Based on selecting the proper formulas of thermal conductivity and viscosity for nanofluids, a three-dimensional fluid-solid conjugated model was developed to analyze the effect of the heat sink structure, the nanopar...
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Based on selecting the proper formulas of thermal conductivity and viscosity for nanofluids, a three-dimensional fluid-solid conjugated model was developed to analyze the effect of the heat sink structure, the nanoparticle kind, diameter and volume fraction, and the base fluid kind on the cooling performance of microchannel heat sink. The results showed that: (1) thermal dispersion effect caused by nanoparticle random motion enhanced the thermal convection of nanofluid thus enhances significantly the cooling performance of heat sink;(2) the enhancement of nanofluids was closely dependent on the heat sink structure and the dependence was distinct from the pure fluid, hence the heat sink structure was needed to be optimized for nanofluids as coolants;(3) as the nanoparticle volume fraction increases, the thermal resistance reduced and the pressure increased, the water-based Al2O3 nanofluid with 0.5% volume fraction was the optimal coolant which caused 10.1% decrease in the thermal resistance and only 0.38% increased in the pressure drop;(4) although the nanoparticle size had a small effect on the thermal resistance, nanoparticles with small diameter were recommended with consideration of stability of nanofluids;(5) Al2O3 nanoparticle was superior to TiO2 and CuO, and water was the better base fluid than ethylene glycol and engine oil.
Lithium extraction is a great challenge from the high magnesium content salt solution. In this work, an integrated polyamide tight ultrafiltration (UF) and nanofiltration (NF) membranes are systematically investigated...
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Low temperature corrosion is one of the key issues in application of low-low temperature electrostatic precipitator. The concentration of SO3 affects the acid dew point temperature of flue gas. The exhaust temperature...
Low temperature corrosion is one of the key issues in application of low-low temperature electrostatic precipitator. The concentration of SO3 affects the acid dew point temperature of flue gas. The exhaust temperature after the air preheater should be higher than the acid dew point temperature. The residual heat of flue gas is fully utilized by the low-temperature economizer. The efficiency of low-low temperature electrostatic precipitator is improved by the comprehensive effect of the condensation of SO3 on the surface of the fine particles, the decrease of the specific resistance of the particles and the agglomeration of the fine particles.
The influences of the preset angle on the dynamic responses of the typical airfoil section with cubic nonlinear stiffness were investigated under consideration of the aerodynamic flutter onset due to certain angle of ...
The influences of the preset angle on the dynamic responses of the typical airfoil section with cubic nonlinear stiffness were investigated under consideration of the aerodynamic flutter onset due to certain angle of attack. The typical airfoil model with cubic nonlinear stiffness is developed to analyze the plunging and the pitching motions for the airfoil section. Based on the Grossman's quasi steady aerodynamic model, the aerodynamic lift and the moment can be obtained and then the equation of motion for the airfoil section is derived by applying the Lagrange theorem. The effects of the preset angle and the oncoming flow speed on the nonlinear dynamics are analyzed by means of the bifurcation diagram, the frequency-amplitude diagram, the time history, etc. Simulation results show that the preset angle influences the intensity of the vibration, moderate or severe, stable or unstable, even under certain circumstance, the jump and chaos phenomenon occur; and the oncoming flow speed affects the distribution of the vibration energy for the plunging and the pitching motions. The unstable stall region for the responding parameters should be avoided to keep the airfoil safe in engineering practice. Some qualitative and quantitative rules are obtained for the airfoil design and the flutter suppression.
This study investigates the impact of blade gap angle on spiral axial flow gas–liquid multiphase pump performance. Using five numerical models and the shear stress transport k-omega (SST k-ω) turbulence model, we in...
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Coal-bed methane (CBM) reserves are rich in Sinkiang of China, and liquefaction is a critical step for the CBM exploration and utilization. Different from other CBM gas fields in China, CBM distribution in Sinkiang is...
Coal-bed methane (CBM) reserves are rich in Sinkiang of China, and liquefaction is a critical step for the CBM exploration and utilization. Different from other CBM gas fields in China, CBM distribution in Sinkiang is widespread but scattered, and the pressure, flow-rate and nitrogen content of CBM feed vary significantly. The skid-mounted liquefaction device is suggested as an efficient and economical way to recover methane. Turbo-expander is one of the most important parts which generates the cooling capacity for the cryogenic liquefaction system. Using turbo-expander, more cooling capacity and higher liquefied fraction can be achieved. In this study, skid-mounted CBM liquefaction processes based on Claude cycle are established. Cryogenic turbo-expander with high expansion ratio is employed to improve the efficiency of CBM liquefaction process. The unit power consumption per liquefaction mole flow-rate for CBM feed gas is used as the object function for process optimization, compressor discharge pressure, flow ratio of feed gas to turbo-expander and nitrogen friction are analyzed, and optimum operation range of the liquefaction processes are obtained.
Fluidization of non-spherical particles is commonly found in the biomass and solid waste processing industry, and the jetting characteristic above the aeration plate is critical to the fluidization performance of thes...
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Herein, a new type of photocatalysts, Au [email protected] @ZnIn 2 S 4 nanosheets ( [email protected] @ZIS), is elaborately designed for the photocatalytic H 2 evolution from water splitting, where Au nanodo...
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Herein, a new type of photocatalysts, Au [email protected] @ZnIn 2 S 4 nanosheets ( [email protected] @ZIS), is elaborately designed for the photocatalytic H 2 evolution from water splitting, where Au nanodots (NDs) are anchored in the pore space of thiol-functionalized UiO66 metal-organic framework (MOF) and ZnIn 2 S 4 nanosheets are wrapped around the UiO66 MOF containing Au NDs. It is found that the different Au positions have a grateful effect on the transfer of photogenerated charge carriers. In [email protected] @ZIS, the photoexcited electrons transfers from ZnIn 2 S 4 to UiOS and then to Au NDs, establishing a smooth transmission channel of electrons. As expected, the optimal sample (Au 4 @ [email protected] 40 ) presents a high photocatalytic H 2 production rate of 391.6 μmol/h (10 mg of catalyst) under visible light irradiation, which is 435.1, 61.2 and 10.2 times higher than that of the pure UiOS, ZnIn 2 S 4 and [email protected] , respectively.
As an established method to analyse the thermodynamic process inside the cylinder, the p-V diagram can identify typical faults such as leakages through the sealing rings and self-acting valves, loosening and flutterin...
As an established method to analyse the thermodynamic process inside the cylinder, the p-V diagram can identify typical faults such as leakages through the sealing rings and self-acting valves, loosening and fluttering of the vales, etc. However, the installation of the pressure sensor within the cylinder for recording the p-V diagram may lead to degradation of the cylinder integrity, and hereby potential leakage and lowered strength of the cylinder. This paper presents a new non-destructive method for fault diagnosis of the reciprocating compressor by measuring the piston rod strain, from which the p-V diagram was transformed. An algorithm for reconstruction of the p-V diagram was proposed based on the key feature points on the piston rod load curve that reflect the opening and closing events of the compressor valves. The reconstruction method was validated by comparing the calculated p-V diagrams with the experimental results. The reconstructed p-V diagrams were further used for fault diagnosis of the reciprocating compressors, with which the acoustic emission method was integrated. The results show that this method can easily monitor the working conditions and identify whether and where leakage, fluttering and delayed closing of the valves occur, which indicates that this method can be utilized as a powerful tool of non-destructive condition monitoring and fault diagnosis of the reciprocating compressors.
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