浸没燃烧式气化器换热管内跨临界液化天然气的传热特性

发布时间：2018-08-25 15:49

【摘要】：浸没燃烧式气化器(SCV)换热热阻主要存在于换热管内部,研究管内跨临界液化天然气(LNG)传热特性对提高设备整体的换热效率具有重要意义。本文建立了能够描述换热管内跨临界LNG流动与传热过程的数值计算模型,分析了换热管内LNG的传热规律,获得了入口速度、入口压力和壁面热通量对局部传热系数的影响规律,提出了适用于预测管内跨临界LNG传热特性的量纲为1关联式。结果表明,沿着LNG流动方向,局部流体传热系数先增大后减小,且最大值出现在拟临界温度附近,超临界条件下LNG热物性剧烈变化是引起强化传热的主要原因;在一定范围内,提高入口速度可以有效地强化流体传热能力,局部流体传热系数的最大值主要取决于入口压力,增加壁面热通量会缩短局部流体传热系数达到最大值所需的时间;提出的量纲为1传热关联式平均绝对相对误差为6.53%,且预测值落在±25%相对误差范围内的比例为99.42%。该研究成果可为掌握SCV设计方法和高效运行技术提供参考。
[Abstract]:The heat transfer resistance of submerged combustion gasifier (SCV) mainly exists in the heat transfer tube. It is important to study the heat transfer characteristics of transcritical liquefied natural gas (LNG) in the tube to improve the overall heat transfer efficiency of the equipment. In this paper, a numerical model is established to describe the transcritical LNG flow and heat transfer process in a heat transfer tube. The heat transfer law of LNG in a heat transfer tube is analyzed, and the influence of inlet velocity, inlet pressure and heat flux on the local heat transfer coefficient is obtained. A dimensionality correlation is proposed for predicting the transcritical LNG heat transfer characteristics in a tube. The results show that the local heat transfer coefficient increases first and then decreases along the direction of LNG flow, and the maximum value appears near the pseudo-critical temperature. The severe change of thermal properties of LNG under supercritical conditions is the main cause of enhanced heat transfer. Increasing the inlet velocity can effectively enhance the heat transfer capacity of the fluid. The maximum value of the local heat transfer coefficient mainly depends on the inlet pressure. Increasing the wall heat flux will shorten the time required for the local fluid heat transfer coefficient to reach the maximum value. The average absolute relative error of the correlation equation is 6.53, and the ratio of the predicted value to 卤25% relative error is 99.42%. The research results can provide a reference for mastering SCV design method and efficient operation technology.
【作者单位】：大连理工大学化工机械与安全学院;
【基金】：中央高校基本科研业务费专项资金资项目(DUT16QY29)
【分类号】：TE626.7

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