With New Materials, Air Conditioners Can Be Powered By Waste Heat

By Rebecca Boyle Posted 03.31.2011 at 10:59 am 6 Comments

Air Conditioners Wikimedia Commons

Future buildings may use heat to cool off more efficiently, using new materials developed at Pacific Northwest National Laboratory. The materials could enable compact adsorption chillers inside homes and office buildings.

Adsorption chillers are a type of air conditioner that runs on waste heat, requiring very little electricity. But they’re big and expensive, which has limited their use to large, hot places like power plants or industrial spaces, as Technology Review explains.

PNNL received a $2.54 million grant last summer from the DOE’s Advanced Research Projects Agency, ARPA-E, to build smaller adsorption chillers based on PNNL-developed nanostructured metal-organic heat carriers, or MOHCs. The material is more porous than existing adsorption materials, which makes them more efficient. PNNL researchers displayed the new material at a recent conference.

Adsorption is the binding of molecules or particles to a surface. In an adsorption chiller, hot water drives the cooling process instead of electricity. An evaporated refrigerant (in this case, water) binds to the surface of silica gel. The gel acts as a sponge for water vapor, and when the gel is heated, the water molecules are released, condensing into water droplets when the pressure rises.

The nanostructured MOHCs are even better sponges, trapping three or four times more water by weight, which can reduce the size of the system. They are also more efficient at releasing the water molecules, further reducing the chiller’s size; Tech Review gives the full breakdown here.

5kW Adsorption Chiller: Pacific Northwest National Laboratory

PNNL says a variety of heat sources can be used to warm up the MOHCs and free the water vapor, such as burning natural gas or other fuels, heating with solar thermal, or capturing engine or fuel cell system waste heat.

The research is funded by ARPA-E’s Building Energy Efficiency Through Innovative Thermodevices (BEETIT) project.

[Technology Review]

Previous Article: Gallery: Messenger Sends Back First-Ever Pictures From Orbit Around Mercury [Updated]

Next Article: Classic How It Works Video: A Differential Gear

6 Comments

Link to this comment

thor0997

03/31/11 at 11:28 am

Yea. But with the new stronger materials, and better efficiency we still lose.

If you make a material that makes a house 3x stronger people build them 3x bigger. Or if you have a AC that is 4x more efficient people have a tendency to run it longer.

Link to this comment

SLNuke87

03/31/11 at 11:55 am

so??

Link to this comment

gartox1

03/31/11 at 12:29 pm

No one is talking about the increased maintenance responsibility and typical shorter working life for these types of chillers (10 yrs as opposed to 15-20yrs for normal AC systems). The solution used for the cooling process is also highly corrosive and could be hazardous in residential applications

Link to this comment

B.V.

04/01/11 at 1:38 pm

"the solution used for the cooling process"...

Water?

Link to this comment

unitedelectric

04/01/11 at 1:38 pm

gartox1: You are thinking of aBsorption cooling, which uses lithium bromide or ammonia. This process is called aDsorption, where water is used. Adsorption means that the molecules adhere to the walls of a crystalline structure, meaning the material doesn't absorb the molecule. Big difference.

Link to this comment

Oakspar77777

04/01/11 at 3:22 pm

This would be something that actually makes solar energy interesting. Much like a solar water heater, this uses the sun's energy directly without the need for a catalyst. The difference being, were a solar hot water heaters works the worst when you want hot water the most (winter), this system would work the most when you want air-conditioning (sunny summer days).

A nice green step for those who cannot afford the superior geo-thermal systems.

Popular Tags

Technology

All Tags All Photos All Videos

Technology

+ More Photo Galleries

June 2013: American Energy Independence

Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.