Advanced Materials Research Vols. 1070-1072

Abstract: In order to evaluate the energy saving potential during centrifugal water chillers’ operation, centrifugal water chillers from an industrial enterprise in China are investigated. Based on the actual operation data gained from 3 different water chillers, their working performances and the energy consumption situations are reported and researched in this paper. Meanwhile, the energy saving potential and economic performance of the chillers are also reported and analyzed, when the appropriate variable frequency systems are introduced.

Abstract: Nowadays, energy storage technology is a new technology. In power generation field, energy storage technology can largely solve the problem of the randomness and volatility in the new energy power generation. This technology can realize smooth output of new energy power generation. It can effectively regulate the power grid voltage and frequency in the new energy power generation, and make the new energy power generation friendly connected to the electricity grid. It has great significance to energy conservation, environmental protection, power supply reliability improving, power grid efficiency improving, and resource utilization.

Abstract: The research of improving thermal properties of cool storage medium using nanocomposite technology is proposed in this paper. The nanocomposite cool storage material was prepared by the method of mixing directly. The effect of dispersant, ultrasonic time and concentration of dispersant were deeply researched. The optimizing concentration of dispersant and the optimizing dispersion process conditions are confirmed. The results show that thermal conductivity of TiO₂ /HS-6 nanofluids is noticeably enhanced to compare base fluid HS-6, the increasing extent is 21.5%. The results provide the basic data for the application research of TiO₂ nanoparticles in PCM for air-conditioning system.

Abstract: Using alternative fuels is an effective way to reduce air pollution and transform energy structure. The characteristics of four kinds vehicle alternative fuels (LPG, DME, CNG and hydrogen), and the advantages and disadvantages in practical application are studied in this paper. By using the methods which combines safety system engineering and Computational Fluid Dynamics (CFD), the diffusion process of fuels leakage, and the damage area were analyzed quantitatively. Moreover, potential fire accidents for alternative fuels during storage and transportation were evaluated by consequence assessment method. The study results show damage area of the fireball's radiation, which provides reference for fuel safety analysis.

Abstract: Grid black start refers to the process that power with self-start ability starts and leads the restart of the entire grid in "full blackout" status. In this paper, it selects the wind power plant containing energy storage device as the black-start power to study the charging/discharging problems of VRB in the self- start process in wind field.

Abstract: With the continuous development of distributed solar, wind power and other renewable energy sources, renewable energy sources which has its own features, such as intermittent and randomness volatility, brings great challenges to the stable operation of power grid. Aiming at meeting the requirement of balancing the fluctuating renewable energy sources of micro grid, this paper proposes the operating control strategies of the zinc bromine flow battery storage. Firstly, the equivalent mathematical model based on the working principle of the zinc bromine flow battery is established; Secondly, a dual closed-loop strategy for the DC/DC converter is proposed, of which the inner loop is peak current control on zinc bromine flow battery side inductance while the outer loop is a switch control by constant active power and trickle current. By resorting the DC/AC grid side converter, the stability of DC bus voltage is maintained; Then, this paper proposes the optimization power control strategies of zinc bromine battery energy storage system as a constraint of state of charge and DC bus voltage; Finally, a 50kW zinc bromine flow battery energy storage system test platform is built, and the charging and discharging characteristics of zinc bromine energy storage system (ZESS) is researched in grid-connected mode, the test results have shown that the proposed power optimization control strategies for zinc bromine energy storage system could smooth renewable energy sources power fluctuation.

Abstract: Nitrogen-doped graphene (N-rGO) was synthesized in the process of preparation of reduced graphene oxide from the expanded graphite through the improved Hummers’ method. The morphology, structure and composition of nitrogen-doped graphene oxide (GO) and N-rGO were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The nitrogen content of N-rGO was approximately 5 at.%. The electrochemical performances of N-rGO as anode materials for lithium-ion batteries were evaluated in coin-type cells versus metallic lithium. Results showed that the obtained N-rGO exhibited a higher reversible specific capacity of 519 mAh g^-1 at a current density of 100 mA⋅g^-1 and 207.5 mAh⋅g^-1 at a current density of 2000 mA⋅g^-1. The excellent cycling stability and high-rate capability of N-rGO as anodes of lithium-ion battery were attributed to the large number of surface defects caused by the nitrogen doping, which facilitates the fast transport of Li-ion and electron on the interface of electrolyte/electrode.

Abstract: We introduced a facile method to construct new ternary hierarchical nanocomposites by combining MnO₂ coated one dimensional (1D) conducting polyaniline (PANI) nanowires with 2D graphene oxide sheets (GOs). The hierarchical nanocomposite structures of PANI@MnO₂/Graphene oxide were further proved by XRD, SEM and TEM measurements. The ternary composites possessed higher electrochemical capacitance than each individual component as supercapacitor electrode materials.Such intriguing electrochemical performance is mainly attributed to the synergistic effects of MnO₂, PANI and GOs. The hierarchical ternary nanocomposites show excellent electrochemical properties for energy storage applications, which evidence their potential application as supercapacitors.

Abstract: The gasochromic effect and its potential applications of tungsten oxide (WO₃) thin films are introduced. The research progress in gasochromics mechanism of WO₃ films is reviewed and various mechanism models are summarized and discussed. The double injection model, oxygen vacancy diffusion model and localized water molecules model are extensively used to explain the gasochromic coloration of WO₃ films. A perspective on the gasochromics mechanism development of WO₃ films is tended to fabricate WO₃ film with single crystal and regular structure, which may simply the quantitative characterizations induced by the complicated structure. Elucidating gasochromics mechanism of WO₃ films not only helps to understand gasochromic coloration phenomenon well but also improves the performance of gasochromic coloration devices. It also accelerates the development of the relative science, such as gas detector, atom/ion transport material, surface catalysis of semiconductor, and so on.

Abstract: N-doped ZnO films were deposited on Si (100) substrates by radio frequency (RF) magnetron sputtering in N₂/Ar₂ gas mixture. After the deposition, the films were post-annealed in vacuum at several temperatures from 400°C to 850°C for 60 minutes respectively.X-ray diffraction (XRD), atomic force microscope (AFM), Hall measurements setup (Hall) were used to analyze the structure, morphology and electrical properties of ZnO films.The results show that growth are still preferred (002) orientation of ZnO films following post-annealing. When the annealing temperature is higher than 650°C achieved by the n-type ZnO to the p-type transition and for the better growth of p-type ZnO films, the optimal annealing temperature is 650°C.