A simplified model for thermal discharges

Abstract

In this study a two-dimensional model has been developed in order to estimate the distribution of temperatures in the marine environment following the discharge of thermal effluents. The model is applicable to any type of marine environment; stratified or uniform. Any density or salinity profile can be handled for the stratified environment. The water column above the diffuser port is divided into a number of layers with thicknesses of 1 or 2 m, depending on the salinity and temperature data and the sea water density is assumed to be uniform within each layer. The average and the minimum dilutions and the average and maximum temperatures are calculated at each layer for the rising plume from port to the trapping level by iterative application of the model equations. This way a diffuser design which satisfies the regulations becomes possible. The model also predicts the dilutions and the temperatures due to subsequent dispersion which occurs during the transport of the field from the seawater surface or from the trapping level depending on the currents and turbulence. The heat transfer between the thermal plume and the ambient seawater is neglected to be on the safe side especially in evaluation of the environmental impact of the thermal discharges. The computer program called THERMOD not only calculates the dilutions and the temperatures, but also draws the contours of equal temperature and temperature differantial (ΔT) lines. The model has been succesfully used in Environmental Impact Assesment Studies of the two 500 MW power plants proposed at the east of Marmara Sea, Turkey.