Local and individual demand-controlled ventilation in a passenger train

Kurzfassung

To achieve the desired shift of passenger transport from road to other modes, defined by the EU, passenger rail transport has to become more attractive. In addition to fostering the attractiveness of rail transport, the efficiency of existing air-conditioning systems must be increased to reduce the overall energy demand. The air-conditioning system is the second largest energy consumer during a train journey, accounting for up to 30% of the total energy demand. Nowadays, the ventilation of train compartments is optimized to provide overall comfortable conditions in the whole occupied zone, neither addressing if the seats or occupied nor addressing the individual demands of the passengers. Demand-controlled adjustment of the fresh air rate based on the CO2 levels in the compartment is already well-established to save energy at low occupancy levels. However, still the whole compartment is maintained at comfortable conditions. New concepts are based on the idea to provide comfortable conditions only on occupied seats by providing localized climate zones. Thus, there is a potential so save energy as the whole compartment can be less conditioned and further, the individual subjective demands on comfort can be addressed. In previous studies we presented infrared and seat heating elements to increase the individual equivalent temperature. The present study focusses on the application on individually controllable air nozzles operated are different temperatures and volume flow rates. In the experimental investigation, we set reduced and increased mean temperatures in the compartment and measured the local equivalent temperature body-segment wise on a selected seat which is equipped with an additional six-air-nozzle device being attached to the backrest of the front seat. Thereby, the single nozzles are oriented towards, e.g. the legs, the upper body and the heat. First results revealed that at decreased mean temperature in the compartment, the warm air jets are not capable to reach all body parts due to entrainment and mixing with the ambient air. Hence, in the current set-up, individual heating seems more promising by, e.g., infrared heating elements. In contrast, at increased mean temperatures the air vents provide a possibility to locally decrease the equivalent temperature.