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首页> 外文期刊>International Journal of Heat and Mass Transfer >Experimental study of the pressure drop during condensation in an inclined smooth tube at different saturation temperatures
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Experimental study of the pressure drop during condensation in an inclined smooth tube at different saturation temperatures

机译：不同饱和温度下倾斜光滑管冷凝过程中压降的实验研究

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Several applications exist in industry where condensation does not occur in horizontal or vertical tubes but in inclined tubes. Examples are aeroplanes during take-off, landing and banking, automobiles and trucks driving over hilly terrains and large industrial A- and V- frame condensers. However, very little work has been done for condensation in tubes at different inclination angles, and most work was done for flow in horizontal tubes and vertical tubes. The few studies that were conducted for flow at different inclination angles were limited to saturation temperatures of 40 ℃. Previous work showed that the saturation temperature of condensation influences the heat transfer and pressure drop results. Therefore, it was the purpose of this study to experimentally study the pressure drops during condensation in inclined tubes at different saturation temperatures. More than 700 condensation experimental data points were collected with the refrigerant R134a in a smooth copper tube of inner diameter of 8.38 mm for vapour qualities ranging between 0.1 and 0.9. The mass fluxes varied between 100 kg/m~2s and 400 kg/m~2s and measurements were taken at saturation temperatures of 30 ℃, 40 ℃ and 50 ℃. Inclination angles ranging from -90° (downward flow) to +90° (upward flow) were considered. The pressure drops were measured with a differential pressure transducer connected to the inlet and the outlet of the test section over a length of 1.704 m. The frictional pressure drops were also determined by using a recently developed void fraction drift model. It was found that the pressure drops were significantly influenced by the inclination angle and saturation temperature. The void fractions and frictional pressure drop results also showed that they were largely influenced by these parameters. While the highest and lowest measured pressure drops were obtained during the upward flow and downward flow respectively, the results obtained for the void fraction and the frictional pressure drop showed that the highest pressure drop values were obtained during the downward flow, while the lowest values were obtained during the horizontal and upward flows.
机译：在工业中存在几种应用，其中在水平或垂直管中不会发生冷凝，而在倾斜管中会发生冷凝。例如，飞机在起飞，着陆和航行期间的飞机，在丘陵地带行驶的汽车和卡车以及大型工业A型和V型冷凝器。但是，对于在不同倾斜角度下的管子中的冷凝水所做的工作很少，而对水平管子和垂直管子中的流动进行的工作最多。对于在不同倾角下流动的研究很少，但仅限于40℃的饱和温度。先前的工作表明，凝结的饱和温度会影响传热和压降结果。因此，本研究的目的是通过实验研究倾斜管在不同饱和温度下的冷凝过程中的压降。使用制冷剂R134a在内径为8.38毫米的光滑铜管中收集了700多个冷凝实验数据点，其蒸汽质量范围为0.1到0.9。质量通量在100 kg / m〜2s和400 kg / m〜2s之间变化，并在30℃，40℃和50℃的饱和温度下进行测量。考虑了从-90°（向下流动）到+ 90°（向上流动）的倾斜角度。用压差传感器测量压降，压差传感器连接到测试段的入口和出口的长度为1.704 m。摩擦压降也通过使用最近开发的空隙率漂移模型来确定。发现压力降受倾斜角度和饱和温度的影响很大。空隙率和摩擦压降结果也表明它们受这些参数的影响很大。虽然分别在向上流动和向下流动期间获得了最高和最低的测量压降，但对于空隙率和摩擦压降所获得的结果表明，在向下流动期间获得了最高的压降值，而最低值是在水平和向上流动过程中获得的。

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