Winter frost is an annual struggle. It poses an icy threat to vehicles, aircraft, and essential infrastructure, such as heat pumps. Typically, defrosting the ice relies on energy-intensive thermal heaters or toxic chemicals. However, mechanical engineers at Virginia Tech may have discovered a cleaner and more cost-effective alternative. Their process involves turning ice’s own physics against itself.
Turning Ice Against Itself
Associate Professor Jonathan Boreyko leads the team of engineers. His philosophy exploits the natural characteristics of ice to remove frost. Their latest work revolves around the concept of Electrostatic Defrosting (EDF). This technique leverages tiny charge imbalances, known as ionic defects, which naturally occur as water molecules freeze.
They hypothesized that applying a high voltage to an opposing electrode could forcibly polarize the frost layer. In this state, ionic defects are drawn to the top of the frost, while positive defects are repelled to the base. If the polarization force is strong enough, force crystals would fracture off the surface and propel towards the electrode.
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Researchers experimented with a copper substrate. During these early tests, it showed promise, with 550 volts removing 50% of the frost. However, in an unexpected turn of events, they discovered that increasing the voltage significantly lowered the removal rate.
“We really thought we were onto something here,” Boreyko said. “Keep turning up the voltage and more frost will jump away, right? What was unexpected was when the opposite happened.”
The engineers identified charge leakage from the polarized frost into the underlying copper substrate as the tissue. It was particularly evident at higher voltages. To solve this, the engineers upgraded the surface to an air-trapping and more insulating superhydrophobic substrate. As a result, the leakage was mitigated and the performance dramatically improved. The highest voltage zapped up to 75% of the frost, which aligned with their initial expectations.
“When using the superhydrophobic surface, the electrostatic defrosting was powerful enough to make a hidden Virginia Tech ‘VT’ logo become clearly visible on the surface after the frost jumped off,” said lead researcher Venkata Yashasvi Lolla.
Researchers aim to remove 100% of ice on a surface. However, they pointed out that this initial experiment represents a major step toward non-traditional deicing. “We hope that in the near future, EDF will prove to be a cost-effective, chemical-free, and low-energy approach to deicing,” Boreyko concluded.