基于流态冰的冰源热泵能效及经济性研究

基于流态冰的冰源热泵可以利用近冰点淡水或海水相变潜热作为热源,具有采暖能效高、适用性广的特点。为研究新型冰源热泵在采暖期的能效及经济性,选取我国典型供暖区域的5个城市作为研究对象,结合近5年采暖期各城市的气象参数,分别模拟计算空气源热泵、冰源热泵、地源热泵的系统能效。通过计算各热泵机组的初投资及采暖期运行费用,确定了不同类型热泵系统的静态投资回收期。结果表明,本文提出的新型冰源热泵在采暖期的系统能效较高,为2.8 ~ 3.2。相较于空气源热泵和地源热泵,哈尔滨地区冰源热泵系统的初投资及运行费用最低,不存在静态投资回收期。在北京、郑州、武汉、南京地区的静态投资回收期分别为3.0年、5.1年、2.3年、2.6年。基于流态冰的冰源热泵在冬季供暖方面有很好的应用前景。     

周向弯曲方向对弯掠叶片小流量工况下气动-声学性能的影响

对周向弯曲低压轴流风扇的气动-声学性能进行了数值模拟和试验验证,讨论了不同流量和不同周向弯曲方向对叶栅做功能力、稳定工作范围和叶顶泄漏声源特性的影响规律.结果表明:随着流量减小,周向弯曲使叶栅叶顶区域栅的气流轴向做功能力增强,周向做功能力减弱,叶片负荷减小,周向后弯的效果最明显;周向前弯曲改善了端壁附近的流动状况,是拓宽叶轮的稳定工作范围的重要因素;周向弯曲可增加叶顶泄漏涡的稳定性,减弱叶顶泄漏涡区的Powell声源强度,周向前弯效果最好.叶顶泄漏声源特性随流量变化的规律与宏观声学表现一致.     

可拓识别方法在矿井突水水源判别中的应用

为了快速判别矿井突水水源,进而为防治矿井水害服务,以水质指标为判别因子,应用可拓识别方法,建立了谢桥矿井突水水源判别模型,改进了该方法中经典域的形式,提出以各指标的统计值F来量化各指标的识别能力,并作为确定权重的依据.将结果与模糊综合法、灰色关联度法、Bayes逐步判别分析法分别进行比较,其正确率略高于前两者,与Bayes逐步分析法判别结果相同.     

Thermal and flammability properties of a silica–poly(methylmethacrylate) nanocomposite

PMMA, poly(metheylmethacrylate), nanocomposites were made by in situ radical polymerization of MMA, methylmethacrylate, with colloidal silica (ca. 12 nm) to study the effects of nanoscale silica particles on the physical properties and flammability properties of PMMA. Transparent samples resulted and the dispersity of the particles was examined by transmission electron microscopy and atomic force microscopy. The addition of nanosilica particles (13% by mass) did not significantly change the thermal stability, but it made a small improvement in modulus, and it reduced the peak heat release rate roughly 50%. Last, the flame‐retardant mechanism provided by the addition of nanosilica particles in PMMA is discussed. Published 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2072–2078, 2003     

加成型液体乙烯基硅橡胶的研制Ⅱ.白炭黑表面处理对硅橡胶性能的影响

以六甲基二硅氮烷为主要表面处理剂，考察了表面处理剂、处理助剂、水的用量等对白炭黑增强效果的影响。结果表明，处理100份白炭黑时，用25份六甲基二硅氮烷，5份二甲基二乙氧基硅烷，5份水，所得白炭黑对加成型液体硅橡胶增强效果较好。     

Optical Properties and London Dispersion Forces of Amorphous Silica Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

Precise and accurate knowledge of the optical properties of amorphous silica is important because of the increasing application of SiO₂ in optical and electrooptical devices, including photolithography masks for semiconductor fabrication, recently as a potential 157 nm mask substrate. The optical properties in the vacuum ultraviolet (VUV) region have been investigated, because they convey detailed information on the electronic structure and interatomic bonding of the material. In this work, we have combined spectroscopic ellipsometry and VUV spectroscopy to directly determine the optical functions of SiO₂ in this range, thereby reducing the uncertainty in the low-energy extrapolation of the data, essential for Kramers–Kronig analysis of VUV reflectance. We report the complex optical properties of SiO₂, over the range of 1.5 to 42 eV, showing improved agreement with theory when contrasted with earlier results. In addition to the features previously reported at 10.4, 11.6, 14.03, and 17.10 eV, new interband transitions have been observed at 21.3 eV along with O 2 s transitions at 32 eV. We found the bulk plasma peak to be 23.7 eV in the energy loss function spectrum. Based on the magnitude of these new results, the Hamaker constant for SiO₂|Vacuum|SiO₂ is 71.6 zJ, which is larger than the previously reported value of 66 zJ.     

Synthesis and characterization of organic-inorganic hybrid thin films from poly(acrylic) and monodispersed colloidal silica

Hybrid thin films containing nano-sized inorganic domain were synthesized from poly(acrylic) and monodispersed colloidal silica with coupling agent. The 3-(trimethoxysilyl)propyl methacrylate (MSMA) was bonded with colloidal silica first, and then polymerized with acrylic monomer to form a precursor solution. Then, the precursor was spin coated and cured to form the hybrid films. The silica content in the hybrid thin films was varied from 0 to 50 wt%. The experimental results showed that the coverage area of silica particle by the MSMA decreased with increasing silica content and resulted in the aggregation of silica particle in the hybrid films. Thus, the silica domain in the hybrid films was varied from 20 to 35 nm by the different mole ratios of MSMA to silica. The results of scanning electron microscope, transmission electron microscope, and elemental analysis support the above results. The prepared hybrid films from the crosslinked acrylic polymer moiety showed much better film uniformity, thermal stability and mechanical properties than the poly(methyl methacrylate) (PMMA) based hybrid materials. Large pin-holes were found in the PMMA-silica hybrid films probably due to the significant difference on thermal properties between the two moieties or the evaporation of solvent. The refractive index decreased linearly with increasing the silica fraction in the hybrid films. Excellent optical transparence was obtained in the prepared hybrid films. These results show that the hybrid thin films have potential applications as passive films for optical devices.     

二氧化碳水合物导热和热扩散特性

热导率和热扩散率是天然气水合物资源开采关键性基础热物性数据,采用反应釜内壁衬有氟塑料材料,低过冷度,让水合物在反应釜内逐层生成的合成方法,获得可直接用于导热测试的二氧化碳水合物样品。采用瞬变平面热源法原位测试了温度264.68～282.04 K、压力1.5～3 MPa二氧化碳水合物热导率、热扩散率,并测试了二氧化碳水合物在268.05 K、0.6 MPa左右发生自保护效应过程中热导率、热扩散率,获得了晶态下和自保护效应过程中的二氧化碳水合物热导率、热扩散率变化特性。测试结果将为天然气水合物资源的开发利用提供基础数据和理论依据。     

改性介孔硅负载铂催化合成农用增效剂

通过壳聚糖（CS）改性介孔二氧化硅,并负载铂得到Pt/CS-SiO₂催化剂,采用红外光谱（FTIR）、氮气吸附脱附（BET）、热重分析（TG）等对催化剂进行表征,同时考察了Pt/CS-SiO₂催化聚醚和三硅氧烷反应合成农用增效剂。结果表明：Pt成功负载在改性介孔硅上,Pt含量为0.85%;催化剂具有良好的重复使用性,使用7次后仍有较高活性,转化率和选择性均在90%以上;合成农用增效剂的最优工艺为n（MD^HM）：n（HDE）=1：1.1,反应温度为105℃,反应时间为3 h。测试产物在不同pH的水溶液中的水解性能,发现其在中性条件下可以比较稳定地存在。     

电解电渗析法制备硅溶胶

以RuO_x／Ti为阳极、铁镀镍为阴极与Nafion901阳离子交换膜组装成两室的电解电渗析槽,探讨了电解电渗析法制备硅溶胶过程中槽电压和pH值变化的基本规律,证实了增大电流密度和阳极液的进料液流速率可减少二氧化硅在阳极上的吸附沉积,增大二氧化硅的收率．在滴加操作中,通过实验找到了制备浓硅溶胶的较佳的初始组成和操作条件,基本上解决了二氧化硅在阳极上的沉积问题,最高槽电压不超过10V,最高电流密度可达150mA·cm~(-2),膜的平均电流效率在93％左右．