Two Phase Flow Boiling Heat Transfer and Pressure Drop of Two New LGWP Developmental Refrigerants Alternative to R-410A
Notice bibliographique
Résumé
To meet the terms of the Montreal Protocol, CFCs and HCFCs have been gradually phased out and they have been replaced by refrigerants that have zero ozone depletion potential. However, some of these fluids, such as R-410A, have global warming potential (GWP) that might still be of concern from an environmental perspective in case of leakage or improper charge management. Few studies of refrigerants that have zero ozone depletion potential and GWP less than 500 are available in the literature. Preliminary findings from these studies suggested that new development refrigerants were viable options. System COP and capacity were promising but there is not much information on the heat transfer and pressure drop characteristics of these low GWP refrigerants. This paper contributes to address this gap and provides new data for the two phase flow boiling heat transfer coefficient (HTC) and pressure drop of two new low GWP developmental refrigerant alternatives for R-410A. Heat transfer measurements were conducted for a copper tube commonly used in direct expansion evaporators of air conditioning systems with a 9.5 mm (0.375 in.) outside diameter and internally enhanced micro-finned surface. Data of local two phase flow HTC and pressure drop are presented for refrigerants R-410A, R-32, R-1234yf and the two new developmental refrigerants referred to as DR-5 and DR-5A. The experimental findings from this work indicated that the refrigerant R-32 had similar and slightly higher heat transfer coefficient than that of R-410A at same refrigerant mass flux and similar heat flux conditions on the outer surface of the tube. Refrigerant R-1234yf had about 15 to 20% lower heat transfer coefficient than R410-A at 4?C saturation temperature. For this saturation temperature the developmental refrigerants DR-5 and DR-5A had heat transfer coefficients between R-32 and R-1234yf when the vapor quality ranged from 0.2 to 0.7. An increase of the saturation temperature from 4°C to 9°C decreased the heat transfer coefficients for all of the refrigerants tested. The two phase flow boiling pressure drops increased monotonically if the vapor quality of the refrigerant increased. The pressure drops of refrigerant R-410A were the lowest while the pressure drop for refrigerant R-1234yf were the highest measured among the fluids investigated. The developmental refrigerants DR-5 and DR-5A showed identical characteristics in terms of pressure drop at both saturation temperatures of 4°C and 9°C.
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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 | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 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 ».