Evaluation of Available Correlations for Rate of Evaporation from Undisturbed Water Pools to Quiet Air

Abstract

Calculation of evaporation from undisturbed water surfaces to quiet air is required for many applications, including unoccupied indoor swimming pools, pools containing spent nuclear fuel, indoor water reservoirs, process tanks, and contaminated water spills. Many correlations have been proposed for such calculations but none have had sufficient verification. Data from 11 sources that included pool sizes from 0.07 to 425 m2, water temperatures from 7 to 94°C, air temperatures from 6 to 35°C, and humidity from 28 to 95% were available in the literature, and 11 correlations had been developed. The available correlations were compared to the data to test their validity over a wide range of conditions. The correlation of Shah (1992), which is derived from the analogy between heat and mass transfer, gave the best agreement with a mean deviation of 18.2%. The second best was the correlation of Boelter et al. (1946), with a mean deviation of 26.2%. All other correlations had unacceptably high deviations. The Shah correlation is recommended for design calculations, with the Boelter correlation as an alternative.