Analytical and Experimental Study on Coaxial Borehole Heat Exchangers
Notice bibliographique
Résumé
This research focuses on methods of direct-use geothermal energy considering a coaxial borehole heat exchanger (BHE) as a major component in a ground-source heat pump (GSHP) system. A GSHP system is a sustainable energy system that transfers thermal energy between the surrounding ground and the conditioned space of a building. Various methods exist to accomplish the ground-side heat exchange for a GSHP, where the focus of this thesis remains on closed-loop systems which utilize loops of fused high-density polyethylene (HDPE) pipes buried vertically in boreholes ranging between 80 and 200 meters deep. This thesis provides an overview of the critical design considerations used in sizing a BHE where a comparison is made between a typical U-tube BHE and a thermally improved coaxial BHE where various benefits may be realized by the latter. The motivation for this research is to provide a tool to accurately compare various coaxial systems, where a semi-analytical model for heat transfer is proposed. The proposed model, referred to as the composite coaxial (CCx) model, is semi-analytical in nature being that it relies on a curve-fitted cylindrical response function, or g-function. The CCx model is made to produce accurate simulations for the fluid temperature measured at the outlet of a coaxial BHE over the course of a typical thermal response test (TRT). The model considers coaxial configurations where the inner and outer pipes may have differing thermal properties, diameters, and thicknesses. The model is validated using known input parameters and physical measured temperature data for three different TRTs showing root mean square errors (RMSE) as low as 0.09 °C, which is well within the uncertainty of the measurement for the given test. The general development of the model is largely empirical in nature, where various aspects were introduced keeping logical constraints in mind to produce an acceptable fit to each of the three physical tests. Further experimental analysis is performed using a lab-scale coaxial heat exchanger to verify the trends produced by the CCx model during short term operation considering laminar annular flow. The measured outlet fluid temperature is again compared to the temperature simulated by the CCx model showing an RMSE of 0.16 °C, which is again found to be within the uncertainty of the measurement. In summary, the primary contribution of this research is the CCx model itself, where this model has been developed as a tool for future use in the case-by-case optimization of coaxial systems. This model is capable of capturing the effect of various pipe materials and sizes as shown through the validation presented in this thesis.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».