Convective Heat Transfer Enhancement of Laminar Herschel–Bulkley Non-Newtonian Fluid in Straight and Helical Heat Exchangers with Twisted Tape Inserts
Bibliographic record
Abstract
Herschel–Bulkley non-Newtonian fluid flow and heat transfer are commonly encountered in chemical processing industries, such as pharmaceutical, food, oil, and gas industries. Unlike Newtonian fluid, which has been intensively studied, the flow profile and heat transfer characteristic study of this non-Newtonian fluid is relatively scarce. This may hinder further thermal technology advancement for this unique rheological fluid. This study is therefore focused on the flow and heat transfer of Herschel–Bulkley non-Newtonian fluids in heat exchangers with twisted tape insert as a passive heat transfer enhancement method. Based on the conservation principles of mass, momentum, and energy for the non-Newtonian fluid flow by considering the effect of viscous dissipation, a three-dimensional computational fluid dynamics (CFD) model was developed and validated against the available published experimental data. Once a good agreement was achieved, the validated model was then utilized to study the effect of key parameters such as tape twist ratio, flow indices, yield stress, consistency index, and generalized Reynolds number. It was found that the helical heat exchanger with twisted tape demonstrates superior heat transfer performance, illustrated by a higher Nusselt number, at the cost of a higher pressure drop. For straight tubes, however, the addition of twisted tape deteriorates the heat transfer performance, mirrored by a lower Nu and a higher pressure drop. Among the considered twist ratios, moderate and high twist ratios (less number of turns) of 7.86 and 15.73 offer the optimum balance between higher heat transfer performance and additional pressure drop. Meanwhile, it was found that increases in the studied parameters, i.e., flow indices, yield stress, consistency index, and generalized Reynolds number, have a positive impact on the heat exchanger performance, indicated by a higher performance index. Finally, friction factor and Nusselt correlations were developed as a function of fluid thermal properties and heat exchanger geometrical parameters for practical applications.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".