Transient Analysis for Shallow Cooling Ponds

A transient model, based on the concept of equilibrium temperature T_E, and surface heat transfer coefficient K, is used to explore the transient response of shallow cooling ponds subject to fluctuating meteorology. The model can be viewed as quasi-steady in that steady state pond temperatures are computed as a function of exponentially filtered meteorology. For linear heat transfer, K is constant while values of T_E are filtered. For nonlinear heat transfer both K and T_E are filtered. Comparison with results from a numerical model with fully nonlinear heat loss suggests that the linear model provides acceptable results and errors on the conservative side of overpredicting extreme temperatures, while somewhat greater accuracy can be obtained with the nonlinear model. Use of a steady state model with averaged meteorology is also discussed. These models are suggested for use at the preliminary design stage where many potential ponds must be evaluated.