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以火电空冷机组常用的蛇形翅片扁平管为实验件,设计并搭建了风洞实验台,研究蛇形翅片扁平管顺流单元的传热性能,得到顺流单元翅片管空气侧在不同风速下的换热系数和水侧在不同流量下的换热系数,并拟合成Nu随Re变化的无因次关联式。将得到的关联式应用到火电厂实际的运行工况中,得到在不同迎面风速、不同环境温度及不同水流量下管内凝结水温度的变化规律。据此,以实际低温运行直接空冷机组为例,预测出空冷凝汽器顺流单元在不同迎面风速、环境温度和机组负荷下管内凝结水的冻结特性。
Taking the serpentine fin flat tubes commonly used in thermal power air-cooled units as experimental parts, a wind tunnel experiment bench was designed and constructed to study the heat transfer performance of the serpentine fin flat tube downstream units. The heat transfer coefficient at different wind speeds and the heat transfer coefficient at different flow rates at the water side were obtained and fitted to the dimensionless correlation between Nu and Re. The correlations obtained are applied to the actual operating conditions of the thermal power plant, and the variation law of the condensing water temperature in the pipe under different frontal wind speeds, different ambient temperatures and different water flows is obtained. Based on this, taking the actual low-temperature direct air-cooled unit as an example, the freezing characteristics of the condensate water in the tube of the air-cooled condenser downstream unit at different oncoming wind speed, ambient temperature and unit load are predicted.