Cooling with 55 degree water?

[BioHazard]

I'm trying to quickly put together a A/C system for my shop using the creek out back as my main source of cooling. The creek is currently running at about 55 degrees F, it should stay close to that throughout the summer.

My first thought was to modify a regular window type air conditioner so that the condensor coil is cooled by cold water instead of hot air. I've started to wonder though....might it be possible to cool directly with my 55 degree water? That's about the temp of an A/C evaporator.

If I pump the cold water through a radiator in the shop, will very much cold air come out? I've also thought about making some sort of swamp cooler with this water, but I don't want the extra humidity...

Additionally I plan on using the water to sprinkle the roof and concrete walls during the hottest parts of the day. (not unusual for all my huge thermal mass of concrete to hit 85 degrees)

Another problem I have is that the creek is about 50 feet below the shop, so I have a lot of pumping to do, and I want to do that as efficiently as possible. Is it more efficient to pump water in a closed loop from the creek, up the hill, and then back down into the creek? Does the water flowing back down cancel out the head pressure? I would rather use an 'open' system and use the excess water for irrigation but it takes a lot of juice to pump all that water up hill.

[mike90045]

if you pump from one level, and have the return to the same level, (closed loop, like a siphon) you will only have the initial filling of the pipe, and from then it's just friction loss.

My friends back east, had a house cooler, run from spring water, that worked as you describe. You will have to craft a "drip tray" to carry the condensate away.

As for spray evaporative cooling, I think that minerals from the water, will get things looking really nasty in a year or 3.

[WStayton]

Hi Guys:

  Actually, the water-out cancel the the water-in only work to about 30', after that the weight of the water exceed the vapor pressure of the water and "boils" the water, hence the pump on the well with the cylinder on top (as opposed to a deep well pump with the cylinder down in the well and a rod running to it from a handle) will only pump water up from about 30" lower than the surface of the water.

  All is not lost, though - 30 feet of the 50 foot total drop/rise is essentially for free, so you will only have to pump againts something like a 20' head, instead of a 50" head.

  Also, note that the pump need to be at the source of the water, or not more than about half way up, because it is subject to the same 30' rule that the hand pump on the well is subject to.

  You will, however, have to overcome the friction in the whole 100 feet of pipe (50' up and 50' back), so a fair bit of power is still required, but you would have the same problem if you took the water out and pumped it up to only 30 feet and then back 30' because it is the differance in the altitude of the outlet and inlet that generates the "lift" for the water - so 30' up and 30' back still equals no flow!

  Hope this did not completely confuse you do to the (non) clarityof the foregoing!

Regardz,

Wayne Stayton

[Tom Reed]

Interesting thought Wayne, this boiling is ..... refrigeration! But frozen means plugged, so there is the rub. I wonder if a thermostatically controlled outlet on the water could be created to keep the water temp above say 35f.

[BioHazard]

Great information guys, as usual.   What do you think about using this as a circulator pump?
http://www.harborfreight.com/1-inch-clear-water-pump-1479.html
I plan on installing some 1" PVC from the creek to the shop. I'm also going to run a 3 phase power line down there for lights and other stuff, making my own little camp ground.

Think an old chevy truck radiator would do the trick?

[squarebob]

I have that same pump. When they say "clean water pump" they mean it. I used it on a 1000 Gal. pond to suck algae off the rocks with a "window screen" filter on the pickup at the suction end. The pump plugged up in a heartbeat. I have used it to transfer "clean water" and have had no problem. Don't know if it will have much flow at the 50' lift you are looking at.

Bob

[Tom Reed]

I had an apartment in DC with chilled water A/C. The unit ran wall to wall near the ceiling, around 12'. The coil had 1/2" copper pipe with fins about 9" square. I've been told they were from supermarket freezer cases. There was a big gutter underneath with a drain for the condensation. I'd guess it was placed near the ceiling where the hottest air was and allowed the cool air to fall into the room. It worked well except for the constant drip. 

[WStayton]

BioHazard:

  I don't think that you will be very happy with the performance of the system as you have described it.

  Let's assume you have 50 degree water going in to your radiator.  Let's further assume that you have 80 degree air blowing across your radiator.  I think that you will be hard pressed to extract more than about 20 degrees of "coolth" out of the water.

  Let's further assume that you have something like 200 gallons per minute flowing through the system.

  That means that you will have 200 gal * 8 lbs/gal * 20 degrees delta for a total of 53.3 BTU per minute net heat transfer and you'll have 70 degree air coming out of the device.

  A real air conditioner uses 35 degree evaporator coils and transfers more like 10,000 BTU / minute with 50 dgree air, max, coming out of the machine.

  You'll wind up with a system that just vaguley makes you feel slightly cool IF you stand right in front of it - ten feet away, you won't even know that it is there, except for the noise of the fan running! <grin>  Sort of the "peeing-on-a-forest-fire" concept!

  YMMV, but I don't really think that you will get much bang for your buck with this set up, sorry!

Regardz,

Wayne Stayton

[BioHazard]

Hmmm....I hate it when math gets in the way.  I have read a bit about cold water hydronic cooling systems, but they normally use water colder than 55F. I think I might be better off going with the water cooled air conditioner, certainly 55 degree water will work a lot better on the condenser than 80-90 degree air!

[LowGear]

I'm pretty sold on the slow speed fan and a water bottle sprayer approach.  Why cool the entire room and surfaces down when we really just want to cool the body.  I wonder if you sat on a sterling engine if that could power the fan? 

How about just running the water line into the cushions of your favorite chair?

Casey

[BioHazard]

The problem is I'm always running around like a chicken with my head cut off at the shop.  I'm very intolerant to heat/humidity...anything over 65 and I start sweating like Shaq. Last year, without A/C I had to take maybe 4-5 showers during my work day.

Although that is an interesting idea....a water cooled chair. Hmmmmm..........

[WGB]

Bio all good info so far!
Your big issue is humidity, not going to remove much at 55.
If your in a arid part of the country it will do a better job.
Kind of like going in to a cool basement, feels good when you first go in, but then you feel clamy.

[BioHazard]

Ok...how about this for an example:

If I take a 5000 BTU window air conditioner that uses 500 watts while being air cooled on a hot day...

And I replace that hot air with cold water...what's going to happen exactly? Will the A/C make more than 5000 BTU? Will it use less than 500 watts?

It has to be "more efficient" but then again I can't understand how that would make it use less power?

[WStayton]

BioHazard:

   I THINK (ALWAYS dangerous!! <grin>) that a conventional airconditioner cycle the compressor on and off to maintain a certain pressure in the highpressure vapor side of the unit, which is where the condensor is.

  If you add on a water cooled condensor, you are going to lower the pressur ine the vapor side quicker than the air-cooled condensor will di it, so the compressor will come back on sooner.

  I think that the net effect will be that ou increase the capacity of the unit, without much change to the total efficiency of the unit.  So, you might have 30% more capacity with the compressor running 25% more than an air cooled unit - just number that I sort of picked out of the air, but I would THINK they would be representative of what happens - but I think that you will use more electricity with an increased output, for a net of slightly better efficiency.

  Worth exactly what you paid for it!

Regardz,

Wayne Stayton

[BioHazard]

Well, today I took apart one of my air conditioners and pulled the condenser away to put it in a bucket of water. Very happy with the results! The air coming out was colder than when it was air cooled. I was surprised how quickly the water warmed up, now I'm going to have to think of some sort of hot water pre-heater with that.  I was only using hose water, which is about 10 degrees warmer than the creek.

End result, I can remove the fan that normally cools the A/C, saving some watts, and then cool a bigger space with a smaller unit. And I won't have to cut a hole in the wall to put the air conditioner in! 

How do they actually calculate how many BTU is actually coming out of the front of an air conditioner?