An experimental comparison of thermal discharges to a waterway by a single jet and by a multiple port diffuser

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Virginia Polytechnic Institute and State University


An experimental comparison has been made of the behavior of thermal effluents released by two different basic discharge methods. First, a multiple port diffuser, which acts to enhance mixing of the discharge with the receiving, water, was studied. Second, a single jet discharge, which is simpler, but achieves less rapid dispersion and dilution, was investigated for discharge at the surface and submerged.

The study consisted of three experimental phases. First, dye tests were conducted and photographs of the dyed, heated discharges were taken to record flow patterns. Second, the temperature field in the receiving stream was measured with thermocouple probes. Third, thermographic color patterns were developed with sheets of liquid crystals, and photographed in color.

The results showed that the multiple port diffuser minimized temperature gradients in the receiving stream, but resulted in greater heat storage within the stream. Also, the single jet located at the water surface, tended to maximize temperature gradients, but allowed better heat dissipation to the atmosphere.