The solar tower thermal power technology is a method to achieve the large-scale utilization of solar energy. A user defined TYPE of the heat receiver for the solar tower thermal power plant (STTPP) is established in t...
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The solar tower thermal power technology is a method to achieve the large-scale utilization of solar energy. A user defined TYPE of the heat receiver for the solar tower thermal power plant (STTPP) is established in the TRNSYS program with Fortran codes. Full-year simulation of the STTPP is investigated based on different input parameters, weather conditions and plant control strategies by taking Beijing as a case study. Through this case, the influences of the receiver diameter, flow form and inlet/outlet temperature on the thermal efficiency, total pump power, power efficiency and 'solar-thermal-electricity' transfer efficiency are studied. Simulation results show that the thermal efficiency of receiver rises with the decrease of pipe diameter. The lower the inlet temperature is;the lower the annual pump power consumption is, and the higher the power efficiency would be. An instantaneous increase of the receiver outlet temperature would reduce the power efficiency. The plant control strategies suggest that the "south-in-north-out" arrangement of the heat receiver working fluid holds the highest power efficiency but lowest annual pump power consumption. The annual power generation increases effectively by introducing the hot and cold molten salt storage tanks. The annual power efficiency increases with the power plant capacity.
The structures of two laminar premixed n-heptane/O2/Ar flames (F1.60: F = 1.60, C/O = 0.51, and F1.80: F = 1.80, C/O = 0.57) and one laminar premixed n-heptane/methanol/O2/Ar flame (F1.80 M: F = 1.80, C/O = 0.51) are ...
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The developing and developed nanofluid Rayleigh-Bénard flows between two parallel plates was simulated using the mesoscopic thermal lattice-Boltzmann method (LBM). The coupled effects of the thermal conductivity ...
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The objective of the present work is to investigate the air-water two-phase flow patterns in pipeline-riser system with an S-shaped flexible riser. The test loop with 50 mm ID consists of a horizontal pipeline with 11...
The objective of the present work is to investigate the air-water two-phase flow patterns in pipeline-riser system with an S-shaped flexible riser. The test loop with 50 mm ID consists of a horizontal pipeline with 114 m in length, a downward inclined section with 16 m in length, and an S-shaped flexible riser with 24 m in height when downward section inclined at −2° with respective to the horizontal. The inclination angle of the downward section varied from −2° to −5°. The liquid superficial velocity ranged from 0.03 to 1.5 m/s, and the gas superficial velocity from 0.4 to 6.0 m/s. Identification and characterization of flow regimes were attained by pressure at riser-base and liquid holdup at riser top. Severe slugging I, severe slugging II, transition flow and stable flows are observed to exist. flow pattern maps for each declination are presented and the transition criteria are proposed. It's found that as higher liquid and gas velocity is required for the transition of the flow in the pipeline from stratified to intermittent with increasing the declination angle, severe slugging was observed to occur over a wilder range of flow conditions. The effect of riser geometry and separator pressure on the occurrence of the flow patterns was also examined. It shows that the S-bend tends to suppress the initiation of severe slugging.
Cerebral aneurysm, a local enlargement of an artery caused by weakness in the wall of a cerebral artery, has the high death rate and disability rate, and is a threat to public health. The forming mechanism of aneurysm...
Cerebral aneurysm, a local enlargement of an artery caused by weakness in the wall of a cerebral artery, has the high death rate and disability rate, and is a threat to public health. The forming mechanism of aneurysm is complex, which motivated many researchers to conduct studies in this field. The results indicated that increasing heart frequency can aggravate the oscillation of wall shear stress, and push The growth points of aneurysm along the aneurysm wall, thereby significantly affecting bthe growth and rupture mechanism of aneurysm. In addition, it is found that the curvature of the vessel is the key to induce the secondary vortex in the aneurysm; the secondary vortex increases the magnitude of WSS near the dome of aneurysm, which can cause the rupture of aneurysm dome. there is a linear relationship between the velocity of blood flow and the square root of hear frequency.
An improved meshless numerical method (MPS-MAFL) is utilized to simulate single Taylor bubble rising in liquid LBE to study its hydrodynamic characteristics. The computational region is a circular tube in which the li...
An improved meshless numerical method (MPS-MAFL) is utilized to simulate single Taylor bubble rising in liquid LBE to study its hydrodynamic characteristics. The computational region is a circular tube in which the liquid is described using discretized particles by un-uniform grid scheme. The gas-liquid interface was approximately treated as a free surface boundary and nonslip conditions are applied on tube wall. Several simulation results and corresponding analysis including Taylor bubble propagation procedure, pressure distribution, velocity profile around bubble nose and in the wake region as well as in the falling film are presented. Some experimental results and CFD numerical simulations from other previous researchers are compared with the present study as validation. The simulation results agree well with both theoretical analysis and experimental results, which demonstrate the reasonable selection of model as well as the accuracy and reliability of moving particle method.
Through constructing micro-scale model, the kinetic of micelles in surfactant solution and the corresponding rheological properties are studied numerically by Brownian dynamics simulation. Rigid osculating multibead r...
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Through constructing micro-scale model, the kinetic of micelles in surfactant solution and the corresponding rheological properties are studied numerically by Brownian dynamics simulation. Rigid osculating multibead rods which can be connected at the endcaps are used to represent micelles. By analysis of potential and frictional effect, the force and kinetic of micelles in shear flow field are studied. The simulated results indicate that flexible micelles elongate along the cylindrical axis with addition of bending potential. As the persistence length increases, the characteristic zero-shear viscosity increases.
This article proceeds a new method which can continuously prepare emulsion by using a venturi tube, to achieve the goal of emulsify diesel oil, methane and water. The diesel oil comes in at the entrance of the venturi...
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This article proceeds a new method which can continuously prepare emulsion by using a venturi tube, to achieve the goal of emulsify diesel oil, methane and water. The diesel oil comes in at the entrance of the venturi tube. The solution of methane and water comes in at the throat of venturi tube and mixes with diesel oil to form emulsion. The preparation system is designed and the structure parameter of the venturi tube is calculated. Then FLUENT is used to do a series of numerical simulation of the flow in the venturi tube under different parameters of spread angle and ratio of length to diameter, thus deciding the best parameters which are 8 degree and 1.25. The basic data for the design of experimental system is provided.
Turbulent drag reducing characteristics of CTAC/NaSal aqueous solution (CTAC had same mass concentration with NaSal.) were investigated in a two-dimensional channel of 30 mm height and 375 mm width, which was made of ...
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Turbulent drag reducing characteristics of CTAC/NaSal aqueous solution (CTAC had same mass concentration with NaSal.) were investigated in a two-dimensional channel of 30 mm height and 375 mm width, which was made of transparent acrylic resin. The measured drag reduction data were scaled up by using Hoyt's scaling method and were compared with other reported drag reduction data for different channel sizes. It could be concluded that both the critical temperature and critical Reynolds number at which turbulent drag reduction of surfactant solution occurred increased with concentration. There was a maximum drag-reduction about 60% for the measured CTAC/NaSal solutions. The Hoyt's scale-up method correlated well the experimental data for different channel heights when the SIS (shearing induced structure) was established very well in surfactant solutions.
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