不同组分天然气在绕管内流动传热特性数值研究

摘要

To study the impact of natural gas with different components on the performance of LNG spiral-wounded ex changer,numerical simulation was conducted in this paper to analyze the flow and heat transfer characteristics of different components natural gas in the spiral-wounded tube.Six natural gases with different composition of methane and ethane at 6.4MPa were used as working fluids.The impact of the proportion of component ethane in the mixture,Re and Pr on the pressure drop and Nu of these 6 natural gas mixture in the spiral-wounded tube were studied carefully.The results show that with the increase of the proportion of component ethane in the mixture,the increasing amplitude of the pressure drop of the gaseous mixture with the increase of Re will become smaller,while that of the pressure drop of the liquid mixture will become larger.In the state of gas,the increase of ethane component will enhance the heat transfer in the tube,whereas in the state of liquid,the increase of ethane component will weaken the heat transfer in the tube.The Nu formulae are also fitted in terms of simulation results.%针对目前LNG绕管换热器设计时,考虑不同天然气组分对流动换热性能的影响,采用数值模拟方法分析了不同组分天然气在绕管内流动的传热特征.研究采用6.4MPa的6组不同组分的甲烷和乙烷混合物作为工质,探讨了混合物乙烷组分比重、雷诺数Re、普朗特数Pr对压降和努塞尔数Nu的影响.结果表明:在气态时随着乙烷组分比重的增加,混合物压降随Re数增加幅度变小;而在液态时混合物压降则随着混合物中乙烷组分比重的增加,压降随Re数增加幅度变大.在气态时乙烷组分增大有利于传热,而在液态时乙烷组分增大不利于传热,最后根据模拟结果拟合出适用的Nu公式.