Online monitoring of wall temperature fluctuations of horizontal mixing T-junction pipe

The monitoring of wall temperature fluctuations induced by unsteady mixing of hot and cold fluids in T-junction pipes of nuclear plants is increasingly performed, mainly on pipe systems the failure of which could present severe implications on the environment. In this study, mock-up tests and analyses were conducted to develop an online monitoring program for monitoring the wall temperature fluctuations of mixing T-junction pipes. Using a test loop, we simulated the mixing flow of hot and cold fluids in a horizontal T-junction pipe at a nuclear plant. To monitor the wall temperature fluctuations of the horizontal T-junction pipe, we developed a program in MATLAB. The program was able to filter out noises from the raw measured temperature data by singular spectrum analysis and guarantee a grid-independent and time-step-independent solution. The program provided two monitoring models: uniform thermal conductivity (UTC) and temperature-dependent thermal conductivity. The UTC model and a reasonable number of iteration steps in a cycle were able to improve the computational efficiency of the program.