基于翅片板结构的烟气对流冷凝传热性能

在冷凝实验台上对一种用于冷凝式烟气余热回收的翅片板换热器进行实验,研究了该结构的传热和流动性能,分析了烟气温度、流速等对冷凝的影响,得到了Nu-Re和 f-Re曲线,并对该换热结构在干空气风洞实验台上测试的结果进行了比对.结果表明:由于大量不凝性气体的影响(质量分数为92%),冷凝传热对整体传热性能的强化并不明显,伴随有冷凝的烟气表面传热系数约为相同工况下无凝结表面传热系数的1.1～1.2倍.得到了无量纲数冷凝传热准则关联式,可以为冷凝式翅片板换热器的设计提供参考. 

Experiment on forced convection-condensation heat transfer characteristics based on finned plate configuration

Experimental investigation of forced convection-condensation heat transfer and flow characteristics based on finned plate heat exchanger for condensing heat recovery was studied.With the experimental data, the effect of outlet flue gas temperature and velocity on condensation performance was studied, and the performance curves of Reynolds number-Nusselt number and Reynolds number-friction factor have been obtained.Meanwhile, the comparison of experimental results between wind tunnel test (using air as working fluid) and condensation test (using flue gas as working fluid) was also presented.From these results it can be seen that, due to the extensive non-condensable gas (about 92%), enhancement of overall heat transfer performance is not obvious, and the forced convection-condensation heat transfer coefficient is 10%-20% times more than that of the forced convection without condensation.A heat transfer criterion-based relational expression under the operating condition was also obtained.These results provide insight into improved designs of finned plate heat exchangers for condensing heat recovery.