Numerical Simulation of Liquid Film Evaporation and Condensation forWater Reactors
Bibliographic record
Abstract
A detailed analysis of liquid film evaporation and condensation has become increasingly important, especially in water reactor designs.For example, the prediction of liquid film evaporation is critical to the design of Passive Containment Cooling Systems (PCCS), which are important passive safety facilities in modern Pressurized Water Reactors (PWR).To keep the maximum design values of pressure and temperature under control, a water/air counter-current flow is often employed within the external channel of the PCCS.It is thus essential to analyse the evaporation mass flow rate and heat transfer of the water film for the overall performance of PCCS.On the other hand, hydrogen might be released into the reactor containment during an incident due to cladding oxidation at elevated temperatures.Given the high flammability of gaseous hydrogen, it is paramount to know its local distribution in the containment building while considering wall condensation, which will increase the non-condensable gas concentration on the walls.Another example is evaluating the containment loads in the Light Water Reactor (LWR) plants and predicting their condensation behaviour in the presence of non-condensable gases.With the advantages of Computational Fluid Dynamics (CFD) and recent model developments, the numerical analysis of evaporation and condensation of liquid films has become more convenient than expensive experiments for real-world applications.In this paper, the numerical model of Eulerian Wall Film (EWF) implemented within Ansys Fluent® has been validated based on two canonical cases.The first one refers to the experiments performed by Hu et al. [1], where the heat transfer during the water film evaporation on a vertical plate has been studied.The average heat flux and water film evaporative ratio match the available experimental data well.The second case relates to the experiments done by Ambrosini et al. [2], also known as the "CONAN" case, where the wall film condensation in the presence of non-condensable substances has been studied under different steam mass fraction and velocity conditions.The surface heat flux and condensate mass flow rate also match the experimental measurements.The present numerical workflow using EWF could be applied to more complex devices for liquid film evaporation and condensation simulations.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".