Modifications of steam condensation model implemented in commercial solver

A set of steam condensation experiments is conducted to evaluate the heat removal capacity of a vertical passive condenser. A condensing tube is submerged in a water pool where condensation heat is transferred by secondary boiling heat transfer. Condensation heat transfer coefficients (HTC) are obtained under various test conditions, such as different primary pressure (150 - 450 kPa), inlet steam flow rate (1 - 5 g/s), air mass fraction (0 - 20%) and tube size (26.6 mm and 52.5 mm ID). The effects of these parameters to condensation performance are evaluated in this paper. Experimental data are compared with code predictions from RELAP5 with 2 condensation models. The comparison result shows that an improved condensation model is needed in RELAP5.

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A new modified diffusion boundary layer steam condensation model in the presence of air under natural convection conditions

International Journal of Thermal Sciences ◽

10.1016/j.ijthermalsci.2019.05.004 ◽

2019 ◽

Vol 145 ◽

pp. 105948 ◽

Cited By ~ 2

Author(s):

Haozhi Bian ◽

Zhongning Sun ◽

Nan Zhang ◽

Zhaoming Meng ◽

Ming Ding

Keyword(s):

Boundary Layer ◽

Natural Convection ◽

Diffusion Boundary Layer ◽

Steam Condensation ◽

Diffusion Boundary ◽

Condensation Model

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Analysis of the Condensation Model Used in Severe Accident Integral Codes

Volume 6B: Thermal-Hydraulics and Safety Analyses ◽

10.1115/icone26-82020 ◽

2018 ◽

Author(s):

Yiming Zhu ◽

Zhuo Liu ◽

Xiaoming Yang

Keyword(s):

Calculation Model ◽

Severe Accident ◽

Steam Condensation ◽

Iterative Calculation ◽

Condensation Model ◽

Relative Errors ◽

Simplified Calculation ◽

The Heat Transfer Coefficient ◽

Calculation Code ◽

Calculation Models

Steam condensation plays a key role in removing heat from the containment atmosphere, therefore the calculation of the steam condensation has a significant effect on the judgment of severe accident process. This paper discussed the calculation models of condensation used in severe accident integral codes. Firstly two kinds of condensation calculation models introduced and analyzed for application in integral codes: models based on experiment correlations — Uchida model, Dehbi model, and the models based on analogy of heat-mass transfer — Kreith model and Collier model. And then two calculation models based on Kreith model were proposed: simplified calculation model and completely iterative calculation model. After that, a heat structure calculation code was designed and the two model was applied. The results of the code with the two model along with Uchida and Dehbi models were compared with the experiment result of Wisconsin. It was found that the simplified model had a satisfied calculation speed and the relative errors were under 13% in total situations, which was acceptable for the integral code. Besides, it was shown that the completely iterative calculation model had smaller relative errors, which was under 11%. In addition, this paper also investigated the effects of some parameters on the heat transfer coefficient for these different models, the velocity of the bulk of gas, length of surface, pressure of the gas and mole fraction of air were selected and studied separately.

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An Influence of the Numerical Modeling of the Transition Between the Stator and Rotor on the Thermodynamic Condensation Loss in the Low-Pressure Part of a Steam Turbine

Volume 8B: Heat Transfer and Thermal Engineering ◽

10.1115/imece2018-86571 ◽

2018 ◽

Author(s):

Guk-chol Jun ◽

Lukáš Mrózek

Keyword(s):

Numerical Simulation ◽

Numerical Modeling ◽

Steam Turbine ◽

Nucleation Rate ◽

Low Pressure ◽

Steam Condensation ◽

Transition Area ◽

Condensation Model ◽

Pressure Part ◽

Non Equilibrium

Accuracy of numerical simulation of non-equilibrium steam condensation is strongly influenced by a condensation model, i.e. a nucleation rate model and a droplet growth model. Numerical studies of steam condensation in Laval nozzles show that the choice of the condensation model has a significant influence on nucleation rate, position of nucleation zone and consequently steam wetness and the droplet size in the nozzle outlet. It is necessary to model the transition area between rotating-rotor and stationary part-stator in numerical simulations of steam flow in steam turbines. For this purpose, “Stage” and “Frozen rotor” rotor-stator interface models are widely used. The aim of the present work has been to analyze how the numerical modeling of the rotor-stator transition area together with the condensation model influences the result of numerical simulation of flow with non-equilibrium steam condensation in the low pressure part of steam turbine of large power output.

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