The most prominent aspect of multiphase flow is the variation in the physical distribution of the phases in the flow conduit known as the flow pattern. Several different flow patterns can exist under different flow conditions which have significant effects on liquid holdup, pressure gradient and heat transfer. Gas–liquid two-phase flow in an annulus can be found in a variety of practical situations. In high rate oil and gas production, it may be beneficial to flow fluids vertically through the annulus configuration between well tubing and casing. The flow patterns in annuli are different from pipe flow. There are both casing and tubing liquid films in slug flow and annular flow in the annulus. Multiphase heat transfer depends on the hydrodynamic behavior of the flow. There are very limited research results that can be found in the open literature for multiphase heat transfer in wellbore annuli. A mechanistic model of multiphase heat transfer is developed for different flow patterns of upward gas–liquid flow in vertical annuli. The required local flow parameters are predicted by use of the hydraulic model of steady-state multiphase flow in wellbore annuli recently developed by Yin et al. The modified heat-transfer model for single gas or liquid flow is verified by comparison with Manabe’s experimental results. For different flow patterns, it is compared with modified unified Zhang et al. model based on representative diameters.

中文翻译：

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直井筒环空气液流动传热机理模型。


多相流最突出的方面是流道中相的物理分布的变化，称为流型。不同的流动条件下可能存在多种不同的流动模式，这对持液率、压力梯度和传热有显着影响。在各种实际情况中都可以发现环空中的气液两相流。在高速石油和天然气生产中，使流体垂直流过油管和套管之间的环形结构可能是有益的。环空中的流动模式与管道流动不同。环空中段塞流和环空流中均存在套管液膜和油管液膜。多相传热取决于流动的流体动力学行为。在公开文献中可以找到的关于井筒环空多相传热的研究成果非常有限。针对垂直环空中向上的气液流动的不同流动模式，建立了多相传热的机理模型。利用Yin等人最近开发的井筒环空稳态多相流水力模型来预测所需的局部流动参数。通过与Manabe实验结果的比较，验证了修正后的单一气体或液体流的传热模型。对于不同的流型，与修改后的统一Zhang等人进行了比较。基于代表性直径的模型。