新型传热管材——导热塑料

<正> 导热塑料是一种功能性高分子材料.采用导热塑料翅片管作为换热器的新型传热管,具有耐腐蚀、抗结垢、重量轻、易成形、加工方便、成本低等优点.导热塑料的基材品种很多,如聚丙烯、聚酰胺、聚全氟乙丙烯、聚三氟氯乙烯等.     

氟塑料换热器工艺（液—液状态热交换）设计的一般原则

（1）一般情况下选择加工性能良好的聚全氟乙丙烯作为换热管的材质。当对工作温度或压力有高要求且传热面积不大和流体有强腐蚀性的情况下采用聚四氟乙烯作为换热管的材质。     

聚全氟乙丙烯聚合工艺研究

通过改变聚合介质、改进共聚反应控制方法,对聚合物进行改性及产业化工艺优化,研究出工艺合理、流程简易,生产过程中能耗物耗低、人工少的聚全氟乙丙烯聚合工艺,且聚全氟乙丙烯产品性能稳定。     

PP中空纤维换热管外表面改性强化蒸汽冷凝传热

针对塑料换热管传热性能不佳的问题,采用界面聚合法,以间苯二胺(MPD)为水相单体,均苯三甲酰氯(TMC)为有机相单体,对聚丙烯(PP)中空纤维换热管疏水性外表面进行局部亲水性改性,以形成呈"孤岛"分布的亲水性聚酰胺层,从而构建蒸汽冷凝用亲-疏水性组合表面.在此基础上,研究改性PP换热管强化蒸汽冷凝传热效果.换热管改性后...     

石墨及其表面改性对硅橡胶导热性能的影响

用双辊混炼机将导热填料分散到聚甲基乙烯基硅氧烷中,再配以增强剂、硫化剂等,经模压硫化制得导热硅橡胶。研究了导热填料种类、石墨的表面改性和用量以及石墨与炭黑的复配对硅橡胶导热性和力学性能的影响。结果表明,在用量相同的情况下,导热填料的导热系数越高,其填充硅橡胶的导热性越好,且硅橡胶的导热系数随导热填料用量的增加而增大。石墨的表面改性改善了石墨与硅橡胶的界面相容性,使硅橡胶的力学性能和导热性都得到提高。不同粒径及颗粒形态的炭黑与石墨复合可改善硅橡胶的导热性和力学性能,导热硅橡胶的拉伸强度和扯断伸长率随复合填料中炭黑用量的增加而提高,当石墨与炭黑质量比为25/5时,硅橡胶的导热系数最高,综合性能较好。     

氟塑料换热器可以推广使用

锦西化工厂试制的氟塑料换热器(F-46换热器),通过技术鉴定,认为可在工业生产中推广使用。氟塑料换热器是用国产聚全氟乙丙烯树脂制成的。其主要特点是:换热管和花板都用氟塑料制造。它与金属换热器比较,具有耐腐蚀、不结垢、体积小、重量轻、适应性强、传     

换热器表面复合涂层的制备及耐腐蚀与导热性能

为了提升换热器表面耐腐蚀性且不影响换热器的换热效果,以石墨烯、石墨粉末、环氧树脂等为原料,制备了应用于换热器表面的耐腐蚀高导热石墨烯复合涂层。对涂层进行了硫酸腐蚀、导热、结合强度实验,结果表明:涂层的耐腐蚀性能随石墨烯含量的增加而提升,当石墨烯质量分数达到0.06%时,涂层的腐蚀速率达最低值0.2338 mg/(cm~2·h),其耐腐蚀性能远强于304不锈钢的1.500 mg/(cm~2·h);涂层的导热性能随石墨粉含量的增加而提升,且当石墨粉质量分数为8%时达到最大值35.848 W/(m·K);涂层的结合强度达到ASTM等级5B。     

PVDF中空纤维换热管超疏水表面强化蒸气滴状冷凝传热

为了提高塑料换热管的传热性能,通过两步涂覆法制备了具有超疏水表面的复合塑料换热管。首先采用多孔PVDF中空纤维膜为支撑层,以导热材料纳米ZnO填充聚二甲基硅氧烷(PDMS)为皮层,制备了具有致密外表皮层的复合塑料换热管。其次为了强化蒸气的滴状冷凝传热,通过考察正硅酸乙酯含量,氨水含量等条件的影响,制备出了具有超疏水表面的PVDF复合塑料换热管。结果表明,所制备的换热管表面接触角可达154°,与熔融法及NIPS法制备的换热管相比,总传热系数可提高85.3%～147.3%。     

PVDF中空纤维换热管超疏水表面强化蒸气滴状冷凝传热

为了提高塑料换热管的传热性能，通过两步涂覆法制备了具有超疏水表面的复合塑料换热管。首先采用多孔PVDF中空纤维膜为支撑层，以导热材料纳米ZnO填充聚二甲基硅氧烷（PDMS）为皮层，制备了具有致密外表皮层的复合塑料换热管。其次为了强化蒸气的滴状冷凝传热，通过考察正硅酸乙酯含量，氨水含量等条件的影响，制备出了具有超疏水表面的PVDF复合塑料换热管。结果表明，所制备的换热管表面接触角可达154°，与熔融法及NIPS法制备的换热管相比，总传热系数可提高85.3%～147.3%。     

聚全氟乙丙烯高分子物化性能

关于聚全氟乙丙烯树脂的一般性能通常都列在产品标准、产品说明书、产品介绍及加工指导等资料中，在这些理化指标的后面则是为什么聚全氟乙丙烯会有这样一些性能？是什么原因使聚全氟乙丙烯与其他氟塑料之间存在差异？本文收集并整理了大量的资料，对其中有关聚全氟乙丙烯高分子物理化学方面的一些研究成果加以归纳，从中可以基本反映出聚全氟乙丙烯大分子内部的结构和特性。     

高分子中空纤维蒸发器传热过程分析

蒸发器广泛应用于化工、食品等行业,传统的金属管蒸发器由于其耐酸碱腐蚀性差、表面易结垢等弱点,一定程度上限制了其应用范围,而具有优良性能的高分子中空纤维管可有效解决这些问题,具有很好的应用前景。采用自制的高分子改性中空纤维管,制备出非金属换热器,并进行了蒸发传热实验。结果表明,高分子中空纤维蒸发器的性能与料液温度有密切关系,沸腾进料时蒸发器的传热系数、产水量和热量利用率均高于低温进料;传热热阻主要集中在管外蒸汽加热侧和管壁的导热性能,当沸腾进料时管壁热阻占总传热热阻的66%以上,而管内蒸发侧传热热阻所占比重较低,均低于15.3%,且随着料液流速的增大而降低到5%以下;随着料液温度的降低,蒸发过程的传热系数、能量利用效率以及产水量均显著下降。     

导热聚烯烃复合材料及其应用研究

研究了聚烯烃导热塑料复合材料及其应用,研究表明,由于填充不同的导热材料(如铜纤维、铝纤维、铝粉、石墨、鳞片石墨),导热聚丙烯复合材料导热系数为0.800~8.650W·m-1·K-1,达到普通塑料导热系数(约0.2W·m-1·K-1)的4~42.25倍。导热线型低密度聚乙烯有优良的力学性能和导热性能。导热聚烯烃复合材料已用于采暖、地热利用和蓄冰空调工程。     

用于烟气余热回收的塑料翅片管换热器的设计及分析

排烟热损失约占锅炉全部热损失的一半以上,回收烟气余热有助于节能减排。针对烟气余热回收中的腐蚀问题,基于导热塑料设计了耐腐蚀的翅片管换热器。结合1000 WM火力发电机组烟气余热回收的运行参数,运用经验证的模型计算了换热器的换热面积和外形体积,简要分析了塑料热导率和凝结水流程对这些设计参数的影响,所得到的结果有望为烟气余热回收的工程应用提供参考。     

Woven graphite fiber structures for use in ultra-light weight heat exchangers

Lightweight, robust woven graphite-fiber structures were developed for heat exchangers which provide high conductivity paths along the direction of the graphite fibers. These structures were produced and characterized for air permeability/pressure drop and thermal (heat transfer) performance. Results indicate that the materials are suitable for use in ultra-light weight heat exchanger applications such as vehicle radiators or other areas where light weight, compact, conformable heat transfer devices are needed.     

塑料换热器在海水淡化中的应用

阐述了塑料换热器在海水淡化中应用的研究状况,分析了塑料换热器所具有的优势如成本更低、更好的防腐防垢性能,质量更轻和能耗更低等,重点讨论了塑料换热器在露点蒸发淡化技术中的应用和有利条件,并对塑料换热器在海水淡化中的应用前景作了进一步的展望。     

Thermally conductive nylon 6,6 and polycarbonate based resins. I. Synergistic effects of carbon fillers

Increasing the thermal conductivity of typically insulating polymers, such as nylon 6,6, opens new markets. A thermally conductive resin can be used for heat‐sink applications. This research focused on performing compounding runs followed by injection molding and thermal conductivity testing of carbon filled nylon 6,6 and polycarbonate based resins. The three carbon fillers investigated included an electrically conductive carbon black, synthetic graphite particles, and a milled pitch‐based carbon fiber. For each polymer, conductive resins were produced and tested that contained varying amounts of these single carbon fillers. In addition, combinations of fillers were investigated by conducting a full 2³ factorial design and a complete replicate in each polymer. The objective of this article was to determine the effects and interactions of each filler on the thermal conductivity properties of the conductive resins. From the through‐plane thermal conductivity results, it was determined that for both nylon 6,6 and polycarbonate based resins, synthetic graphite particles caused the largest increase in composite thermal conductivity, followed by carbon fibers. The combination of synthetic graphite particles and carbon fiber had the third most important effect on composite thermal conductivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 112–122, 2003     

Lightweight,robust, porous heterocyclic para-aramid aerogel hollow fibers for multifunctional applications

In nature, many fibers with warmth-retention properties, such as the hair of polar bears and rabbits, both have a hollow cross-section structure. The static air in fiber cavities can effectively inhibit heat conduction and serve as an effective thermal insulator. In this work, the high-performance heterocyclic para-aramid polymer was selected as the spinning solution, and aerogel hollow fiber was prepared by coaxial wet spinning and freeze-drying techniques. The effects of spinning solution concentration and lyophilized solvent on the micromorphology, mechanical properties, and specific surface area of heterocyclic para-aramid aerogel hollow fiber (HPAAHF) were systematically studied. The produced HPAAHF possessed excellent mechanical properties (tensible strength ~3.85 MPa), high specific surface area (~ 260.90 m² g⁻¹), and lightweight advantages. The thermal conductivity of HPAAHF was only 0.0278 W m⁻¹ K⁻¹, indicating its excellent thermal insulation properties. The aerogel fabric exhibited outstanding flame retardancy properties, with a total heat release of only 0.7 MJ m⁻² in the cone calorimetric experiment, making it a self-extinguishing fabric. In addition, phase change material was injected into the hollow structure to obtain aerogel-phase change material composite fibers, which exhibited great energy storage prospects. As a result, the high-performance heterocyclic para-aramid polymer-based aerogel hollow fiber was successfully prepared and had multifunctional applications in thermal insulation, flame retardancy, and heat energy storage fields.     

几种新型换热器的特点及使用状况对比

对板式换热器，波纹管换热器和超导热管换热器的特点及使用场合进行了分析，对比。指出只有根据不同的使用场合正确选用换热器，才能取得良好的应用效果。     

波纹板换热器的传热过程分析

波纹板换热器由于传热效率高,占地面积少,热损失小等优点,在工业生产中得到了广泛的应用。文章对波纹板换热器的传热过程进行分析,测试了流体流速对换热器传热性能影响。指出在换热器选型时,要综合考虑各个因素,使换热器的传热性能与经济性之间达到优化匹配。