Mixing Zone of Single Port Submerged Diffuser with Threaded Outlet for Thermal Discharge from Thermal Power Stations
Year: 2023
Type: article
Abstract: A lot of Thermal power stations use a once-through cooling system, which causes thermal pollution. That led to changes in the properties of water (physical, chemical and biochemical properties). A single-port submerged diffuser is a method used for the disposal of hot water, and it is in the middle between the surface and the multi-port submerged discharge in comparison with cost and dilution. This study aimed to examine the mixing zone of a single port submerged diffuser with a threaded outlet discharging hot water in ambient water. Three flow rate ratios (Qr) between hot water and ambient water flow were considered (0.2, 0.4, and 0.67). The measurements were at three different water depth ratios; the water depth ratios (H) were 1, 2 and 3. The temperature difference was plotted as(ΔTf / ΔT). The single port submerged diffuser was tested with and without threads, and the results were compared. The study included two types of threads great and fin pitch. The experimental results showed that for a single port submerged diffuser with a great threaded outlet at H =1, 2 and 3 and Qr = 0.2, the mixing zone maximum temperature ratio (ΔTmax) increased by 1.41%, 1.54% and 62.5%, respectively. The results also showed that, at H =1, 2 and 3 and Qr = 0.4, the ΔTmax increased by 3.61%, 1.45% and 58.97%, respectively. For Qr = 0.67, the ΔTmax increased by 6.4%, 1.37% and 18.18%, respectively. The experimental results also showed that, for fin threaded outlet at Qr = 0.2, the ΔTmax increased by 2.74%, 7.14% and 36%, respectively. Also, at Qr = 0.4, the ΔTmax increased by 2.35%, 8% and 29.09%, respectively. For Qr = 0.67, the ΔTmax increased by 1.15%,5.19% and 3.51%, respectively. The results also included the average temperature at the end of measurements (ΔTe) increased by different values in the studied cases. The thread has a bad effect on the temperature distribution in the mixing zone due to the spread obstruction of the hot water in the outlet area. The small thread size has a good effect compared with the great one. Finally, adding a thread at the diffuser outlet does not reduce the mixing zone but increases it and thus reduces temperature dilution.
Authors: Mofreh A. Hashim, Ibrahim R. Teaima
Institution: National Water Research Center
Language: English
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W4324072012