论文部分内容阅读
自然通风间接空冷塔水温分布特性对于其冬季防冻措施优化具有重要的意义.针对某660MW机组间接空冷系统,该文建立了其空冷塔气侧流动传热计算的三维数值计算模型,结合该系统设计工况验证了所建模型的正确性,从系统角度计算分析了环境气温、环境风速等对其冷却柱、冷却三角、冷却扇段及空冷塔出口水温分布的影响规律.研究指出环境气温对空冷塔出口水温不平衡温差影响很小,某一环境气温下空冷塔出口水温分布规律有一定的代表性;环境风恶化空冷塔冷却性能,使其出口水温不平衡温差显著增大,但对散热管束出口水温最低值影响很小;严寒气象条件下,为防止散热管束冻结,空冷塔出口水温控制值应随环境风速增加而增加.“,”The water temperature distribution characteristics of natural draft dry cooling tower (NDDCT) were very important in order to prevent freezing.Based on the NDDCT of a natural draft dry cooling system (NDDCS) in a 660MW power unit,a three-dimensional numerical model was established to compute the air-side flow and heat transfer for the NDDCT and it was validated by the design data of the NDDCS.Analyses about the impacts of the ambient air temperature and ambient crosswind on the exit water temperature distributions of cooling columns,cooling deltas,cooling sectors,and the NDDCT from the view of the NDDCS suggested that the effect of ambient air temperature on the exit water temperature non-equilibrium temperature difference (NETD) of the NDDCT was very small.Thus,at some ambient air temperatures,the exit water temperature distribution characteristics were representative of the NDDCT.Ambient crosswinds deteriorated the cooling performance of the NDDCT,and sharply increased its exit water temperature NETDs,but had little effect on the minimum exit water temperature.In order to protect the finned-tube radiator from freezing under severe cold weather,the average exit water temperature of the NDDCT should increase as the velocity of the crosswind increases.