Enhancement on steam condensation heat transfer with hydrophilic/hydrophobic combination surfaces of PVDF hollow fiber heat exchange tubes

doi:10.11949/j.issn.0438-1157.20171639

Abstract

Abstract:

To solve the problem that plastic heat exchange tubes presented a low thermal conductivity, the surface hydrophilic(PVDF/SPES) and surface hydrophobic(PVDF) hollow fiber heat exchange tubes with dense/non-dense layer composite structure were prepared by controlling the content of sulfonated poly(ether sulfone)(SPES) in the casting solution during the course of non-solvent induced phase separation(NIPS). The outside surface contact angle of PVDF/SPES and PVDF tubes were 49.8° and 78.1°, respectively. The non-dense layer was filled with water to improve the thermal conductivity of heat exchange tubes. Single surface hydrophobic and hydrophilic heat exchange tube were weaved together to prepare tubular plastic heat exchanger. Thus, a hydrophilic/hydrophobic combination surface for steam condensation from outside surfaces of two tubes was built in the shell of heat exchanger. On this basis, the strengthening effect of steam condensation heat transfer on the combination surface was studied. The results showed that compared with the hydrophobic surface of dense PVDF heat exchange tubes prepared by melt-spinning method, the total steam condensation heat transfer coefficient on hydrophilic, hydrophobic and hydrophilic/hydrophobic combination surface prepared by NIPS method were improved by 46.6%, 56.5%, and 99.7%, respectively. Therefore, the hydrophilic/hydrophobic combination surface could strength obviously steam condensation heat transfer in comparison with single hydrophilic and hydrophobic surface.

Key words: PVDF, hollow fibers, heat exchange tubes, hydrophilic/hydrophobic, surface, condensation, heat transfer

摘要：

针对塑料换热管热导率低的问题，采用非溶剂致相分离法（NIPS），通过控制铸膜液中磺化聚醚砜（SPES）添加量，制备出具有致密层/非致密层复合结构，外表面接触角分别为49.8°、78.1°的中空纤维表面亲水（PVDF/SPES）、表面疏水（PVDF）换热管，在非致密层内填充水，从而提高换热管导热性能。将单根的表面亲水、疏水换热管编织，在列管式塑料换热器壳程，利用两根换热管的外表面，构建蒸汽冷凝用亲/疏水组合表面，研究该表面上蒸汽冷凝传热强化效果。研究表明，较熔融拉伸法制备的致密PVDF换热管疏水表面，NIPS法制备的亲水表面、疏水表面及亲/疏水组合表面上的蒸汽冷凝总传热系数分别提高46.6%、56.5%、99.7%。可见，较单一的亲水或疏水表面而言，亲/疏水组合表面能够显著强化蒸汽冷凝传热性能。

关键词: PVDF, 中空纤维, 换热管, 亲/疏水, 表面, 凝结, 传热

CLC Number:

TQ028.8

JIA Wei, GAO Qijun, LÜ Xiaolong, CHEN Huayan, WANG Xuan, DONG Chang. Enhancement on steam condensation heat transfer with hydrophilic/hydrophobic combination surfaces of PVDF hollow fiber heat exchange tubes[J]. CIESC Journal, 2018, 69(7): 2935-2943.

贾巍, 高启君, 吕晓龙, 陈华艳, 王暄, 董畅. PVDF中空纤维换热管亲/疏水组合表面强化蒸汽冷凝传热[J]. 化工学报, 2018, 69(7): 2935-2943.

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