Investigations on water condensation in the main steam pipe of a pressurized water reactor nuclear power station: Part I – Experimental tests

Abstract

Experiments were conducted to measure the water condensation rates and to investigate the heat transfer characteristics in the main steam pipe of pressurized water reactor nuclear power plant during starting up and stable operation conditions. Through a series of electric control valves, two representative experimental tests were attempted to validate the proposed theoretical method (see Part II of this two-part paper). Reliability of the experimentations was checked and guaranteed by repeating the stable operation condition experiment. To reveal the steam temperature fluctuation in different operation conditions, two K-type sheathed thermocouples were installed at the pipe inlet and outlet to monitor the transient temperature fields through an NI data collection system. Apart from these, five sections of thermocouple-wires (NiCr–NiSi) were welded onto the pipe outer wall surface to obtain the time-dependent temperature. Results show that the measured and theoretically predicted water condensation rates agree well (0.5% deficiency) for the startup process, while for the stable operation condition, the deficiency between measurements and predictions were around 30%. Water condensation in the startup process is dominated by the heat capacities of the pipe and insulation layer, while water condensation in the stable operation process is determined by the radiation and natural convection heat transfers from the insulation layer. The accuracy of the predicted water condensation rate in the stable operation condition is mainly affected by the thermal conductivity of the insulation layer. The transient temperature on the piping outer wall surface shows non-uniformity along the circumferential direction. However, due to the mixing and turbulence effects of the flowing vapor, the non-uniform effect becomes weaker along the axial direction.

Online hydraulic calculation and operation optimization of industrial steam heating networks considering heat dissipation in pipes

“…Based on the study of R.W. Bjorge and P. Griffith [27], M. H. Chunet et al [22] presented a computer code entitled "KAIST-CIWH" and the sample guide charts to find CIWH free regions for a given combination of major flow parameters in a long horizontal [28,29] studied the water condensation rates in a single steam pipe theoretically and experimentally. The previous research listed above mainly focused on the hydraulic calculation of heating networks and CIWH phenomenon, and there has been limited research about online hydraulic calculation of steam heating networks, the effect of drainage on the overall calculation and operation optimization of ring-shaped steam heating networks with multiple heating sources.…”