水热控制下杨木的表层密实化及固定技术

通过改变木材的表层水分含量,并利用热压机压板的热量对木材进行水热控制,开展毛白杨木材的表层密实化研究,分析毛白杨木材表层压缩密实化后的密度、硬度和恢复率等能指标。结果表明:表层密实化后的毛白杨木材的表层密度达到0.92g/cm3,为对照材的1.8～2.1倍;硬度达到22.3N/mm2,为对照材的2.4倍;压缩木经180℃、4h的热处理后,变形恢复率可降低30%。

水热炭在水处理中的应用进展

近年来,将生物质通过水热炭化法制备成水热炭的技术开始成为研究热点。水热炭化法可将高含水率的生物质转化成富含活性官能团的水热炭,通过控制不同的水热工艺参数可以得到不同性质的水热产物。水热炭在水处理领域中有重要作用,其可以去除水体中的色度浊度、捕获污水中有机物以及吸附废水中的污染物。阐述了水热炭化法的反应原理和特点;综述了水热温度、水热时间、含水率和活化方式等四个主要水热工艺参数对制备水热炭的影响,改变参数可以获得更有针对性的产物;总结了水热炭在水处理领域中的应用,并对水热炭未来研究方向进行了展望。

空心Fe_3O_4纳米微球的制备及生长机制分析

采用控制变量法,探讨了水热法合成Fe_3O_4时,不同实验参数对其形貌、尺寸、分散性的影响。用x射线衍射仪(XRD)、扫描电子显微镜(SEM)对样品的结构和形貌进行表征,并分析Fe3O4纳米微球的生长机制。实验结果表明:以FeCl_3?6H_2O 0.27 g、柠檬酸三钠0.88 g和尿素(Urea)0.36g为原料,聚丙烯酰胺(PAM)0.35 g为稳定剂,200℃下反应12 h制备得到了具有尖晶石结构的Fe3O4,形貌为疏松多孔的空心球状结构,具有粒径分布均匀、分散性良好和无毒的特点。Fe3O4纳米微球尺寸约160 nm,具有独特的分等级结构,即整个微球由粒径18 nm左右的初级晶粒自组装堆叠而成,其形成过程可以用Ostwald Ripening(OR)熟化机制进行解释,即内部晶粒的再溶解和外部晶粒的再长大,最终形成这种特殊的疏松多孔空心结构。

Morphology Control of Anatase TiO2 by Surfactant-assisted Hydrothermal Method

By hydrolysing titanium isopropoxide in a long hydrocarbon chain surfactant-containing solution, TiO2 fine particles with a diversity of well-defined morphologies was synthesized in this study by a hydrothermal route. The structural change during the formation process was monitored by scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. TiO2 with various morphologies such as particle, sheet, rod, tube and flower-like shape was obtained by carefully controlling the preparation conditions. The experimental results show that the pH value is crucial for shape control of the produced TiO2 because it can change the charge state of the surfactant in the solution and the adsorption potential of the surfactant on the TiO2 surface. The shape evolvement of anatase TiO2 was elucidated by quenching the reaction at different stage and the formation mechanism of different shaped TiO2 was suggested.

Controlling dispersion and morphology of MoS2 nanospheres by hydrothermal method using SiO2 as template

Monodispersed MoS_2 nanospheres were successfully synthesized by using SiO_2 as hard template. The size and morphology of the MoS_2 nanospheres could be finely controlled by the content of SiO_2 and sulfur precursors. Furthermore, higher surface area of monodispersed MoS_2 nanospheres exhibited high reaction rate for hydrodesulfurization(HDS) of dibenzenethiophene(DBT).

Effects of Postharvest Hot Water and Hot Air Treatments on Storage Decay and Quality Traits of Kumquat （Fortunella japonica Lour. Swingle, cv. Ovale） Fruit

Heat treatments such as hot-water dipping （HWD）, hot water rinsing and brushing （HWRB）, and hot air treatment （HAT） have been applied on a wide range of horticultural crops to control postharvest decay and to maintain quality characteristics. In this study we compared the influence of hot-water dipping （HWD） for 2 rain at 50℃and hot air treatment （HAT） at 37 ℃ for 30 hours, on postharvest performance of kumquat （Fortunellajaponica Lour. Swingle, cv. Ovale） fruit. Decay development, transpiration rate （fruit weight loss）, external appearance, and nutritive （sugars and organic acids） and functional properties （ascorbic acid, total phenolic compounds, and total antioxidant activity） were evaluated over 21 days＇ simulated shelf-life at 17 ℃. Untreated fruits were used as control. There was no visible damage to the fruit following HWD or HAT and after storage. However, while HWD and control fruit maintained their fresh appearance during the first 14 days of storage and were rated as fairly fresh after the 21 days, HAT fruits had lost their gloss and no longer appeared fresh. HWD did not affect fruit weight loss while HAT induced significant weight loss with respect to control. HAT did not significantly affect decay incidence after 14 days＇ storage but effectively reduced decay after 21 days＇. HWD notably reduced decay development after 14 and 21 days of storage and proved significantly more effective than HAT. Neither HWD nor HAT significantly affected the nutritive and functional properties of fruit. Thus, present results indicate that while HWD can be applied on kumquats to control postharvest decay without impairing the quality traits, HAT conditions （treatment time and temperature） should be optimized, due to adverse effects to fruit quality.

Coordinated control strategy for wind power accommodation based on electric heat storage and pumped storage

To solve the severe problem of wind power curtailment in the winter heating period caused by ＂power determined by heat＂ operation constraint of cogeneration units, this paper analyzes thermoelectric load, wind power output distribution and fluctuation characteristics at different time scales, and finally proposes a two level coordinated control strategy based on electric heat storage and pumped storage. The optimization target of the first level coordinated control is the lowest operation cost and the largest wind power utilization rate. Based on prediction of thermoelectric load and wind power, the operation economy of the system and wind power accommodation level are improved with the cooperation of electric heat storage and pumped storage in regulation capacity. The second level coordinated control stabilizes wind power real time fluctuations by cooperating electric heat storage and pumped storage in control speed. The example results of actual wind farms in Jiuquan, Gansu verifies the feasibility and effectiveness of the proposed coordinated control strategy.

Microwave Drying of Flax Fibre at Controlled Temperatures

Drying is essential for the production of fibre after retting process. Flax fibre was subjected to microwave drying at controlled temperatures to study the change in drying rate and qualities. The rate of drying was then compared with conventional hot air drying. The product temperature was maintained at 40 ℃, 60 ℃or 80 ℃ for both microwave and hot air drying. The initial moisture content of flax fibre was about 60% （wet basis）. The microwave drying was conducted in a microwave apparatus which recorded mass, product temperature, incident microwave power, reflected microwave power and inlet/outlet air temperature. The final moisture content was set to 9% （wet basis）. Microwave-convective drying ensured about 30% to 70% reduction of drying time for drying flax fibre as compared to hot air drying. Curve fitting with different mathematical models were carried out. While a significant difference in colorimeter-assessed co/our existed between microwave-convective dried flax fibre and hot air dried flax fibre. The tensile strength of flax fibre, measured with an Instron apparatus, increased with an increase in the processing temperature of both processes. Hot air dried flax fibre showed the greatest tensile strength and modulus of elasticity at processing temperatures of 60 ℃ and 80 ℃.

Characterization of deep ground geothermal field in Jiahe Coal Mine

Research into the characteristics of geothermal fields is important for the control of heat damage in mines. Based on measured geothermal data of boreholes from 200 m to 1200 m in a Jiahe Coal Mine, we demonstrate non-linear but increasing relations of both geo-temperatures and geothermal gradients with increases depth. Numerically, we fitted the relationship between geo-temperatures and depth, a first-order exponential decay curve, formulated as: T(h) = 4.975 + 23.08 exp(h/1736.1).

Integration of CATHENA Thermal-Hydraulic Model with CANDU 6 Analytical Simulator Controller

This paper introduces a powerful design and analysis tool named SIMCAT, that is developed to support applications to license a CANDU nuclear reactor, refurbish projects, and support the existing CANDU stations. It consists of the CATHENA （Canadian Algorithm for Thermo-Hydraulic Network Analysis）, the control logics from C6SIM （CANDU 6 Analytical Simulator）, and a communication protocol, PVM （parallel virtual machine）. This is the first time that CATHENA has been successfully coupled directly with a program written in another language. The independence of CATHENA and the C6SIM controllers allows the development of both CATHENA and C6SIM controller to proceed independently.

Dynamic simulation of drum level sloshing of heat recovery steam generator

Drum level sloshing is the latest discovery in the application of heat recovery steam generator (HRSG) in combined cycle, and shows certain negative influence on drum level controlling. In order to improve drum level controlling, influence factors on the drum level sloshing were investigated. Firstly, drum sub-modules were developed using the method of modularization modeling, and then the model of drum level sloshing was set up as well. Experiments were carried out on the experimental rig, and the model was validated using the obtained experimental results. Dynamic simulation was made based on the model to get a 3-D graph of drum level sloshing, which shows a vivid procedure of drum level sloshing. The effect of feed-water flow rate, main-steam flow rate and heating quantity on the drum level sloshing was analyzed. The simulation results indicate that the signals with frequency higher than 0.05 Hz are that of drum level sloshing, the signals with frequency of 0.0-0.05 Hz are that of drum level trendy and "false water level", and variation of the feed-water flow rates, main-steam flow rates and heating quantities can change the frequency of drum level sloshing, i.e., the frequency of sloshing increases with the increase of feed-water flow rate, or the decrease of the main-steam flow rate and the heating quantity. This research work is fundamental to improve signal-to-noise ratio of drum level signal and precise controlling of drum level.

Dissolution-filling mechanism of atmospheric precipitation controlled by both thermodynamics and kinetics

Affected by structural uplift, the Ordovician carbonate rockbed in the Tarim Basin, China, was exposed to dissolution and reformation of atmospheric precipitation many times, and formed a large quantity of karst caves serving as hydrocarbon reser- voir. However, drilling in Tahe area showed that many large karst caves, small pores and fractures are filled by calcite, result- ing in decrease in their reservoir ability. Calcite filled in the karst caves has very light oxygen isotopic composition and STSr/S（＇Sr ratio. Its c^OpDB ranges from -21.2%o to 13.3%o with the average of -16.3%e and its 87Sr/86Nr ratio ranges from 0.709561 to 0.710070 with the average of 0.709843. The isotope composition showed that calcite is related to atmospheric precipitation. Theoretic analyses indicated that the dissolving and filling actions of the precipitation on carbonate rocks are controlled by both thermodynamic and kinetic mechanisms. Among them, the thermodynamic factor determines that the pre- cipitation during its flow from the earth surface downward plays important roles on carbonate rocks from dissolution to satura- tion, further sedimentation, and finally filling. In other words, the depth of the karstification development is not unrestricted, but limited by the precipitation beneath the earth surface. On the other hand, the kinetic factor controls the intensity, depth, and breadth of the karstification development, that is, the karstification is also affected by topographic, geomorphologic, climatic factors, the degree of fracture or fault, etc. Therefore, subject to their joint effects, the karstification of the precipitation on the Ordovician carbonate rocks occurs only within a certain depth （most about 200 m） under the unconformity surface, deeper than which carbonate minerals begin to sedimentate and fill the karst caves that were formed previously.

Investigation on Active Thermal Control Method with Pool Boiling Heat Transfer at Low Pressure

In order to maintain a desirable temperature level of electronic equipment at low pressure, the thermal control performance with pool boiling heat transfer of water was examined based on experimental measurement. The total setup was designed and performed to accomplish the experiment with the pressure range from 4.5 kPa to 20 kPa and the heat flux between 6 kW/m^2 and 20 kW/m^2. The chosen material of the heat surface was alu- minium alloy and the test cavity had the capability of varying the direction for the heat surface from vertical to horizontal directions. Through this study, the steady and transient temperature of the heat surface at different pressures and directions were obtained. Although the temperature non-uniformity of the heat surface from the centre to the edge could reach 10℃ for the aluminium alloy due to the varying pressures, the whole temperature results successfully satisfied with the thermal control requirements for electronic equipment, and the temperature control effect of the vertically oriented direction was better than that of the borizontally oriented direction. Moreover, the behaviour of bubbles generating and detaching from the heat surface was recorded by a high-resolution camera, so as to understand the pool boiling heat transfer mechanism at low-load heat flux. These pictures showed that the bubbles departure diameter becomes larger, and departure frequency was slower at low pressure, in contrast to 1.0 atm.

Hierarchically porous composite fabrics with ultrahigh metal–organic framework loading for zero-energy-consumption heat dissipation

The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of our society needs advanced thermal management with low,even zero,energy consumption.Harvesting water from the atmosphere,followed by moisture desorption to dissipate heat,is an efficient and feasible approach for zero-energy-consumption thermal management.However,current methods are limited by the low absorbance of water,low water vapor transmission rate(WVTR)and low stability,thus resulting in low thermal management capability.In this study,we report an innovative electrospinning method to process hierarchically porous metal–organic framework(MOF)composite fabrics with high-efficiency and zero-energy-consumption thermal management.The composite fabrics are highly loaded with MOF(75 wt%)and their WVTR value can be up to 3138 g m^(-2) d^(-1).The composite fabrics also exhibit stable microstructure and performance.Under a conventional environment(30℃,60%relative humidity),the composite fabrics adsorb water vapor for regeneration within 1.5 h to a saturated value Wsat of 0.614 g g^(-1),and a corresponding equivalent enthalpy of 1705.6 J g^(-1).In the thermal management tests,the composite fabrics show a strong cooling capability and significantly improve the performance of thermoelectric devices,portable storage devices and wireless chargers.These results suggest that hierarchically porous MOF composite fabrics are highly promising for thermal management of intermittent-operation electronic devices.