Empirical Heat Transfer Model for Slug Flow and Bubble Flow in Vertical Subsea Pipes

Abstract

Abstract The prediction of flow assurance related problems for subsea pipelines, such as paraffin deposition, alphaltene deposition, corrosion, hydrate formation, cold oil line startup etc, all partially rely on valid heat transfer models. Compared with single-phase heat transfer and two-phase hydraulics, two-phase heat transfer is much more complicated because the mechanisms of heat transfer for specific flow patterns are different. A variety of empirical models have been developed for specific flow pattern of two-phase liquid-gas heat transfer. Some of them have been proved fairly accurate through research and literature review, such as Aggour model for bubble flow and Rezkallah model for slug flow both in vertical pipes. However, when these models are applied to subsea cooling conditions, the accuracy is not satisfactory. In this paper, the basic knowledge of two-phase flow is introduced. A new empirical heat transfer model is developed for both slug flow and bubble flow in vertical subsea pipelines. Experimental data proves this model works better than the existing models. Literature review indicates that this is the first model that can be applied to two flow patterns. From the results seen, the model can predict good accuracy. The paper therefore recommends the application of this model.