论三峡水库“蓄清排浑”运用方式及其优化

泥沙问题是三峡工程的关键技术问题之一,在三峡工程论证和初步设计阶段提出水库采取"蓄清排浑"的运用方式,可以解决泥沙问题。2003年水库蓄水运用以来的实践表明,水库基本遵循了"蓄清排浑"调度运用原则,并根据上游来水来沙减少等新情况对水库运用方式进行了优化调整。本文系统分析了三峡水库"蓄清排浑"运行方式及其优化调整的利弊,包括提前5年实施175 m试验性蓄水、汛期水位动态变化、汛末提前蓄水等对水库淤积和坝下游河道演变的影响,提出了进一步优化水库调度方式,形成"蓄清排浑"运用的新模式,保持水库长期使用的建议,试图为三峡水库科学高效安全运用提供科技支撑。     

重力注水过程流动不稳定现象关键影响因素研究

重力驱动注水过程中由于流量较小以及蒸汽的积聚可能导致流动不稳定现象的发生，对核反应堆安全运行具有重要的影响。通过实验研究的方法，搭建了重力注水模拟实验装置，研究了不同蒸汽出口形阻、高位储水箱水位和加热棒初始温度下流动不稳定现象的变化规律。结果表明，重力驱动注水过程流动不稳定现象包含冷却水初次注入阶段、注入水逐出阶段和冷却水再注入阶段等。在一定冷却水初始温度、冷却水入口形阻以及系统压力下，蒸汽排出速度以及实验本体内筒顶部的聚集情况取决于蒸汽出口形阻，减小蒸汽出口形阻可加快蒸汽排放速度，压力峰峰值降低、振荡周期变长，有利于系统稳定；提高高位储水箱水位加快了冷却水注入速率，增加了加热棒被淹没率，降低了流动不稳定现象的发生次数和持续时间；随加热棒初始温度的升高，冷却水流量出现了波动向停滞的转变，流动不稳定现象发生的次数增加且持续时间加长。     

Thermal hydraulic analysis of supercritical water reactor cooled by TiO2 nanofluid

Heat transfer study of nanofluids as coolant in SCWRs core has been performed at Helwan University. A thermal hydraulic code has been produced to study the effect of TiO₂ nanofluid water based as a coolant with comparison with pure water as a coolant. Various volume fractions of nanoparticles TiO₂ (2, 6 and 10%) were used in order to investigate its effects on reactor thermalhydraulic characteristics. Based on Parameters of a SCW Canadian Deuterium Uranium nuclear reactor (CANDU), the fuel assembly was modeled to study the effect of nanoparticles volume fraction on thermos-physical properties of basic fluid and the temperature distribution of fuel, cladding surface and coolant in axial direction. The theoretical results showed that the density, viscosity and thermal conductivity of the coolant increases with the increase of nanoparticles volume fraction, contrasting to specific heat, which decreases with the increase in nanoparticles volume fraction.     

基于EFEN-SP3方法的pin-by-pin中子动力学计算方法研究

为能直接给出安全分析所需的最热棒功率而不引入组件均匀化近似和精细功率重构近似，本文研究了基于栅元均匀化的pin-by-pin中子动力学计算方法。通过全隐式向后差分对多群时空中子动力学方程组的时间变量进行离散，采用指数函数展开节块-SP₃（EFEN-SP₃）方法求解含裂变介质的多群中子固定源方程组，通过高阶源展开技术消除了中子源分布与缓发中子先驱核分布形状不一致的问题。采用Ks因子、LW外推和粗网再平衡等加速技术提高计算效率。三维pin-by-pin中子动力学问题的数值结果表明：pin-by-pin中子动力学计算能直接给出单棒功率密度分布；高阶源展开技术可有效抑制计算偏差随时间步的累加效应；加速技术可将SP₃动力学计算的求解速度提高134.9倍。     

水射流表面改性对国产Zirlo锆合金包壳管加速腐蚀氧化膜形貌的影响

为进一步提高国产锆合金包壳管性能,提高反应堆安全性,对国产Zirlo锆合金进行水射流冲击强化,研究在高温高压水腐蚀条件下不同冲击压力对样品表面氧化膜的影响,并与未冲击样品进行对比。结果表明,样品表面在不同压力的冲击下耐蚀性差异较大,当冲击压力达到40 MPa时样品表面氧化膜状态较好,相比于未冲击样品氧化膜厚度减少4.3%,在10 MPa和20 MPa冲击下则出现腐蚀加速情况。     

恒湿文物展柜用吸附式空气取水方法

博物馆恒湿文物展柜的湿度控制至关重要，为实现展柜的自动恒湿功能，本文基于吸附式空气取水原理，提出了一种将环境水汽自动补充至恒湿文物展柜系统水箱的方法，并搭建了相应的小型空气取水装置，证明了该方法的可行性；同时，构建了传热传质耦合的空气取水装置数学模型，在获取环境温湿度对装置取水量的影响规律后，分析加热功率和吸附床结构对装置单位能耗取水量的影响；此外，为便于装置的后期推广应用，提出了两个基于吸附床高度和直径的量纲为1参数。结果表明：进口空气的温度对取水量影响较小，但进口空气的湿度对取水量影响较明显，取水量随着湿度增加而增加；加热功率存在最优值，单位能耗取水量随着加热功率先增大后减小；在当前几何参数组合下，两个量纲为1参数η=2、β=4时，装置的单位能耗取水量最高。     

Combined application of electrolysed water and ultrasound to improve the sanitation of knives in the meat industry

This study investigated the effect of the combination of basic electrolysed water (BEW) and slightly acid electrolysed water (SAEW) with ultrasound (US) for cleaning and sanitation of the knives used in slaughtering processes. The knives were sonicated in a US bath using two modes of operation (normal and sweep) in two steps: (i) 5 min with BEW and (ii) 10 min with SAEW at 35 °C. The microbiological counts and the possible changes in the physical structure of the knives were evaluated. The association BEW + SAEW + US, in the sweep mode, provided lower mesophilic, enterobacterial, Staphylococcus aureus and yeast counts when compared to the values recommended by the international legislation. In addition, these conditions removed all organic residues from the knife blades and promoted the highest migration rate of the residues to the US water bath (12.35 mg/L·min), without modifications in the knife blades. Thus, cleaning and sanitation of knives was feasible with the association of BEW + SAEW + US, which could be a useful alternative for the meat industry.     

分级加载电压下考虑有效电势变化的软黏土电渗固结理论

分级加载电压技术能够有效延长电渗处理的时间,改善地基的处理效果并能有效降低能耗。在利用分级加载电压技术开展电渗试验时,随着土体的排水固结,土体各点的电势会发生明显的变化,这与现有的电渗固结理论假设土体各点电势保持不变有所差异。利用自主设计的电渗试验仪器开展了分级加载电压下的电渗室内试验,分析了电渗过程中土体有效电势变化的规律。基于该规律并结合Esrig固结理论建立了在阳极处不排水、阴极处排水条件下考虑土体有效电势变化的电渗固结理论,得到了分级加载电压条件下考虑土体有效电势变化的超静孔隙水压力和平均固结度的解析表达式。研究表明,在电压分级加载过程中,土体有效电势变化规律表现为随时间先基本保持不变,后呈抛物线状先增后减。通过试验案例验证了考虑土体有效电势变化所求得解析解的合理性,且该数值计算结果相较于Esrig数值计算结果,前者更加接近实测值,该固结方程的建立为后续分级加载电压技术的推广应用提供了理论依据,也为实际工程提供了参考。     

德士古水煤浆加压气化技术运行中的问题和处理对策

水煤浆气化装置运行问题较多。对煤浆制备单元进行煤浆提浓改造,通过与类似项目生产装置对比,解决存在的问题,使甲醇产品能根据市场价格调节其产量,提高装置盈利能力。     

Modified sepiolite/PVDF-HFP composite film with enhanced piezoelectric and dielectric properties

Flexible film with both piezoelectric and dielectric properties is considered to be a potential candidate for the energy conversion and storage devices. In this study, the Li⁺ and H₂O modified sepiolite/poly(vinylidene fluoride-co-hexafluoropropylene) (LiSEP-H₂O/PVDF-HFP) composite films with both good piezoelectric and dielectric properties were prepared by traditional coating process. When the H₂O content was 13 wt %, the LiSEP-H₂O/PVDF-HFP composite exhibited high d₃₃ of 32 and dielectric constant of 48. Moreover, the effects of the Li⁺ and adsorbed H₂O on the d₃₃, F(β), dielectric constant, short-circuit currents were discussed. The adsorbed H₂O enhanced the β-phase by the hydrogen bonds and Li⁺ improved the polarization to realize the composite film with increased piezoelectric and dielectric properties respectively. We expected the common modification to lead other clay minerals realizing the future applications in the adjustment of composites' electric properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48412.