Advanced Materials Research Vols. 383-390

Abstract: Pressure-wave supercharger (PWS) is one technical way to boost the engine intake air pressure. PWS has several advantages such as less emission (especially NOx emission), rapid response when load changes, higher torque even at low engine speed. In this research a 493 diesel engine is charged by a pressure-wave supercharger (PWS). The emission performance of the PWS diesel engine is mainly investigated. Together with experimental test, the CFD simulation is completed basing on a 3D model of the PWS rotor channel. The CFD simulation results show that the inner EGR phenomenon happens especially when PWS runs at middle PWS rotational speed with part load. The test results demonstrate that the PWS diesel engine performs well with less NOx and soot emissions than the turbocharged diesel engine.

Abstract: Several water-based nanofluids were prepared under the action of surfactant by using ultrasonic dispersion method. The absorbency and viscosity of the nanofluids prepared under different conditions were measured and analyzed. The results showed that, when the mass fractions of nanoparticles were 0.2%, the most appropriate surfactants for Al₂O₃, FeO, γ-Fe₂O₃ water-based nanofluids were SDBS (Sodium Dodecyl Benzene Sulfonate), ACT (ammonium citrate), CTAB (Cetyltrimethyl Ammonium Bromide), respectively and the optimum mass fractions of the surfactants corresponding to the three nanofluids were 0.2%, 0.1%, 0.2%, respectively, to obtain the best dispersion stability. The optimum ultrasonic condition was 60 min of ultrasonic time under 300 W of ultrasonic power or 90 min of ultrasonic time under 200 W of ultrasonic power, in which the water-based nanofluids had the largest absorbency, the smallest viscosity and the strongest stability. In addition, the greater the size of the nanoparticles the easilier the reunion, and the poorer the dispersion stability was. When the pH value was about 4, the absorbency of Al2O3 nanofluid was larger and the dispersion stability was better. The inherent mechanism of keeping stability of nanofluids was discussed.

Abstract: Using the time history analytical method to study the location effecting of the braces to the lateral displace of the steel frame. Base on the really project and the calculation comparing of the example in the time history analysis, the authors discuss the regularity of the location effecting of the braces to the lateral displace of the steel frame and analysis the structure. It can be referred to design in China.

Abstract: Direct air-cooled power plant is popularized in north China because of the water conservation. Different from the water-cooled condenser, the ambient air absorbs the latent heat that turbine exhaust in the heat exchangers releases. In this paper, the numerical model of a 2×600MW power plant is prepared to simulate the performance of the air–cooled steam condenser under different wind speeds. Heat transferring with phase change is very complicated so that User Define Function(UDF) is applied to calculate the heat transfer rate in the air-cooled condenser. The fan flow rate will drop obviously during the increasing of the wind speed. As a result, the heat transfer rate between the steam and the ambient air also decreases and the pressure of the condenser rises. Finally, the stable condenser pressures under different wind speeds are predicted. The result shows that the air-cooled condenser is very sensitive to the wind speed.

Abstract: Increasing attention has been focused on capturing solution gas vented or flared from oil wells to reduce the emission of the greenhouse gases and effectively utilize the natural energy. With the aim of recovering the gas for its economic value, this paper presents a hermetic horizontal oil- injected scroll compressor to meet the unique demands of this application which the traditional compression technology has not been able to meet. A hermetic horizontal oil-injected scroll compressor was developed, in which the special internal oil system was designed. An experimental system was designed and set up to investigate the performance of the scroll compressor. With the experimental results, the effect of the discharge pressure and oil injection flow rate on performance of the compressor was analyzed and applied to provide the basis for developing reliable and flexible hermetic horizontal oil injected scroll compressor in taking use of the oil wells casing gas.

Abstract: This paper bring forward a new system of heat pump air-conditioner and hot water combination, base on the analysis of the advantages and disadvantages of two different domestic air-conditioner heat recovery systems. With experiment research, it also summarized improvement methods and problems which should be pay attention to in the design of this kind of system.

Abstract: Hydrothermal degradation (HTD) experiments of lawn-grass by the catalytic action of low acid were carried out in the pilot digestor. The effect of the low acid on treated lawn-grass products was investigated in different treatment severities. A severity parameter which combines time and temperature was introduced for comparing results among experiments. The results show that, with the severity increasing, the weight of the solid products, the hemicellulose and cellulose content remarkably decrease; the conversion rate of the organic matter increases; the HTD products by low acid catalysis reach stable in the low severities. At the same time, the soluble sugars and the acetic acid content increase until the treatment severity is over 4.05, however, and furfural content always increases in the liquid products.

Abstract: On the basis of wholly analyzing the mechanism of the heat transfer in the 1880 regenerative furnace, the physical and mathematical 3-D model was set up to describe the heat transfer and combustion in the furnace, and the CFD software was used to simulate the whole combusting process in detail. From this, the law of the flow affected by four classical switching modes was studied in emphasis. The conclusions in the study were helpful to the reasonably design and optimization controlling of such furnaces.

Abstract: We propose control techniques to extend the fabrication area that is the limit of traditional laser fabrication systems. The current world trend of PCB core technology development is focused on next generation semi-conductor package board and special high value-added PCB including a buildup board. Laser fabrication is necessary when the process microscopic line width and the line over the scanner area and it should be synchronized scanner-stage. This cannot be done with the current Step & Scanning method. To solve this problem synchronization of the stage and scanner was facilitated to continuously process a wide-area. The processing speed and laser fabrication quality were also improved.

Abstract: Laser beam welding (LBW) is a fusion joining process that uses the energy from a laser beam to melt and subsequently crystallize a metal, resulting in a bond between parts. In this study, finite element method (FEM) is used for predicting the weld bead profile of laser welding butt, lap and T-joints. A three-dimensional finite element model is used to analyze the temperature distribution weld bead shape for different weld configurations produced by the laser welding process. In the model temperature-dependent thermo physical properties of AISI304 stainless steel, effect of latent heat of fusion and convective and radiative boundary conditions are incorporated. The heat input to the FEM model is assumed to be a 3D conical Gaussian heat source. The finite element software SYSWELD is employed to obtain the numerical results. The computed weld bead profiles for butt, lap and T-joints are compared with the experimental profiles and are found to be in agreement.