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Adsorption technologies provide high selectivity and low energy consumption making this technique very attractive to be employed in post-combustion carbon capture. In this publication, a material made of activated carbon and zeolite 13X is considered for a hybrid process termed Temperature Electric Swing Adsorption (T/ESA). This hybrid T/ESA can work as a traditional Temperature Swing Adsorption (TSA) heated by hot gas, but can also increase the temperature of the adsorbent very fast by Joule effect as long as the activated carbon provides a continuous conductive matrix for electricity. This paper discusses a detailed modeling of the T/ESA process when applied to three cases. The first case is the simulation of the T/ESA process with exhaust with 12% of CO 2 concentration, which has been chosen to validate the model against literature results. The second and third case studies consider the T/ESA application in a natural gas combined cycle (NGCC) traditional power plant, and in a NGCC plant with exhaust gas recycle (EGR). These cases were selected to investigate the adsorption technology at low CO 2 concentration and quantify the benefit of the EGR for carbon capture applications. Starting from an NGCC overall electric efficiency of 58.3% LHV based, the efficiency of the NGCC with T/ESA technology reduces to 35.3% while with EGR is 38.9% against the 49.9% with the MEA absorption plant. The same results are confirmed by the SPECCA index 13.05 MJ LHV /kg CO2 to 9.64 MJ LHV /kg CO2 against the reference of 3.36 MJ LHV /kg CO2 . The energy penalty of the T/ESA is significant because of electric consumptions required for the heating and fast cooling of the adsorbent. [ABSTRACT FROM AUTHOR]

In order to reduce line spectrum of radiation noise from submarine, a type of weak radiation double cylindrical ring stiffened shell was proposed. Mechanical impedance theory was used to analyze mechanism of controlling the modal response amplitude of ring-stiffened cylindrical shell. Radial modal mechanical impedance of the ring was derived by introducing the assumption of inner-motion of cylindrical shell's section. Based on the concepts of impedance mismatch and wave conversion, the model of impedance enhancement rib was built and its isolation performance was analyzed. With the consideration of the brace's strong coupling effect, the brace's wave attenuation was designed. Combining the structures of reinforced impedance rib and wave attenuation brace, the structure-borne sound design of double cylindrical shell was done. Further, the characteristics of vibration and sound radiation were numerical analyzed. The results show that the proposed double cylindrical ring stiffened shell could realize radiation noise line spectrum reduction effectively. The vibration mean square velocity, radiation sound power and sound pressure are depressed greatly. The effect of noise depression and vibration reduction is obvious. [ABSTRACT FROM AUTHOR]

This paper investigates passive and semi-active vibration control using fluidic flexible matrix composites (F²MC). F²MC tubes filled with fluid and connected to an accumulator through a fixed orifice can provide damping forces in response to axial strain. If the orifice is actively controlled, the stiffness of F²MC tubes can be dynamically switched from soft to stiff by opening and closing an on/off valve. Fiber reinforcement of the F²MC tube kinematically relates the internal volume to axial strain. With an open valve, the fluid in the tube is free to move in or out of the tube, so the stiffness is low. With a closed valve, however, the high bulk modulus fluid resists volume change and produces high axial stiffness. The equations of motion of an F²MC-mass system are derived using a 3D elasticity model and the energy method, The stability of the unforced dynamic system is proven using a Lyapunov approach. A reduced-order model for operation with either a fully open or fully closed valve motivates the development of a zero vibration (ZV) controller that suppresses vibration in finite time. Coupling of a fluid-filled F²MC tube to a pressurized accumulator through a fixed orifice is shown to provide significant passive damping. The open-valve orifice size is optimized for optimal passive, skyhook, and ZV controllers -by minimizing the integral time absolute error cost function. Simulation results show that the optimal open valve orifice provides a damping ratio of 0.35 compared with no damping in closed-valve case. The optimal ZV controller outperforms optimal passive and skyhook controllers by 32.9% and 34.2% for impulse and 34.7% and 60% for step response, respectively. Theoretical results are confirmed by experiments that demonstrate the improved damping provided by optimal passive control F²MC and fast transient response provided by semi-active ZV control. [ABSTRACT FROM AUTHOR]

An experimental study of supersonic flow over wall mounted cavities with different aft wall angles is carried out. Unsteady pressure measurements were made on the walls and floor of the cavity. Data analysis was performed on the experimental results using statistical methods. In the case of higher angled cavities, the presence of an upstream traveling acoustic wave could be confirmed. For lower angled cavities (60 degrees and less) where the acoustic wave could not be identified, the flow inside the cavity was more or less stable. Mode switching occurring in higher angled cavities was confirmed by spectrogram studies. [ABSTRACT FROM AUTHOR]

The design optimization of lightly damped cavities makes the more reasonable layout and improves the acoustic capability of the cavities. Based on the control differential equation and boundary conditions of three dimensional cavity acoustics, the numerical methods of finite element analysis, sensitivity calculation, and design optimization of the lightly damped cavity acoustic problems are studied. The sensitivity analysis and design optimization methods of eigenfrequencies with respect to shape parameters are applied to the interior noise problem for lightly damped cavities. The numerical methods have been implemented in the large-scale engineering finite element analysis and optimization software system — JIFEX. The examples verify the accuracy and efficiency of the finite element analysis, sensitivity analysis and design optimization method. [ABSTRACT FROM AUTHOR]