Abstract: With the in-depth study on the blast furnace iron-making process and the operational characteristic of auxiliary materials in iron-making process, the comprehensive coke rate’s main influencing factors based on the operation characteristics of auxiliary materials were found. Then, a BP neural network model was used to simulate the mathematic mapping relationship between comprehensive coke rate and main influencing factors. Based on the established BP neural network model, through setting the comprehensive coke rate lowest as the goal and using the actual production data of a iron &steel company’s 6# blast furnace ,a genetic algorithm method is adopted to find the best optimal combination among the main influencing factors. The results show that after optimization calculation the comprehensive coke rate could be reduced about 35.85kg. A new perspective and a scientific method are proposed to realize the target of energy conservation and emission reduction in ironmaking process in this paper.
Abstract: By using the three-dimensional governing equations of plumes, the cumulative volume fraction and the model of water suppress fire, the variation characteristics of the reactive plumes in the process of water mist suppress the diesel jet flame are studied. For the different effects of water mist and no water mist, the eddy structure of plume, averaged velocity and averaged temperature in the above of fire source are analyzed, respectively. It seems that there are expansibility and geometric symmetry for the eddy structure in the early stage of the water mist control. However, as a whole, the water mist has cooling effect for the plume area, and it can also reduce the spread velocity of plume. The large-scale structure can be formed quickly, and the temperature is affected by the droplet size and droplet density. However, for the case of no water mist, the bursting of smaller scale vortices can be enhanced, and its structural characteristic has an affect on the distribution of averaged temperature. Computational results have important significance for the water mist to be used in the ship engineer room.
Abstract: This paper briefly introduces the principles and structure of grid-connected solar micro-inverter system. Depending on different input solar power conditions, one novel method is proposed to generate the connection mode between solar panel group and micro-inverter group. Compared with existed technology, the proposed technical solution can not only enlarge the operating voltage range of the grid-connected solar micro-inverter system, but also increase the total conversion efficiency of micro-inverters.
Abstract: 1-Octadecanol/SiO2 hybrid material, as a novel form-stable phase change material for thermal energy storage, was prepared via the sol-gel method. The crystallographic, phase-change, structural, and thermal stability properties of the samples were well characterized by X-Ray Powder Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetry (TG). The results indicated that the 1-octadecanol/SiO2 hybrid material showed typical form-stable phase transition properties, e.g. suitable transition temperature (Tr=56.4 °C), high transition enthalpy (ΔH≥120.8 J/g) and good thermal stability. It is a functional hybrid material with good energy storage effect, and the heat storage mechanism of 1-octadecanol/SiO2 is the transfer between crystalline and amorphous states of the phase change component 1-octadecanol, and the silica serving as “cage-skeleton”, restricted the molecular chain of the 1-octadecanol’s free movement at high temperature. Thus, 1-octadecanol/SiO2 hybrid material can keep its solid state in the transition processing.
Abstract: Hydrogen energy has been considered as a clean alternative energy source substituting fossil fuels. Many countries consider it as the ultimate solution to the energy and environmental problems, even draw up the blueprint of “hydrogen economy” and heavily invest for research and development. However, after decades of research, the hydrogen energy technologies are still being prospective and explored, and haven’t been put into large scale production by now. This article begins with expatiation on the essence of hydrogen energy, makes analysis of various big challenges for hydrogen energy technologies, and reaches the conclusion that we should hold the rational and cautious attitude towards hydrogen energy source because the transition to hydrogen economy of unclear prospect must pay a very high cost, which is unbearable for the social and economic development status of developing countries.
Abstract: The efficiency of a thermoelectric device depends on material properties through the figure of merit, Z = σS2/κ, where σ, S, and κ are electrical conductivity, Seebeck coefficient, and thermal conductivity, respectively. To maximize the thermoelectric figure of merit of a material, high electrical conductivity, high Seebeck coefficient, and low thermal conductivity are required. This work has focused on the synthesis of a mesoporous titania films for its application in thermoelectric generation. The mesoporous titania film was synthesized with titanium tetraisopropoxide. The triblock copolymer, Pluronic P-123 (EO20 PO 70EO 20) was used as surfactant in 1-propanol. As a result, an improvement of electrical conductivity and reduced annealing with a lowering of thermal conductivity by distributions of pores were found to be effective to enhance the thermoelectric property.
Abstract: In this work, effect of the number of stainless steel-aluminum nitride (SS-AlN) cermet layers and stainless steel (SS) volume fraction in each of cermets on the optical properties of SS-AlN solar selective coatings was theoretically investigated based on the effective medium theory and optical properties of SS and ceramic AlN. Results shows that increasing the number of cermets does not improve the optical performance of solar selective coatings in terms of solar absorptance and thermal emittance at 80 oC, and the two-cermet-layer structure, one having a high metal volume fraction (HMVF) and other having a low metal volume fraction (LMVF), is the most suitable due to better optical performance and easier preparation. Theoretical results also shows that, for double SS-AlN cermets structure selective coatings, optimized LMVF and HMVF are 0.35 and 0.6, respectively, optimized thickness of cermets with LMVF and HMVF are 50 and 60 nm, respectively, and optimized thickness of AlN anti-reflection film is about 60 nm. Comparisons of reflectance of a sample deposited by a pulse magnetron sputtering coater between measured and calculated showed that theoretically predicted reflectance were highly agreed with those experimentally measured, indicating that the theoretical method used in this work can pretty predict the optical properties of SS-AlN cermet solar selective coatings.
Abstract: Anthropogenic emission of greenhouse gases (GHGs) result in global climate destabilization, and the elements of GHGs associated with climate change are now well understood and a link to urban GHGs emissions has been well articulated. Compact city concept has been proposed for a while to response high energy consumption and GHGs emission in urban area. However, over compact might come up some problems, such as over-crowded of population, buildings, and cars which brining up other environmental issues. This study attempts to investigate potential negative impacts of urban compactness on energy consumption. The result shows that under a threshold of high density and mixed land use, it might come up energy saving outcome. However, it will become energy consumption while exceeding the threshold.
Abstract: Electric power storage facilities for stabilization of the voltage and the frequency are necessary to interconnect wind power generations with power systems. However, conventional pumped storage generation systems can’t combine with wind power generations because these can’t work intermittently. Therefore we consider a new system featuring a pumped storage generation with the Archimedean screw. The Archimedean screw can hold water without electricity supplied, and can continue pumping while it is powered on. Therefore, the Archimedean screw enables the combination of the pumped storage generation and wind power generation. In this study, simulation has been done to examine the feasibility.