New energy-efficient method can defrost ice in seconds

A group of researchers at the University of Illinois at Urbana-Champaign and Kyushu University has found ways to defrost ice, by using less than 1 per cent of the energy and less than 0.01 per cent of the required time from the traditional defrosting methods.

Instead of conventional defrosting, which melts all the ice or frost from the top layer down, the researchers established a technique that melts the ice where the surface and the ice meet, so the ice can simply slide off.

The invention was made at the backdrop of the large energy efficiency losses of building energy systems and refrigeration systems due to the need to do intermittent defrosting. The systems must be shut down, the working fluid is heated up, and then it must be cooled down again.

According to the authors, the biggest source of inefficiency in conventional systems is that much of the energy used for de-icing goes into heating other components of the system rather than directly heating the frost or ice. This further amplifies energy consumption and system downtime.

Instead, the researchers proposed delivering a pulse of very high current where the ice and the surface meet to create a layer of water. To ensure the pulse reaches the intended space rather than melting the exposed ice, the researchers apply a thin coating of indium tin oxide (ITO) – a conductive film often used for defrosting – to the surface of the material. Then, they leave the rest to gravity.

To test this, the scientists defrosted a small glass surface cooled to minus 15.1 degrees Celsius – about as cold as the warmest parts of Antarctica – and to minus 71 degrees Celsius –  colder than the coldest parts of Antarctica. In all tests, the ice was removed with a pulse lasting less than one second. These temperatures were chosen to model heating, ventilation, air conditioning, and refrigeration applications and aerospace applications, respectively.