Methods and Apparatus for Modifying Ice Adhesion Strength
Ice adhesion causes many problems. For example, ice on aircraft wings endangers the plane and its passengers. Ice on ship hulls creates navigational difficulties, the expenditure of additional power to navigate through water and ice, and certain unsafe conditions. Icing of power lines often results in their break and loss of power. The need to scrape ice that forms on automobile windshields is regarded by most adults as a bothersome and recurring chore; and any residual ice risks driver visibility and safety.The above-referenced problems generally derive from the propensity of ice to stick and form onto surfaces. However, ice also creates great difficulties in that it also has an extremely low coefficient of friction. Each year, for example, ice on the roadway causes millions of automobile accidents, costing both human life and extensive property damage. If automobile tires gripped ice more efficiently, there would likely be fewer accidents.
It is well-known that ice and snow cause power outages. Briefly, ice and snow adheres to power lines and adds so much weight that the power lines break. Such outages can cost human life. Further, the repair of power outages is extremely costly and can involve remote geographic repair teams.
Known methods for dealing with ice adhesion vary, though most techniques involve some form of scraping, melting or breaking. For example, the aircraft industry utilizes a de-icing solution such as Ethyl Glycol to douse aircraft wings so as to melt the ice thereon. This process is both costly and environmentally hazardous; however the risk to passenger safety warrants its use. Other aircraft utilize a rubber tube aligned along the front of the aircraft wing, whereby the tube is periodically inflated to break any ice disposed thereon. Still other aircraft redirect jet engine heat onto the wing so as to melt the ice.
These methods have serious limitations and difficulties. First, propelled aircraft do not have jet engines. Secondly, rubber tubing on the front of aircraft wings is not aerodynamically efficient. Third, de-icing costs between $2500 - $3500 per application; and it can be applied many times per day on some aircraft.
Dartmouth’s scientists have invented a system and various methods to modify ice adhesion and ice friction to alleviate these problems. Dartmouth’s system will reduce ice adhesion on vehicle surfaces such as aircraft wings, ship hulls, power lines, and windshields. It also increases the coefficient of friction between ice-clad roads and automobile tires, and between ice and other objects such as shoe soles and cross-country skis. The system is cheap, simple and durable.
The device developed at Dartmouth applies an electric field to the interface between ice and surfaces in contact with the ice. By appropriate control of the field strength, the ice becomes essentially *stick-free* to such a degree that ice can be removed from the surfaces with very little effort. The device thus has particular importance in aircraft safety since ice which forms on aircraft wings can be removed during flight and by normal aerodynamic forces, as opposed to complex and environmentally hazardous de-icing techniques which can only occur on the ground. Ice from car windows is similarly removed with less force and scraping.
The device includes a power supply, e.g., a battery, and a plurality of electrodes. One electrode connects electrically with the surface of interest - e.g., the aircraft wing - while at least one other electrode is suspended in close proximity to the surface. As ice bridges the gap between the electrodes, the field is generated at the ice-surface interface. The suspended electrode might include a multitude of electrodes which form-fit to the surface of interest, so as to remove unconnected patches of ice.
In certain configurations, the device also includes control electronics to measure and modulate the applied electric field to minimize the adhesion strength for a given set of circumstances.
Finally, the device can also operate to increase the ice adhesion strength thereby increasing the interactive forces between the ice and surfaces in contact with the ice. Such operation is for example desirable between icy roads and automobile tires, thereby increasing the friction between the car and the ice-clad road. The electronics used to generate the electric field are autonomously located on the vehicle and operate at very high frequencies.
It should be noted that in order for the device to operate properly, the surface of interest must be conductive. Therefore, in the applications above, the windshield glass and automobile tires must be doped with conductive material to adequately conduct electricity. Special coating applied to the power line during manufacture or as a subsequent treatment would generate an exact amount of heat suitable to melt ice and snow and only when the temperature dips below freezing. This method provides 100% protection. However, most surfaces, such as aircraft wings, are already conductive and so the conductivity is not an issue.
This technology is claimed in the issued United States patent No. 6,027,075 entitled METHODS AND APPARATUS FOR MODIFYING ICE ADHESION STRENGTH, and United States patent No. 6,427,946 entitled SYSTEMS AND METHODS FOR MODIFYING ICE ADHESION STRENGTH. We are seeking an industrial partner to further refine and market this technology. (Ref: J49)
Type of Offer: Licensing
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