绝热发动机陶瓷活塞的设计和材料选择

本文结合绝热机陶瓷活塞设计,在对热压氮化硅(HPSN)、常压烧结氮化硅(SSN)以及部分稳定氧化锆(PSZ)这三种高温结构陶瓷材料的选择及对空气隔热层的布置特点,以提高隔热效果与保证足够应力强度裕度,使两者相协调的观点进行分析。并提出一些有益的见解和讨论。     

稠油热采注汽管线新型节能保温材料

针对稠油热采注汽管线保温技术差,散热损失大等问题,从影响注汽管线保温效果的关键环节入手,采用先进的保温工艺和材料,重点做好管线保温材料的优选、保温层结构的优化和管线支架的散热保温三个方面工作。通过应用效果比较,对注汽管线保温采用纳米气凝毯复合反射式保温结构和节能支架进行技术改造,节能效果明显。     

Simulation of energy saving in Iranian buildings using integrative modelling for insulation

According to one survey on energy consumption in Iran, commercial and building sector consume more energy than any other economic sectors. For example, about 38% of total energy that consumed in year 2001 has been used for space heating. Insulation in external walls of buildings has an important role to reduce the environmental effects on indoor space condition. Therefore, always using insulation is an alternative to avoid from the energy loss. In this paper, the effects of the using of a proper insulation on the energy saving in Iranian buildings are studied. For this purpose, an integrative modelling is used for simulation of the energy consumption in buildings. It is shown that energy consumption per square meter of buildings can be reduced up to 35.2% when insulation is used for external walls.     

MLCC内电极厚度对其性能影响的研究

贱金属多层陶瓷电容器(MLCC)的内电极镍层厚度对其常规电性能、耐热冲击和绝缘稳定性有严重的影响.通过试验研究发现,镍层厚度在1 μm左右,可获得常规电性能良好和高可靠性的贱金属多层陶瓷电容器产品(BME-MLCC).     

Influence of barrier on partial discharge activity by a conducting particle in liquid nitrogen under AC voltages adopting UHF technique

The UHF signals are generated due to PD formed by particle movement in liquid nitrogen under AC voltages. The levitation voltage of a particle in liquid nitrogen measured through UHF technique and by conventional PD measurement technique is the same, confirming the sensitivity of UHF technique for identification of PD activity. The frequency content of UHF signal generated due to particle movement in liquid nitrogen, under AC voltages, lies in the range 0.5–1.5 GHz. The characteristics of UHF signal generated due to particle movement between the barrier and high voltage/ground electrode is much similar to the signal generated by particle movement in clean electrode gap. Pseudo resonance phenomena can occur in liquid nitrogen due to particle movement. It is also observed that the partial discharge magnitude, in general, be high when the particle moves between the barrier and high voltage electrode when compared to the barrier and the ground electrode. Percentage of clay in epoxy nanocomposites has not altered the levitation voltage of the particle in the electrode gap. Zero span analysis clearly indicates that pseudo resonance occurs when particle moves (in a short gap) between the barrier and high voltage/ground electrode.     

舰船岸电低压配电系统接地型式分析

舰船停靠码头后需要由岸上的电力系统为其供电．舰船上低压配电系统接地型式大多采用电源中性点不接地的IT系统．而陆地上民用低压配电系统的接地型式采用电源中性点直接接地的TN或TT系统。对于同一个低压配电系统．当船电和岸电电源中性点接地方式不同时．系统接地型式发生了改变。通过对引接岸电电源的舰船低压配电系统接地型式比较、分析...     

福州锦江G区外墙保温工程施工探讨

本文介绍了福州锦江G区高档住宅项目利用蒸压砂加气混凝土砌块做为外墙保温层及外墙面砖粘帖的施工案例,重点论述了保温层的施工构造、施工工艺、验收标准等。该施工工艺主要应着重解决蒸压加气混凝土保温砌块粘结可靠性、安全性,以及保温层与基层、外墙面层间因材料不同形变能力,受温度变化引起的不同变形所采取的相关措施,并介绍了施工中应注意事项等。经工程实践证明,该施工工艺克服了聚苯板、聚苯颗粒砂浆等保温做法在其面层施工易造成面层涂料开裂或面砖脱落等质量问题。具有施工简便、可操作性好、稳定性强等特点,便于大面积推广使用。     

Experimental evaluation of insulation material in roofing system under tropical climate

The objective of this study is to determine the influence of radiant barriers on conductive and radiative heat transfers when they are integrated to a building envelope and to compare their efficiency to traditional insulation material (mineral wools, polystyrene). It is also about determining which insulation material and process can lead to a better heat flux reduction through a building roof. For this study four identical small-scale test cells were used. Their respective roof was equipped with the insulation material to be tested: One with polystyrene, the second with a radiant barrier the third one with fibber glass and the last one with no insulation material was considered as the reference cell. Different test were performed with a view to evaluate the influence of parameters such as roof absorptivity and roof air layer ventilation on the heat flux reduction through the roof. With the measured temperature, the conductive and radiative heat fluxes were calculated. With a white corrugated iron roof top the heat flux reduction provided by the radiant barrier is 37%. With a black one this material allows a reduction of 33%. It is shown that whatever the roof absorptivity value, the radiative heat flux is predominant over the conductive one. With no ventilation, the radiant barrier is comparable to polystyrene and fiber glass; when the airspace is ventilated the radiant barrier provides a better insulation.     

Altering existing buildings in the UK

The profiles of both existing housing and existing public and commercial buildings show that many have very poor thermal efficiency. The UK housing stock is replaced at a low rate of about 1% a year, so to cut energy use it is essential to address the challenges of existing buildings. This will involve reducing energy demand through passive measures such as retrofitted insulation, replacement of windows and proper airtightness, while ensuring adequate ventilation. Active measures include upgrading improved boilers and adding locally produced energy from wind, biomass, solar power and other sources. The introduction of Display Energy Certificates will increase energy awareness but there will also need to be a programme of increased demolition for the worst-performing homes. In addition, buildings will need to be adapted to cope with worse weather, higher temperatures and increased flood risk as climate change takes effect. Overheating, rather than excessive cold, is set to become a growing problem for householders and employees in existing UK buildings.     

LW25-126型SF6断路器绝缘拉杆接头断裂原因分析与对策

介绍了在较短时间内连续发现2台LW25126型SF6断路器绝缘拉杆接头断裂的情况和处理过程,分析了接头断裂的原因,认为接头断裂的根本原因是接头处因电位悬浮而金属边缘或尖角部位形成放电,产生电腐蚀致使销孔处机械强度减弱,不足以承受分闸拉力而在分闸操作时被拉断。文章还从设备制造、现场试验、运行巡检、倒闸操作等方面提出了防范措施。