An analysis of the accuracy and computational efficiency of the use of one-dimensional fluid models in borehole heat exchangers
Bibliographic record
Abstract
• Novel methodology of modelling borehole heat exchangers to reduce computational time within COMSOL Multiphysics. • Symmetry planes with equation adjustments implemented with one-dimensional linear fluid elements to provide accurate results and reduced computation efforts. • Comparison of full three-dimensional CFD model in ANSYS CFX solving Navier-Stokes and energy equations within the fluid. • Models validated with experimental thermal response test data. This paper compares the accuracy of a one-dimensional fluid model to that of a fully three-dimensional model for the simulation of a thermal response test performed on a single borehole heat exchanger. The simplification of the fluid domain within the one-dimensional model allows for reduced computational time while still maintaining an accurate prediction of transient fluid temperature. The model uses a simplified one-dimensional fluid model while solving the full three-dimensional transient heat conduction equations in the borehole heat exchanger and surrounding ground. A symmetry plane is implemented to further reduce the computational effort, and the model and equation adjustments necessary to merge the use of symmetry planes and 1D linear elements along the central plane without loss of model accuracy is explained in detail. The proposed model is compared to a full CFD model and validated using experimental data for a constant heat rate test, commonly known as a thermal response test, to ensure no accuracy is lost due to model adjustments. Additionally, the computation times are compared for each case to quantify the time savings that result from model implementation.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| 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".