Objective The energy consumption of metro station ventilation and air-conditioning systems accounts for more than 30% of the total operating cost. During non-air-conditioning seasons, refrigeration units are still required to operate for equipment rooms, resulting in energy waste. To reduce energy consumption, it is necessary to investigate the feasibility of applying free cooling technology of cooling towers in metro station small cooling systems is investigated and the cooling tower schemes suitable for different scenarios are explored.

Method By analyzing the air-conditioning load characteristics of metro stations, five cooling tower-based cooling system design schemes are proposed, including open cooling tower indirect cooling, closed cooling tower direct cooling, open cooling tower direct cooling, series-connected cooling tower direct cooling, and variable-frequency cooling tower direct cooling. Considering the water circuit characteristics, heat exchange efficiency, and applicable conditions of different system configurations, their advantages and disadvantages are compared, and key issues such as water treatment, pipeline optimization, and control strategies are discussed.

Result & Conclusion  Studies show that the cooling load of metro small systems is mainly sensible heat. During winter and transition seasons, adopting an open cooling tower indirect cooling system is the optimal solution for small cooling systems in metro stations, so as to reduce energy consumption significantly. It is recommended to select the optimal scheme based on climatic conditions, initial investment, and operation maintenance costs, and to implement intelligent control strategies to maximize energy-saving benefits.