非共沸混合工质在花瓣形翅片管管束上的冷凝传热及强化

1实验系统本文选定花瓣形翅片管作为强化管型,并探讨非共沸混合工质在其管束上的冷凝传热性能。实验系统如图1所示。本实验系统设计成既可进行大空间内的自然对流冷凝传热实验研究,又可进行套管空间内的强制对流冷凝传热研究。实验工质民;和R;。在蒸气发生器中由电加热器加热沸腾后所产生的蒸气分两路进入冷凝器空间内,并在管束上冷凝。实验管（管参数如表1所示）内的冷却水来自调温水箱,实验时控制三条管内水流量基本上相同。对于大空间内的自然对流,分别研究了光管和花瓣形翅片管管束直列与错列下的冷凝传热性能对比。对于套管空…     

制冷空调用冷凝强化传热技术研究进展

管内冷凝与管外冷凝的风冷与水冷冷凝器是制冷空调系统中的重要部件。文中介绍了近期国内外冷凝强化传热技术的研究进展,包括管内冷凝与管外冷凝强化换热。简述了典型的冷凝强化传热元件的开发与应用,并对其强化传热性能进行了比较。     

不互溶混合工质R-113和水在水平管内冷凝及强化传热研究

本文以R-113和水为混合工质,在水平光滑管和七种管型的内螺旋翅片管内进行不互溶混合工质蒸汽的冷凝传热研究.根据光管实验,发现冷凝液相的流动结构是影响传热的主要因素,建立了凝液两相流动的三个流动模型;并据此获得提高管内传热膜系数之途径.     

肋密度对齿状翅片管外冷凝换热和流动的影响

采用数值和实验相结合的方法研究了齿状翅片管周围的冷凝流动和传热特性。利用经过验证的计算模型，分析了齿状翅片管在周向和轴向上的膜流动特性和冷凝传热系数，提供了有关高性能管中冷凝过程的信息。结果表明，齿状翅片管的周向和轴向薄膜厚度随着肋密度的增加而增加。对齿状翅片管特殊的传热结构进行了研究，发现复杂的传热结构导致表面张力的变化，从而改变了液膜的分布。齿状翅片管的局部冷凝传热系数对液膜分布非常敏感。得到了与最大总传热系数相对应的最佳肋密度，表明齿状翅片管的强化传热机理是传热面积和液膜厚度的共同作用。     

内插螺旋线强化糖浆立式降膜蒸发传热

搭建了新型立式单管蒸汽-糖浆降膜蒸发实验平台,进行连续4 h加与不加螺旋线的降膜蒸发运行对比实验,研究管内插入特定结构和工艺参数的螺旋线对变粘性糖浆降膜蒸发传热性能的影响.结果表明,内插螺旋线可明显改善糖浆降膜蒸发传热效果,相同条件下,内插螺旋线时总传热系数比空管提高了25.9%~82.9%,且随时间延长其下降速率明显低于空管;从管内蒸发侧和管外冷凝侧传热角度分析降膜蒸发传热性能,传热温差增大,管内蒸发侧传热性能变好,管外冷凝侧传热性能变差,增大传热温差改变物料物性(粘度减小)可强化传热效果.在非结垢影响的传热时间内,对管内蒸发侧传热系数进行处理,得到了管内综合传热系数与传热温差的实验关联式.     

菱形翅片管的强化传热特性

简要介绍了一种新型强化传热管－－菱形翅片管的结构和强化传热机理，并通过两组对比试验研究其强化传热特性。研究结果表明：菱形翅片管的三维翅片可以较大幅度提高换热器总传热系数和壳侧传热膜系数，对于对流和冷凝传热都有较好的强化效果。菱形翅片管加工成本较低，传热性能较好，在石油化工等行业推广应用前景广阔。     

强制对流冷凝传热强化

研究了强制对流条件下，非共沸混合工质Ｒ１１／Ｒ１１３在三排水平直列光滑管及花瓣形翅片管束外的冷凝传热。实验结果表明：花瓣形翅片管由于具有特殊的三维翅片结构，既能激发流动的蒸气产生强烈地湍流，减小其气膜热阻，又能充分发挥冷凝液表面张力的作用，减少其液膜热阻，从而显著地强化了非共沸混合工质在管束外的冷凝传热。在相同热流率下，其管束平均冷凝传热系数是光滑管管束的３～５倍。     

固液界面能差效应与冷凝传热强化研究进展

综述了固液界面能差效应强化冷凝传热的新机制及其对纯蒸气及含不凝气的蒸气冷凝传热过程影响的理论和实验研究进展.阐述了引入固液界面能差效应后的膜状冷凝、滴状冷凝和过渡状冷凝传热模型,及模型与实验数据的对比结果.介绍了利用固液界面效应强化纯蒸气和含不凝性气体的混合蒸气冷凝传热的强化技术.     

工艺参数对三维翅片管强化传热机理影响的热力学探讨

通过实验验证了由滚压—犁切/挤压工艺加工成形的三维整体外翅片管相对于光管的强化传热性能。实验表明,三维翅片管的管外传热系数是光管的6~10倍。从热力学的观点出发对三维翅片管的强化传热原理进行了探讨,结论显示翅片间的毛细结构是影响传热性能的主要因素。同时,该结论表明加工参数之一的进给量和三维翅片管传热性能之间存在影响关系,进给量越大,传热性能越差。     

内翅片管蒸发式中冷器获专利

洛阳隆华传热科技股份有限公司自主研发的内翅片管蒸发式中间冷却器2013年3月获得国家专利授权。据悉,这种中冷器与传统换热器相比节电20％以上,节水30％以上。内翅片管蒸发式中冷器采用潜热换热原理,以喷淋水作为冷却介质,依靠水在换热管外形成水膜蒸发吸收管内工艺流体的热量,通过轴流风机的强制排风带走热量。达到冷却或冷凝管内工艺流体的目的。该中冷器蒸发换热部件采用内翅片管,增加了管侧的换热面积,有效提高了换热效率,解决了压缩机实际运行中存在的冷却能力不足等问题,节电、节水效果显著。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.