Experimental verification of an optimised heating system for hollow sleepers containing points positioning systems

Abstract

Points allow trains to move uninterruptedly from one railway line to another. In winter, blowing snow and ice can freeze the points positioning and locking system contained in hollow sleepers to fail. Then trains can no longer passage between railway lines and are delayed or cancelled. Conventional heating systems with one flat heater cannot prevent from freezing. Therefore in 2013 an optimised design of a heating system was proposed by the means of the Thermal Network Method. Based on this proposed design, a heating system with two heating jackets and a flat heater with lower power consumption were manufactured and mounted into a hollow sleeper containing a positioning system at a high-speed railway line in Austria. With a field study, the temperature distributions and power consumptions of the optimised heating system and the conventional heating system of adjacent points were studied over two winter periods. Also endoscope cameras were mounted inside the hollow sleepers to record infiltrating snow and thawing processes. Previously with the thermal network computed temperature distribution and now measured temperature distribution of the optimised heating system correspond approximately. Compared to the conventional heating system, temperatures of the critical components of the positioning system are significantly higher but do not exceed admissible temperatures. Due to harsh environment conditions, the recorded pictures inside the hollow sleeper with the conventional heating system are inconclusive. But recorded pictures from inside the hollow sleeper with optimised heating system show steadily thawing of infiltrated blowing snow. Efficacy of the optimised heating system also improved. The power consumption is slightly lower compared to the conventional heating system.