Small-Scale Solar Powered Air Conditioning Is Here (in Spain, Anyways)
For years we have been saying that solar powered air conditioning just makes sense- if you are boiling in Phoenix the sun is probably shining really hard. We have seen big units, evaporative units that won't work in humid climates, a few vaporware units and even home-made absorption chillers
Now it looks like a Spanish company, Rotartica, has put it all together, by combining evacuated tube thermal collectors with a water-heated absorption chiller, and sized it at 4.5Kw (1.28 tons) for residential use, all packaged in a neat little box.
From an operation point of view it is very simple: you put hot water in, you get cold water out, which you can run to a conventional fancoil. The hot water in can come from any source, but evacuated tube collectors, which used to be very expensive, are pretty affordable now. If you want to get more techie:
In an absorption chiller unit the evaporator and condenser are the same as in conventional systems but the function of the compressor is performed by a chemical absorbent (LiBr) and a
heat generator, with only a pump being required to provide the change in pressure. As there is
no compressor, electricity consumption is reduced significantly.
The diagram is a graphic representation of the Single Effect Absorption Cycle, which
functions as follows:
1. The refrigerant, together with the salt or absorbent in the Generator, evaporates due
to the heat provided by a burner or an external circuit leading to a heat exchanger.
2. The absorbent is conveyed to the Absorber as a solution with a low refrigerant content,
while the refrigerant that has evaporated in the Generator travels to the Condenser
where it is condensed and releases heat.
3. Due to the difference in pressure, the refrigerant flows to the Evaporator where, at a
low temperature and as a result of the low pressure, it evaporates and absorbs heat
from the circuit which subsequently goes on to cool the room.
4. Lastly, the evaporated refrigerant is attracted by the absorbent in the Absorber, where
the refrigerant-rich absorbent solution is created once more and is conveyed to the Generator where the whole cycle begins again.
We don't know the price, (probably expensive) but operating costs will be negligible and it runs when the sun is hottest and electricity the most in demand; once those smart meters become common this may be the only way to affordably cool on the hottest days. If you are worried about being cool at night, perhaps you can add an ice bear. ::Rotarica