Underground railway environment in the UK: Part 3: Methods of delivering cooling

Ventilating an underground railway environment in which there is to be heavy traffic of electrically propelled rapid transit trains differ from those normally encountered in air-conditioning work. The heat generated by the train motors and electric lighting, together with body heat from passengers, is so great that excessive temperatures would prevail in summer unless a volume of air in excess of that required for breathing is supplied. The installation of in car air-conditioning units adds another major heat release source in the tunnel. This heat must be ejected to make using in car air-conditioning units worthwhile. This part of the paper investigates potential methods of delivering cooling to underground railways environment. The suitability of each cooling method is assessed with the help of a purposely developed mathematical model, which has been discussed at length in part two of the paper, to investigate the heat load in a generic underground railways environment. For each cooling method, the model predicts the tunnel and train carriage temperatures and relative humidities together with the PPD.