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Wet flue gas desulfurization (WFGD) wastewater treatments used by most coal-fired power plants have difficulty in realizing completely zero emission. An atomizing and crystallization treatment of desulfurization wastewater using high-temperature gas from SCR (selective catalytic reduction) denitrification reactors was proposed. Using ANSYS software, 3D modeling of a crystallization tower and a numerical simulation of evaporation were conducted, and the crystallization process of wastewater droplets was studied. Based on the results of the simulation, effects of four main factors on evaporation efficiency were analyzed. The results indicate that droplet group with the same initial diameter of 10 μm can evaporate entirely within a time of 0.6 s and a height of 2.4 m when the mass flow rate of 620 K flue gas increases to 2.1 kg/s. In a practical process, fluctuations in the temperature and humidity should be avoided to guarantee complete evaporation. The results provide data support for technology design of crystallization towers applied in power plants. [ABSTRACT FROM AUTHOR]

• A new algorithm was proposed and applied to numerical simulations of the flow properties in the fibrous porous media. • Experiments of permeability measurements were conducted on carbon fiber felts with different porosities. • Comparison of the simulation results with plenty of correlations showed that the new method is convenient and accurate. • Lattice Boltzmann method was used based on its advantage in the simulations with narrow geometries. Three flow types and previous modeling methods for the fibrous porous media (FPM) are summarized. A novel algorithm for modeling FPM structures was proposed to overcome shortcomings of other modeling methods. Carbon fiber felts were observed by a scanning electron microscopy to obtain geometrical information. Lattice Boltzmann method (LBM) was used in simulations for predicting flow properties. Permeability measurements and other correlations validated the new simulation method. Compared with other two common algorithms, the new algorithm predicted the flow properties in FPM more precisely. Results indicate that tortuosity in FPM increases as the porosity decreases, and the general range of the tortuosity is larger than that in the granular porous media. The effect of fiber diameter on the dimensionless permeability and the tortuosity is less than that of the porosity. A slight decline in dimensionless permeability was observed as the fiber diameter increases from 0.5 to 300 µm. [ABSTRACT FROM AUTHOR]

In this paper, a loop heat pipe (LHP) with a carbon fiber capillary wick was taken as the research object to study the steady state inside the LHP and validate the effectiveness of proposed improvements through CFD numerical simulations. A 3D model of the LHP was built and numerical simulations of steady state operation were conducted by ANSYS software. Through comparison of experiment and simulation results, heat leakage from the heated surface to the compensation chamber (CC) was identified as the major cause of failure in the feasibility experiment. The addition of a heat insulation layer on the contact surface between shells of the evaporator and the compensator was validated as an improvement in reducing heat leaking through the metal shells. The substitute of the copper plating by an alumina-copper coating on surface of the carbon fiber capillary wick was proposed as an improvement to decrease the heat transferring through the capillary wick. The simulation shows that a silicon sheet with low thermal conductivity can increase the liquid volume fraction in the CC to 23%, while an yttria-stabilized zirconia (YSZ) heat insulation layer can raise the figure to 74%. According to simulation results, the combination of YSZ layer and alumina-copper coating can realize a temperature drop of 5.7 K comparing with the combination of silicon sheet and copper plating. The optimized experiment indicates that the use of the heat insulation layers improves stability of operation and increases bearing heat load of the LHP. The dependability of simulation results and the rationality of experimental error were proved by comparing results of experiment and simulation under the same operation conditions. • Heat leakage form shells and capillary wick causes the failure of startup and operation. • Silicon sheet is effective on reducing heat leakage as heat insulation material. • YSZ coating can obstruct most of the heat leakage, which makes it more effective than the silicon sheet. • Alumina-copper coating is an ideal substitute of copper plating of carbon fiber capillary wick. [ABSTRACT FROM AUTHOR]