Heat Transfer in Two-Phase Vertical Co-Flow in the Presence of a Mesh-Type Bubble Breaker
Bibliographic record
Abstract
Bubble breakers have been shown to be effective at reducing bubble size and delaying transition from bubbly to slug and churn flow regimes in the two-phase vertical pipe flow. If used in bubble column reactors, bubble breakers can increase the surface area-volume ratio of the gas-liquid interface allowing for an enhanced mass transfer or chemical reaction rate. Studies have been done showing the effect of bubble breakers on bubbles size and flow regime but none exist to show the effect of a bubble breaker on heat transfer for a two-phase pipe flow. A new method of measuring the heat transfer for a two-phase vertical pipe flow is proposed in the current study. The method uses thermocouples inserted directly into the flow for bulk fluid temperature measurements and a thermal camera for surface temperature measurements of a thin walled stainless steel pipe. Heat transfer measurements, expressed as a Nusselt number, for a single phase laminar liquid flow are compared to accepted values to show the validity of the experimental method. Preliminary results of two-phase gas-liquid heat transfer rates with and without a bubble breaker present in the vertical pipe are compared. The liquid flowrates used in the experiment represented superficial Reynolds numbers of ReI<2000 and the gas flowrates used in the experiment represented superficial Reynolds numbers of Reg<100. Without a bubble breaker, the convective heat transfer coefficient, represented as Nusselt number, was found to decrease with increasing gas flowrate. When a bubble breaker was added, the effect on the heat transfer was dependent on the flow regime. For most cases, the bubble breaker had very little effect on the measured heat transfer rate. In a case where the bubble breaker was able to generate slug flow rather than churn flow that was generated when no bubble breaker was present, the measured Nusselt number was increased.
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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 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".