Question for the engineers out there.

[Philberto]

Hey everybody,

I'm just wondering if anybody knows of a potable water-safe radiator, preferably in a small size. I'm wanting to get one for a project.... I've been looking at the aluminum ones used for computer watercooling, but I'm not sure about how they are for drinking water. Thanks in advance for all the input.

[cbbryan]

Why are you trying cool down your drinking water? What exactly are you trying to do, and why wouldn't a cooler or fridge work?

[Philberto]

I'm looking for on-demand cooling, since the same water supply that would feed the drinking water also feeds misters and eventually will feed a hot-water shower. So I don't want to necessarily cool the water that I'm pumping through until after the pump. I have two ideas, one involving a small radiator inside the rear AC box, and the other involving a heat exchanger connecting to the condenser for the AC. Complicated, but I can do it for just the cost of the radiator, which isn't that much, and it'll be nice to have out in the desert.

[cbbryan]

I guess I've spent too much time in the military and boy scouts because I can do without hot shower and cold drinking water while in the field.

I am interested to see what you come up with. How much weight do you think this will add? Also how much space?

[Philberto]

Weight: 2 lbs or less for radiator, 5 lbs or less for heat exchanger, trivial amount for hoses and hose nozzle.

Space: none to minimal... I already have the water tanks and pump working... pump is under the rear seat and water tanks are in the back. Radiator will go in space already taken up by rear AC box, and heat exchanger for shower will go under hood.

I know I can do without hot and cold water, but for the sake of simplicity (and the sake of my girlfriend), I'd like to have those options

[Trail X]

Your delta T will be quite minimal by cooling off the AC unless you have a double core radiator or something...

Your issue is because the difference in temperature between your water and the A/C is minimal... maybe 30 degrees (70 deg water, 40 deg air).

Air is much less dense than water, so it holds less energy per flow. So your air flow must be much much greater than your water flow in order to cool the water enough to make this endeavor worth it.

Honestly, I don't deal with desert temps much, but I'd bet you'd have better luck adding ice to your water tanks, and trying to insulate the tanks as best as possible. That means insulation, and NO direct sunlight. I'd reccommend you even permemantly cover your rear side windows with some sort of insulator/reflector.

[Philberto]

hmmm... good point... what about adapting an evaporator to flow water instead of air? The temperature differential between the refrigerant and the water should be sufficient, no?

-edit: I just noticed according to compnine that there's actually an auxiliry evaporator for the rear AC... hmmmmm

[Philberto]

Here are the water tanks in question:

[The Roadie]

A swamp cooler for a small water jug might be a better solution, but you have to admit Tom Sheppard would mock it. He won't even do roof rack storage.

Really, just refill your personal water carry bottles from a 2-3 liter rectangular rubbermaid container you keep in the fridge.

For more reading about how the inventive folks at Burning Man deal with the issues, I found this:
http://www.appropedia.org/Burning_Man_E ... ive_Cooler

Or these products - evap car coolers:


Now THERE'S a goal we could aim for in a year or two, after I get back to work - an OffroadTB Burn Expedition!

[bgwolfpack]

Roadie, when you were a kid, didn't they have a bag that would hang out the window with water in it to keep chilled?

[Philberto]

I have the misters to keep the vehicle cool if I need to, but I see the point... Burning Man might just be something to do as an OffroadTB goal lol. Oh wait, you guys haven't seen the misters yet... I have to get a camera and take those for you sometime.

[Trail X]

hmmm... good point... what about adapting an evaporator to flow water instead of air?

The whole system would just be horribly inefficient. You're cooling fluid, to cool air, to cool water.

The best method would be to have the refrigerant directly cool the water as you were, I beleive, hinting to. You'd require a similar heat exchanger to the type that works with your coolant for heating... except, you'd need to plug into the R-134a lines somewhere after the condenser. If you delete the evaporator, you'd likely need a new expansion valve, as I beleive it's normally built into the evap.

[The Roadie]

Roadie, when you were a kid, didn't they have a bag that would hang out the window with water in it to keep chilled?

OMG, haven't thought of canvas water bags for years! Of course, we had them. Found a pic, too:

[Philberto]

hmmm... good point... what about adapting an evaporator to flow water instead of air?

The whole system would just be horribly inefficient. You're cooling fluid, to cool air, to cool water.

The best method would be to have the refrigerant directly cool the water as you were, I beleive, hinting to. You'd require a similar heat exchanger to the type that works with your coolant for heating... except, you'd need to plug into the R-134a lines somewhere after the condenser. If you delete the evaporator, you'd likely need a new expansion valve, as I beleive it's normally built into the evap.

Got it... what if I extended the refrigerant lines and just added the exchanger to the system before the evaporator? I most likely wouldn't be using the AC and cooling the water at the same time.

-edit: and would icing be something I'd have to worry about? I'm not too clear on what the refrigerant temp is after it leaves the condenser.

[bgwolfpack]

What will he come up with next?

1955_doc_a.jpg

[Philberto]

What will he come up with next?

1955_doc_a.jpg

no no no... It's more like this:

PHIL NYE THE SCIENCE GUY!

[g wallace]

You need to find somebody with a old water cooled condenser and you convert it to what you need . it a perfect heat exchanger for what you want to do . Now I'm talking refrigeration condenser. You can get them in gallon up to 3 gallons coil it has a two coils in it's 1 coil in it that you can circulate your water through and the other your refrigerator or even hot water off your engine.

[dvanbramer88]

Wow, talk about bringing back a Zombie of a thread that never went anywhere in the first place, from a member no longer active, who no longer owns a TB either. And at almost 4 years, this has to be some sort of record or something.

You need to find somebody with a old water cooled condenser and you convert it to what you need . it a perfect heat exchanger for what you want to do . Now I'm talking refrigeration condenser. You can get them in gallon up to 3 gallons coil it has a two coils in it's 1 coil in it that you can circulate your water through and the other your refrigerator or even hot water off your engine.

And more seriously, I know you are kinda new here still and just didn't know this guy is no longer with us, let alone working on this project anymore.

You're idea isn't bad. It works. The coil idea is time proven, but the problem is, the DC powered fridges aren't that great. They do a great job keeping cold things cold, but they're slow to actually cool warm things down. The water would have to spend a lot of time in the coil in the fridge for it to work. Now if you filled the coil with water today, to fill your water bottles with tomorrow, you'd have your gallon coil of cold water. But at that point, what Bill said would be far more easier and space efficient, just using plastic rectangular containers in the fridge. And that way you could cool off or partially freeze a portion of your water at home before you even leave, and the fridge will do the job it was designed to do, keep cold things things cold.

[g wallace]

I thought he was heating it up for hot water for a shower. Now as far is cooling with 12 volt if you want it to get cold fast you add more peltier devices. I am working on a ice machine that uses peltier devices.

[dvanbramer88]

I thought he was heating it up for hot water for a shower. Now as far is cooling with 12 volt if you want it to get cold fast you add more peltier devices. I am working on a ice machine that uses peltier devices.

Nah, he said he had hot water already but wanted to cool down drinking water too and run it off his single pump that he already had plumbed in.

But this ice machine will be interesting to see if it works out.