On the influence of sensible heat release on displacement ventilation in a train compartment

Abstract

The aim of this study is to quantify the influence of heat release on ventilation efficiency and thermal comfort parameters of displacement ventilation in a generic train compartment. A series of human subject studies was conducted for various mean room temperatures. Complementary, measurements using thermal manikins with variable sensible heat release were performed for the same mean room temperatures. Three main findings were achieved: First, values of latent and sensible heat release of human subjects in displacement ventilation are in very good agreement with the standard using T_chest as mean room temperature. Second, the heat removal efficiency (HRE) decreases with increasing mean cabin temperature, that is decreasing sensible heat release, during human subject tests. However, the HRE remains stable during the test with thermal manikins at a constant sensible heat release. Third, we found that variation of the sensible heat has a negligible impact on the flow velocities near the passenger dummies. This indicates that the cooling performance is limited by the rate of fresh air available through the fresh air lake.