Impact of soil freezing on the thermal performance of geothermal borehole heat exchangers across Canadian climates
Bibliographic record
Abstract
This study evaluates the thermal performance of geothermal borehole heat exchangers (BHEs) in various Canadian locations during winter, focusing on soil freezing effects. Using a computational fluid dynamics approach, it examines how soil porosity and thermal conductivity influence BHEs’ thermal performance. Ninety case studies across nine Canadian zones assessed these effects under winter conditions. The RNG k-ɛ turbulent model tracked fluid flow, and the solidification model monitored ice formation. Soil temperature fluctuations along the ground depth were incorporated using user-defined function codes. Coefficients of performance (COP) were calculated for heat pump thermal performance. Results showed substantial soil freezing around the borehole in Saskatchewan and Manitoba. The BHE systems in Alberta and Manitoba had the highest thermal resistance, while those in Saskatchewan and Prince Edward Island had the lowest. Increasing soil porosity from 0.4 to 0.55 and decreasing thermal conductivity from 2.0 to 1.385 W/mK led to up to 40% and 58% increases in ice formation, respectively. The COP of the heat pump in British Columbia was maximized, reflecting the peak temperature of the outlet fluid from the BHE. By incorporating site-specific climatic data and addressing gaps in existing standards, this research enhances geothermal system guidelines with practical design recommendations. Practical application This study provides built environment professionals with valuable insights into optimizing geothermal borehole heat exchangers (BHEs) for cold climates, particularly across various Canadian regions. By incorporating site-specific soil and climatic data, the research identifies key factors, such as soil porosity and thermal conductivity, that influence system performance. The findings will guide professionals in designing more efficient BHE systems, reducing ice formation, and improving heat pump efficiency. These design enhancements ensure that geothermal systems operate effectively in cold climates, contributing to sustainable heating solutions in residential and commercial buildings.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".