Английский язык: Аннотирование и реферирование текста

261 the most effective ways to cool objects." That effect is based on a phase change in which an ordered system (solid ice) transforms into a disor- dered one (liquid water). In time, the scientists identified several prom- ising polymers in which an applied voltage caused the atoms or mole- cules to align, thus creating greater order. The electrocaloric materials, Zhang reports, consist of long mo- lecular chains with a positive electric charge on one end and negative on the other. These dipolar chains, which can move around freely, are normally oriented randomly. But "when you apply an electric field, the dipoles tend to spin around until they align with the field," he says. Thermodynamically speaking, this molecular ordering lowers the sys- tem's entropy, so the system compensates by heating up as a conse- quence of energy conservation. When the field is disengaged, the chains randomize and the polymer cools off. The rigid microstructures of electrocaloric ceramics, in contrast, "can move only a little bit," Zhang notes, which accounts for their weak tem perature response. The polymers c-an also absorb seven times as much heat as the ceramics. In an ideal solid-state refrigerator, a chilling cycle starts when contact breaks between the polymer and the object that is being cooled, thermally isolating the polymer. An applied electric field causes the temperature of the polymer to rise. It is then placed into momentary thermal contact with a heat sink, which absorbs any heat and entropy that the polymer has. The polymer is next isolated from the heat sink; the electric field is then lowered, which reduces the temperature of the polymer and enables it to cool the target object once again. A workable system could in particular prove a boon for the com- puter industry. Silicon chips run hotter than is desirable for optimal per- formance, comments Benson Inkley, a senior power/thermal engineer at Intel in Hillsboro, Ore. Cooling with electrocaloric plastics offers in- triguing possibilities, Inkley states: "Imagine coating an entire circuit board with a layer of polymer, in effect, forming a cooling blanket."