Numerical analysis of a counter-flow wet cooling tower and its plume

Abstract

A one-dimensional model to study the heat and mass transfer inside and immediately above a wet counter-flow cooling tower is described. The wet cooling tower thermodynamic model assigns zone-specific Merkel numbers to each of the rain, fill, and spray zones, and it includes an atmospheric plume model. Using the present formulation, zone-by-zone rates of heat rejection and water evaporation can be estimated, as can the visible plume height. The model is validated against the well-established Poppe and Merkel methods as well as select field data. Cooling tower performance and plume visibility are evaluated under a variety of climatic conditions (hot-dry, hot-humid, cool-dry and cool-humid), cooling tower designs (e.g. fill zone height, Hfz), and operating conditions (e.g. water-to-air mass flow rate ratio, L/G). The parametric study in question highlights the ability of the proposed model to predict the impact of ambient conditions, cooling tower design parameters, and operating conditions on overall performance and patterns of atmospheric dispersion. The proposed model is ideal for numerical optimization of cooling towers that need to meet stringent thermal performance and plume visibility requirements.

Keywords

• Counter-flow cooling tower
• Evaporative cooling
• Wet cooling tower
• Visible plume
• Turbulent plume model