By taking a natural draft wet cooling tower(CT) with drenching area of 10 000 m~2 as the research object

calculation of rain zone resistance coefficient under conditions with different drenching densities and packing section velocities was conducted. The formula to calculate rain zone resistance coefficient which is more applicable than existing formula was obtained. A one-dimensional(1 D) thermal calculating model for CT was established based on Merkel enthalpy difference method. The maximum relative deviation of the CT outlet temperature between the computed values and the measured values is only 1.6%. Moreover

the above established 1D thermal calculation model was applied to analyze the characteristics of the CT under variable condition. The results indicate that

the CT outlet water temperature rises with the circulating water flow. However

the variation of the CT outlet water temperature corresponding to the same variation of circulating water flow increases with the increase of heat load

decrease of dry bulb temperature and relative humidity. The influence of circulating water flow and dry bulb temperature on effect of heat load on CT outlet water temperature is larger than that of relative humidity. The CT outlet water temperature rises and the cooling approach decreases with increase of ambient dry bulb temperature and relative humidity

while the effect of atmospheric pressure can be neglected.