The Increasing of the Heat Transfer Coefficient of Short Linear Heat Pipes
Bibliographic record
Abstract
The results of the experimental studies of heat transfer coefficients KHP of short linear heat pipes (HP’s) with a Laval nozzle-liked vapour channel, and with a partially swirled vapour flow inside the channel are presented. A partial azimuthal swirling of the jet vapour stream is created using inclined injection channels 1 mm in diameter in a flat multilayer mech evaporator, with an inclination angle φ relative to the longitudinal axis in the azimuthal direction, in the range of 0° < φ < 60°. The heat transfer coefficients KHP of a set of the identical HP’s with a different inclination angles φ of the injection channels in the evaporators, with the same working fluid mass filling (δm/m ≤ 0.1 %), at the same evaporator temperature heat load δT = Tev –TB = (20 ± 0.03) K, represent an extreme convex function, depending on the inclination angle φ magnitude of the injection channels, with a maximum at the swirled angle of the vapour flow φ = 26° ± 2°. The magnitude of the excess of the KHP with a swirling vapour flow over the identical HP’s with a direct vapour flow reaches 10%. An analysis of the recommended vapour channel shape, carried out by the estimating of the Richardson number Ri of the vapour flow jets above the evaporator, allowed us to estimate the value of the dimensionless longitudinal radius of curvature δ/Rconf of the confuser part of the vapour channel, which is determined from the condition of minimal friction losses during the flow of moist vapour in the boundary layer δ along the concave wall of the confuser part of the vapour channel with a longitudinal radius of curvature Rconf. The concave diffuser part shape of the vapour channel is determined by the condition that the moving vapour jets velocity vectors must be parallel to the longitudinal axis of the diffuser part of the HP’s vapour channel. The results of the numerical simulation of the hydraulic resistance coefficients ξvp of the HP’s vapour channel, closed with flat covers, with partially swirling jet vapour flow, obtained by using the ANSYS FLUENT program, show a decrease in ξvp coefficients at high values of the evaporator temperature load, in the range of vapour flow velocities 1 m/s < uz ≤ 100 m /s, and in the range of swirling angles 0°<φ<30°. With the increasing the swirling angles φ>30°, a sharp increase in the hydraulic resistance coefficient ξvp begins.
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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) | 0.000 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
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Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
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