614 / 2019-01-20 20:33:31

Research on the performance of natural draft counter-flow wet cooling towers with cross wall in the rain zone under crosswind

Key words：cooling tower; crosswind; cross-wall; performance research.

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Research on the performance of natural draft counter-flow wet cooling towers with cross wall in the rain zone under crosswind
Huadong Song1, Fengzhong Sun*, Hongguo Wang
1 School of Energy and Power Engineering, Shandong University, 17923 Jingshi Road, Jinan 250061, China; 15966630503@163.com, Tel: 15966630503, Fax: +86 0531 88395691.
* School of Energy and Power Engineering, Shandong University, Jinan 250061, China; sfzh@sdu.edu.cn.
Abstract: In presence of crosswind, the performance of natural draft counter-flow wet cooling towers degrades with destroyed aerodynamic field and the circumferential non-uniform ventilation. Installing cross-wall in the rain zone is one of the windproof solutions. To study the effect and the associated mechanismof cross-wall on NDWCTs, a 600MW unit was tested in the field. Based on the results of the tower operational condition under different crosswind, this study found that :(1) Ventilation and cooling number reduces first and then increases with the increase of crosswind velocity, and less than the value under windless conditions. At the same time, the value of ventilation and cooling number are related to installation method of the cross-wall. In the case of the wall straight upwind, both the ventilation and cooling number are least and can be decreased by about 30% compared with the value under windless conditions when the crosswind velocity is equal to 6.0m/s; but the crosswind velocity is equal to 8.0m/s when the cross-wall’s installation angle is 45°, reduced nearly 50%. Under the crosswind conditions, the ventilation volume and cooling number of the cooling tower are less than the value of the straight upwind when the cross-wall installation angle is 45°. (2) Air velocity distribution of characteristic section, air humidity and temperature distribution of lower part of fill and temperature distribution of pool surface found that: parameters of each section have a certain correspondence. Under the windless, The parameters of each section are uniform along the circumferential distribution and along the tower radius to the center, air velocity decreases, humidity and temperature, and temperature of pool surface water increases. Under the crosswind, the uniformity of the parameters on each section is destroyed. The air velocity on the windward side is relatively high, the temperature and humidity are lower, and the water temperature is lower. The air velocity on the leeward side is lower, and there is a vortex at the inlet or even a tower airflow. In the field test, the variation of ventilation and cooling number with the external side wind speed provides support for further study of the influence of crosswind on cooling performance.
Key words：cooling tower; crosswind; cross-wall; performance research.