Layout Comparison and Parameter Optimization of Supercritical Carbon Dioxide Coal-Fired Power Generation Systems under Environmental and Economic Objectives.

In the current studies, the supercritical carbon dioxide coal-fired power generation systems show efficiency and cost advantages over the traditional steam-based power systems. However, few studies have considered simultaneously environmental and economic objectives in the multi-objective analysis process. This study conducts a layout comparison and parameter optimization of the systems under the above two objectives. Initially, the thermodynamic, environmental, and economic models of the systems are established. Subsequently, the optimal layout is determined by the two-stage layout comparison. Further, multi-objective optimization is performed for the selected layout, and the optimal design parameters are determined by the decision process. Finally, the sensitivities of three selected parameters to the optimization results are analyzed. The results show that the basic layout coupled with overlap and intercooling schemes is optimal. Its ultimate environmental impact (UEI) and levelized cost of electricity (LCOE) are 219.8 kp-eq and 56.9 USD/MWh, respectively. The two objectives UEI and LCOE are conflicting. Based on a trade-off between them, the maximum temperature/pressure of the system is determined to be 635.3 °C/30.1 MPa. The coal price per unit of heat shows the highest sensitivity, and the pinch temperature difference of the recuperator shows opposite sensitivities at the UEI below 218 kp-eq and above 223 kp-eq.

Carbon nanotube-fullerene hybrid nanostructures by C60 bombardment: formation and mechanical behavior.

This study reports the investigation on C60 bombardment on the carbon nanotube (CNT) by molecular dynamic (MD) simulations. We found that carbon nanotube nanobuds or nanotube-fullerene hybrid nanostructures can be formed by C60 bombardment. Different from the nanobuds in earlier studies, more structural patterns are found in the bombardment formed nanobuds and nanotube-fullerene hybrid nanostructures. In addition, the attaching strengths of the carbon nanobuds are explored, and results indicate that the junction between C60 and CNTs in the nanobuds is very stable. Moreover, we also found that the bombardment formed nanobuds and nanotube-fullerene hybrid nanostructures generally decrease the maximum tensile strength and Young's modulus of carbon nanotubes.