Experimental investigation of a de-icing system for wind turbine blades based on infrared radiation

Wind power is one of the fastest growing production methods of electric energy. The expansion of wind power in Sweden are focused to northern counties. There are advantages as good wind conditions and large unexploited areas to build wind farms in the north, but there are also problems caused by the long winters. Due to the long periods of cold climate, ice and snow accumulation on blades are a safety risk, induces production losses and causes wear at wind turbine components. The commercial de-icing systems are not fulfilling the demands of being cost effective and are mainly focusing the heating to the leading edge. Therefore a new de-icing system based on infrared radiation has been investigated. This system is supposed to be placed at the wind turbine tower and de-ice one blade at a time. Experiments with this new de-icing system has been performed in small and full scale at a section of a real wind turbine blade. The experiments were carried out in facilities of Arctic Falls in Piteå. Different parameters as power demand of the heaters, distance between blade and heaters, wavelength of the radiation, influence by the surrounding temperature and total de-icing time were evaluated. Results showed that the largest impact of the efficiency and de-icing time were induced by the distance and width of the radiation spectrum for the heaters. Three types of filaments with different peaks of wavelengths were investigated and the most efficient de-icing was achieved when using a combination of heaters. Measurements of intensity together with de-icing experiments showed that the optimal distance from the blade was 1.5 m for heaters with standard reflectors. The main conclusion from the experiments with an infrared de-icing system is that it works. But not efficient enough to compete with the commercial systems of today even though it manage to de-ice the whole blade instead of just the leading edge. But this de-icing system has good potential if the heaters first of all are developed to radiate a more concentrated beam of radiation that is only focusing at the blades. The new method is estimated to be an lower investment due to that the techniques of infrared heaters are already well implemented in other areas. But more economic calculations has to be done to further motivate the work