Test on fouling detection of ballast based on infrared thermography

Abstract

To facilitate rapid, accurate, and convenient detection of ballast fouling, this paper proposes simplified computational models based on thermodynamic principles to analyze the surface temperature of clean and fouled ballast. The feasibility of employing infrared thermography for fouling detection on ballast is validated through analysis. Outdoor experiments are conducted to investigate the impact of various factors, such as the degree of fouling, the type of fouling, the intensity of solar radiation, and rainfall, on the surface temperature of the ballast. The research findings reveal that water exacerbates the difference in heat transfer rates between clean and fouled ballast. The fouled ballast has a higher thermal capacity compared to the clean ballast. In general, a lower fouling level and a higher solar radiation intensity result in a higher average surface temperature of the ballast when the external environment is stable and there is no shading. The intensity of solar radiation directly affects the temperature of the ballast surface. Additionally, the level of fouling primarily affects the temperature difference on the ballast surface for different degrees of fouling. When the percentage difference in average surface temperature between clean and fouled ballast exceeds 3.9% in this experiment, it is advisable to promptly assess the operational condition of the ballast and perform maintenance if necessary. On the sunny day, the temperature differences between the clean ballast and those with fouling levels of 20% and 40% are 1.22 °C and 2.01 °C, respectively. However, on the cloudy day, the maximum difference is only 0.3 °C. The temperature differences increase from 1.51 °C and 2.42 °C to 2.29 °C and 4.72 °C before and after rainfall, respectively. During nighttime, the average surface temperature of the ballast does not differ significantly between different levels of fouling. It is recommended to use infrared thermography for fouling detection on ballast during sunny afternoons or after rainfall. But further research is needed to explore its application during nighttime.