Optimization of the topology of a plate coupled with an acoustic cavity is presented in an attempt to minimize the fluid-structure interactions at different structural frequencies. A mathematical model is developed to simulate such fluidstructure interactions based on the theory of finite elements. The model is integrated with a topology optimization approach which utilizes the Moving Asymptotes Method. The obtained results demonstrate the effectiveness of the proposed approach in simultaneously attenuating the structural vibration and the sound pressure inside the acoustic domain at several structural frequencies by proper redistribution of the plate material.The presented topology optimization approach can be an invaluable tool in the design of a wide variety of critical structures which must operate quietly when subjected to fluid loading.
This article deals with the thermodynamic assessment of supercritical carbon dioxide (S-CO 2 ) Brayton power cycles. The main advantage of S-CO 2 cycles is the capability of achieving higher efficiencies at significantly lower temperatures in comparison to conventional steam Rankine cycles. In the past decade, variety of configurations and layouts of S-CO 2 cycles have been investigated targeting efficiency improvement. In this paper, four different layouts have been studied (with and without reheat): Simple Brayton cycle, Recompression Brayton cycle, Recompression Brayton cycle with partial cooling and the proposed layout called Recompression Brayton cycle with partial cooling and improved heat recovery (RBC-PC-IHR). Energetic and exergetic performances of all configurations were analyzed. Simple configuration is the least efficient due to poor heat recovery mechanism. RBC-PC-IHR layout achieved the best thermal performance in both reheat and no reheat configurations (η th = 59.7% with reheat and η th = 58.2 without reheat at 850 • C), which was due to better heat recovery in comparison to other layouts. The detailed component-wise exergy analysis shows that the turbines and compressors have minimal contribution towards exergy destruction in comparison to what is lost by heat exchangers and heat source.Entropy 2020, 22, 305 2 of 19 than that of turbomachines. Sarkar and Bhattacharyya [15] did sensitivity analysis to reach optimized thermal performance of S-CO 2 recompression Brayton cycle with reheating. They observed maximum 3.5% improvement in thermal efficiency with reheating at optimum operating conditions.Al-Sulaiman and Atif [16] investigated the thermodynamic performance of various S-CO 2 Brayton cycles integrated with solar power tower. Their findings demonstrated that the recompression cycle has the highest thermal efficiency and the highest net power output, whereas, regenerative cycle stands second. Later, they performed detailed energy and exergy analysis of recompression cycles driven by solar thermal systems. They concluded that the highest average exergy loss occurs in heliostat field [17]. Kim et al. [18] discussed thermodynamic performance of nine S-CO 2 bottoming power cycles with topping gas turbine cycle powered by landfill gas. They found recompression cycle is not best suited for waste heat recovery purposes due to limited fraction of heat recovery from exhaust gas. On the other hand, partial heating cycle, being simple with single compressor and turbine, has relatively higher power density. Gavic [19] investigated various options for the heat rejection from the S-CO 2 cycle including wet cooling, dry cooling and hybrid. He found that the hybrid cooling is flexible with reduced water usage and capital cost. Sing et al. [20] developed a model for dynamic simulation of S-CO 2 Brayton cycle heated directly via parabolic trough collectors. He found that the active control of solar collectors is necessary to maintain the supercritical operation of the cycle and to improve power output in winte...
Supercritical carbon dioxide (S-CO 2 ) Brayton cycles (BC) are promising alternatives for power generation. Many variants of S-CO 2 BC have already been studied to make this technology economically more viable and efficient. In comparison to other BC and Rankine cycles, S-CO 2 BC is less complex and more compact, which may reduce the overall plant size, maintenance, and the cost of operation and installation. In this paper, we consider one of the configurations of S-CO 2 BC called the recompression Brayton cycle with partial cooling (RBC-PC) to which some modifications are suggested with an aim to improve the overall cycle's thermal efficiency. The type of heat source is not considered in this study; thus, any heat source may be considered that is capable of supplying temperature to the S-CO 2 in the range from 500 • C to 850 • C, like solar heaters, or nuclear and gas turbine waste heat. The commercial software Aspen HYSYS V9 (Aspen Technology, Inc., Bedford, MA, USA) is used for simulations. RBC-PC serves as a base cycle in this study; thus, the simulation results for RBC-PC are compared with the already published data in the literature. Energy analysis is done for both layouts and an efficiency comparison is made for a range of turbine operating temperatures (from 500 • C to 850 • C). The heat exchanger effectiveness and its influence on both layouts are also discussed.
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