Water and energy conservation for a counterflow cooling tower using UV light disinfection and variable speed fan

摘要

The present study proposes a new water and energy conservation method for a counterflow cooling tower by using UV light disinfection and variable speed fan. In the proposed approach, the constant speed tower fan was modified to become a variable speed fan by installing an inverter on the fan's motor such that the air flow rate of the cooling tower could be reduced to properly match the partial load operation. Furthermore, a by-pass loop with microfilters and UV lights was also added to our test rig to investigate the elimination effectiveness of tower-related bacteria and to reduce the blowdown loss. The experimental results reveal that for 50% load tests, the energy savings was about 76% and the overall water saving was about 23%. Moreover, from our tests we found that with a daily one-hour disinfection, the population of bacteria can be greatly suppressed to far below infection levels, and an increase in water conservation can be achieved. In addition, the possibility of human infection by bacteria originating from cooling towers should thus be greatly reduced.