结霜工况下翅片管气化器表面气流换热特性试验研究

Experimental study on heat transfer characteristics of flowing air on the surface of finned-tube vaporizer under frosting conditions

为深入掌握气化器翅片管表面结霜过程中翅片管表面气流换热特性,以液氮为介质进行了翅片管表面结霜试验,分析了翅片表面结霜特性及气流温度、相对湿度沿翅片管轴向变化规律。结果表明:翅片管表面结霜最先出现在入口处的翅尖位置,沿翅片管径向越靠近翅根结霜现象越晚出现。结霜初期,翅片管(0mm—300mm)表面换热程度由强逐渐减弱,翅片管(600mm—900mm)表面换热程度由弱变强,随后逐渐减弱;结霜后期,整个翅片管表面换热程度呈稳定状态。可见,在设计气化器第一根翅片管时,应考虑适当增加翅片高度以延缓基管表面霜层的出现,提高气化器换热效率。这为进一步探寻合理有效抑制翅片管表面结霜方法提供了一定的理论基础。

An experiment on frosting on the finned - tube vaporizer surface was conducted with liquid nitrogen as the medi- um to investigate the flowing air heat transfer characteristics around the finned - tube surface. Frosting characteristics and the variation of the flowing air temperature as well as the relative humidity along the finned - tube axial direction were analyzed. The results indicate that frosting on the finned - tube surface appears earliest at the fin top of the finned - tube in the entrance region. The frosting occurs later at the position closer to the fin root along the radial direction of the finned - tube. At the beginning of frosting, the heat transfer intensity of the finned -tube surface （0mm--30Omm） gradually turns from strong to weak, and that of the finnedtube surfaee（600mm--900mm） varies from weak to strong then begins to descend. In the later frosting period, the heat transfer intensity of the whole finned - tube surface presents a stable state. Therefore, when the first finned - tube is designed, its height should be increased properly to delay frosting on the basic finned -tube surface and improve the heat transfer efficiency of the vaporizer, which provides a theoretical basis for the further study on reasonable and effective method to restrain frosting on the finned -tube surface.