C104 Development of two-phase flow analysis system for increasing thermal efficiency of power plant : (2)Development of steam generator and BOP model for plant cycle evaluation of thermal efficiency

The steam generator (SG) in a pressurized water reactor (PWR) is an important component as boundary between the primary loop and the secondary loop. In this study, we performed two-phase flow analysis of SG reliability tests conducted by the Nuclear Power Engineering Corporation (NUPEC) using the two-fluid models of a thermal-hydraulic computer code PHOENICS. It was difficult to calculate the location of the boiling initiation accurately because the location was greatly affected by the friction coefficients (i.e. velocity distributions) and the heat transfer distributions. However, the friction coefficients and the heat transfer distributions did not greatly affect the void fractions in the upper region of the U-bent tubes and the calculated average void fractions agreed with the measured within 4%.

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Simulation of Two Phase Flow Dynamics in Flexible Riser Exit Geometries for Oil and Gas Applications

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.39.1 ◽

2018 ◽

Vol 39 ◽

pp. 1-13

Author(s):

Ikpe E. Aniekan ◽

Owunna Ikechukwu ◽

Satope Paul

Keyword(s):

Oil And Gas ◽

Two Phase Flow ◽

Flow Analysis ◽

Computational Cost ◽

Maximum Velocity ◽

Oil Well ◽

Phase Flow ◽

Two Phase ◽

The Third ◽

Riser Pipe

Four different riser pipe exit configurations were modelled and the flow across them analysed using STAR CCM+ CFD codes. The analysis was limited to exit configurations because of the length to diameter ratio of riser pipes and the limitations of CFD codes available. Two phase flow analysis of the flow through each of the exit configurations was attempted. The various parameters required for detailed study of the flow were computed. The maximum velocity within the pipe in a two phase flow were determined to 3.42 m/s for an 8 (eight) inch riser pipe. After thorough analysis of the two phase flow regime in each of the individual exit configurations, the third and the fourth exit configurations were seen to have flow properties that ensures easy flow within the production system as well as ensure lower computational cost. Convergence (Iterations), total pressure, static pressure, velocity and pressure drop were used as criteria matrix for selecting ideal riser exit geometry, and the third exit geometry was adjudged the ideal exit geometry of all the geometries. The flow in the third riser exit configuration was modelled as a two phase flow. From the results of the two phase flow analysis, it was concluded that the third riser configuration be used in industrial applications to ensure free flow of crude oil and gas from the oil well during oil production.

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Time Domain Simulation of the Vibration of a Steam Generator Tube Subjected to Fluidelastic Forces Induced by Two-Phase Cross-Flow

Journal of Pressure Vessel Technology ◽

10.1115/1.4023426 ◽

2013 ◽

Vol 135 (3) ◽

Cited By ~ 5

Author(s):

Téguewindé Sawadogo ◽

Njuki Mureithi

Keyword(s):

Steam Generator ◽

Two Phase Flow ◽

Work Rate ◽

Fretting Wear ◽

Phase Flow ◽

Reference Case ◽

Two Phase ◽

Steam Generator Tube ◽

Wide Range ◽

Instability Regime

Having previously verified the quasi-steady model under two-phase flow laboratory conditions, the present work investigates the feasibility of practical application of the model to a prototypical steam generator (SG) tube subjected to a nonuniform two-phase flow. The SG tube vibration response and normal work-rate induced by tube-support interaction are computed for a range of flow conditions. Similar computations are performed using the Connors model as a reference case. In the quasi-steady model, the fluid forces are expressed in terms of the quasi-static drag and lift force coefficients and their derivatives. These forces have been measured in two-phase flow over a wide range of void fractions making it possible to model the effect of void fraction variation along the tube span. A full steam generator tube subjected to a nonuniform two-phase flow was considered in the simulations. The nonuniform flow distribution corresponds to that along a prototypical steam-generator tube based on thermal-hydraulic computations. Computation results show significant and important differences between the Connors model and the two-phase flow based quasi-steady model. While both models predict the occurrence of fluidelastic instability, the predicted pre-instability and post instability behavior is very different in the two models. The Connors model underestimates the flow-induced negative damping in the pre-instability regime and vastly overestimates it in the post instability velocity range. As a result the Connors model is found to underestimate the work-rate used in the fretting wear assessment at normal operating velocities, rendering the model potentially nonconservative under these practically important conditions. Above the critical velocity, this model largely overestimates the work-rate. The quasi-steady model on the other hand predicts a more moderately increasing work-rate with the flow velocity. The work-rates predicted by the model are found to be within the range of experimental results, giving further confidence to the predictive ability of the model. Finally, the two-phase flow based quasi-steady model shows that fluidelastic forces may reduce the effective tube damping in the pre-instability regime, leading to higher than expected work-rates at prototypical operating velocities.

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