A promising future for electric field refrigeration

A team of researchers from Pennsylvania State University, supported by the US Department of Energy and led by Qiming Zhang are investigating electrically induced heat effects of some ferroelectric polymers which could allow for compressor-free refrigeration systems. The electric system is comparable to magnetic refrigeration but electricity is claimed to be more convenient. In these promising polymers, an applied voltage causes the atoms or molecules to align, thus creating greater order. The electrocaloric materials consist of long molecular chains -with a positive electric charge on one end and a negative one on the other which can move around freely and are normally disorganized and oriented randomly. But when electricity is applied, the molecules become highly ordered and the material gives off heat and becomes colder. When the field is disengaged, the chains randomize and the polymer absorbs heat. The researchers have reported a 12°C temperature change at ambient temperature as low as 55°C, which constitutes an improvement in terms of magnitude over other electrocaloric materials at that temperature range. Another interesting feature: these polymers can be used for cooling and heating and are flexible. A variety of clothing can be considered, including protective gear for fire fighters, heating garments for athletes and outdoor working gear, and coating polymers on electronic boards could form a cooling blanket. Source: Cold Chain, May-June 2010