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现行 3293(RP-469)
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Heat Transfer and Pressure Drop Performance of Smooth and Internally Finned Tubes with Oil and Refrigerant 22 Mixtures 润滑油和制冷剂混合物光滑内翅片管的传热和压降性能
通过使用强化性能比(定义为传热强化与压降增加之比)来比较光滑管和两个强化管的总体性能。将增强管与纯R-22的光滑管以及R-22与150或300-SUS环烷酸矿物的混合物进行比较。此外,将含有制冷剂混合物的三根管子的性能与含有纯制冷剂的同一根管子的性能进行了比较。测试了高达5%(按重量计)的各种off浓度,质量通量在92~000到294000磅/小时之间变化(125到400千克/平方米秒)。标称蒸发条件为37华氏度(3摄氏度),入口和出口质量分别为15%和85%。冷凝条件为105°F(41°C),入口和出口质量分别为85%和15%。微控制器的增强性能比- 翅片管始终高于使用纯制冷剂或制冷剂油混合物的低翅片管。对于纯制冷剂,增强管的增强性能比通常大于1,表明相对于光滑管的性能有所改善。然而,对于混合制冷剂油,增强管相对于光滑管的增强性能比趋于降低;增强管的整体优势并不像制冷剂混合物那样具有决定性。引文:ASHRAE Transactions,第95卷,pt。1989年,温哥华
The overa// performance of a smooth tube and two augmented tubes is compared by using an enhancement performance ratio, defined as the ratio of heat transfer enhancement to pressure drop increase. The augmented tubes are compared to the smooth tube with pure R-22 and with mixtures of R-22 plus 150- or 300-SUS naphthenic mineral off. Additionally, the performance of all three tubes with refrigerant-off mixtures is compared to performance of the same tube with pure refrigerant. Various off concentrations up to 5% by weight were tested and mass flux was varied from 92~000 to 294,000 Ib/h.~ (125 to 400 kg/m2.s). Nominal evaporation conditions were 37°F(3°C) with inlet and outlet quafities of 15% and 85%, respectively. The condensation conditions were 105°F (41°C) with inlet and outlet quafities of 85% and 15%, respectively.The enhancement performance ratio of the micro-fin tube is consistently higher than that of the low-fin tube with either pure refrigerant or refrigerant-oil mixtures. With pure refrigerant, the enhancement performance ratio of the augmented tubes is generally greater than unity, indicating improved performance relative to a smooth tube. With refrigerant-oil mixtures, however, the enhancement performance ratio of the augmented tubes relative to the smooth tube tends to decrease; the overall advantage of the augmented tubes is not as definitive with refrigerant-off mixtures.
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