Advanced Materials Research Vols. 317-319

Abstract: By analyzing the operating principle and building the mathematical model, the pressure characteristics of the tri-proportion controller are obtained. A simulation about the pressure characteristics is carried out, which shows the differential pressure and rotational speed are subjected to a linear relationship within the full measuring range. The simulation result agrees with experimental data very well, which shows the feasibility of this simulation method. Analyzing the pressure characteristics and the proportional control accuracy, we obtained the minimum differential pressure, the maximum differential pressure, the factors which affect the differential pressure and the relationship between the differential pressure and leakage. And finally we obtained the solutions of decreasing the leakage and improving the proportional control accuracy.

Abstract: Geomagnetic induced currents (GIC) that flows between the earth and the power grid may pose a threat to the safe operation of power system. Modern power grid construction with the features of high voltage, long distance and high-capacity, these will cause the network increases the risk. This paper briefly introduces the evaluation methods of GIC and influence and control measures, etc. The theory of algorithms, and measures to eliminate GIC should be more in-depth research.

Abstract: As an important component of intercooled cycle gas turbine, intercooler directly affects the ratio power, thermal efficiency and various situation quality of gas turbine system. In this paper, efficiency-heat transfer units were used for the design of intercooler, and the structure parameters were optimized by genetic algorithm. The optimization results show that under the condition of required heat load and allowable pressure drop, the heat exchanger can be guaranteed as the smaller weight and the larger heat transfer efficiency, which can offer reference for the design of the actual intercooler.

Abstract: The discrete-element method(DEM) was employed to simulate the mixing and segregation process for size-type binary particulate systems in a rotating horizontal drum for dry particulate systems and wet particulate systems. The effect of interstitial liquid on the mixing and segregation process were studied. The simulation results showed that the liquid bridge between particles play an important role in mixing and segregation process, as a result, segregation may be mitigated and mixing may be enhanced. To assess the accuracy of the simulation result, some comparisons were made with the experimental results in the literature.

Abstract: The electronic structures of thermoelectric material NaCo2O4 were studied by the first-principles calculations with plane-wave pseudopotential method and generalized approximation (GGA) based on density functional theory (DFT). On the basis of calculation for electronic structures, thermoelectric properties of NaCo₂O₄ were also investigated in this paper. The reasons for large thermoelectric potential are large effective mass of holes at the top of valence band and 6μB net spin magnetic moment. While high electrical conductivity should be attributed to small effective mass of electrons at the bottom of conduction band, large carrier concentration near the Fermi level and narrowed energy gap. In addition, covalent bond between Co atom and O atom promotes carrier mobility and thus benefits to electrical conductivity. Na1 and Na2 have different effects on the NaCo₂O₄. Na1 provides local state electrons and yet Na2 provides itinerant-electrons which play important role to strongly correlated system.

Abstract: The aim of this study was to provide a theoretical basis for a high-energy carbon ion irradiation process for inducing mutations for selective breeding in Isatis indigotica Fort. The experiments were designed to evaluate the effects of different doses of high-energy ¹²C⁶⁺ ions (10-140 Gy) on physiological changes in I. indigotica seedlings. Dry seeds of I. indigotica were irradiated using different doses of 270 MeV energy 12C6+ ion beam, and the response of the subsequent seedlings was monitored using well-established indexes of physiological characteristics. Results showed that optimum results were achieved with a high-dose ¹²C⁶⁺ ion beam at 35 Gy where the activities of superoxide dismutase (SOD) and catalase (CAT) were enhanced. However, excessive irradiation reduced the activities of SOD and CAT. As the dose increased, the activity of peroxidase increased initially and then decreased compared with controls that were not irradiated (0 Gy). The content of malondialdehyde first decreased and then increased with the treatment. Total soluble protein content initially increased and then decreased with increasing doses of radiation; the proline content improved sharply compared to the control. The results of this study suggest that that a low dose of ¹²C⁶⁺ ion beam could enhance the activities of protective enzymes and the levels of proline and soluble protein, and that a dose range of 35–60 Gy is likely to be optimum for inducing useful mutations in I. indigotica for a stable selective breeding program.

Abstract: A new type of stationary blade rotary compressor is developed to overcome the rolling piston compressor’s weaknesses such as severe leaking loss and friction waste. The new compressor has unique sealing structures and friction-reducing techniques, featuring in that the compressor adopts a stationary blade whose out-end is hermetically fastened to the cylinder’s inner wall and the blade’s two side-ends are hermetically fastened to the end-covers which respectively set in both ends of the cylinder. Due to that the cylinder, the blade and the end-covers all are closely fitted to each other, the leakage and friction occurred from these parts are completely eliminated. This paper introduces the compressor’s working principle and structure characteristics, deduces the calculation formulas for displacement volume, chamber pressure and thermodynamic properties, and discusses the design principles of compressor structure parameters and what effects these parameters have on leakage and friction. The research result shows that the stationary blade compressor, in comparison with the conventional rolling piston compressor, has displayed some unique advantages in seal property, friction reduction, manufacturing and assembling techniques.

Abstract: In this paper, we use ANSYS to simulate the cyclone separator, analysis the velocity of the internal airflow field, pressure distribution and temperature distribution. The result shows that the mainstream of a cyclone separator is double rotating flow, and in the outer downstream areas, with the increase of the radius, the airflow rate decreases accordingly; In the inside upstream region, flow velocity at the center is larger, while flow around is smaller relatively; Besides, the total pressure in the inport section of the cyclone is highest, and the pressure inside of the exhaust pipe is lowest. The mainstream of the airflow field is double-rotating in the cyclone flow; The distribution of airflow temperature is related to the flow field distribution.

Abstract: A new type of dust-collecting and dedusting system with air curtain was developed to solve the problems of the dust-prevention in mine tunnel. The speed of air-curtain fan, the structure size and pressure of dedusting duct are the critical factors, which effect dust control of the whole system. In order to achieve optimal efficiency of dust control, the simulation was conducted with FLUENT(computational fluid dynamics software) to analyse the air-curtain fan surface path lines and dust particle tracks at different wind speeds of air curtain fan, dedusting duct diameters and outlet pressures. We obtained the law of fan speed, the diameter and outlet pressure of dedusting duct, which effect the whole system on dedusting. This law would play a guiding role on the structural optimization of dust-collecting and dedusting system with air curtain.

Abstract: The composition and principles of the digital measuring system was investigated on the basis of digital oil measuring method. Fly attitude-oil quality - measuring height data tables were generated by using UG software calculation of oil quantity characteristics. Then the oil surface angle under different fly attitude and overload was calculated through coordinate transformation method. Finally the amount of oil was calculated by three-dimensional liner interpolation method. Meanwhile, the free surface movement of lubricating oil tank under different overload was simulated through VOF numerical model. The results showed that using UG software to build model and generate fly attitude-oil quantity-measuring height data tables is accurate and useful. The VOF model method is a complement to digital measurement, which can track the phase interface of continuum, analyze the movement of oil qualitatively and calculate the dead volume of digital method.