The effect of an emulator inductive power transfer pad on the temperature of an asphalt pavement

This paper utilises experimental and numerical methods of determining the temperature distribution in an asphalt slab containing an energized embedded emulator Inductive Power Transfer (IPT) pad. In the series of experiments, five different ambient temperatures from 15 to 50 & DEG;C, four IPT pad power loss values from 5 to 30 W, and three pavement layer configurations were considered. A thermal camera was used to measure the surface temperature distribution of the asphalt slab, while a Fiber Bragg Grating (FBG) sensor and six thermistors were used for point temperature measurements. A numerical simulation, using a combination of experimentally determined, and literature-sourced thermal properties was developed for the experimental set-up, which was validated against the measured temperatures. Results show good agreement between the experimental and the simulation models with a maximum point-wise differential of 12.9%. It was found that increasing the ambient temperature from 15 to 50 & DEG;C, at a constant pad power loss of 30 W, increased the simulated asphalt surface temperature (25 mm offset from the pad) from approximately 32 to 65 & DEG;C. Moreover, varying the IPT pad power loss from 5 to 30 W, at an ambient temperature of 50 & DEG;C, increased the simulated asphalt surface temperature at the same location from approximately 53 to 65 & DEG;C. However, changing the asphalt thickness from 43 mm to 86 mm, or adding a compacted aggregate base course layer below the IPT-asphalt slab, only marginally decreased the temperature values. An increase in the thermal conductivity of the asphalt from 1 to 3 Wm-1 & DEG;K-1, results in the temperatures reducing by a maximum of approximately 21% at the bottom of the pad. However, changing the specific heat has a very small effect on the heating and cooling rates. A numerical study of an in-service New Zealand asphalt pavement, containing an emulator IPT pad and utilising a three-day period of recorded New Zealand summer climatic data is presented. The method can be used to identify IPT-pavement hotspots and aid in the design of thermally robust IPT-pavement systems.