[Objective] In the desert-Gobi regions, water resources are scarce and the climate is dry, with the traditional wet cooling system being highly water-consuming. Although air-cooling technology is suitable for such water-scarce environments, existing studies mostly focus on the main unit cooling system, with insufficient research on the heat transfer characteristics and adaptability of air -cooled cooling towers in the auxiliary cooling system, failing to meet the demand for efficient and water-saving operation. 

[Methods] This paper takes the auxiliary cooling water system of a 4×1 000 MW air-cooled unit in the Jiuquan region as the research object, establishes heat transfer models for pre-cooled and combined dry and wet cooling towers, and performs model validation. The influences of ambient temperature, humidity and air velocity on the heat transfer and airflow resistance characteristics of the two types of towers are investigated, and a comparative analysis is conducted from the perspectives of overall performance, regional adaptability and water-saving performance. 

[Results] Under design conditions, the heat flux of the pre-cooled cooling tower is 1.1 times that of the combined dry and wet cooling tower, whereas the pre-cooler increases the system airflow resistance by 30% and raises metal consumption to 1.76 times that of the combined dry and wet cooling tower. The ambient wet‑bulb temperature is the main factor determining the difference in wet mode performance between the two types of cooling towers. Due to its decoupled heat and m ass transfer design, the pre‑cooled cooling tower achieves a greater improvement in heat transfer performance under low ambient 2 humidity conditions compared with the combined dry and wet cooling tower. Climatic analysis indicates that precooled cooling towers are more applicable for arid regions such as Jiuquan in Northwest China, with their heat flux improved by 20%~85% under low-humidity conditions; by contrast, combined dry and wet cooling towers perform better in humid eastern areas such as Tianjin. Benefiting from its efficient heat transfer under dry mode operation, the pre‑cooled cooling tower raises the spray start temperature and reduces the operating time under wet mode operation compared with the combined dry and wet cooling tower. As a resu lt, its annual savings in water cost s amount to 735 000 yuan, and its annual water saving reaches 76%, demonstrating outstanding water‑saving benefits. 

[Conclusion] Therefore, the pre‑cool ed cooling tower offers both water‑saving and efficiency‑enhancing advantages. In water‑scarce and arid regions such as the northwest barren desert‑Gobi area, it is recommended to prioritize this tower as the cooling scheme for the auxiliary cooling system, thereby contributing to the high‑quality construction of new generation coal‑fired power auxiliary cooling water systems in the barren desert‑Gobi region.