Design, implementation, and characterization of a gravity heat pipe
Bibliographic record
Abstract
Gravity heat pipes (GHPs) are closed two-phase thermosyphons, which are also referred to as gravity-assisted wickless heat pipes. They are constructed by first evacuating a closed tube and then filling it with an appropriate amount of a chosen working fluid. The bottom portion of the tube is partially or fully filled with the liquid phase of the working fluid, and it is heated to perform as an evaporator. The upper portion of the tube is cooled and serves as a condenser. The central portion of the tube is usually very well insulated and referred to as an adiabatic section. A GHP operates as follows: the heat input to the evaporator causes the liquid contained within it to boil or evaporate; the generated vapor (being lighter than the liquid) moves upwards and then condenses in the condenser section; the condensate returns back to the evaporator under the action of gravity. Due to the latent heat associated with the phase-change processes, GHPs are able to sustain high rates of heat transfer with relatively small temperature differences, and their effective conductance can be significantly greater than copper rods of corresponding dimensions. This feature, along with their operation as a thermal diode (only one-way transfer of heat), simple construction, and wide operating temperature range, have made GHPs attractive for many applications: examples include heating, ventilating, and air-conditioning (HVAC) systems; enhanced latent-heat thermal energy storage units; permafrost preservation systems; geothermal systems for deicing roads and bridges; and cooling of electronic devices and fuel cells. In this work, a GHP was designed and constructed, along with a set-up that allows basic experimental investigations of this device. Water was used as the working fluid in this research. Experiments were conducted for several different combinations of parameters that lead to periodic unsteady and steady-state operation of the GHP. The design considerations and details of this GHP, the experimental investigation, and the results are presented and discussed concisely in this thesis.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".