This will not be quick and theprojected market is toward the larger installations. However, this is the one sector were majorenergy savings can be effected on our installed plant. Perhaps, we will make it all compact enoughto use in ordinary housing.
It uses heat to drive the processand likely concentrated heat, which makes implementation a real challenge. Yet once the option is available, theincentive will exist to engineer cute solutions that lower the energy profileof dwellings.
It may be time to rethink therole of building codes and push for energy standards, as well as strengthstandards.
I know how to manufacture housingat today’s cost profile that is at least an order of magnitude stronger andprovides R-30 insulation. It would takelittle to adapt additional engineering solutions into that protocol to minimizeall energy consumption.
It has not happened simplybecause the mandate is not there that is able to induce a switch and theconsumer is still fussy on all that.
Using Heat to Cool Buildings
Novel materials could make practical air conditioners and refrigeratorsthat use little or no electricity.
WEDNESDAY, MARCH 30, 2011
BY KEVIN BULLIS
It could soon be more practical to cool buildings using solar waterheaters and waste heat from generators. That's because of new porous materialsdeveloped by researchers from the Pacific Northwest National Laboratory. These materials can improve a process called adsorptionchilling, which can be used for refrigeration and air conditioning.
Adsorption chillers aretoo big and expensive for many applications, such as use in homes. Peter McGrail, who heads the research effort, predicts thatthe materials could allow adsorption chillers to be 75 percent smaller and halfas expensive. This would make them competitive with conventional,compressor-driven chillers.
All refrigerators and air conditioners cool by evaporating arefrigerant, a process that absorbs heat. They differ in how that refrigerantis condensed so that it can be reused for cooling. Unlike the technology insidemost air conditioners, which employs electrically driven compressors tomechanically compress the vaporized refrigerant, adsorption chillers useheat to condense the refrigerant. Adsorption chillers are typically far lessefficient than chillers that use electrical compressors, and are bulky andexpensive. But they have the advantage of being cheap to operate, sincethey require very little electricity. "If you have waste heat, you can runit for free," McGrail says.
So far these chillers have been limited to applications where thereis a lot of wasteheat—such as industrial facilities and power plants—or where electricityisn't always available.
Cutting their size and cost could make them attractive in moreapplications, including in homes, where they could be run using hot water from solarheaters, McGrail says.
The key is improving the solid adsorbent material. In an adsorptionchiller, evaporated refrigerant is adsorbed—it adheres to a surface of a solid,such as silica gel. The silica gel can hold a large amount of water in a smallspace—it essentially acts as a sponge for the water vapor. When the gel itheated, it releases the water molecules into a chamber. As the concentration ofwater vapor in the chamber increases, the pressure rises until the watercondenses.
McGrail is replacing silica gel with an engineered material made bycreating nanoscopic structures that self-assemble into complexthree-dimensional shapes. The material is more porous than silica gel, givingit a larger surface area for water molecules to cling to. As a result, it cantrap three to four times more water, by weight, than silica gel, which helpsreduce the size of the chiller.
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