Advanced Materials Research Vols. 160-162

Abstract: This paper adopted computational fluid dynamics (CFD) method, used k-ε RNG turbulence model-closed control differential equations for numerical simulation. Through numerical simulation and analysis of wind environment in a middle school campus, the round wind field under dominant wind direction was got in the summer and winter. According to the results of velocity field and pressure field, analysis the wind environment, compared the influence of wind direction and surrounding buildings space to the natural ventilation, provided guidance introduce for the layout of the school.

Abstract: Because of many advantages, radiation panel is a very promising air terminal device now. The paper analyzed the advantages and disadvantages of the existed radiation plate, proposed new radiation panel structure, then made the CFD modeling and flow optimization analysis. This article put forward theoretical analysis and suggest for the research and design of the radiation condole system. This new radiation panel make refrigerant water directly contact with radiation , reduce the contact resistance and increase heat thermal significantly , in addition to simple processing technology reduce the initial investment. Flow is the main factors of heat flow. With increasing of flow, temperature adds more uniform, and increase rate reduced after achieve after turbulence flow. This economic flow of new radiation panel is 1m3/h, heat transfer and energy consumption indicators to achieve optimal.

Abstract: Using the method of computational fluid dynamics (CFD), numerically simulates office building with chilling ceiling /displacement ventilation (CC/DV) and analyzes indoor airflow velocity field, temperature field and thermal stratification height of the building. Consider that the CC/DV system can improve indoor air quality and save energy. And the CC/DV system could solve many constraints of displacement ventilation system. when the cooling load is large, due to the limit of air supply and temperature supply the displacement ventilation system can not be used, but the CC/DV system could well satisfied the requirement of body. The CC/DV system also has the problem of lower thermal stratification height because the chilling ceiling has a lower temperature.

Abstract: Due to T-tube tee is used mostly to connect ducts of the central air conditioning system, different angles of branch pipes caused different local resistance changes. This paper studied two-dimensional turbulent numerical simulation about inter flow of two kinds T-tube by numerical calculation software (CFD),in the method of implicit separation and standard k- ε two equations model, it is clear known that two kinds of forms tee fitting Angle of the internal flow field, Through the contrastive analysis of flow characteristics, it is obvious that local resistance of the oblique angled T-tube tee is much smaller than the common T-tube tee, and also is much more homogeneous.

Abstract: Polyacrylamide after the molecule degradation is used as dispersant and the coal gangue as the raw material to prepare the nanometer Al (OH)3 powder in this paper. Calcining at high temperature to activate coal gangue and controlling the change of C2S crystal were adopted to prepare the self-pulverized material of coal gangue. When the aluminum component part is distilled with NaAlO2 form from the self-pulverized material of coal gangue by using 8% Na2CO3 solution, the high-pure superfine aluminum hydroxide powder is prepared by using the high efficiency dispersant carbonization method. When the influence factor that the high efficiency dispersant carbonization method prepares high-pure superfine aluminum hydroxide powder has been studied, it has been found that the optimum condition of the high efficiency dispersant carbonization method can prepare the high-pure superfine aluminum hydroxide powder. The average granularity of aluminum hydroxide powder that has been prepared is less than 100 nm and the purity is more than 99.9%, for a new way has been opened up for the high value utilization of coal gangue.

Abstract: The initial nickel deposition for the direct electroless nickel plating on active SiCp/Al composites is critical. So it is necessary to investigate the process of the electroless Ni-P plating deposition on SiCp/Al composites by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In addition, the mass gain/loss in the initial nickel deposition process was measured by using the electro-balance. The results show that after being treated using phosphoric acid and hydrogen peroxide, the compositions of SiCp/Al composites substrate contains Al, SiC and Al2O3. The Al2O3 film was gradually corroded by the plating solution. And then Ni-P coating was deposited on the substrate without Al2O3 film during the initial electroless plating process, which was mostly growing on the boundary between the SiC particles and the Al crystal of the activation substrate, and then came to two sides. After that, the Ni-P coating growth rate to cover with the SiC particles and Al crystals was prior to the Al2O3 film. The electroless plating was in company with the substrate corrosion, but the electroless plating rate catalyzed by the exchanged nickel was more than the substrate corrosion rate.

Abstract: Analysis of the nature frequency of flexural vibration is vital to be able to provide effective shock absorption for a ship’s tail shaft. The paper built mathematic model of ship’s tail shaft flexural vibration by transfer matrix method, and put forward an effective method for calculating the natural frequency of vibration system: a genetic algorithm (GA). Through example calculation compared with Prohl method under conditions bearing isotropic supporting, the result showed that the method can meet the requirements of engineering calculation, and overcome the disadvantage that initial value of calculation is difficult to be obtained with other methods. Then the method has advantage especially when the degrees of frequency equation increase.

Abstract: Laboratory hot rolling experiments on a low-carbon TRIP steel containing vanadium have been carried out to study the microstructure characteristics and mechanical properties. The results showed that the multiphase microstructure with ferrite, granular bainite and retained austenite could be obtained if the finish rolling initial temperature was properly decreased and the finishing temperature was controlled in the range of Ae3~ Ar3, and the tensile strength achieved 930 MPa or above. The average ferrite grain size was about 4.5 μm in this experiment, the vanadium nitrides and vanadium carbides precipitated dispersedly within ferritic grains or at grain boundaries, and the higher dislocation density existed in ferrite matrix. EBSD analyses revealed that the high angle boundaries accounted for a large proportion and the misorientation angles were within the interval between 29° and 60° mostly. When the finishing temperature was 800°C and the final air cooling temperature was 630°C, the steel had excellent mechanical properties, which was characterized by combination of high strength(about 930MPa), high elongation(21.7%), low yield/strength ratio(0.49) and as well as high work-hardening exponent(0.23).

Abstract: Base asphalt can be separated into four fractions, which are saturates, naphetene aromatics, polar-aromatics and asphaltenes. The thermal oxidation process of each fraction was studied by in-situ Fourier transform infrared (FTIR) analysis in different atmospheres in this paper. And the results show that each fraction in nitrogen atmosphere has no obvious aging phenomenon, while in oxygen and air atmosphere, only saturates and naphetene aromatics have a drastic change because of thermal oxidation, and polar-aromatics and asphaltenes almost keep unchanged. When adding 2.5% antioxidant 300 or 5% SBS respectively to saturates and naphthene aromatics, it can be found from the results that the degree of thermal oxidation of these two components decrease.

Abstract: Mn-Co-Ox catalyst was prepared by the co-precipitation method. The most active catalysts were obtained with a molar Co/(Mn+Co) ratio of 0.1. The results showed that over this catalyst, NO oxidation conversion reached 56% at 150°C and 59% at 175°C with a high space velocity of 35000h-1. Their surface properties were evaluated by means of scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The process of Non-thermal plasma-assisted catalytic oxidation of NO under low-temperature was studied. And the NO conversion could reach 71% with the Non-thermal plasma-assisting at 125°C when the input voltage was 30V. The increasing activities at low temperature (50-150°C) were more apparently higher than high temperature by plasma. And the low-temperature catalytic activity of the catalyst was increased with the increase of the input voltage.