Coolerado Coolers: Getting Close to Solar Powered Air Conditioning
by Lloyd Alter, Toronto on 06.11.07
We are intrigued by the idea of solar powered air conditioning; it is just so logical as you need it most when the sun is blazing. Right now the heavy-handed approach is to spend a lot of money on photovoltaics to run conventional units; there has to be a lower cost, more efficient way.
The approach of warm weather (and a nudge by LEED Pro) has reminded us of Coolerado Coolers, a low energy air conditioning unit that delivers up to 5 tons of cooling while drawing only 1200 watts, a power load that can easily be handled by a solar installation. It is an evaporative cooler like the desert coolers we have shown before, but unlike most desert coolers, the cool moist air is put through an air-to-air heat exchanger so that the air supplied to the space is cool and dry, which is far more effective at keeping you cool.
Unfortunately the performance of evaporative coolers drops with humidity, so they work best in arit and semi-arid parts of the country but that includes much of the southwest, where there has been so much development that depends on air conditioning.
Coolerado has built a solar powered one ton unit that draws only 36 watts for an earthquake monitoring station; they are also now selling their heat exchanger cores so that others can build their own units. The commercial solar powered air conditioner is just around the corner. ::Coolerado
Whatever happened to the solar-fired chiller/heater? Does that not work? I mean, the commercially availible equipment on the market now requires a lot of engineering of off-the-shelf componentry to produce a working system, but a cooling system that gets the bulk of its power from the sun in the form of thermal energy seems to be a much more powerful and sustainable solution that works in any climate, even the most humid ones. This just seems like a glorified swamp cooler, and the thing that makes it so effective in the desert (evaporation)also makes it a liability in the form of, one would assume, increased water useage.
Don't get me wrong. I'm not complaining. Every little bit helps. But this seems like a stopgap when much more robust solutions have been availible for some time.
Some time ago we worked on an water evaporation cooler which removed the humidity from the air using desiccants that were later dried by solar energy. In this way you can get evaporative cooling in high humidity climates. This heat exchanger would make an excellent addtion to that concept.
Has anyone ever tried making a solar-heated sterling engine to drive an air conditioner's compressor? It seems like it might work. The cool part of the sterling engine could be inside/next to the cool part of the compressor, and the warm part obviously goes outside.
Okay, if you can make a solar ac unit, couldn't you put a bunch outside to cool things down there? Taken to it's conclusion, couldn't all the deserts in the world be cooled a few degrees (at least) using these? Just build 'em and leave 'em.
Paul
see http://photo2text.com/
EVAPORATIVE COOLER. That's the problem. Note that the unit must generate cool by evaporating water into the surrounding air. This will only work if there is a ready supply of water nearby, which in arid conditions is unlikely.
Further, if the water is salty, as it probably will be to some degree as all groundwater is, the evaporation will leave salt deposits on the evaporator, probably decreasing the efficiency of the heat exchanger, but generally GUMMING UP THE WORKS with salt.
On desert islands (like Aruba, Bonaire, and Curacao in the Carribean), sea salt water would have lots more salt and lead to larger deposits. There are some freshwater lakes on Bonaire, but these are too valuable to use for evaporative air conditioning when the air temp doesn't get much above 90 anyway year round.
@Paul
No, you can't just stick an AC unit outside and expect it to cool the outdoor environment. AC Units work by displacing heat, removing from an enclosed environment and placing that heat where we don't care. Your refrigerator works in the same way. You can't leave the door open and cool the whole house because the compressor generates heat, and the coils that cool the refrigerator releases heat. This process negates whatever cooling you hoped to achieve.
Now, if you instead decided to convert that heat into electricity (I saw an article on this using sound waves), then you could get AC cooling as a byproduct of that electricity.
Just remember the law of conservation of energy.
John (June 12) stated that the salt left by evaporation would negate the benefits of an evap cooler. In the case of the Coolerado cooler, this is not the case.
The thing about the Coolerado is that it forces us to re-think all the self-evident truths. It really is a very startling and original concept, and has been endorsed by a large number of very authoritative organizations. Regarding mineral deposits: There are several patented aspects of the design that prevent mineral accumulation. The main one is simply that enough water is discharged back out to flush away the minerals. The evaporation surfaces never dry out.
How do I know? My company makes electronic controls, and I wrote the control software. I have seen this thing work and it really does work.