Abstract:

Computational model of natural draft wet cooling tower (NDWCT) under no crosswind condition was built based on the coupling equations of heat and aerodynamic balance. The two equations were solved by the method of iteration using MATLAB code, so as to calculate the ideal values of airflow rate and number of transfer unit (NTU), which  neglect crosswind effect under the same meteorological and operating conditions as field tests. Then by combining the actual values of airflow rate and NTU of tests, new indexes were recommended to represent the specific effect of crosswind on tower performance. The results of a 3500m2 NDWCT showed that, at the same heat loss of model and test, the airflow rate decreased 38.5％ at most by crosswind, and simultaneously 33.9％ volume fraction of fill was not employed efficiently. Crosswind also increased the cooling duty of NDWCT and hence more cooling capacity was needed, which was  of great help to understand  the theory of crosswind effect on the tower performance and of significance for cooling tower design and modification.

Key words: cooling tower, thermal performance, crosswind, mathematical model, quantitative analysis