Set up of a thermal network method model for the calculation of temperature distribution in heated points
Last modified: 2019-03-01
Abstract
During winter season, the failure of point systems is a common problem in the rail sector. Snow and ice accumulate between stock rail and tongue rail; thereby, prevent a complete switching of the point. Electrical heating rods are installed to remedy this problem in order to avoid major restrictions of the rail traffic.
Despite the established technical solutions for the heating of points, such as electric heating rods or gas heating systems, the heat transfer itself is not yet sufficiently understood. It must be determined under which boundary conditions (heat outputs, ambient temperatures, precipitation, etc.) the heating systems can ensure a reliable functioning of the switch.
Therefore, a thermal model of a heated point has to be set up using the thermal network method (TNM). In order to gain a better understanding of the heat transfer processes, the first step is to develop the heating network of the stock rail and to calculate the heating under different ambient conditions.
The stock rail constitutes one of the most important components in terms of the heating calculation. On the one hand, the heat flow is directly fed into the stock rail by the heating rod. On the other hand, the heat transfer within the stock rail has a big impact on the heating of the other components due to its large volume and surface. The usage of a TNM model has the advantage that the execution of calculations is less time-consuming and easily applicable to changing parameters. The single TNM models of various switch point components can be easily connected to each other.
We used a FEM model to compare its results with the TNM model in order to verify the temperature distribution within the stock rail. Additionally we verified the heat conduction and emission to the ambience of our TNM model with an experimental setup. As a result, we obtained a TNM model that is able to calculate the heating of a stock rail under various ambient temperatures as well as heating powers and we verified it successfully with a FEM model and an experimental setup.
Despite the established technical solutions for the heating of points, such as electric heating rods or gas heating systems, the heat transfer itself is not yet sufficiently understood. It must be determined under which boundary conditions (heat outputs, ambient temperatures, precipitation, etc.) the heating systems can ensure a reliable functioning of the switch.
Therefore, a thermal model of a heated point has to be set up using the thermal network method (TNM). In order to gain a better understanding of the heat transfer processes, the first step is to develop the heating network of the stock rail and to calculate the heating under different ambient conditions.
The stock rail constitutes one of the most important components in terms of the heating calculation. On the one hand, the heat flow is directly fed into the stock rail by the heating rod. On the other hand, the heat transfer within the stock rail has a big impact on the heating of the other components due to its large volume and surface. The usage of a TNM model has the advantage that the execution of calculations is less time-consuming and easily applicable to changing parameters. The single TNM models of various switch point components can be easily connected to each other.
We used a FEM model to compare its results with the TNM model in order to verify the temperature distribution within the stock rail. Additionally we verified the heat conduction and emission to the ambience of our TNM model with an experimental setup. As a result, we obtained a TNM model that is able to calculate the heating of a stock rail under various ambient temperatures as well as heating powers and we verified it successfully with a FEM model and an experimental setup.
Keywords
Thermal network method, temperature calculation, stock rail
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