Advanced Materials Research Vols. 875-877

Abstract: Design consideration of nanoelectromechanical switches with low actuation voltage is presented. For a fixed-fixed beam structure design, it has been found that the actuation voltage can be largely reduced by integrating corrugations onto the fixed beam. An actuation voltage less than 3 V can be achieved with a relaxed design rule.

Abstract: This publication is focused on thermal balance of the experimental pyrolysis system furnace. Especially, a relationship between a kind of input material for thermal processing and pyrolysis furnace efficiency has been researched here. Mass intake of materials was 60 kg per an hour and the process temperature of 600 °C was set in the reactor. Presented findings relate to three kinds of materials that have been tested - brown coal, rubber and polyethylene. The main aim of this research is to answer the following question: "In which case does the furnace have the highest efficiency" Inter alia, the article contains a description of the individual input and output energy flows within the system that is thermal input in heating gas, profitably utilised heat, heat losses in waste burnt gases, heat losses by convection and radiation from the unit surface and coherent information. The best efficiency of the system is shown under thermic processing of the rubber.

Abstract: The DC bus voltage is the main criteria to reflect whether the converter system is working properly or not, and the stability control of the DC bus voltage is the key to ensure that wind power generators not take off the grid when grid voltage drops. This paper had done research on a direct-drive wind power system and proposed a coordinated control method based on the grid voltage information feedforward with a crowbar circuit. The hardware was combined with the improved control strategy in this method. When the grid voltage drops, the extra energy of the DC bus can be unleashed by the crowbar circuit, at the same time, the output power of motor-side can be controlled according to the grid-side information, and the mechanical speed of motor-side can be suppressed by the pitch angle regulation when the output power reduces. Thus, the DC-bus voltage can be keep stability. Results based on Matlab/Simulink simulation shows that this method not only improves the stability and dynamic response performance of the DC bus voltage, but also effectively maintains the output power of generator and reduces the action time of crowbar circuit. The ability of the wind power system riding through the grid fault has been effectively improved.

Abstract: Microalgae are a form of prospective biomass energy. Cultivation of wild mixed microalgae not only develop a new way for biomass energy production, but reduce the emission of carbon dioxide in flue gas, which is important to the alleviation of global climate change. The production of bio-flues using microalgae included microalgae cultivation, harvesting and product post-treatment. The cost-effective microalgae harvesting ways was beneficial for all the production process. This study was carried out on the basis of microalgae cultivation. The microalgae collection ways including centrifuge, filtration by slow filter paper, 13# and 25# plankton net were compared, the results showed that, the algae cell collection efficiency decreased as follows, centrifuge > filtration by slow filter paper >25# plankton net>13# plankton net. For the same collection way, the collection efficiency had a little difference according to different microalgae species. The most suitable collection way was centrifuge for the microalgae cultivation in lab.

Abstract: Micro-grid can effectively solve many problems caused by distributed generation connecting with grid, so many countries and regions pay more attention to the research and usage of the micro-grid. In this paper, modeling and simulating of micro-powers, including wind turbine generator model, fuel cell model, photovoltaic cell (PV) with MPPT (maximum power point tracking) model and diesel generator model, as well as the secondary load which can be equipped with the capacity of frequency modulation, are implemented with MATLAB/Simulink platform, and simulations are carried to prove the model rationality and validity. On this basis, a micro-grid with various energy sources and loads is built. By evaluating its capacity of maintaining power quality and quick recovery under load mutations and serious fault scenario, it is showed that the constructed micro-power and micro-grid models can simulate the practical situation well.

Abstract: In recent years, direct air cooling units have developed rapidly in China, but in the actual operation, the back-pressure often deviate from the optimal back-pressure, which affect the economy of the unit. The paper has figured out the optimum back-pressure, fan speed and power gain with the method of equivalent enthalpy drop; the paper also worked out the exergy loss of each device before and after the optimization. Through the exergy efficiency analysis of the devices before and after the optimization, we find out that after optimization, exergy loss of the turbine reduces by 0.954MW and the net amount of the generated power increases 130.5kW, the net exergy efficiency of units improves about 0.018 percent points.

Abstract: In order to decrease the operation cost of a power plant, a 1000MW coal-fired power plant is studied as the research objective, and an evaluation model about unit thermoeconomic cost is built based on the thermoeconomic theory. By using the Matlab calculation tool, the thermoeconomic optimization of the energy system about the plant is presented. The results show that it is necessary to update the correlated equipment to increase its exergy efficiency in the design of the entry unit. Moreover, the exergy efficiency of the boiler is close to the optimum value, as for the steam turbine, its efficiency can be increased with the increment of investment.

Abstract: In order to decrease the operation costs of air conditioning systems, an evaluation model based on unit thermoeconomic costs of thermoeconomic theory is presented in this paper. By using real components and fictitious components in an air conditioning system, the relationships between the fuel and product are established, and then the operation performances of the air conditioning system can be analyzed and evaluated. The unit thermoeconomic costs can be obtained with the experimental data. The results show that the unit thermoeconomic cost of the system is the lowest when the vaporizing temperature is at 16.3°C, and the unit thermoeconomic cost of the compressor component is the highest. Therefore, the direction and emphases of the technique improvement and performance enhancement are provided.

Abstract: In recent years, the 1000MW ultra-supercritical unit has developed rapidly for its high efficiency and low energy consumption in china. In order to further reduce the energy consumption, the energy consumption distribution of a typical ultra-supercritical unit is analyzed in detail, which can make contribution for the energy conservation of units. Based on the theory of unit energy consumption and according to the thermodynamic calculation of a 1000MW ultra super critical generating unit under the design condition and off-design loads, this paper reveals the distribution of energy consumption rules of the whole unit, including every subsystem. The results indicate that when the load deviates from the design load, the total energy consumption of system will increase.

Abstract: To identify the potential of energy conversation in power units, the energy consumption distribution model of supercritical power generation unit under various conditions are established based on a 600MW supercritical power generation system. Methods of unit energy consumption are applied and the total additional energy consumption is calculated under various loads, which varies from 30% TMCR load to full TMCR load. The energy consumption distribution of every heater in the boiler, cylinders of the turbine and the whole plant unit are analyzed. And the distribution rules of energy consumption of various conditions are revealed. The effects of key parameters on unit energy consumption are also investigated.