Advanced dry cooling tower concept

Abstract

The purpose of this year's work has been to develop a new dry cooling tower surface. The new surface utilizes a modification of film type packing in wet cooling towers. It is a concept which may eliminate excessive water loss. Cost of fabrication, and effectiveness of heat transfer surface were among the major design considerations. Based on preliminary water wetting investigations over simple geometric surfaces, a conductive plate was shaped to form a series of V-troughs. It provided open chennelled water flow separated by fin-like dry surfaces, and simultaneously self distributed random spraying water. The design not only channels the water flow, but also provides a convenient means to vary the air-water interfacial area to the water-plate and dry plate contact area. Varying these ratios will become necessary as optimization studies are completed. To investigate the effectiveness of this design and of future advanced wet-dry concepts, a model heat transfer test apparatus was constructed. It provided operating conditions (water temperature, water flow rates and air flow rates) similar to those of existing wet cooling tower packing sections. All of the design requirements have been satisfied: hot water flow recirculation and counter flow air stream. A computer simulation of the proposed surface was made. The simulation modeled heat and mass transfer from the air-water interface as well as heat transfer from the dry surface area. Initial parametric runs were made using the program. They indicate that when the ratio of wet surface area to total surface area is five percent, approximately seventy-five percent of the energy transfer takes place as sensible heat transfer; whereas, for a wet tower at similar conditions approximately eighty-five percent of the total energy transfer takes place by evaporation.