CFD in HVAC for railway applications

CFD simulation for HVAC studies

When travelling, arriving to your destination on time is not the only concern. Comfort also plays a very important role on the travelling experience and may have an impact on your evaluation about the trip.

Railway transportation is one of the most used systems in the world, from high-speed trains allowing people to travel long distances quickly to underground railway facilitates mass transit for people movement inside a big city.

What all these types of trains have in common is their need for a Heating, Ventilation and Air Conditioning [HVAC] system to ensure environmental comfort inside the vehicle. In order to regulate these conditions, there is a strict normative related to comfort for both the passenger cars and driving cabins.

These regulations, specified in Standards such as EN-13129 or EN-14813, determine the comfort parameters inside the vehicles related to air temperature, humidity, air renovation and surface temperature in a wide range of locations, with the final objective of guaranteeing the maximum passenger comfort during the travel.

Computational Fluid Dynamics [CFD] is a powerful tool that can help assessment in the design phase of HVAC systems, since it can simulate the flow and temperature distribution inside the carriages and any environmental and input conditions even before the system is built. With these previous evaluations, it can be easier to determine optimal flow distribution, impulsion parameters, flow rates, poorly optimized areas and so on. CFD also counts with the advantage of not being restrained by any physical components, so data can be analysed in any spot of the geometry, giving even more additional information that can be useful to the designer than the parameters asked by the Standards.

Both EN-13129 and EN-14813 stablish the probing coordinates and sections during test conditions; so in the CFD model these locations can be fully monitored during the calculation to ensure the convergence and stability, and later on, these data can be compared to the requirements asked in the Standards.

HVAC systems have to meet an exhaustive process of evaluation in terms of thermal homogeneity in a large amount of different locations: seats, aisles, bathrooms, windows, walls, etc. in order to provide a comfortable feeling to the passengers along the ride. Air velocity is also regulated in order to prevent that any area is exposed to any jet stream or, on the contrary, be improperly conditioned. All these requirements involve a deep understanding of fluid dynamics and air behaviour.

SDEA Solutions provides a fully customized service using its knowledge on CFD HVAC modelling, simulation and expertise on Standards to fulfil any client’s request in HVAC systems assessment. Our services include the whole process of designing the geometry from drawings or modification of a given one to the creation of a high quality model to be simulated and a complete analysis of the results, giving the client the precise data they need to know in order to better understand and improve their system, with complete and exhaustive reports made to ensure that every condition and result is well interpreted.