热泵蒸发及其在浓缩垃圾渗滤液中应用的初探

在热泵蒸发过程中,二次蒸汽压缩比是个至关重要的参数,它直接关系到热泵蒸发的经济程度。对热泵蒸发中的传热过程及可利用的余热作了全面分析。最后对热泵蒸发在浓缩垃圾渗滤液中的应用进行了探讨。     

基于数值模拟方法的船用离心泵减振研究

某船用离心泵的振动较大,已经影响到船舶执行任务。在工程实践的基础上,通过对振动测试数据的分析,提出了造成设备振动偏大的原因。基于数值模拟分析的现代设计方法,对该泵进行了改进设计。结果表明,改进后的船用离心泵能够安全稳定的运行,泵内流体流动比较均匀,在设计工况下的运行状态良好。改进后,样机的水力性能满足技术要求,振动水平大幅下降。     

矿井围岩应力松弛区理论计算与试验研究

通过对掘进工作面前方煤体的受力特点进行分析,理论研究了掘进工作面应力分布特征,得出了掘进巷道前方卸压带宽度计算公式,分析了各因素对煤与瓦斯突出发生的影响,现场利用电磁辐射监测技术进行测试,与理论计算结果相吻合。结果表明,掘进工作面前方卸压带的宽度与巷道的高度、巷道煤岩与顶板的摩擦角等因素有重要关系,研究为掘进工作面煤与瓦斯突出预测及防治具有重要的指导意义。     

基于FLAC2D的西安地面沉降数值模拟分析

针对西安地区抽汲地下深层承压水所引发的地面沉降进行了分析,以Biot三维固结理论为基础,采用FLAG2D软件对西安地区地质技工学校处的地面沉降进行了二维数值模拟与土体-渗流耦合计算.通过分析模拟的计算结果,对抽水引起的深层承压含水层垂直沉降和水平变形作了详细的分析,并阐明了沉降漏斗形成的机理;发现模拟结果与实际监测的结果是基本吻合的,表明了地面垂直沉降和水平位移的特征和机理分析的正确性.     

石油化工生产危险场所的密封问题

从管道密封和机泵密封两个方面论述了在石油化工生产危险场所中降低密封泄漏率和提高密封可靠性的问题.     

冶炼厂废水泵的汽蚀

常用离心泵排送冶炼厂废水时,废水泵易发生汽蚀。分析了形成废水泵汽蚀的各种因素,特别分析了废水生成“汽蚀核子”的特点,找出了防治废水泵汽蚀的有效措施。     

A systematic review of snake translocations to identify potential tactics for reducing postrelease effects

Advancements in the field of reintroduction biology are needed, but understanding of how to effectively conduct translocations, particularly with snakes, is lacking. We conducted a systematic review of snake translocation studies to identify potential tactics for reducing postrelease effects. We included studies on intentional, human-mediated, wild–wild, or captive–wild translocations to any location, regardless of motive or number of snakes translocated. Only studies that presented results for at least 1 of 4 outcomes (movement behavior, site fidelity, survival, or population establishment) were included. We systematically searched 4 databases for published studies and used 5 methods to search the gray literature. Our search and screening criteria yielded 121 data sources, representing 130 translocation cases. We quantified the association between 15 translocation tactics and short-term translocation outcomes by calculating odds ratios and used forest plots to display results. Snake translocations involved 47 species (from mainly 2 families), and most were motivated by research, were monitored for at least 6 months, occurred in North America, and took place from the 1990s onward. The odds of a positive snake translocation outcome were highest with release of captive reared or juvenile snakes, release of social groups together, delayed release, provision of environmental enrichment or social housing before release, or minimization of distance translocated. The odds of a positive outcome were lowest when snakes were released early in their active season. Our results do not demonstrate causation, but outcomes of snake translocation were associated with 8 tactics (4 of which were strongly correlated). In addition to targeted comparative studies, we recommend practitioners consider the possible influence of these tactics when planning snake translocations.     

An investigation of a heat pump system using CO2/propane mixture as a working fluid

In order to decrease the heat rejection pressure of heat pump using pure working fluid, CO₂ or R744, other natural component including hydrocarbons (R290, R600a, R600, R1270, R170, R601) and dimethyl ether (RE170) is added to CO₂, respectively, and then six binary mixtures are achieved. By environmental and thermodynamic comparisons, R290 is selected to be the most appropriate component candidate to mix with CO₂, and meanwhile to weaken the flammability and explosivity for pure R290. Then, the system performances of heat pump using mixture of CO₂ and R290 were experimentally studied when R290 is added to CO₂ with a small fraction, and compared with that of the pure CO₂. The experimental test rig is designed and set up for the transcritical heat pump system. When the refrigerant charge is variable, the heating coefficient performance, optimum heat rejection pressure, compressor power, mass flow rate of refrigerant, and total heat coefficient of gas cooler were researched. The variation ratios of heating coefficient performance and heating capacity with deviation from the optimum refrigerant charge were also investigated. The optimum refrigerant charge of CO₂/R290 is obtained and the research results show that the addition of R290 to CO₂ can efficiently reduce the heat rejection pressure and improve the system performance. The results in the present work could provide useful guidelines for the design and operation of heat pump system using CO₂-based mixture.     

海水热扩散研究进展与新问题分析

从实际的工程背景出发,较为详细地介绍了国内外关于热扩散问题的研究进展。还针对海水源热泵系统应用分析了当前研究存在的不足,指出了今后在该问题方面的研究方向。     

合理回收和利用蒸汽凝结水

洛阳石化总厂原有蒸汽凝结水回收设施由于设施和管理等方面存在缺陷，不能有效地运行，通过对其进行有针对性的改进，使大量高品位优质凝结水得到有效回收和利用，产生了巨大的经济效益。