A new ventilation mode of air conditioning in subway vehicles and its air distribution performance

Abstract

The traditional ventilation mode of subway vehicles adopts the form that the inlets and outlets are placed on the upper part of the cabin. The air distribution formed in this mode often cause serious problems of thermal comfort and energy consumption. In order to solve these problems caused by the traditional ventilation mode, a new hybrid ventilation mode was proposed. The hybrid ventilation mode uses both upper and underside air supply inlets. A method for evaluating the air distribution performance of subway air conditioning was developed. The method applies non-uniformity coefficients, maximum temperature difference, air diffusion performance index, modified energy utilization coefficient and Air short-circuit comprehensive coefficient. Air short-circuit comprehensive coefficient was a new index to evaluate the degree of air short-circuit of supply air. Based on the airflow simulation, the air distribution performance for the hybrid ventilation mode was evaluated using these indexes, and compared with the traditional ventilation mode. The results show that compared with the traditional ventilation mode, the hybrid ventilation mode has more uniform temperature distribution, better thermal comfort, higher energy utilization efficiency and lower degree of air short-circuit of supply air.

Keywords

• Air conditioning supply
• Air distribution performance
• Air short-circuit
• Subway