Pulse electro-thermal de-icer (PETD)

Abstract

Abstract De-icing is a process in which interfacial ice attached to a structure is either broken or melted and then the ice is removed by some sort of external force (e.g. gravity or wind-drag). Conventional thermal de-icing is effective but requires too much energy. Mechanical de-icing requires less energy but is less effective, often leaving significant amounts of ice behind, and may also damage structures and accelerate wear. We have invented, developed, and tested a pulse electro-thermal de-icer (PETD) that reduces the energy needed for de-icing by up to a factor of one hundred. PETD achieves this by melting only a thin layer of interfacial ice, leaving the temperature of the environment unchanged. In conventional de-icers, the heater is thermally connected to the ice, the structure, and the outside environment. This makes heat losses through conduction and convection inevitable to the point where the losses exceed by orders of magnitude the amount of “useful” heat needed to melt the interfacial ice. PETD cuts these losses by using a short heating pulse – approximately 1 ms to 5s long – to heat a minimal layer of interfacial ice. This short heating time limits the heat penetration depth into both the ice and the structure. A PETD pulse heats the ice-structure interface just above the melting point causing the ice to slide off on the resulting thin water film. PETD was successfully tested for a variety of applications including the de-icing of airplanes, car windshields, bridge over-structures, glass roofs, commercial and residential icemakers, and windmill rotors. The tests demonstrated almost instant action along with up to 99% savings of the electricity required by conventional thermal de-icers. This paper presents the PETD method, its theory, results of computer simulations, and extensive data from laboratory tests as well as several large-scale implementations of PETD on an airplane, a bridge, a building roof (> 10,000 m 2 ), a car windshield, and a commercial ice maker.