Cooling by Solar heating air?

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  • #76
OmCheeto
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everything came out wrong. From the data, my house should have cooled down by a degree, but the temperature rose by 3.5°F.
...

I was sitting on my front porch thinking about this, decided that the air in the crawl space was probably stratified, and probably contributed little to the whole house heat equation. So I removed the 22,000 BTU it would have absorbed. The net BTU gain turned out to be 14,000 BTU, which, at 5000 BTU/°F, yields 2.8°F, which is very close to the 3.5°F temperature gain.

The only other significant heat source in the house was the refrigerator.
 
  • #77
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I'm kind of exhausted from this thread already. Trying to understand and find meaning to so many posts and experiments made me loose interest on this. I’m out until it gets interesting again.
 
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First let me say, thank you to everyone who has contributed here, this has been a GREAT thread!
I think I was a bit misleading in my OP, allow me to clarify: I’m still living in an RV, and am in the process of designing the house (and pond). I’m going to implement “green” building techniques, and be using highly insulating materials. My solar power system, and water-well are already in place.
Based on everyone’s input, the swamp cooler AND “solar tower” ideas will both be used as follows:
An AIR intake will be located on the north side of the house, near the ground. A duct will lead from there into the basement. This duct will have an evaporation material/screen inside it, kept wet by a pump. (Need to determine how to trigger/throttle the pump)
The air will be forced through the duct as follows: The south side of the house will have many windows with curtains, to let in a certain amount of sunlight. Vents in the floors on this side of the house will allow the sun-heated-air to rise to the roof, where a close-able (for winter) vent at the top allows the hot air to continue up and out (sucking fresh air into the house behind it).
It appears this type of solar generated air flow is common practice in green building, I’m just adding the evaporator in the intake duct.

While I certainly love DIY stuff, once things get beyond a certain complexity, my DIY skills are insufficient. This is why I think modifying a commercial propane/natural gas fridge, would be the way to go, at least for me. It’s got those special refrigerant chemicals for better heat transfer, and most importantly: SEALS those chemicals in, better than I could.

Electric powered compressor based AC unit: Sophie you made an excellent point about only needing the cooling when the sun is up, eliminating the need for batteries. Unfortunately the commercial DC powered air-conditioners I have found all require a battery bank and charge controller, in addition to the solar panels. This makes sense, designing a motor of any-kind, to work properly on a VARIABLE DC voltage (a solar panel’s direct output), is very tough/impossible. Still , if I spend money to increase the capacity of the existing solar power system, I should also factor in the additional flexibility more electric power will provide.

>>Going over the basics of a refrigeration cycle, it appears you know more than I do.
I just know the ideal gas law: PV=nRT : Pressure x Volume = number of Moles * ConstantR * Temperature
I DON’T know how various refrigerant types behave differently from this IDEAL gas law. But note that this law is only for an “ideal” gas and so does not take phase changes into account.

>> I determined that 10 cc's of water starting @ 60°F could be turned into steam in about 7 seconds with a 2 meter parabolic reflector.
Good gosh! This raises a whole new set of possibilities! It could pass through a turbine (to provide rotational power to a compressor/pump, generator, WHATEVER!) It could be used to distill my well water (water treatment plans will be my next post). It could keep help keep my house warm in the winter. It could pre-heat the hot water. I really like the idea of having steam as a power source, even if only during the day. Thinking about it now, I have indeed seen this technology in use- they use long tubes and curved reflectors. I’m going to research some of those systems now.
 

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