New Air Conditioner Process Cuts Energy Use 50-90% 445
Posted
by
kdawson
from the tortured-backronym dept.
from the tortured-backronym dept.
necro81 writes "The US National Renewable Energy Laboratory has announced that it has developed a new method for air conditioning that reduces energy use by 50-90%. The DEVap system (Desiccant-Enhanced eVaporative air conditioner) cools air using evaporative cooling, which is not new, but combines the process with a liquid dessicant for pulling the water vapor out of the cooled air stream. The liquid dessicant, a very strong aqueous solution of lithium chloride or sodium chloride, is separated from the air stream by a permeable hydrophobic membrane. Heat is later used to evaporate water vapor back out — heat that can come from a variety of sources such as solar or natural gas. The dessicants are, compared to typical refrigerants like HCFCs, relatively benign on the environment."
Is this a closed system? (Score:5, Informative)
Re:lithium chloride or sodium chloride? (Score:1, Informative)
Your suggestion is hardly a solution for the vast majority of people who cannot renovate their home to meet standards. Apartment superintendents, landlords, and hell even members of your community can throw a wrench in your plans. Even if theres no opposition, renovation still requires licenses, permits and other red tape. $DEITY forbid you live in a "historic" area. Air conditioning is a technological advancement just as any other. Take advantage of it and move along.
Re:Is it better than this? (Score:5, Informative)
The key to TFA (Score:5, Informative)
Or, maybe,
As TFA states, desiccant cooling has been known since at least Carrier's work at the turn of the 20th Century. The trick has always been to make a practical desiccant cooling system.
Calcium chloride not sodium chloride!!!! (Score:1, Informative)
but it doesn't matter, its still years away from practical
NREL has patented the DEVap concept, and Kozubal expects that over the next couple of years he will be working on making the device smaller and simpler and perfecting the heat transfer to make DEVap more cost effective.
Re:Good for server farms? (Score:3, Informative)
Why not? In the opposite situation to AC, I know the PDC [pdc.kth.se] supercomputing center in Stockholm, Sweden feeds the surplus heat from their machines into the local district heating system.
Perhaps even more originally, those crafty Swedes have also hooked up their crematoriums [telegraph.co.uk]!
Re:The heat goes in... The heat goes in... (Score:3, Informative)
In the street, just like every other air conditioner in the world.
Adsorption coolers (Score:1, Informative)
Adsorption coolers (http://en.wikipedia.org/wiki/Absorption_refrigerator) are far better as they use water as a coolant and heat energy from solar panels. In fact, they consume only electrical energy for the controlling electronics...
Re:OK, so when can we buy one? (Score:5, Informative)
Re:Dr. John Gorrie (Score:3, Informative)
Re:lithium chloride or sodium chloride? (Score:2, Informative)
I won't be using it in my house for a simple reason: If that "membrane" gets punctured you're going to have one hell of a cleanup cost. I won't even go into the aerosolized effects. Check out any SDS.
Re:lithium chloride or sodium chloride? (Score:2, Informative)
Re:This method has been used for centiries (Score:3, Informative)
Re:Insulate even in the warm climate! (Score:3, Informative)
Americans? I would say that most Western nations like America, Canada, and Western Europe are doing pretty well when it comes to insulation compared to other countries. Hong Kong makes me cringe. Cement walls and large rows of single pane glass windows for residential and most shops have open storefronts with the air conditioning blasting. Given the high heat and humidity, air conditioning accounts for a large amount of energy expenses.
Re:OK, so when can we buy one? (Score:1, Informative)
From that statement I assume you do not have one or have ever used one for more than a recreational cooler. Electroic instruments don't like the environment they create either.
Re:Good for server farms? (Score:1, Informative)
They are about to elect a president who has stated, "Swedes are jealous of you immigrants because you have a proper culture and traditions while we just have stupid and silly stuff like Midsummer's night". Imagine Obama saying that to Mexicans. Not too long ago there was a nice program of how the state crisis shelters for women effectively taught them that all men are rapists - the question was asked, "do you think that there are some men who don't rape women?" and the response from the state-employed counselor was, after a long pause, "may, just a few".
When a journalist asked the relevant person at ministerial level about this she was told she was a traitor to the women's cause and should hope she never needed help from a shelter because she wouldn't get it.
Yes, they are socialist - yes, they are singing the International. It is no less "funny" than if they were neo-nazis.
Re:Are you planning on paying? (Score:3, Informative)
A better way is self expanding foam, it will even insulate homes that have the crappy 1st gen fiberglass batting. it just requires COMPETENT installers so they dont put in too much and burst the walls.
I did an entire 2100 sq ft home for less than $2200.00 that included adding an extra 18 inches of fiberglass batting to the attic. My heating bills dropped from $210 to $80 a month in the winter with a 25 year old 55% efficient furnace. this summer that get's replaced with a 90% efficient furnace.
Re:It's not either/or (Score:5, Informative)
no they dont. 4" exterior walls are common now. it USED to be 6" was required for exterior walls. but contractors wanted to increase profit margins clamored to make houses more "shitty".
Homes should also be sheathed with 3/4" plywood instead of the craptastic fiber board they use now. I've been doing high end installs of whole house audio in $1,000,000+ homes on the side for 5 years now. Home construction has went down hill quite a bit from the late 80's where you had to have good construction quality.
Re:Insulate even in the warm climate! (Score:3, Informative)
Even re-insulating the walls is fairly easy once you start doing the whole house, room-by-room. The first room is going to be hard, the second much less so, and the third one will be a non-thinker, almost.
I have recently faced taking off a horrible straw mat wallpaper. After spending 2 hours cleaning up one 4x7' section, it became obvious that taking down the drywall will be much easier. Especially that I had to run some new wire, and I hate unsupported wires just hanging in there; there is a point when patching up drywall takes longer than putting up new sheets.
With a tiny bit of experience (partial gut of a small half-bath), for two people working together I estimate taking down all wall drywall in a 10x20' room in one evening (6pm to 11pm) -- starting with a clean room with no furniture, and ending with a clean room with no drywall. Putting up the drywall would take say two more evenings, plus one evening for hauling the materials home from the store. Another evening for taping the joints and patching up all the screws. Then figure three partial evenings to prime and paint. You could be done in a week, and if you start on Monday, you should even have most of your Saturday and Sunday free -- painting won't take long with a sprayer.
If you have to re-run plumbing/electrical due to the age of the building, I'd figure another 2 evenings per room. So that gives you sort of a baseline to estimate how long things should take. Advance planning is key, and unless you are very close to a home improvement center, you definitely don't want to keep going to the store every day.
Depending on the home's layout, you may want to leave some walls exposed until the job is mostly done, if there are convenient places to run the wires/pipes to a central location.
All the costs you will incur, assuming your time is free, are for materials -- and drywall and insulation are not particularly expensive. Of course I assume that you have all the necessary tools, but if you're clever about it you can get everything you need for such a job, starting with no tools at all, for $1k or so.
Re:Is this a closed system? (Score:5, Informative)
Wikipedia doesn't do the principle justice. A swamp cooler is essentially a big fiber mesh (which can look and feel similar to cardboard but holds up when it gets wet). This mesh is constantly sprayed with jets of water to keep it wet -- damp isn't enough. A big fan, bigger than a typical air conditioner, forces air through this mesh and pushes it into the house. Each room that needs to be cooled needs to vent air out, typically into the attic and out into the outside. The more air you move through this mesh, the cooler the house, so it's typical that the air volume is much higher than an air conditioner.
The humid air introduced into the house is essentially at dew point (if it's lower than dew point, the mesh / jets aren't doing their job forcing the water into the air), so the house will likely be warmer than that, making a few assumptions about the conditions outside. Now, if you had this pre-drier in Alabama, dropping the dew point to 40 or 50, you'd be able to cool the air 20 or so degrees -- about what your air conditioner does.
By the way, I grew up in Phoenix. Instead of the $400/month power bills from running the air conditioners, my parents opted to run swamp coolers. The water bill regularly got above $100/month, but the electric bill didn't. Financially, it was a good trade-off. I'm told there are health benefits from breathing more humid air instead of dry desert air, and the air was constantly being refreshed from the outside, so there certainly weren't any toxic house concerns that people in some areas of the country have. On the flip side, there's the monsoon season, which is typically the whole month of August; the dew point rises to the point where swamp coolers just don't cool much. Several of my Magic: The Gathering cards (mostly Revised aka 3rd Edition) felt like they had a powdery coating on them. I assume this is mold. If it was on my cards, I'm certain it was on countless other surfaces we just never touched enough.
Re:Well... (Score:5, Informative)
The kind NREL uses are syrupy liquids — highly concentrated aqueous salt solutions of lithium chloride or calcium chloride.
Re:OK, so when can we buy one? (Score:2, Informative)
Problem is most homes are built wrong. the same damn cookie cutter McMansions that are designed by idiot architects.
Designing by your principles won't pay the bills. It's not like architects are actively trying to push the worst home on their clients. Have you even talked to an architect this century? The last thing we want to do is design an inefficient building that the owner will hate. 90% of our business is "word of mouth" or repeat customers. Every employee in my firm is required to go through a pretty rough "green" building indoctrination when hired, and we have to maintain a certain amount of continuing education. Over the past ten years, this has become the standard, not the exception, in most major firms in the US.
Now if you meant to say home builders instead of architects, I couldn't agree more, with a few rare exceptions.
And FWIW, the A/C, windows, insulation is a good start. But, you can't just throw "efficient" and "green" products at your 4,000s.f. home expecting it will give you $50 electric bills. Until people go back to thinking 1,400s.f. is an appropriate home size, the problem will always exist.
No, it's a firebreak (Score:3, Informative)
Do you perhaps mean a row of horizontal studs?
Do you perhaps mean joists [wikipedia.org]?
Neither. The horizontal pieces between the studs are called firebreaks. They are there solely to slow fire down and help prevent it from spreading between building floors vertically through the wall stud space. They don't serve much mechanical structural purpose, but they do also help prevent vertical cold air flow inside the walls which helps the insulation (fiberglass insulation doesn't stop airflow, it just filters out the dust).
The 1920s portion of my house does not have any firebreaks in two of the exterior walls, as it's built using so-called "balloon framing" which used long vertical studs that run continuously from the rim beam on top of the foundation all the way to the attic. Because of this, cold air can flow down the walls from the attic in winter. I've injected firestop foam into strategic parts of the wall to stop this, as I found some parts of the interior wall surface were below freezing last winter.
Re:Good for server farms? (Score:3, Informative)
Pedant.
this is slashdot... of course i am a pedant
:P
you must be new here
Oh come on (Score:1, Informative)
I hear you, but the thing is, you don't really want to encourage people who don't know what they're doing to be dinking with their electrical and plumbing (especially both at the same time!) Not only is there the risk of a house fire/flood their insurance won't cover, but running afoul of the building inspector (in jurisdictions where homeowners aren't supposed to touch the machanicals), or needing to call a pro to fix a botched DIY job is expensive.
Also, while any schmo can patch 2" holes with a joint knife and a bucket of compound, rehanging and taping full sheets of drywall requires a lot more competence, upper body strength, and access to a pickup truck or larger.
Based on your recommendations, I am going to abandon my precision engineered abode and live in a cave.
Be reasonable. Drywall may be messy, but it's not exactly an engineered science. Anybody who isn't an invalid can do it.
Re:Is this a closed system? (Score:3, Informative)
Why do you believe it can use salty water?
"a very strong aqueous solution of lithium chloride or sodium chloride"
That's salty water.
Re:Well... (Score:2, Informative)
It won't work where I live. Evaporative cooling only works in areas where there's little humidity; they've used "swamp coolers" as they're called in Arizona for decades, and although this method seems more efficient than the old swamp coolers, it still won't be enough. Your normal AC both cools and lowers humidity, and it won't work for the same reason sweating won't cool you off in a humid place; when the air is saturated with water, it's hard to make it evaporate. Hang laundry out here in the summer and it takes forever to dry. Same principle. Plus, the drier air feels cooler than the same temperature at high humidity.
Re:OK, so when can we buy one? (Score:3, Informative)
You should realize that heat flow is a two-way street. Using low -e glass to trap heat in the summer is a good thing, it reduces the amount of black body radiation of the hot outdoors that gets indoors.
Most of that energy comes in horizontally (if it's not moving horizontally, then any not radiated from near the house cannot make it inside) and so most of it bounces right back out again if whatever is on the wall behind it is light in color. In fact, proper overhangs all but eliminate that which comes in and does not come out again. This is actually an issue with passive solar heating; you may have to have a wall or ceiling at an angle to keep energy from the sun inside the house! Having one plane in a room at a non-right angle helps reduce echoes, though, so it's a desirable feature in any room. To minimize this effect (and provide other benefits) the property should be landscaped, possibly with hedges (especially in windy areas, again for other reasons.)
Re:Are you planning on paying? (Score:2, Informative)
I have a house with a similar system (just purchased).
My first house had an 80's correctly sized boiler with natural gas. It was a 1200 sq ft row home.
It cost me more to heat than my new home (both built 1928), with foam blown in and real attic insulation. The new home had a fifties, very oversized, oil boiler. The new home is 1400 sq ft, and both had similar windows (old windows with storm added). At the time gas vs oil was similar per/BTU.
Re:OK, so when can we buy one? (Score:3, Informative)
I don't know how your swamp cooler works, but any halfway decent one won't be pumping any extra water into your air. They use heat exchangers to get the cold into the building, and evaporate out the water to the open air to cool off the heated piping.
If yours is indoors, you're doing it wrong.
Re:Well... (Score:3, Informative)
The cooler is two stage, the air is first highly humidified (if not too humid already), lowering it's temperature, the second stage the endothermic effect cools it further. This would work in a humid environment and indeed allows control of humidity outlet.
Re:Insulate even in the warm climate! (Score:3, Informative)
Lots of higher-efficiency furnaces already have a spot to tie an intake plenum into place. My current ancient house uses black 2" ABS pipe for intake and exhaust. My previous ancient house used 2" PVC for exhaust, and had nothing for intake, like yours. It wouldn't have been obvious to me that it was designed to support a dedicated intake line if I hadn't read the book for that particular unit, but the fittings were right there if one knew to look for them. (I never did hook that up, because we were having some real flooding problems, and the bloody thing was getting replaced on average every six months, anyway. But that's a different story.)
On my current furnace, this intake plumbing goes straight to the combustion blower. There's also a valve in-line in the basement that is supposed to open up in the event that the outside intake becomes clogged with birds or snow or something. The old furnace was a lot different, in that the intake plumbing would have simply vented into the furnace's housing instead of directly to the blower, but the housing itself was pretty well gasketed and sealed up so it was essentially the same thing.
And in any case, everything should slope down toward the furnace, so any condensation or moisture that occurs in these lines will find its way out through the condensate drain on the furnace rather than sit around and be annoying.
I'd be wary about intentionally installing a leaky pipe near the furnace as an intake. It seems like a good idea, but without a system to contain the airflow, any pressure differential (from wind, say) between the rest of the house and the basement will create draft, whether the furnace is running or not. You'd go from having a predictable loss some of the time, to having an uncontrolled loss all the time.
But, meh, anyway. I'm pretty sure I'd lose a lot more heat through using the clothes drier, the bathroom exhaust fan, and the range hood, than the bit of air the furnace uses for combustion.