Aircraft de-icing system and method
An aircraft de-icing system and method for removing the ice from the surface of an aircraft. The aircraft de-icing system reduces power requirements by allocating power from a single power source between the parting strip elements and the shed zone elements. The aircraft de-icing system may utilize a measurement of heat transfer to schedule the time necessary to shed ice from the surface of the aircraft. The de-icing system may also utilize a method for calculating the ice accumulation on the surface of the aircraft based on the outside air temperature.
1. A method for de-icing a surface of an aircraft having at least one parting strip heating element in thermal communication with the surface of the aircraft, a plurality of shed zone heating elements in thermal communication with the surface of the aircraft, a power source for heating the at least one parting strip heating element and the plurality of shed zone heating elements, and a controller for directing power from the power source to the at least one parting strip and the plurality of shed zone hating elements, comprising the steps of:
directing a first amount of power from the power source to each of the at least one parting strip heating element sufficient to heat a first portion of the aircraft surface adjacent to the parting strip heating element to a first target temperature until such time as said first portion of the aircraft surface reaches the first target temperature, and concurrently directing any residual power, if any, from the power source to one of the plurality of shed zone heating elements; and
reducing the amount of power directed to the at least one parting strip heating element to a second amount of power less than the first amount of power;
directing an amount of the power from the power source to said one of the plurality of shed zone heating elements sufficient to bring said shed zone heating element to a second target temperature for a scheduled period of time;
increasing the amount of power directed to the at least one parting strip heating element to the first amount of power.
2. The method of claim 1 further comprising the step of:
repeating the method for each of the plurality of shed zone heating elements.
3. The method of claim 2 further comprising the step of:
directing the first amount of the power from the power source to the at least one parting strip heating element sufficient to heat said first portion of the aircraft surface to the first target temperature for a period of time to allow ice accumulation on the plurality of shed zone heating elements.
4. The method of claim 3 wherein the period of time to allow ice accumulation is scheduled based on the maximum potential accumulation of ice at an average air temperature measured outside the aircraft.
5. The method of claim 3 wherein the period of time to allow ice accumulation is calculated based on measurements of the air temperature outside the aircraft and the heat transfer through the at least one parting strip heating element.
6. The method of claim 5 wherein the period of time to allow ice accumulation is calculated by the steps of:
measuring the outside air temperature;
measuring the temperature of a heating element used to maintain the surface of the aircraft at a target temperature;
measuring the power required to maintain the heating element at a target temperature;
estimating the heat transfer through the surface using a one-dimensional steady-state heat relationship; and
acquiring the time required to melt a thin layer of ice from a schedule that correlates heating time to a combination of outside air temperature and heat transfer.