超级开架式气化器传热管换热过程的数值模拟分析

Numerical simulation analysis of a heat transfer tube in SuperORV

超级开架式气化器(SuperORV)是一种以海水为热源的新型气化器,它采用双层结构的传热管,可有效改善传统开架式气化器管束外结冰的状况并提高换热效率,而目前国内对该装置传热性能的研究还较少。为此,对SuperORV关键传热单元——传热管的换热过程进行了模拟研究,建立了SuperORV传热管整体换热过程的传热计算模型。该模型利用两组离散化方程组分别描述了SuperORV传热管气化段和加热段的传热过程,在给定的尺寸和边界条件下对传热管的整体换热性能进行了数值模拟,得到了传热管各个局部的表面换热系数和温度分布曲线,进而推导出了传热管总换热系数和热流密度的分布曲线。海水和外翅片管上的温度分布曲线可用于预测传热管外表面易结冰的位置,传热管总换热系数和热流密度的分布曲线则可为传热管的整体换热性能描述提供帮助。该模型及相关模拟分析可望为该类气化器的设计、选型和运行管理提供参考。

Super Open Rack LNG Vaporizer （SuperORV）, a new type of vaporizer using sea water as a heat source, has a doubled tube structure which can so markedly weaken icing conditions outside the tube as to improve the overall heat transfer efficiency. However, such related research in China has not yet been found on this subject. Therefore, in this paper, a simulation study was conducted to investigate the LNG （Liquefied Natural Gas） evaporating process in a SuperORV heat transfer tube. At first, calcula tion models were established of the overall heat transfer process. Two groups of discrete equations were then utilized to describe the heat transfer process in vaporizing and heating sections of this equipment. Under the given size and boundary conditions, a numerical study was carried out of the performance of the heat transfer tube and the heat exchange coefficient and temperature distribution curves were obtained for the surface of each zone, based on which the distribution curves of heat flux density and cumulative heat ex- change coefficient were thus derived. These curves would be helpful for the description of overall heat exchanging performance of the tube; on the other hand, the temperature distribution curve of sea water vs. the exterior fin tube could be used to predict the freeze position on the external surface of the heat transfer tube. This study provides reference for the design, type selection and operation management of LNG SuperORV facilities.