Polymorphism and reactivity of [Ni(pyridine)4(NCS)2]: Two new supramolecular isomers and one macro-ionic derivative

Solvothermal treatment of [Ni(pyridine)₄(NCS)₂] in the presence of 4,5-imidazoledicarboxylic acid allows the isolation of two new polymorphs depending on solvents (CH₃CN or CH₃CN/CH₃OH). Furthermore, one unusual conductive macro-ionic complex is obtained when the reaction is carried out in CH₃OH, providing a new insight into polymorphism and reactivity of [Ni(pyridine)₄(NCS)₂].     

The influence of aluminum phosphates on graphite oxidation

Aluminum phosphates are of interest for use as inhibitors for the oxidation of carbonaceous materials. This investigation analyzes three aluminum phosphates of nominal compositions, Al₂O₃ · P₂O₅, Al₂O₃ · 3P₂O₅, and Al₂O₃ · 9P₂O₅, in terms of thermal stability and efficacy to inhibit the thermal oxidation of graphite flake in pure oxygen. Temperature programmed oxidation reveals that the onset temperature for oxidation is increased by 75-100 °C as a result of the aluminum phosphate treatments. Isothermal oxidation rate measurements show that while the overall oxidation rate constants are lowered by the aluminum phosphate treatments, the apparent activation energy remains constant (54-59 kcal/mol), which indicates that the reduction in rate constant with temperature is due to a lowering of the pre-exponential term.     

活性石灰在贮存、运输过程中氧化钙含量与活性度变化测试分析

活性石灰吸收空气中的水和二氧化碳后会逐渐失效，在不同贮存、运输条件下，活性石灰在不同贮存时间的氧化钙含量和活性度是不断变化的。通过测试分析，寻找其变化规律，为活性石灰的使用决策提供依据。     

Injection Strategy in Natural Gas–Diesel Dual-Fuel Premixed Charge Compression Ignition Combustion under Low Load Conditions

Dual-fuel premixed charge compression ignition (DF-PCCI) combustion has been proven to be a viable alternative to conventional diesel combustion in heavy-duty compression ignition engines due to its low nitrogen oxides (NO_x) and particulate matter (PM) emissions. When natural gas (NG) is applied to a DF-PCCI engine, its low reactivity reduces the maximum pressure rise rate under high loads. However, the NG–diesel DF-PCCI engine suffers from low combustion efficiency under low loads. In this study, an injection strategy of fuel supply (NG and diesel) in a DF-PCCI engine was investigated in order to reduce both the fuel consumption and hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. A variation in the NG substitution and diesel start of energizing (SOE) was found to effectively control the formation of the fuel–air mixture. A double injection strategy of diesel was implemented to adjust the local reactivity of the mixture. Retardation of the diesel pilot SOE and a low fraction of the diesel pilot injection quantity were favorable for reducing the combustion loss. The introduction of exhaust gas recirculation (EGR) improved the fuel economy and reduced the NO_x and PM emissions below Euro VI regulations by retarding the combustion phasing. The combination of an NG substitution of 40%, the double injection strategy of diesel, and a moderate EGR rate effectively improved the combustion efficiency and indicated efficiency, and reduced the HC and CO emissions under low load conditions.     

Oxidation of carbons in the presence of chlorine

The oxidation reaction of carbon black, sucrose carbon and graphite in the presence of chlorine was studied by thermal analysis (TGA and DTA). The oxidation rate was shown to depend upon the characteristics of each carbon. Heating in chlorine caused different degrees of mass increase in each of the three carbons, with two reaction zones due to physisorption and chemisorption of chlorine on the carbon surface. Burning of the carbons in oxygen gave the following reactivity order: carbon black>sucrose carbon>graphite. Burning of the carbons in the presence of chlorine showed its inhibiting effect, being strongest in carbon black. Oxidation in absence of chlorine started at 525, 560 and 660°C for carbon black, sucrose carbon and graphite, respectively. When chlorine was present in the gaseous phase, oxidation started at 650, 590 and 770°C. Therefore, the reactivity order in the presence of oxygen was sucrose carbon>carbon black>graphite.     

Inhibition of catalytic oxidation of carbon/carbon composites by boron-doping

The inhibition effect of high temperature boron-doping on the catalytic oxidation of carbon/carbon composites was investigated. Boron-doping at 2500 °C was found to improve the oxidation resistance of catalyst-loaded composites. Evident inhibition mechanisms include the reduction of active site number by increasing the crystallite size and the site blockage by formed boron oxide. Boron-doping at less than 1.0 wt.% was found to almost completely suppress the catalytic effect of calcium acetate after a slight carbon conversion. This inhibition effect was much less significant in the case of potassium-catalyzed oxidation where only a slight inhibition effect was observed. This is believed to be the essential result of the unique properties of potassium catalyst. Due to its wetting ability and mobility, potassium catalyst could form and maintain good interfacial contact with any exposed carbon surface regions.     

A study on improvement of sodium cooled TRU burner design using burnable poison

A new design approach to improve safety characteristics of sodium cooled core for transuranic element transmutation is discussed. In the new option, some amount of fertile material is removed for reduction of sodium void reactivity. Simultaneously, a burnable absorber material is loaded in replacement of fertile material to compensate for reactivity drop during the fuel depletion. Two methods of burnable absorber loading are considered such as the homogeneous and the heterogeneous. In the results, it is found that the homogeneous loading cannot reduce the sodium void reactivity but makes the reactivity more positive. On the other hand, the heterogeneous loading can reduce the sodium void reactivity successfully. It is also found that the increment in burnup reactivity swing is negligible when the burnable poison is heterogeneously loaded. It is concluded that if the burnable poison material is loaded appropriately, the sodium void reactivity can be reduced without any significant penalty of increase in burnup reactivity swing.     

Development of the package-reactor (2) -core characteristics-

A new small reactor concept named the Package-Reactor has been jointly developed by Hitachi, Ltd. and Mitsubishi Heavy Industries, Ltd. The reactor technology was built from that of conventional LWRs. The reactor core consists of 12 cassettes containing fuel rods with a similar design to that of PWR fuel rods. Each cassette has about a 0.4 m outer diameter and they are fixed with about 0.5 m pitch to each other in the atmospheric pressure condition. A tube-type control cluster was developed. It can decrease the rise of reactivity for the one-rod-stuck condition. An advanced cassette design was studied in which the down-comer is placed at the center of the fuel region. This concept, which improves neutron economics and the cold shutdown margin, will increase the marketability of the Package-Reactor. An operation period of more than 8 years can be achieved with UO₂ fuel enrichment of 5.0wt%.     

秦山核电厂反应堆控制棒价值和硼价值测量试验

本文系统地介绍了秦山核电厂反应堆控制棒组价值和硼价值在首次物理启动中的测量试验。简要介绍了测量方法、仪器装置、试验经过、实测结果和误差分析。试验结果表明:测量值与理论计算值符合得很好,达到了验收准则的要求。     

Effect of Reactivity of Quick Lime on the Properties of Hydrated Lime Sorbent for SO_2 Removal

The hydration of quick lime and the sulfation of hydrated lime were carried out for verification of relationship between the reactivity of quick lime and the properties of hydrated lime as a sorbent. The effect of reactivity of quick lime was investigated with the change of calcination temperature and time. Results obtained showed that the temperature rise during the hydration of quick limes varied from 31 to 69℃ with the variation of calcination temperature and time. The specific surface area and the sulfa...