逆流式自然通风冷却塔流场及热质交换的数值模拟

以双曲型逆流式自然通风冷却塔为典型的研究对象，建立“热态模型”，即建立塔内气、水流动以及热质交换问题的数学和物理模型，在贴体非正交曲线坐标网格上用有限体积法构造差分格式，并运用ＳＩＭＰＬＥ算法对冷却塔流场和温度场进行了数值模拟．

提高冷却塔效率的可调引风换热和填料差异化布置技术

针对闭式湿冷火力发电机组冷却塔换热性能差、冬季挂冰严重的问题,为强化冷却塔换热途径,本文提出一种可调引风换热和填料差异化布置技术。利用可调引风换热装置,根据环境风向、风速自动调整冷却塔进风量,优化冷却塔流场,提高冷却塔换热能力;充分考虑冷却塔内部流场差异,采用淋水填料差异化布置方式,提升冷却塔换热效果。将该技术在某电厂150MW机组冷却塔进行实际应用,冷却塔冷却能力提高了约7%,机组供电煤耗降低了约1.5g/(kW·h)。

冷却塔外复杂流场的数值模拟与实验研究

对某能源中心楼顶的冷却塔组、烟囱、通风孔等散热设备及整个楼顶空间的流场与温度场进行了整体数值模拟,探讨了高温烟囱帽引起的排烟方向改变对冷却塔组进风处空气温度场及流场的影响,并进行了实验测试。结果表明,烟囱帽使排烟向下折转,导致冷却塔进风处下部位置空气温度显著升高;较低的烟囱烟气直排时,高温烟气会先抬升一段距离,然后受冷却塔进风处负压区吸引进入冷却塔内。

Influence of thermal flow field of cooling tower on recirculation ratio of a direct air-cooled system for a power plant

In order to get thermal flow field of direct air-cooled system,the hot water was supplied to the model of direct air-cooled condenser(ACC). The particle image velocimetery (PIV) experiments were carried out to get thermal flow field of a ACC under different conditions in low velocity wind tunnel,at the same time,the recirculation ratio at cooling tower was measured,so the relationship between flow field characteristics and recirculation ratio of cooling tower can be discussed. From the results we can see that the flow field configuration around cooling tower has great effects on average recirculation ratio under cooling tower. The eddy formed around cooling tower is a key reason that recirculation produces. The eddy intensity relates to velocity magnitude and direction angle,and the configuration of eddy lies on the geometry size of cooling tower. So changing the flow field configuration around cooling tower reasonably can decrease recirculation ratio under cooling tower,and heat dispel effect of ACC can also be improved.