Acquisition of spatially resolved CO2 distribution in a generic train compartment

Abstract

The presented study was conducted within the framework of the Next Generation Train project (NGT) of the German Aerospace Center (DLR). This project addresses many aspects of future high-speed trains and modern passenger and freight transport. Among others, thermal passenger comfort and energy efficiency of different ventilation systems have been analysed by implementing new ventilation and illumination concepts in a full-scale mock-up of the NGT-HST (high-speed train). With up to 20-30% of the total energy demand, the HVAC system of a train is the second largest energy consumer during a train journey. The demand-oriented ventilation of passenger compartments is one possibility to save energy by reducing the rate of fresh air. For demand-oriented ventilation based on the CO2 distribution, energy savings between 10% and 20% were observed in previous studies in wind tunnel experiments and in operational mode. However, all of the studies conducted so far are based on CO2 measurements in the exhaust air of the train compartment. Investigations of the local CO2 distribution in the compartment, i.e. possible locally increased CO2 values on individual seats, are still lacking. The objective of the present study is to investigate a novel hybrid ventilation concept in terms of CO2 distributions and CO2 discharge in a generic train mock-up (GTM). This novel concept is based on a combination of cabin displacement ventilation and a hat-rack-integrated low-momentum ventilation system. Four thermal manikins and up to 20 human subjects were placed in the GTM. The influence of different numbers of human subjects on the performance of ventilation systems in trains was studied using CO2 sensors in the vicinity of the persons as well as in the air supply and air exhausts.