The influence of γ-Al2O3/FC-72 nanofluids on pooling boiling heat transfer with a smooth surface was experimentally investigated. The fluorocarbon surfactant FSO-100 was also used in the experiment. In order to disti...
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The influence of γ-Al2O3/FC-72 nanofluids on pooling boiling heat transfer with a smooth surface was experimentally investigated. The fluorocarbon surfactant FSO-100 was also used in the experiment. In order to distinguish the effects of surfactant, four groups of contrast tests were designed as follows: base fluids (FC-72), base fluids with nanoparticles (γ-Al2O3+FC-72), base fluids with surfactant (FC-72+FSO-100) and nanofluids with surfactant (γ-Al2O3/FC-72+FSO-100). The results of nanofluids with surfactant showed that the heat transfer performance is enhanced compared with base fluid, but will weaken with the increase of particle concentration. In general, nanofluids can enhance the boiling heat transfer to some extent, and the enhancement is affected by the adjunction of surfactant and the sedimentation of nano-particules. Nanofluids prepared with only nanoparticles were not stable due to nonuniform distribution of the particles. The adjunction of surfactant (without nanoparticules) will lead to a significant deterioration in both heat transfer coefficient and CHF (Critical Heat Flux), but it can keep nanofluids stable and homogeneous to some degree for heat transfer enhancement.
The conditions for sodium hypochlorite aqueous solution (NaClO(aq)) o xidizing and absorbing gaseous elemental mercury (Hg0(g)) and nitrogen oxides (NOx(g)) were examined. First, some chemical thermodynamic parameters...
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In a novel bio-electrochemical system (BES) for hydrogen and electricity co-production with acetate substrate, the anolyte pH and cathode Pt loading effects are investigated to improve the cell performance for hydroge...
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TWR can make use of non-enriched fuel and obtain very high burnup without the need of fuel reprocessing. TWR is an effective way of fuel utilization besides the closed fuel cycle. In this paper, the feasibility of MA ...
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Renewable energy or low grade energy utilizations need high performance of phase change heat exchangers. Suspending micromembrane cylinder in tube(called modulated heat transfer tube) increases the void fractions or v...
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Renewable energy or low grade energy utilizations need high performance of phase change heat exchangers. Suspending micromembrane cylinder in tube(called modulated heat transfer tube) increases the void fractions or vapor qualities near the tube wall to significantly enhance heat transfer. The R123 condensation heat transfer with horizontal position was investigated. The results for the bare tube and modulated heat transfer tube were tested case by case. It is found that the modulated heat transfer tube significantly enhance the condensation heat transfer, with the heat transfer enhancement factors(EF)covering the range of 1.118–2.124. The comprehensive performance evaluation criteria(PEC) had the range of0.71–1.66, with most of runs behaving PEC larger than *** the two-phase outlet conditions, the EF values are increased with increases in the vapor mass fluxes, Gxin,where G is the mass flux and xinis the inlet vapor mass quality. The EF values are inversely related to Gxinfor the subcooled liquid outlet cases. The enhanced heat transfer mechanisms are analyzed with the observed images together with the discussion of pressure and velocity distributions.
Some coking plants discharge coke-oven gas to the environment,this pollute the *** order to solute the problem,the paper proposed a method:using coke-oven gas instead of light oil to ignite the *** virtue of doing thi...
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In order to solute the question of boiler ignition in thermal electrical factory of an Aluminun plant, Coke-oven gas was used to substitute for ligtht oil. At the same output of boiler, the cost of start up can be red...
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The paper describes a method for monitoring CO2 leakage in geological carbon dioxide sequestration. A real time monitoring parameter, apparent leakage flux(ALF), is presented to monitor abnormal CO2 leakage, which can...
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The paper describes a method for monitoring CO2 leakage in geological carbon dioxide sequestration. A real time monitoring parameter, apparent leakage flux(ALF), is presented to monitor abnormal CO2 leakage, which can be calculated by atmospheric CO2 and O2 data. The computation shows that all ALF values are close to zero-line without the leakage. With a step change or linear perturbation of concentration to the initial CO2 concentration data with no leakage, ALF will deviate from background line. Perturbation tests prove that ALF method is sensitive to linear perturbation but insensitive to step change of concentration. An improved method is proposed based on real time analysis of surplus CO2 concentration in least square regression process, called apparent leakage flux from surplus analysis(ALFs), which is sensitive to both step perturbation and linear perturbations of concentration. ALF is capable of detecting concentration increase when the leakage occurs while ALFs is useful in all periods of leakage. Both ALF and ALFs are potential approaches to monitor CO2 leakage in geosequestration project.
Structural integrity of steam generator should be maintained during operation, since it performs as the pressure boundary of primary side coolant. Localized thermal-hydraulic parameters of secondary side are essential...
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ISBN:
(纸本)9781632668264
Structural integrity of steam generator should be maintained during operation, since it performs as the pressure boundary of primary side coolant. Localized thermal-hydraulic parameters of secondary side are essential for the analysis of tube wastage, fatigue and failure. In this paper, a three-dimensional thermohydraulics analysis code, named STAF, is developed based on FLUENT. With STAF code, three-dimensional thermohydraulics of secondary side of AP1000 steam generator are generated. This code is developed based on the porous media theory. In this code, the drift flux two-phase model coupled with a simplified flow boiling model is utilized to present two-phase flow among the U-tube bundle. Downcomer, tube bundle, support plates and primary separators in steam generator are considered in STAF code. The calculated results are compared with a general steam generator thermohydraulic analysis code ATHOS, which is developed by the Westinghouse. The comparison indicates that STAF code performs well in evaluating thermal-hydraulic parameters in steam generator. The results show that the flow field varies significantly at different position in AP1000 steam generator. flow vapor quality at the inlet of primary separators varies significantly, which is a severe challenge to the capacity design of separators.
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