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The consumer-grade absorption chiller under development by UC3M uses the heat of the sun to cool water.  (Source: Universidad Carlos III of Madrid)
The sun will keep you cool in just a few seasons.

The Montreal Protocol, crafted in 1987 and signed by 191 countries as of 2007, put the hot iron to the cooling industry. It has seen several revisions since 1987 and some of its strictures affect industry as a whole while others involve mainly cooling and refrigeration.

The ultimate goal of the protocol is to reduce the amount of several ozone-depleting chemicals used by industrialized nations to zero. Most CFCs (chlorofluorocarbons) were to be phased out of use by 1996; other less dangerous CFCs and chemicals are to be phased out by 2010; HCFCs (hydrochlorofluorocarbons) are on a longer leash, and have cease and desist date of 2030, 2020 in developed nations.

Unfortunately for the air-conditioning and refrigeration industries, this means an industry-wide change in practice, as HCFCs are commonly used as refrigerants in modern cooling machines. There are several technologies that cool without the use of these refrigerants, but until recently, they have been utilized mostly only in large-scale applications. Absorption chillers are used in many industries, from commercial to machinery cooling.

Absorption chilling differs from standard mechanical air conditioning in that it doesn't use an active force, such as a compressor, to condense the coolant chemical, but rather uses heat to drive a circulatory system. Many absorption chillers are utilized in areas where ample amounts of waste heat are available (turbine power or water heating systems are common sources). This allows them to make use of waste heat for a secondary purpose, thereby making the entire system more efficient and cost-effective.

This nearly century-old technology has not been widely used in consumer arenas like home cooling as the heat needed to power the system would cost more than the typical compressor-driven air-conditioning unit and there are not usually readily available sources of waste heat powerful enough to harness. Professor Marcelo Izquierdo of the Universidad Carlos III of Madrid and his group of researchers are aiming to put this technology into homes, however, with a little help from a very large furnace – the sun.

Izquierdo's team built an absorption chiller unit that closely resembles a typical exterior air-conditioning unit, and it works by capturing solar energy and residual heat to provide the impetus for the system's circulation. The device uses a refined lithium bromide-based coolant process – most absorption chillers use either an ammonia, hydrogen and water or a lithium bromide solution and water system – and is capable of cooling water to a temperature of 7C to 18C with an ambient temperature of 33 to 43C. The machine can produce enough chilled water to cool a 120 cubic meter area via a water-to-air heat exchanger.

Neither the lithium-bromide solution nor the more common ammonia and hydrogen systems are ozone depleting. This makes them a viable alternative to the HCFC refrigerants used in modern compression systems. In the very near future, consumer-grade absorption chiller units could become common in many regions that experience high temperatures during one or many seasons. Using the Big Heater in the Sky itself to power the cooling units is an ironic twist and one definitely worthy of more research.

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By soloman02 on 7/20/2008 5:25:17 PM , Rating: 3
This is all well and good, but what if there is no sunlight? Right now it is hot (80F) and very humid but no sun. Also will this system dehumidify? My current AC unit (conventional) cools the air and dehumidifies the air. Can this new one dehumidify as well?

RE: But...
By Spyvie on 7/20/2008 5:53:16 PM , Rating: 2
It's not possible to cool air without dehumidifying it, unless the air is already dry. As air passes over the chiller coils condensation will form on the surfaces pulling moisture out of the air.

The only type of refrigeration system that minimizes moisture loss is a static coil system, like the kind used in deli cases. This is where a large evaporator coil is positioned at the top of the refrigerated space, and the heat is absorbed from the product below. (cold air just spills off of the coil. This is a fairly inefficient setup, but it keeps the ham sammiches from drying out.

RE: But...
By soloman02 on 7/20/2008 8:12:40 PM , Rating: 2
Ok, but that still doesn't answer the question of the sun. If it is humid and 80-90F out and we want cool dry air, this thing won't work. Even if the sun is out this new system won't work unless the temperature is 91F or higher. There some people on this rock who prefer cold weather and not hot weather. If I could live farther north I would, but I refuse to be taxed in Maine and refuse to live in Canada. So I like my AC unit to work when I want it to, not when the temperature outside reaches91F or higher.

RE: But...
By smitty3268 on 7/20/2008 9:26:06 PM , Rating: 2
Presumably, any commercial implementation would also plug into the wall to get extra electricity whenever the solar unit couldn't meet demand.

RE: But...
By Ringold on 7/20/08, Rating: 0
RE: But...
By ipay on 7/21/08, Rating: -1
RE: But...
By ZmaxDP on 7/21/2008 6:07:45 PM , Rating: 1
As long as there is light enough to see some solar radiation is falling on the earth. The presence of clouds does not equate to the lack of solar energy.

Since it is unclear from either article how exactly this unit uses solar energy. (The picture shows no solar collectors so it could be photovoltaics providing electric current used in a resistance heater, or it could be evacuated tubes providing a hot water source, or it could be some less sexy solar heat collecting mechanism alltogether. Heck, it could even be nothing but ambient temperature driving this thing in which case lack of direct sunlight is a complete non-issue. Even assuming it required some amount of direct sunlight...

I would counter that some people from Europe and other countries as well should realize that sometimes the usefulness of a technology (or lack thereof) is merely a limitation of physics and not some egotistical conspiracy by a bunch of self-centered Americans.

Or, equally...

Some people from Europe should realize that the US is very large place and it isn't Sunny and 90+ degrees Fahrenheit everywhere here either.

Or, more importantly...

Everywhere I've been in Spain is freakin' beautiful compared to the states, from the architecture to the climate to the landscape. So, deal with the fact that our fancy new absorption AC won't work in Spain. We're just trying to make up for the lack of history and presence that pervades most of Europe. It's all Napoleon complex (which y'all should know a little about - no pun intended), we're just trying to compensate here. Cut us a little slack... (having a little fun)

RE: But...
By ZmaxDP on 7/21/2008 6:09:15 PM , Rating: 2
Man, I hate not being able to edit. When you come back to a response after a little interruption it really kills your grammar...

RE: But...
By ZmaxDP on 7/21/2008 5:42:58 PM , Rating: 2
It got voted down because the technology (unlike the headline of the article) does not require sun, but merely a source of heat. This can be supplied by any number of "technologies" from solar collection to lumps of coal. Well, that and that it sure didn't seem like a question at first glance. Also, like most thing it doesn't simply stop working below 91 degrees but is merely less efficient translating to less capacity. Sometimes you need to read a little more into these things than what Dailytech puts into their snippet.

A far more relevant question about the actual technology is it's efficiency compared to a more traditional system, and in what regions and over what time span would this type of unit be cheaper to operate.

An even more relevant question would be about the makeup of the space they were cooling. A traditional home system relies on air loss through doors, windows and other gaps in the envelope to replace interior air with exterior air. This tends to be good for building costs since you don't need the additional ductwork and equipment (and labor to properly seal a home) but it tends to be rather expensive for operation costs since you loose the opportunity to reclaim that energy. Also, the average R values for the various envelope components have a major effect over what a unit of a given size can cool.

So, for instance, we built as a test case a 600 sq. ft. home that was properly sealed had R30 continuous insulation (no studs) for the walls, ceiling, and floors and had a separate dehumidifier and air exchanger in addition to the AC unit. We were able to use a cooling unit sized to a 400 sq ft room and we couldn't run it nearly enough to properly dehumidify the air (hence the separate dehumidifier). We did a calculation later and determined that if we'd installed a unit sized to roughly 150 sq ft instead of 400 that we wouldn't have needed the dehumidifier. So, the envelope's performance can make a HUGE difference in the size of unit you require. In short, build your house right and this very unit could cool an entire 2000 sq. ft. house. (Just be prepared to pay a bit more for construction and to recoup your costs over a period of time...)

RE: But...
By caqde on 7/21/2008 2:17:22 AM , Rating: 3
I think this was meant for people living in areas like AZ where the sun is almost always out and it is often well over 90 degrees and dry. So for me right now this thing would probably save me around $100 or more a month.

RE: But...
By wookie1 on 7/21/2008 12:14:29 PM , Rating: 2
Not so good for AZ, after the sun goes down it is still over 100 degrees for several hours.

RE: But...
By Solandri on 7/21/2008 1:04:32 AM , Rating: 3
It's not possible to cool air without dehumidifying it, unless the air is already dry. As air passes over the chiller coils condensation will form on the surfaces pulling moisture out of the air.

Actually, evaporative cooling (swamp coolers, those misters you see in some desert cities, your sweat) will cool the air and increase the humidity at the same time.

RE: But...
By TennesseeTony on 7/21/2008 5:58:03 PM , Rating: 2
An excellent point, about the evaporative cooling, the mist making machines, but clearly that is not the system we're discussing here. We're talking about moving air over a chilled water coil (radiator).

In this application, this method of cooling, it is impossible to cool the air without getting the air nearer to it's dew point or below it's dew point. If it drops below the dew point (65F almost certainly would do the trick), then yes, it will remove the humidity.

RE: But...
By JonnyDough on 7/22/2008 3:19:36 AM , Rating: 2
Are you a complete moron or just another Hollywood actress?

If there's no sun we don't really need air conditioning now do we? It might be a bit hard to imagine if you're from SoCo, but take it from someone that lives in the northern northern hemisphere - without the sun we would need heaters, not air conditioning. Just trust me when I tell you...(because I actually graduated from a high school that didn't pass me based on my wealthy father's generous aspirations for me)'s true!

RE: But...
By elgueroloco on 7/22/2008 3:37:00 PM , Rating: 2
I would ask if you are the moron. Apparently you've never been anywhere below Canada or wherever you're from up north, but in many places it stays dreadfully hot well after the sun goes down. Virginia is one example. I could hardly sleep there during the summer without air conditioning. It was around 90 degrees all night, and so humid the sheets felt sticky. All this despite it being night time (i.e. no sunlight).

I don't know if you just totally misunderstood his post, or can't imagine that places exist where it might be hot at night. Funny thing is, you criticize him for being unable to imagine any other place than SoCo (Southern Comfort? Good Drink. Southern Colorado? If you meant Southern California, as hinted by your reference to Hollywood, you should have put SoCal), then you go on to make a statement which indicates you can't imagine any place exists other than the far northern hemisphere, as if the weather conditions in other parts of the world don't actually exist because where you live it's cold at night.

I'm baffled as to how you thought the other guy was the idiot. As for the high school you graduated from, it sounds like you might want to go back. Probably to 9th grade and start all over again.

RE: But...
By JonnyDough on 7/22/2008 3:23:49 AM , Rating: 2
Dehumidifier = thanks. Obviously, as everyone else already told you.

I keep my house @ 80ish in the summer here in Michigan, and the winters get below 0. 80 is just fine as long as you're not an old person or a fatty. You can wear shorts and no top provided you're a guy, and if we weren't pushed around by a bunch of religious freaks you could go topless as a woman too. But not if you're guy. It's impossible, regardless of what a surgeon says.

Einstein refrigerator
By dnd728 on 7/20/2008 4:09:12 PM , Rating: 2

I always figured it isn't being used this way due to the toxicity of the coolant. :/

RE: Einstein refrigerator
By SiliconJon on 7/20/2008 4:34:43 PM , Rating: 2
During my previous career we had a cooling device that worked with our air-fed outfits which cooled our hood intake air using nothing more than the same compressed air tube that was feeding us the "fresh" air. I can't find what it was called or exactly how it worked, though.

RE: Einstein refrigerator
By dnd728 on 7/20/2008 4:55:00 PM , Rating: 2
Adiabatic expansion / adiabatic cooling, I guess.

RE: Einstein refrigerator
By randomly on 7/20/2008 7:04:02 PM , Rating: 2
it's a Vortex cooler. One of the most elegant and amazing devices. Put in compressed air, out one port comes hot air, out the other part comes cold air. No moving parts. lasts forever.

RE: Einstein refrigerator
By kmmatney on 7/20/2008 9:56:33 PM , Rating: 2
RE: Einstein refrigerator
By stirfry213 on 7/21/2008 11:37:28 AM , Rating: 3
Vortex tubes have lower efficiency than traditional air conditioning equipment. They are commonly used for inexpensive spot cooling, when compressed air is available. Commercial models are designed for industrial applications to produce a temperature drop of about 45 °C (80 °F).

Quoted from previously linked wikipedia article.

RE: Einstein refrigerator
By Spyvie on 7/20/2008 4:54:50 PM , Rating: 3
"This nearly century-old technology has not been widely used in consumer arenas like home cooling..."

Adsorption system have been very widely used in RV or propane/natural gas refrigerators for many many years. Typically powered by propane with the option of resistance heat when hooked up to a campsites AC outlet.

The chiller portion of these refrigerators are generally no maintenance sealed systems, just keep the gas flame burning brite and you're good to go.

RV AC units are always regular mechanical vapor phase refrigeration though, so this is truly a new use for the old tech.

RE: Einstein refrigerator
RE: Einstein refrigerator
By dnd728 on 7/20/2008 5:18:04 PM , Rating: 2
Yes, I'm aware of that. I believe it's used on boats too and in many factories, but I actually wondered in past why it isn't being used for air-conditioning by connecting it to dual purpose solar water heaters. I then figured I wouldn't want a mix of ammonia and butane hitting my bed at night. I wasn't aware I can now choose lithium bromide flavoring too...

RE: Einstein refrigerator
By Spyvie on 7/20/2008 5:30:41 PM , Rating: 2
I wasn't really replying directly to you, just avoiding a new thread while trying to ad a little blue collar knowledge to the discussion.

In my experience, these types of fridges don't really work very well, and take a long time to pull down to temp. Lets hope the solar collectors these guys are developing are really efficient or the systems are greatly overbuilt. At least the energy is free anyway, and combined with right building design this could really come in to it's own in places like the AZ. or NV. Desert.

for the metric ignorant
By fic2 on 7/20/2008 4:53:19 PM , Rating: 1
For the metric ignorant (i.e. U.S. - yes I'm one, too):
120 square meters ~= 1292 square feet.

pretty cool tech.

RE: for the metric ignorant
By masher2 on 7/20/2008 6:52:46 PM , Rating: 3
The article says 120 cubic meters...which is about the interior size of a 420 sq. ft. apartment.

What the article doesn't say, however, is to what temperature it can cool that volume.

RE: for the metric ignorant
By scareg on 7/20/2008 6:53:58 PM , Rating: 2
for the even more metric ignorant

120 (cubic meters) = 4 237.76001 cubic feet


RE: for the metric ignorant
By Screwballl on 7/20/2008 7:44:28 PM , Rating: 2
I don't know why they did not put the US equivalent in addition to the metric since this is a US based site...

and is capable of cooling water to a temperature of 7C to 18C (44 to 65F) with an ambient temperature of 33 to 43C (91 to 109F). The machine can produce enough chilled water to cool a 120 cubic meter area (4237.8 cubic feet) via a water-to-air heat exchanger.

7ºC = 44.6ºF
18ºC = 64.4ºF
33ºC = 91.4ºF
43ºC = 109.4ºF

120 cubic meters = 4237.759 cubic feet or 156.954 cubic yards
4237.759 cubic feet with 8 foot ceilings is ~530 square feet, with 10 foot ceilings is ~424 square feet.

So in order for this to be viable, they would need to double the size of the unit for a small household or scale it even higher for more square footage. For example my house is just shy of 2000 square feet... I would need one 4 times bigger or more efficient to handle the larger square footage.

RE: for the metric ignorant
By JediSmurf on 7/20/2008 9:19:08 PM , Rating: 2
Don't put it to cool your entire house then.

RE: for the metric ignorant
By Diesel Donkey on 7/20/2008 10:56:47 PM , Rating: 2
You could get 4, instead of one that is 4 times as big.

RE: for the metric ignorant
By Spuke on 7/21/2008 12:40:22 AM , Rating: 2
Is it more efficient using multiple smaller units or one big one?

By lolcopter on 7/20/2008 3:47:43 PM , Rating: 4

But can it be scaled down?
By darkpuppet on 7/21/2008 11:17:23 AM , Rating: 3
Can this technology be scaled down to be used, let's say, in cars?

Cars have heat that they're constantly trying to get rid of.. and eliminating a compressor from the accessories would improve mileage and horsepower.

Only problem would be crash safety of the chemicals, and weight of the system -- because the picture in the article doesn't suggest the system is tiny.

I assume there are other possible installations too.. like using waste heat from power stations/substations (ie, new IBM labs take their heat from Hydro's waste hot water -- they could also derive airconditioning from the same water).

There are so many sources of waste heat that this could tap off of.... I hope there's thought going into other uses than just solar..

2 Part System
By snownpaint on 7/21/2008 11:37:24 AM , Rating: 2
The concept is good, but i think the overall it has its short comings. There are too many factors to rely on sun alone.. Need to have a few systems to gather the energy from, with AC assist.. I would still like to see a heating unit and Solar on top of houses.. I would put one on my house if it was refined enough.. Heat my water on my roof(which cuts the attic fan running), Cool my house (solar) and AC to back it up, and provide the last kick to make it acceptable in function..

By Suntan on 7/21/2008 2:48:59 PM , Rating: 2
Back in college, I worked for a professor that was trying to develop something similar (a pump driven absorption air conditioner for residential use). Ultimately it could not be developed sufficiently that it would compete with current vapor compression AC (couldn’t make the absorber small enough.)

My thoughts on this are that it will only be a viability for someone that wants to eliminate power consumption more than *anything else* (which it will still use a fair deal of.) More than eliminating GHG usage as vapor compression with CO2 will most likely be much more efficient (on a cost basis) once it has been developed as the defacto replacement for todays HFCs (which is already the replacement for cfc and hcfc refrigerants and most likely what your current AC unit is running if it was purchased in the last 10 to 15 years) Further, the cost of a system like this would put it completely off the decision list for any sane person that doesn’t feel that saving the planet is their sole responsibility.

Lastly, what is not shown in the picture is the solar collector that would be required. Basically, from reading the information conveniently left out of the Anand story the solar collector needs to be able to keep the generator at close to boiling (80 to 95°C) to make the process work. I don’t know about the rest of you, but at about 7pm in the evening, my house still requires a good deal of cooling, yet I couldn’t harness enough light from the low sun to boil a cup of coffee.

Lastly, based on the internal living space it is said to condition, I would need about 5 or 6 of those to condition my house and that one generator/condenser module in the picture is already about 2 to 3 times larger than the condenser sitting outside my house.

Anyway, it is a good exercise for the university types to do. But don’t expect to see it on sale at the local Train dealer any time soon.


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