Experimental investigation of thermal mixing phenomena in a tee pipe

T-pipe designs have been widely used in the industry. Among them, mixing of hot and cold water is a common application. In the mixing process, cold and hot fluids are respectively injected through main and branch pipes, and are mixed in the downstream area of T-tube. High temperature hot water flows through the main pipe for a long time; hence, the pipe wall is at high temperatures. The fluid injected into the branch pipe is a cooling fluid. After mixing, the wall of the main pipe is under high thermal fluctuations causing strong thermal stresses, which will eventually lead to pipe damage and water loss. Through flow rate adjustments of the branch and main pipes, when the branch/main velocity ratio was greater than 7.8, showing that cold water hit the bottom of the main pipe and created a reverse flow. This reverse flow created large thermal stresses on the wall. Hence, the branch/main velocity ratio and the hot-water-mixing phenomenon are the focus of this study.