MODELLING OF HEAT TRANSFER OF RAILWAY SWITCH HEATING

Sammanfattning: Switches and crossings are vital components of the railway network. Obstacles to the smooth functioning of these components could result in delays and network traffic. Given the geographical location of Sweden, snow is one of the major obstacles for the switches. The presence and hardening of snow act as an obstacle to the movement of the switch rail, thus hindering its function. Electrically heated switches melt and clear the snow for movement of the switch rail. They typically operate at a power level of 10 kW–30 kW. With 6800 switches operational in Sweden, the potential for energy savings is huge. This master thesis intends to investigate the possibility of reducing energy consumption through insulating a side of the rail. To achieve that, a comprehensive transient conjugate heat transfer analysis is carried out using CFD simulations. The initial refinement of the measured data highlighted the uncertainties in them, and which shaped the course of the thesis. The analysis of these uncertainties gave critical insights and led to useful recommendations for future work. The fluid-solid interactions between the rail and flow of air and their impact on transient heat loss have been analyzed to gain critical insights regarding the choice of side of implementation of insulation. The validation of the model at lower electrical power levels threw light on the dire requirement of numerical modeling of snow melting, which happens at the higher power levels of the heating element. One of the critical observations made after the implementation of the insulation is the reduction in the temperature of the heating element, which leads us to conclude that the insulation not only saves energy but also prolongs the life of the heating element by reducing thermal fatigue.