锚型导液器对HFC245fa水平管束外冷凝换热的影响

提出采用锚型导液器消除水平管束外膜状凝结换热管束效应的方法，通过对比试验研究了导液器对HFC245fa水平管束外膜状凝结换热特性的影响。设计了带锚型导液器的试验管束，试验管束由4列排深为5排的列管构成，试验换热管包括光管、二维肋管与三维肋管，试验换热管公称外径均为19.05 mm。结果表明：① 锚型导液器可有效控制管束效应对光管与三维肋管外膜状凝结换热影响，使排深为5处光管与排深为4处三维肋管冷凝传热系数分别提升33%与80%；② 锚型导液器对管束中单管冷凝换热性能的影响可忽略；③ 加装锚型导液器可使DN600卧式光管（或三维肋管）管束降低管材消耗20%（或30%）以上。

Effects of anchor-type ducts on film condensation of HFC245fa on horizontal tube bundle

Tube row effect, part of the inundation effect induced by falling condensate formed on neighboring tubes above, has hindered the heat transfer of shell and tube condenser for a long time. This paper put forward a scheme to eliminate the tube row effect by anchor-type ducts and further investigated its effect on film condensation heat transfer coefficient (CHTC) of HFC245fa on the tube bundles. A 4-line-wide and 5-row-deep tube bundle consisting of smooth tubes and finned tubes, with two columns out of the four equipped with the anchor-type ducts, was built in the test section. Equivalent outside diameter and active length of all tubes in the test section were 19.05 and 500 mm, respectively. The modified Wilson plot method was used to determine the waterside convection heat transfer. The short-period-calibrate method and homogenous method were used to determine the tube row effect with high-precision. Results show that: ① tube row effect can be well controlled by the anchor-type ducts; ② adverse effect of anchor-type duct on CHTC of each tube in the bundle is negligible; ③ with the anchor-type duct, more than 20% (or 30%) of smooth tubes (or enhanced tubes with three dimension fins) can be saved for a tube bundle in a shell-tube condenser of diameter 600 mm. This paper can be used to guide the design of high efficiency shell-tube condenser.