水力控制棒驱动系统失压工况的实验研究

利用200MW低温核供热堆水力控制棒驱动系统的1：1实验台架模拟系统失压况，进行控制棒步升，步降，开阀落棒及关泵开阀落棒实验，并与正常工况下的提棒，落棒的实验结果进行比较，实验结果表明：在系统失压工况下，控制棒能正常提棒，落棒系统失压工况下的弹棒，系统压力与压力壳压力具有瞬时跟随特性，未出现控制棒弹棒事故，对实验的失压速率和事故分析得到的失压速率进行了比较，验证了系统具有良好的安全性和可靠性。     

Numerical Study on Wake Flow Field Characteristic of the Base-Bleed Unit under Fast Depressurization Process

Numerical analyses have been performed to study the influence of fast depressurization on the wake flow field of the base-bleed unit (BBU) with a secondary combustion when the base-bleed projectile is propelled out of the muzzle. Two-dimensional axisymmetric Navier-Stokes equations for a multi-component chemically reactive system is solved by Fortran program to calculate the couplings of the internal flow field and wake flow field with consideration of the combustion of the base-bleed propellant and secondary combustion effect. Based on the comparison with the experiments, the unsteady variation mechanism and secondary combustion characteristic of wake flow field under fast depressurization process is obtained numerically. The results show that in the fast depressurization process, the variation extent of the base pressure of the BBU is larger in first 0.9 ms and then decreases gradually and after 1.5 ms, it remains basically stable. The pressure and temperature of the base-bleed combustion chamber experience the decrease and pickup process. Moreover, after the pressure and temperature decrease to the lowest point, the phenomenon that the external gases are flowing back into the base-bleed combustion chamber appears. Also, with the decrease of the initial pressure, the unsteady process becomes shorter and the temperature gradient in the base-bleed combustion chamber declines under the fast depressurization process, which benefits the combustion of the base-bleed propellant.     

水合物降压分解的实验及数值模拟

在天然气水合物一维分解模拟系统上进行模拟多孔介质中水合物降压分解的实验。在考虑天然气水合物分解动力学机理以及流体渗流模型的基础上;建立天然气水合物降压分解的数学模型。利用模型对降压实验进行拟合;获得了多孔介质内水合物分解本征速度常数数量级为10 mol·m^-2·Pa^-1·s^-1;比文献中测定的纯水中水合物分解本征速度常数低3个数量级。对模型进行了参数分析;发现对于实验室规模的一维系统;分解动力学过程控制整个分解过程;而对于现场规模的水合物藏;整个开采过程受水合物藏流动特性的控制;而受水合物分解过程的影响较小。     

超临界CO2脱附作用调控负载纳米颗粒结晶动力学研究

依据经典成核理论和超临界领域中的结晶动力学相关模型,分析影响成核速率的主要因素及其规律。研究共溶剂辅助超临界CO₂溶解无机盐,在SBA-15介孔材料表面沉积实验的结果,发现伴随初始阶段的泄压速率逐步提升（0.05~18 MPa/min,20~14 MPa）,载体所负载的纳米颗粒的粒径逐渐减小至1.5 nm左右,与典型的晶核尺寸1 nm相接近,而担载量却出现逐渐增加的趋势。晶体的临界成核半径取为0.5 nm,通过Türk模型和Debenedetti模型计算超临界流体快速膨胀（RESS）工艺其喷嘴内的成核速率,与超临界反溶剂（SAS）群体平衡模型（PBM）的边界条件即SAS过程的初始成核速率相比较,三者的成核速率相接近,且利用快速泄压方法的沉积实验结果与按Cu担载量所估算的成核速率相接近。分析在沉积反应后的泄压阶段,超临界条件下的CO₂的脱附作用,可能成为吸附于载体表面的前驱物离子结晶的诱导因素。并且CO₂瞬时脱附量能够调控负载型纳米颗粒的成核速率,同时控制复合材料的金属担载量。为研究微观尺度下SAS过程的实现提供了实验与理论基础。     

河南WR-1地热井降压试验水位校正的应用研究

一般的单井稳定流抽水试验,可直接利用从孔口测得的水位降深与对应的流量关系,求取含水层的水文地质参数。但对地热井而言,由于在抽水过程中,井筒内水温的变化可对井中水位产生较大影响,故不宜直接利用降压试验前测得的静水位埋深和孔口所测的水位降深值,而应该进行静水位和动水位的校正(刘永贵,2016),才能与观测的水位埋深、水量、水温相匹配进行参数计算(高新智,2015)。文章以尉氏县WR-1地热井馆陶组降压试验静水位、动水位校正实例,阐述地热井降压试验水位校正的有效性和必要性。     

Two types of a passive safety containment for a near future BWR with active and passive safety systems

The paper presents two types of a passive safety containment for a near future BWR. They are named Mark S and Mark X containment. One of their common merits is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. The PCV pressure can be moderated within the design pressure. Another merit is the capability to submerge the PCV and the RPV above the core level. The third merit is robustness against external events such as a large commercial airplane crash. Both the containments have a passive cooling core catcher that has radial cooling channels. The Mark S containment is made of reinforced concrete and applicable to a large power BWR up to 1830 MWe. The Mark X containment has the steel secondary containment and can be cooled by natural circulation of outside air. It can accommodate a medium power BWR up to 1380 MWe. In both cases the plants have active and passive safety systems constituting in-depth hybrid safety (IDHS). The IDHS provides not only hardware diversity between active and passive safety systems but also more importantly diversity of the ultimate heat sinks between the atmosphere and the sea water. Although the plant concept discussed in the paper uses well-established technology, plant performance including economy is innovatively and evolutionally improved. Nothing is new in the hardware but everything is new in the performance.     

石油磺酸盐降压增注试验研究

针对低渗区块注水困难的状况,在室内开展了石油磺酸盐的溶解性、表面张力变化及岩心试验,检验石油磺酸盐的降压增注效果,并对添加石油磺酸盐是否对注水井造成损害进行了结垢趋势和腐蚀试验。结果表明低浓度石油磺酸盐可降低污水的表面张力,具有降压增注的功效,并且可以起到一定的缓蚀作用。     

A Study on the Formation and Removing Mechanisms of a Gas Hydrate Slug in Gas Pipelines

Most of the existing hydrate prediction models cannot describe the formation process of hydrate slug in gas pipelines. The authors developed the physical model of hydrate formation state in gas pipelines, and the corresponding mathematical model is proposed by utilizing the theories of heat transfer, multiphase flow, and phase equilibrium. The formation process of hydrate slug is described by simulation, and the removing mechanism of hydrate slug using depressurization is analyzed. The change of related parameters is obtained. which can effectively provide theoretical guidance for preventing and removing the hydrate slug.     

多孔介质中水合物生成与分解的电阻率性质

A new one-dimensional system for resistivity measurement for natural gas hydrate (NGH) exploitation is designed, which is used to study the formation and decomposition processes of NGH.The experimental results verify the feasibility of the measurement method, especially in monitoring the nucleation and growth of the NGH.Isovolumetric formation experiment of NGH is performed at 2 ℃ and 7.8 MPa.Before the NGH formation, the ini-tial resistivity is measured to be 4-7 Ω·m, which declines to the minimum value of 2-3 Ω·m when NGH begins to nucleate after the pressure is reduced to 3.3 MPa.As the NGH grows, the resistivity increases to a great extent, and finally it keeps at 11-13 Ω·m, indicating the completion of the formation process.The NGH decomposition ex-periment is then performed.When the outlet pressure decreases, NGH begins to decompose, accordingly, the resis-tivity declines gradually, and is at 5-9 Ω·m when the decomposition process ends, which is slightly higher than the resistivity value before the formation of NGH.The occurrence and distribution uniformity of NGH are determined by the distribution and magnitude of the resistivity measured on an one-dimensional sand-packed model.This study tackles the accurate estimation for the distribution of NGH in porous medium, and provides an experimental basis for further study on NGH exploitation in the future.     

The Possible Role of Indoor Radon Reduction Systems in Back-Drafting Residential Combustion Appliances

Abstract A computational sensitivity analysis was conducted to identify the conditions under which residential active soil depressurization (ASD) systems for indoor radon reduction might most likely exacerbate or create back-drafting of natural-draft combustion appliances. Parameters varied included: house size; normalized leakage area; exhaust rate of exhaust appliances other than the ASD system; and the amount of house air exhausted by the ASD system. Even with a reasonably conservative set of assumptions, it is predicted that ASD systems should not exacerbate or create back- drafting in most of the U.S. housing stock. Only at normalized leakage areas lower than 3 to 4 cm² (@ 4 Pa) per m² of floor area should ASD contribute to back-drafting, even in small houses at high ASD exhaust rates (compared to a mean of over 10 cm²/m² determined from data on over 12,000 U.S. houses). But on the other hand, even with a more forgiving set of assumptions, it is predicted that ASD systems could contribute to back-drafting in some fraction of the housing stock – houses tighter than about 1 to 2 cm²/m²– even in large houses at minimal ASD exhaust rates. It is not possible to use parameters such as house size or ASD system flow rate to estimate reliably the risk that an ASD system might contribute to back-drafting in a given house. Spillage/back-draft testing would be needed for essentially all installations.