Experiments on the effects of outdoor air-based methods for water saving and plume abatement of cooling tower

Cooling towers are widely used for commercial, industrial and power plant cooling purposes. In Korea, coal-fired power plants and nuclear power plants are generally located on the coast, while most combined-power plants are located inland and use cooling towers to condense steam. The number of power plants operating will change according to the government energy policies and in the future, it is expected that the need for cooling towers for inland power plants will increase. Since power plants are massive water consuming facilities, methods for saving water in cooling towers should be considered. Also, in industrial facilities, the plume, which often occurs when relative humidity is high, constantly raises social conflicts between residents and manufactures. However, similar technologies can be applied to water saving and plume abatement. In this study, we first investigated the performance of the condensing module using outside air to reduce the relative humidity of exit air (outdoor-air-condensing method). This module has the advantage that a cooling heat source is not necessary but an excessive increase of fan air volume is required, and the structure for water recovery could become complicated. The application of a membrane module which selectively transfers water vapour was also investigated (membrane dehumidification method). The results showed excessive energy disadvantage to generate pressure differences. Since the membrane method considered requires a high bypass airflow for higher dehumidification, it also has a disadvantage similar to that of the outdoor air module. Finally the dehumidification / regeneration module (heat pump method) was examined and this method gave the best performance in water saving and plume abatement.