Abstract:

The heat transfer in the cooling process of subsea oil and gas pipeline is a key factor of the flow assurance in offshore petroleum industry, such as wax, hydrate etc. In this study, capacitance probe, thermocouple and resistance thermometer were used to measure the flow and heat transfer characteristics of oil-gas slug flow in different cooling conditions and the effect of flow parameters on heat transfer of slug flow was analyzed. It was demonstrated that the convective heat transfer coefficient of oil-gas slug flow is mainly affected by the liquid superficial velocity. While the temperature of the outer cooling fluid is decreased, the viscosity of the inner thermal fluid at the bottom of the tube will increase and the thickness of the thermal boundary layer will be increased, therefore the heat transfer will be deteriorated. Also the convective heat transfer coefficient of oil-gas is much lower than that of water-gas due to the different viscous force and boundary layer. The local convective heat transfer coefficient is increasing from the top to the bottom of the tube along the circumferential direction. Moreover, the correlation and heat transfer model of oil-gas slug flow under cooling condition were presented.

Key words: gas-liquid flow, heat transfer, multiphase flow, cooling condition, slug flow

摘要：

海底油气管道的冷却传热过程是结蜡、水合物等海洋石油工业流动保障问题的关键控制因素。采用电容探针与热电偶、热电阻等流动及温度测量手段对不同冷却条件下空气-油段塞流的流动参数和传热参数进行实验测量，分析了空气-油段塞流流动参数对传热特性的影响，并与空气-水对流换热进行对比。结果表明，空气-油段塞流对流传热系数主要受液相折算速度的影响，且冷却液温度越低，管底热流体黏度越大，导致热边界层越厚，传热系数降低；受黏性力及边界层影响，对流传热系数远小于空气-水；沿管壁周向，从管顶到管底的对流传热系数不断增大。提出了适用于冷却条件下的油气段塞流传热关联式和传热模型。

关键词: 气液两相流, 传热, 多相流, 冷却条件, 段塞流