Efficiency of Monolayers in Evaporation Suppression from Water Surface Considering Meteorological Parameters

Abstract

Abstract The evaporation from water reservoirs has become a global issue, due to climate change, limited water resources, and population growth. In this research, three emulsions of octadecanol/Brij-35 (4:1), hexadecanol/Brij-35 (4:1), and a combination of the alcohols with Brij-35, octadecanol/hexadecanol/Brij-35 (2:2:1), were used in water. One-way ANOVA was applied to compare the mean of evaporation in different chemical and physical methods, and factorial ANOVA was used to investigate the main and interactional effects of different meteorological parameters on the rate of evaporation. Results showed that two physical methods of the canopy and shade balls performed better than the chemical methods, with reductions of 60 and 56 percent in evaporation, respectively. Among the chemical methods, the octadecanol/Brij-35 emulsion had a better performance with a 36 percent of reduction in evaporation. One-way ANOVA results showed that among the chemical methods, only the octadecanol/Brij-35 had no significant difference with shade balls with a 99 percent probability level (P < 0.01). On the other hand, factorial ANOVA showed that the temperature and relative humidity had the highest effect on evaporation. Octadecanol/Brij-35 monolayer had a lower performance than two physical methods at low temperatures but after increasing temperature, its performance improved. This monolayer had a good performance at low wind speed compared to physical methods; however, with increasing the wind speed, its performance was severely affected. For temperatures of over 37°, the evaporation rate increased more than 50 percent when the wind speed had changed from 3.5 m/s to more than 8.7 m/s.