On the experimental investigation of novel low-momentum ventilation concepts for cooling operation in a train compartment

Abstract

We report on an experimental investigation of novel, low-momentum ventilation concepts for a train compartment. The concepts were analyzed with regard to thermal comfort, spatial homogeneity, heat removal efficiency and their capability of integration. The studies were conducted using thermal manikins in a generic train cabin, that is, the lower level of a double-deck high-speed train ”DLR’s Next Generation Train - NGT”. Various ventilation concepts comprising state of the art micro-jet ventilation (MJV) as well as novel low-momentum ventilation concepts were investigated. The novel concepts are floor-based cabin displacement ventilation (CDV), low-momentum ceiling-based ventilation (LMCV), a hybrid (HV) combination of CDV and LMCV as well as hatrack-integrated low-momentum ventilation (HLMV). The results proved that all investigated concepts have advantages and disadvantages. The recorded mean air velocities of all concepts are well below the limiting values defined in the standard for long-distance rolling stock. However, the analysis of the instantaneous velocities revealed that classical mixing ventilation exceeded the thresholds from time to time. Regarding the capability of integration, the floor-based CDV and the hatrack-integrated concept turned out to be advantageous since no space in the aisle zone is required. For the HLMV concept, which is fully integrated in the hatracks, stronger horizontal temperature fluctuations were recorded highlighting the need to optimize the HLMV air outlets. In the current stage, LMCV and the hybrid approach were found to be the best concepts. They were not rated as critical in any of the considered categories.