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水平管内油水乳状液流动特性研究 总被引:3,自引:0,他引:3
对水平管内油包水型(W/O)和水包油型(O/W)油水乳状液进行了深入的实验研究。根据实验结果分析得出一个新的油水乳状液表观粘度的表达式,同时也得出一个新的油水乳状液相转变的判别式,并提出采用Re数和摩擦阻力系数的关联式计算摩擦阻力的方法,也得到判别油水乳状液为牛顿流体和非牛顿流体的方法 相似文献
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The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superflcial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems. 相似文献
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油包水乳状液的微观特性是影响乳状液稳定性的重要因素。为了降低采出液破乳难度、减小管线运输负担,有必要弄清楚乳状液的微观特性。影响油包水乳状液稳定性的微观因素主要有四部分:乳滴的大小、形状以及分布,乳状液界面张力,界面膜性质和界面剪切黏度。阐述了影响乳滴大小、形状、分布主要因素的研究进展,并简要介绍了乳状液液滴粒径分布的测量方法;报告了油包水乳状液界面张力大小主要影响因素的研究现状;阐述了界面膜的分子密度与机械强度对油包水乳状液稳定性的影响;对乳状液界面剪切黏度的影响因素进行了研究,对界面剪切黏度的研究现状作出评述,并介绍了测量界面剪切黏度的方法。 相似文献
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在压力11.5~28 MPa,质量流速450~1550 kg·m-2·s-1,内壁热负荷50~585 kW·m-2的范围内,对水在垂直下降管内的传热特性进行了实验研究,得到了垂直下降管内水的传热特性,分析了热负荷对内壁温度和传热系数的影响,给出了能用于工程实际的传热实验关联式,并且对垂直下降流动和垂直上升流动的传热特性进行了比较。实验结果表明:在亚临界和近临界压力区,垂直下降管会发生第一类传热恶化--膜态沸腾和第二类传热恶化--干涸。热负荷的增大,会导致传热恶化的提前发生和传热恶化发生后的壁温飞升值增大。在超临界压力区,壁温在低焓值区随焓值平缓增加,而在高焓值区随焓值明显升高,表明在拟临界点附近发生了传热强化现象。 相似文献
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垂直立管中催化剂流动特性的实验研究 总被引:4,自引:1,他引:3
对垂直立管中催化剂的流动性能进行了实验研究,测定了各种操作条件下立管中的轴向压力分布、催化剂循环速率以及附加吹气的影响. 实验结果表明,立管中的气固流动存在分别处于负压差下移下流区的"脱气段"和处于正压差下移下流区的"持气段"两种流动状态;下料阀开度对固体循环流率有明显的约束作用,且使"持气段"总压降增加较"脱气段"更为明显;对立管引入附加吹气有明显的增压作用,并使立管的压力分布有较大的改变. 根据实验结果及分析,对垂直立管的管形设计和催化剂在垂直立管中的密相输送提出了分析与建议. 相似文献
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对电脱水工艺流程分析及流体力学机理探究,通过理论分析以及对其已有研究成果借鉴参考。分析得出油水乳状液流量分别从流态、流变性及停留时间三个方面影响电脱水器效率,并分别探讨其机理,推导出一些理论成果,对生产及后续研究有一定积极作用。 相似文献
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介绍了油水混合液在电磁场下的分离过程原理,建立了电磁场油水分离物理及数学模型,并进行了油水分离特性模拟研究,重点研究磁场强度、电流密度、入口流速、油滴粒径等关键因素对油水分离过程和流动特性的影响。结果表明:其他条件不变时,随磁场强度或电流密度的增大,分离效果增强,且存在一个临界电磁力值,只有当实际电磁力大于临界电磁力时,才能实现预期的分离效果;随入口流速的增大,油水混合流在电磁场中的分离作用时间减少,分离效果减弱;随油滴粒径的增大,分散油相受到的浮力增大,分离效果增强。 相似文献
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引言螺旋丝是一种有效的传热强化元件,而且安装简便,使用灵活,Chiou〔1〕最先进行了研究.此后,不少学者进行了螺旋丝用于水平管内、水平管外的凝结换热及油类介质传热强化的研究,但对于竖直管内插螺旋丝的凝结换热的研究到目前还是空白.由于管内凝结换热的复杂性,对于换热规律的研究基本是以实验研究为主.其中较有代表性的是Shah〔2〕在综合了474个实验点基础上提出的适用于水平管、竖直管和倾斜管的管内凝结换热通用关联式.在理论解方面,较早且使用较为方便的是Carpenter和Colburn〔3〕提出的计算式.至于凝结换热强化管的传… 相似文献
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本文在考虑影响气体横掠螺旋翅片管管束的对流换热的诸因素的基础上,使用两相闭式热虹管为传热元件,根据等雷诺数法的原则,通过试验及数据处理,对传热特性和阻力特性进行了分析和研究,并提出相应的数学准则式,这些公式可为设计提供依据。 相似文献
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<正>1引言 传热恶化有不同的类型,就工程换热设备设计和运行的实际需要来说,人们最关心的是以下几点:(1)传热恶化发生的位置(壁温飞升起始点),一般用。cr来表示;(2)传热恶化发生后壁温飞升的最大值,一般用A儿。。来表示;(3)壁温飞升最大值的位置,一般用K。。。来表示;(4)传热恶化发生后的。mi。。本文着重分析讨论后3个问题。 相似文献
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An experimental study was performed to investigate the heat transfer characteristics of the non-boiling annular two-phase flow of nitrogen gas and subcooled water through a small vertical heated tube with uniform wall heat flux. The experimental results were compared with the numerical calculations based on the two-phase flow boundary layer model. The experimental data show that the annular two-phase flow of nitrogen gas and subcooled water in a small vertical tube can provide quite high heat transfer ability, while wall temperatures lie in a low range even if at quite high wall heat fluxes. In particular, the highest values of the wall temperatures are insensitive to the change of flowing and heating conditions. This characteristic is quite suitable for highly effective cooling of polymer electrolyte membrane fuel cells. 相似文献
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An experimental study was performed to investigate the heat transfer characteristics of the non-boiling annular two-phase flow of nitrogen gas and subcooled water through a small vertical heated tube with uniform wall heat flux. The experimental results were compared with the numerical calculations based on the two-phase flow boundary layer model. The experimental data show that the annular two-phase flow of nitrogen gas and subcooled water in a small vertical tube can provide quite high heat transfer ability, while wall temperatures lie in a low range even if at quite high wall heat fluxes. In particular, the highest values of the wall temperatures are insensitive to the change of flowing and heating conditions. This characteristic is quite suitable for highly effective cooling of polymer electrolyte membrane fuel cells. 相似文献
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An experimental investigation of sudden initiation and cessation of laminar flow in a tube following the opening and closure of a direct acting solenoid valve is reported for Newtonian fluids in the viscosity range 0.9 ≤ μ ≤ 39.5 centipoise. A non-contact probing Laser Doppler Anemometer and a high speed data logging system are used to make local axial velocity measurements at 85 tube diameters from the entrance to a test section, 1.36 cm I.D. and 1.4 meters long. Some qualitative measurements of the pressure gradient over the test section are also made.
The results show that for Newtonian fluids, with μ ≤ 27.1 cp, the sudden opening or closure of the solenoid valve is not equivalent to a step input in either pressure drop or flow rate. Both show overshoots, the magnitude of which decreases with increasing viscosity of the fluid. The normalized time for a 90% development or decay increases with the viscosity of the fluid. For fluids with μ ≥ 39.5 cp, the behavior appears to approach that due to a step input in pressure gradient. 相似文献
The results show that for Newtonian fluids, with μ ≤ 27.1 cp, the sudden opening or closure of the solenoid valve is not equivalent to a step input in either pressure drop or flow rate. Both show overshoots, the magnitude of which decreases with increasing viscosity of the fluid. The normalized time for a 90% development or decay increases with the viscosity of the fluid. For fluids with μ ≥ 39.5 cp, the behavior appears to approach that due to a step input in pressure gradient. 相似文献
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An experimental investigation of sudden initiation and cessation of laminar flow in a tube following the opening and closure of a direct acting solenoid valve is reported for Newtonian fluids in the viscosity range 0.9 ≤ μ ≤ 39.5 centipoise. A non-contact probing Laser Doppler Anemometer and a high speed data logging system are used to make local axial velocity measurements at 85 tube diameters from the entrance to a test section, 1.36 cm I.D. and 1.4 meters long. Some qualitative measurements of the pressure gradient over the test section are also made. The results show that for Newtonian fluids, with μ ≤ 27.1 cp, the sudden opening or closure of the solenoid valve is not equivalent to a step input in either pressure drop or flow rate. Both show overshoots, the magnitude of which decreases with increasing viscosity of the fluid. The normalized time for a 90% development or decay increases with the viscosity of the fluid. For fluids with μ ≥ 39.5 cp, the behavior appears to approach that due to a step input in pressure gradient. 相似文献
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细竖管内流动凝结液膜的稳定性分析 总被引:1,自引:1,他引:0
从能量分析的角度入手 ,研究细竖圆管内流动凝结过程中各作用因素对凝结液膜波动稳定性的影响 ;分析了管径、重力加速度、干度、表面张力、扰动波长以及相变等因素对液膜波动的作用机理 所得结果将有助于探讨细竖管内流动凝结液膜的波动规律 ,加深对流型的转换和不连续流动成因的理解 相似文献