A Handbook Method for the Estimation of Power Requirements for Electrical De-icing Systems

Electrical de-icing consumes more power than is generally available from the generators. Therefore, electrical de-icing only becomes feasible, if the power is merely used during limited time intervals to melt the ice and separate it from the wing. The airflow then simply carries the ice away which avoids the need for further power to melt or even evaporate the ice totally. The ice slabs forming on the wing can be carried away by the airflow, if the slabs are separated from one another. Separation is achieved by constantly heated parting strips. This paper provides an easy to use method to estimate power requirements for such electrical de-icing systems taking account of described power saving technologies. In contrast to an established method by SAE, equations are derived here from first principles and SI units are applied. Based on the example of the Boeing 787 aggregated general technology parameters (k-factors) are derived. Applying these Boeing 787-based k-factors power estimations for other similar aircraft are greatly simplified. Without own experimental results for verification, the method is eventually calibrated based on findings published in the literature and own assumptions. Example calculations yield power requirements in the right order of magnitude. Based on the calculations of this paper the Boeing 787 would require 3.61 kW/m2 for deicing. The total required installed power for a Boeing 787 with an electrical de-icing system (and technologies as described) would be 75.8 kW which is in good agreement with the published power range of 45 to 75 kW. NOMENCLATURES e surf iced wing span [ m ] cice heat capacity of ice [ kJ kgK ] c liqu heat capacity of water [ kJ kgK ] cpair specific heat capacity [ kJ kgK ] Em water catch efficiency [1 ] e∞ ambient saturation pressure [Pa ] e surf surface saturation pressure [Pa ] h0 local heat transfer coefficient [ W mK ] k 0 thermal conductivity of air [ W mK ] k cycl total cycle time factor [1 ] k ps parting strip factor [1 ] Lc latent heat of vaporization [ kJ kg] L f latent heat of fusion [ kJ kg] ṁlocal local water catch [ kg sm 2 ] Nu Nusselt number [1 ] n freezing fraction [1 ] p∞ ambient air pressure [Pa ] Pr Prandtl number [1 ] P req required electrical power [W ] Pelec available. electrical power [W ] q A/ I overall heat [ kW m ] q KE kinetic heating [ kW m ] qaero aerodynamic heating [ kW m ] qconvec convective heating [ kW m ] qevap evaporative heating [ kW m ] q sensible sensible heating [ kW m ] Rh relative humidity [1 ] Rc boundary recovery factor [1 ] Rc , p Reynolds Number [1 ] T ∞ ambient Temperature [K ] T MSL air temperature at mean sea level [K ] T sk skin Temperature [K ] t maximum airfoil thickness [m ] vTAS true air speed [s ] ρ LWC mass of supercooled water p. vol. [ kg m ] ABBREVIATIONS AIR Aerospace Information Reports CS Certification Specifications FAA Federal Aviation Administration SAE Society of Automotive Engineers