Theoretical Analysis of the Energy Required for Destratification of a Stratified Source Reservoir

Abstract

The minimum energy required for destratification of a source water reservoir is important to determine the design capacity of mixing system used to improve the source water quality. Taking Jinpen Reservoir in Xi’an, as a study case, the water volumes under different water levels of the reservoir were numerically calculated using the geometry data obtained with a RTK system. The total potential energy (PE) was determined by integrating the PE in each thin sub-layer over the water depth with density dependent on the water temperature. The average water temperature after complete mixing was calculated based on the heat exchange theory, and was consistent with the numerical result of temperature simulation. The difference of total potential energy before and after mixing was calculated for each month with the data of water temperature, water density and water volume. The minimum energy required for destratification increasing with the temperature gradient, was relatively high during the period from June to October, and reached a peak of 2412.92 kW·h in July.