79-09: An Evaluation of Schemes for the Prediction of Recirculation on

Significant recirculation of the warm exhausted plume of a mechanical draft cooling tower can occur as a result of wind induced pressure gradients around the cooling tower structure. Despite data and studies (although both somewhat limited) indicating an improved methodology was required for assessment of the contribution of recirculation to thermal performance degradation of these towers, it was only recently that this methodology was developed and demonstrated. This paper presents some of the first field data acquired using this improved assessment methodology. Plume recirculation data from three separate rectangular mechanical draft cooling towers are presented with specific emphasis on entering air wet-bulb temperature profiles and associated performance reductions.