Simulation of the two-phase flow across tube bundle

Experiments on two-phase flow across an in-line tube bundle are analyzed with the STEG code, which has been developed for modeling thermal-hydraulic processes in a horizontal steam generator (SG). An adiabatic, vertical two-phase flows of air-water across horizontal in-line, 5 x 20 rod bundles, with a pitch-to-diameter ratio P/D=1.3 are considered, the mass velocity is varied in the range 27 - 818 kg/m2s. The calculated values of void fraction in the tube bundle are compared with the experimental ones measured by a gamma densitometer. A reasonable agreement between the calculations and the experimental data is obtained.

Study on the Modeling and Simulation of the Horizontal Steam Generator in VVER-1000

Steam Generator (SG) is one of the main components of the power cycle in pressurized water reactor (PWR), and it is the hub of primary coolant circuit and secondary circuit, so the thermal hydraulic analysis of the SG is crucial in the system design and safety analysis of the PWR. The horizontal steam generator (HSG) is one of the main types SG in the PWR nuclear power plant (NPP), and its advantages are that it has more secondary side water capacity and good safety and reliability. The VVER-1000 is a PWR with a thermal power of 3000 MW, and has four HSGs for four loops. The RELAP5 has been used to model the VVER-1000’s HSG and performs the analysis described in this paper. The HSG tube bundle is modeled by three horizontal channels, and the steam control volumes above the heat transfer tube bundle are modeled with three volumes. The steam space is modeled as a steam separator and the steam reception shield is the dryer. The HSG secondary side downcomers are represented with a separate component to provide the power of the natural circulation. To verify the accuracy of the model, three different typical conditions are simulated. The simulation results show that the model built in this paper can correctly simulate the operation of the HSG in VVER-1000.

Optimization of the PGV-1000MKO Steam Generator Using CFD

In the VVER -TOI project, new layout solutions were applied in the reactor plant as part of which the steam removal system from the steam generator was changed. Namely, in contrast to the VVER-1000 and VVER-1200 where the steam removal was organized through ten nozzles combined into a steam collector, in the VVER -TOI SG the steam removal was arranged through one nozzle located on the cold collector side. This change leads to the formation of a non-uniform velocity field in the separation volume. To ensure the steam separation characteristics of a horizontal steam generator with one steam nozzle, it was proposed to create a non-uniform resistance on the way of steam motion from the evaporation surface into steam nozzle applying a non-uniform degree of the distribution perforated plate (DPP) perforation. Two computer models of the SG steam volume with different steam removal schemes (one and ten nozzles) were developed, a set of studies on verification and validation was carried out and a set of calculations were performed. Further, to determine the non-uniform degree of DPP perforation, a set of optimization calculations of the SG steam volume with one steam removal nozzle was performed. The non-uniform degree of DPP perforation of the VVER-TOI SG was selected, which provide steam velocity distribution as close as possible to SG with ten steam nozzles. To justify the chosen design, sensitivity analysis was also carried out according to the hole diameters tolerance and steam load profile.