ATS Science Challange: Air Condition a House in high humidity without standard AC/Refrigeration

Originally posted by beezzer
Dessicants.

Some commonly used desiccants are: silica gel, activated charcoal, calcium sulfate, calcium chloride, montmorillonite clay, and molecular sieves.

en.wikipedia.org...

The uncomfortable feeling one gets in high temp, high humidity environments is the inability of air movement to "wick away" sweat, creating cooling.

Create a dry environment using dessicants and simple fans may help.

My two cents.

edit on 23-10-2012 by beezzer because: (no reason given)

Desiccants would never work for homes, its for small spaces, very small spaces like a box containing hygroscopic materials.

Reason being, a hygroscopic containers, lets say 500ml, would at least need 1/4 of the way filled with silica gel to be effective, and of course, the amount of time you open this would cause outside moisture to go in(so imagine a house that is constantly open and its not airtight).

How would you dry all those silica gel(1/4 of of your house volume) to return them to dehydrated state?

So in short, Desiccants won't work for big areas

reply to post by JohnPhoenix


Choosing where you live is one of the biggest energy saver decisions you can make. The North Pacific coastal area is cooler but not cold. Rarely snows. rarely gets unbearably hot. I used to live in a very rural, treed area. My house never got above 75 degrees even though 7 miles away it could be 100 degrees. Texas and the lower states have hot summers but they are dry. (That's why it's reported that people in TX have the driest skin in the nation.) Move in the northern direction to Midwest and beyond and your humidity climbs. More bodies of water combined with the summer crops and the air/moisture currents gets you high temps and extremely high humidity. I have seen reports of 87 percent humidity in my area. Let me tell you, if the temps are say 85, that in itself is tolerable. But throw in the high humidity, it SUCKS. Trees can help lower the temps but they don't lower the humidity. So if it's 100F the trees might lower the temps 10-20 degrees but the humidity combined with those temps is what kills you. When I go out to take care of my animals every morning in the summer, the grass is loaded with water as if I had been watering my lawn all night. Other than nature, none of the farms here use additional water sources for their crops. We had bumper crops this year even though the rest of the nation was suffering from drought.

So what I'm saying is, you need to get rid of the humidity in your home. Many people use a de-humidifier but these also put out heat. And they use a lot of electricity. Not as much as an AC but still. If you can direct the heat from the de-hu outside, that would help a lot. As far as cooling, many ideas I've read will not help with the humidity.

Porches help a lot with the heat - and the cold. I have one house that has a large closed in porch along the whole south side of the house. The house is kept MUCH cooler than other houses without a porch in the same location. This is a simple, economical and can be beautiful “fix” for helping keep a house cool.

reply to post by Svipdagr


Had to star you. None of what you said involves high costs or the energy grid. Back to nature with simple and clean perception added. Spend three hundred dollars and save it in three years.

There is a new unit out here in Canada that is a solar hot air heater, totally self-sufficient from the grid and what it does is (in the winter time), creates up to 5000 btu's per hour of heat. In the summer, you reverse the process and basically the unit sucks the heat out by reversing the function, ie. your intake is now sucking heat from the warmest place in your house (ceiling or attic) and your output would be outside in the coolest place that you have. The unit is 24' x 4'....it rolls up and easily shipped for cheap across Canada and don't know about the U.S. The suggested retail on this unit is $3000 Canadian. The unit is called 'Eco Shah' Solar Hot Air Heater.

I don't have an answer to the challenge exactly, but I think AboveTopSecret should officially take up this concept of a Science Challenge. Maybe even throw in some kind of a reward, website points, commendations, etc. Anyone else think so?

Op the best I was able to come up with was to use existing air currents/drafts to pull air into the home or business. As the air is coming in the hvac unit that is placed within the ground the cooled hvac allows for cooler ground temps to cool the unit carrying the air which cools the air. Then as the air reaches its point of use its directed around the house/business in more hvac circulating the home/building seen in cyan color around structure in image, that can allow the air through ports connected from hvac to house which then will flow continuous unless shut off. Basically I am presenting a draft type approach that just catches existing wind draft and funnels it into home ect. If you are using solar power you can also attach a fan at the outside air entrance to increase pressure flow. the entrance hvac port can be angled to face upward opening facing sky or as I show in image. The entrance port can also be elevated to increase air flow if needed. Very good question OP SnF



NAMASTE*******

reply to post by JohnPhoenix


Build most of your house below ground..8+ feet.Ambient ground temp is about 50f and should be enough to keep your 'cool' on. You can also use earth friendly roofing tecniques like bio planting or passive reflective materials to reflect the excess solar heat. Low speed/large volume fans can be used to circulate cooler air to upper portions of the house.

Good question because the heat in the south can kill you if you can't tolerate it... even if you are doing nothing at all to exert yourself.

I am still trying to learn about absorption refrigerators which are actually supposed to be extremely common in south east tropical areas for fish storage. It makes sense. I'm picturing them to be in places like the Philippines.

I'm not sure how it works... maybe some type of liquid convection but it is made from plumbing and contains something like ammonia. Supposedly it can freeze a bag of ice in a few hours. I have no idea how big they are or what they look like but it sounds very common, useful and efficient. It is actually a type of solar refrigerator because the sun is involved.

This is what I found when looking up solar refrigerators. I am looking for some instructions to build one because they are supposed to be easy to build and I can do plumbing. Plumbing is cheap and I am pretty certain i could put it together. I'm actually sitting on an extrawide folding hammock with a support stand made from pvc, rope and a couple scrap pieces of steel. It's meant to be lightweight and easy to move and able to be pulled up on one end like a lawn chair so I can lean back without laying down to watch movies.

Plumbing is so cheap, anything made out of plumbing is worth looking into for that reason alone. It's a benefit to learn how to put and what to put together=tiny bit of worthwhile knowledge cause you can do so much with it.

This probably can't be done but I was wondering if you could pull any cool air off the unit without disrupting the freezing process. That would be awesome because a lot of money is spent on this stuff.

I hope somebody reads this and posts instructions. Since I don't know how big they are.... I am interested in both large and small.

Check out Stirling engines. They can use a heat differential to produce mechanical energy or you can input mechanical energy and get a heat differential. They're used in cryonics, so you know they can get pretty cold. Also there are a lot of people making these things, so you should be able to find some entrepreneur with a drill press selling them at a reasonable price.

Use two of them. Run one with a parabolic reflector as a heat source. Use the kinetic energy from that one to power the second one (cooling unit). A person with HVAC experience could probably work out how to get that cool air blowing through his ductwork. If I had two cents to rub together I'd have tried this myself by now.

OP your problem is one of thermodynamics, its not that the air-conditioners are incredibly inefficient (although some are) but more that cooling and heating requires so much energy, especially for large spaces like a home. The best things I can suggest is do everything you can to take the load off the AC (some have given ideas in the thread: trees for shade, roof sprinklers, insulation etc.) - and then power that AC with alternative means.

The compressor on your AC should not be running all day, only in bursts (especially if you've already taken the economizing measures) this means your power production won't have to match the labelled energy consumption of the AC, rather you can store energy then release it in bursts when the compressor comes on. You could use all sorts of storage, like compressed air for example, you could have a very small compressor powered by the solar panel which runs all day - then when the AC compressor comes on your tank will discharge to power the compression of refrigerant. When air cylinders discharge the air is cold on expansion so you could also utilize this as well if you want, although because there's no phase change (liquid air would be very cold) it is not a lot of energy so you could just ignore this.

By doing this the power needed to run the AC will be reduced to a fraction of its labelled consumption. This fraction will be dependent on the fraction of time the compressor in the AC compressor is usually on for, minus any inefficiencies in the system. So the AC's power usage will be spread out and more easily met with solar.

If you live in a hot area where you have a good heat source( the sun) than I think a absorption type cooling system might be the answer. With waste heat you can use lithium bromide or ammonia to do the work. absorption system
The only power you may need is for the circulation pump and condenser fan.
You would need to focus the heat to boil the water from the salt solution.
absorption chiller



Most refrigeration systems or heat pumps require lots of power to run, even geothermal or thermal acoustic. With absorption systems the big thing is a good heat source. If you can harness the solar energy than you might get cheap cooling.

The pumps can be run on one motor. The heat source to make steam is the big thing.

A warm body moves towards a cold one.

Originally posted by JohnPhoenix
Modern Air Conditioners are really super efficient air dehydrators. Air conditioners do not " put cold air into a house". Like your refrigerator/ freezer, air conditioners condition the air by removing heat that is stored in water/humidity leaving you with what is left over - air that is now cool or cold. These rely on the presence of humidity inside the house which has warm air to operate.

More accuratly and specifically...

Air conditioners do not "remove heat" stored in water/humidity.

What modern sealed system air conditioners do do is condense moisture out of the living space.

Now yes, the air is circulated over the fins and coils, which are cold and may provide some cooling effect, that would not last in any large room.

Unless you look at it like this.... By removing some moisture out of the air, you end up with air with less loose particulates and molecules in it.

Bumping molecules and compounds create heat by friction. That is the heat you feel around you.

Removing moisture from the air considerably removes a large amount of molecules and compounds bumping about and causing heat. Instead you have a fresh cleaner air that simply feels cooler.


To the op,... seems like you are looking for a more natural way of attracting, accumulating, and removing amounts of the humidity, with the end resuly being a cooler less cluttered air to breath.

Sorry I have not read all the post (short on time) but the following may help you. Sorry if something similar has already been posted.

The temp. Just beneith the soil, 6 to 8 inches down, is usually around 68'f in the summer months here in the south even with 110' days.
You could possibly bury 100 to 200 foot of copper tubing (coiling it), connect it to a pump, fill it with water and connect it to a squirrel cage/coils from a split unit. You can find these with 110v motors with no problem.
The cool water cools the air passing through the coils of the split unit . As the water circulates through the underground copper tubing coils the heat is transferred from the water to the ground and the water is cooled again before coming back to your unit.
I should think you could do this for less than $1000 easily, using second hand parts.
Quad

reply to post by JohnPhoenix

Simple...buy a few Window Fitting Fans that fan air out of a home and plug in a few Dehumidifiers. The dehumidifiers will take the Water Vapor out of the Air in the Home as the Greater the Quantity of Water Vapor the greater the capacity for Heat Storage in atmosphere.

The Window Fans will do the rest as lowering the atmospheric pressure by even a small amount will drastically lower temps. Split Infinity

reply to post by smirkley


Air conditioners do remove heat. They work exactly like coolers, freezers, and soft ice cream machines.

They move the heat through the vapor compression cycle.





This cycle uses latent heat absorption by forcing a liquid to become a vapor in the evaporator(cold part) then being compressed to a hot vapor and cooled back to a liquid in the condenser. It is all dependent on the pressures of the refrigerant and boiling point.

I'm too lazy to look it up for you, but in southern ca./ az. I have heard of people using a somewhat expensive paint with little tiny balls of ceramic in it to paint their roofs with. Apparently this stuff majorly reduces the heat absorbed.sorry i don't have the name, but i'm sure you can find it if you look.hope this helps!

reply to post by d8track


I like the sound of that one. I wonder if an old satellite dish covered in mirrors or mylar would be enough to focus the suns rays and boil the water.

A bit of theory

PV=nRT is the ideal gas law from Chem 1A

P pressure x V volume = n number of particles x R constant that makes the math work x T temperature.

Since this is an equation, if one side is reduced the other side will be reduced also.

Reducing the pressure would (different equation) make the water more readily condense out of the air. Some expanding-sealed and contracting-vented ( or slowly expanding all day) chamber with a roller sponge getting squeezed and released might make a difference.

An airfoil also causes decreased air pressure, which is the basis of heavier than air flight. Air moving through a tube with an aerodynamic obstruction in it would cause lower temperatures at the surface of the obstruction and a higher condensation rate at that surface.

The airfoil works because a gas in motion exerts less pressure to the sides of its direction of motion. That is how the hot vent post works. This is called the venturi effect. Also see Bernoulli Principle.



Venturi effect

Moving air horizontally across the ceiling, assuming none of the moving air stayed in the room, would reduce the room temperature by reducing the air pressure.

Theoretically, cheap cooling would involve cheap motion, ideally by some trick of venting to use convection.

reply to post by JohnPhoenix


Geothermal and aerogel.