Numerical Simulation of Roof Mounted Rail AC Unit

Indian Railways, often described as the "transport lifeline of the nation", is the fourth largest railway network in the world, from suburbs to urban transit, the Indian rail network covers the length and breadth of the country. To make the journeys easier and memorable it is very much important to provide adequate comfort and easy access to every facilitates. For better comfort inside the coach as well as in the drivers’ cabin, air-conditioning system has to be quite effective and energy efficient. While it is too expensive to go with proto-types at the initial stage, numerical simulation comes very handy in helping and optimizing the unit and come out with viable design concept within very short time. The present study is about improving and optimizing the overall performance of a drivers’ cabin AC unit by using numerical simulation and then experimental validation. The unit was designed for the drivers’ cabin and it was mounted on roof. In order to make the unit more efficient and compact, numerical simulation was performed with the help of 3D- CFD (Computational Fluid Dynamics) using CCM+ software for both the evaporator and condenser side. All the losses in evaporator side was identified at suction, discharge and blower areas while the condenser side airflow was optimized by utilizing the maximum area of the core and for that matter the core was made as ‘U’ shaped for compactness. With bot areas substantial improvement in terms of airflow and performance was observed. Further the prototype was made and tested in climatic chamber. The simulation results of airflow amount correlates very well with that of experimental results.