0.5 MPa下液化天然气在竖直圆管中饱和流动沸腾传热

建立了一套实验装置用于对8 mm内径圆管内的液化天然气流动沸腾传热特性进行实验研究。测试压力为0.5 MPa，液化天然气质量流量为50～200 kg·m^-2·s^-1，热通量为8.0～36.0 kW·m^-2。主要研究了热通量、质量流量和干度等影响因素对传热的影响。发现质量流量对传热有重大影响，液化天然气管内流动沸腾传热系数一般随质量流量的增加而增大。而热通量对传热的影响主要体现在低干度范围内，且在质量流量较小时更为明显。而当干度小于0.5～0.6时，传热系数一般随干度的增加而增大。但当干度大于0.6时，传热系数随干度的增加显著下降。将实验结果与4种现存的混合物流动沸腾传热关联式进行比较，结果表明Zou等提出的计算关联式与实验结果最接近，计算误差约为30.2%。

Flow boiling heat transfer of LNG in vertical smooth tube at 0.5 Mpa

An experimental apparatus was set up for study on the heat transfer characteristics of liquefied natural gas (LNG) flow boiling in a vertical smooth tube with 8 mm inner diameter. The experiments were performed at pressure of 0.5 MPa, with mass fluxes from 50 to 200 kg·m^-2·s^-1 and heat fluxes from 8.0 to 36.0 kW·m^-2. The influences of quality, heat flux and mass flux on the heat transfer characteristics were examined and discussed. The results show that the mass flux has a strong effect on the heat transfer coefficient of LNG. The heat transfer coefficient increases with the mass flux. It also increases with the heat flux when the vapor quality is low. This phenomenon is more noticeable at low mass flux. When the vapor quality is lower than 0.5□6, the heat transfer coefficient increases with the quality; when the quality is higher, the heat transfer coefficient decreases. The experimental heat transfer coefficients were compared with predicted values by four existing correlations. The correlation of Zou et al. gives the best prediction with the deviation of ±30.2%.