ACES TRUMP IN ENERGY GAME!

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There's an old saying used to describe impractical ideas—"That heats about as well as ice in winter"—which may have just become outdated.

Outdated because a team of engineers at the Oak Ridge National Laboratory in Tennessee have designed, constructed, and are currently testing an energy system that actually does heat a house in winter by turning water into ice. Then, to add frosting to the cake, the system turns right around and uses that same ice to inexpensively air condition the building during the summer!

This seemingly magical process—which is known as the Annual Cycle Energy System (or ACES, for short)—is not based on magic at all. Rather, it is firmly founded on two very scientific speculations.

The first of these assumptions went something like this: "Although heating and cooling always go hand in hand in theory, real life systems only seem to use one of the two. Can't heating and cooling be combined into one system?"

Speculation No. 2 hinged on the fact that throughout most of the United States—from Georgia to the Northern Plains—cold and hot seasons are about equally long. "Wouldn't it be something," wondered the Oak Ridge technicians, "if we could come up with a simple way of storing 'excess' summer heat for use in the winter and 'extra' winter cold for summer cooling?"

And that's exactly what the Oak Ridge engineers did. They found a way to use the summer sun to heat a home in winter and to cool the same dwelling through a sweltering summer with winter ice. How? By figuring out a way to extract both heat and cold from a single energy system built around a big tank of water and a heat pump.

Now the heat pump is nothing new. It was first developed by Lord Kelvin back in 1851 and it's most simply described as "a refrigerator in reverse".

Heat energy, as you know, always flows from warmer areas to cooler and a refrigerator capitalizes on this fact by using a liquid (called a refrigerant) which has a "highest possible temperature" (boiling point) that is colder—at about 27° F—than the freezing point of water.

When such a liquid (usually Freon) is circulated through tubes around an insulated storage box, warmth flows from anything in the container—such as a pan of water—to the circulating fluid. The water, in short, gets colder and colder as the refrigerant accepts more and more heat . . . until, finally, the H20 freezes into ice and the Freon boils.

The refrigerant is then pumped out of the tubes in the insulated box and into a "radiator" where it's pressurized by a compressor. Under this pressure, the fluid's boiling point goes up Oust as water boils at a higher temperature at sea level than it does on a mountaintop) and the refrigerant gets hot . . . hotter, in fact, than the air which surrounds the radiator.

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