a couple thoughts from here.

Cheers.

TomW

[Nando]

JeroenH:

With 10 C = 40 F you can cool the house all depends on the water volume you use and the conversion method ( Fan speed etc).

Temperature closer to each other higher the water volume that is needed.

One needs the area & volume to be cooled to determine the litre/minute or gallon/minute of water to get the thermal transfer needed.

You will need many litre/minute to accomplish that ( you need about 40,000 btu/hour) which means a good water pump and a good radiator with a good fan or blower.

It will take much of my time, right now, to calculate what you need and since you are not set for it -- then we can leave it for later.

Nando

[devoncloud]

Tom W, yes, if you were using a swamp cooler the same way you would use it in a dry climate, you would be correct.  But that is not the case here.  Since the water temperature is so cool from the stream, it would work exactly like a refridgerated unit would.  Rather than cooling the air by adding humidity, air will be cooled by passing through pads of water that is much cooler than the temperature inside the house.  It would work exactly like a radiator system minus the radiator making it much more efficient.  this is why I suggested not using the resivoir to recylce water that goes through the pad.  This water will not be as cold as water straight from the stream, so you simply exit the used water back into the stream (or into your garden).  

In other words, it is like putting ice cubes in a swamp cooler.  In a dry climate, a swamp cooler will cool well simply by evaporating water.  If you put ice in the water, it would be much more efficient.

Devon

[devoncloud]

oh, and as to removing moisture from the air, I do not think that your radiator system would make much of a difference there.  Perhaps a few percentage points, but nothing to make a temperature change, at least I would not think anyway....

If you could remove a good bit of the moisture from the air, then yes, I would agree the radiator system would work better, but it would have to be around 30 percent less humidity at least, and I do not think that would be possible.

devon

[elvin1949]

hold on

i live in louisiana humidity capital of the world

we cool greenhouse's with VERY large swamp cooler's

work's well.

i worked in a nursery [plant] for 6 yr's.

have seen 74 degrees inside when it was 100 degree's outside.

will rust your knife with it in your pocket

BUT it is cool

later elvin

[TomW]

OK OK considering plants just love humidity and people do not I still say it won't be very acceptable for home cooling in humid areas. I am certain they cool but it is more than the temperature that impacts human comfort and how much mold grows on your walls.

I just pointed this out because I hate to see folks waste time, energy and resources on unworkable ideas.

Well this will be my last post so enjoy the stupid suggestions we all know won't work.

I think I am finished trying to participate and maintain this doomed board. It was fun for awhile, however.

Have a good day.

TomW

[Gary D]

 Hi Tom W., I hope you decide to stay. Your voice of reason doesn't always fall on deff ears. Burnout on helping maintain the board aside, I'd like to hear how your tower is coming, and such. Obviously it's your decision, just telling you I would miss you. You are part of this community. Gary D.