Calculation of Evaporation Rate of a Droplets Cluster and Conceptual Design of a Structure Utilizing Water Droplets for Evaporation

摘要

It has been known that workers of a honey bee colony bring water droplets into their hive, spraying it on the frames and brood cells, and fanning their wings when ambient temperature rises higher than appropriate. Meanwhile several species from Namibian beetles demonstrate unique water harvesting strategies from the morning fog via the bumps and troughs above their elytra, where water droplets will condense and grow into a size large enough that they will slide down from its back to be consumed afterwards. Interestingly, the drop wise evaporation can be far more effective in its cooling effect than swamp cooler prevalently used in arid regions, according to the calculation conducted in this research. A group of parameters were selected as the boundary condition for calculating the evaporation rate of both a swamp cooler, and that of a drop wise evaporative cooler, according to the direct and indirect implication from the Monte Carlo Simulation, Ranz and Marshall Correlation of heat and mass transfer analogy and modified drag force expression for discharged water droplets. The following calculation shows under appreciable circumstances the drop wise evaporation can rival film evaporation. In consequence, the evaporative cooler system that is designed to utilize drop wise evaporation can be theoretically much more effective and efficient in water and energy use and easier to be regulated by humans than state of art evaporative coolers. The key parameters and some control strategies were pinpointed that can help raise the evaporation rate of a droplets cluster, shedding light on its further applications in industry and supporting human lives, like cooling tower of a power plant, and a fresh water harvesting net. Meanwhile, a conceptual design of an auxiliary structure, called hydro hair system, is proposed according to the implication coming from Honey bees’ legs and hairs, and also the pattern of the surface of the elytra of Namibian Beetles.