The home air conditioner and refrigerator owe their success to vapor-compression technology. First, a compressor squeezes refrigerant vapor before it’s sent to a condenser. There the hot, pressurized gas cools and becomes a liquid. The liquid is then piped into an evaporator, where it depressurizes and sucks up the surrounding heat. As the environmental temperature decreases, the liquid gains heat and evaporates before reentering the compressor and repeating the process.
Although inexpensive, the vapor-compression refrigeration cycle is neither particularly efficient nor the most environmentally friendly process. Hydrofluorocarbons and other refrigerants inevitably leak out of the appliances and into the atmosphere, where they’re potent contributors to the greenhouse effect. Solid-state alternatives that apply a magnetic or electric field or stress to specially designed alloys have been gaining traction for decades. But the technology hasn’t quite achieved the temperature drop necessary to compete with commercially available cooling techniques (see the article by...
