De-icing behavior and efficiency of electrothermal film surfaces with different non-wettability in low-temperature flow field

Abstract

The electrothermal anti-/de-icing technology with excellent de-icing efficiency has been widely applied to eliminate the icing threat on airfoil, whose essence is heat transfer process between heating surface and ice. However, the heat transfer behavior and interfacial transformation form of ice accretion are indistinct on traditional non-superhydrophobic surfaces and rapidly-developed superhydrophobic surfaces in the low-temperature flow field. Therefore, the heat transfer and solid-ice interface transform behavior on film heater surface were explored in this work by analyzing the temperature-rising performance and de-icing characteristics of hydrophobic films (HPoF) and superhydrophobic films (SHPoF) in the icing wind tunnel. The results indicated that the faster wind speed enhanced the convection and radiant heat loss of the film heater, and the peak temperature of film heater was directly affected by the environment temperature. Moreover, the SHPoF had lower de-icing consumption than HPoF in an environment without wind field, which was less related to the ice accretion. However, the de-icing form transformed from shearing to shedding mode with the growth of ice accretion under wind field conditions. In the shearing de-icing mode, the lower environment temperature and faster wind speed caused longer de-icing time, whereas the deicing time shortened with the decrease of environment temperature in the shedding mode. When the icing time was 1 min, the de-icing time of SHPoF increased by 12.25%–25.73 % due to the slower heat transfer at the solid-gas-ice interface compared to the solid-liquid-ice interface of HPoF. With the further increase of icing time, the ice accretion was removed after the melt of interfacial ice. The less solid-ice contact points were present at the solid-gas-ice interface on SHPoF surfaces, resulting in energy saving of 20.16%–40.46 % compared to HPoF surfaces. Therefore, the electrothermal superhydrophobic de-icing technology exhibited energy-efficient characteristics when the self-weight of ice is the primary driving force for de-icing process.