Luo Zhongyang

Dependence of Nanofluid Viscosity on Particle Size and pH Value

We investigate the viscosity of silicon dioxide nanofluid at different particle sizes and pH values considering nanoparticle aggregation. The experimental and simulation results indicate that nanoparticle size is of crucial importance to the viscosity of the nanofluid due to aggregation. As the nanoparticle size decreases, the viscosity becomes much more dependent on the volume fraction. Moreover, when the nanoparticle diameter is smaller than 20 nm, the viscosity is closely related to the pH of the nanofluid, and fluctuates with pH values from 5 and 7.

Mechanism study on cellulose pyrolysis using thermogravimetric analysis coupled with infrared spectroscopy

Based on the investigation of the polysaccharide structure of cellulose by using Fourier transform spectrum analysis, the pyrolysis behaviour of cellulose was studied at a heating rate of 20 K/min by thermogravimetric (TG) analysis coupled with Fourier transform infrared (FTIR) spectroscopy. Experimental results show that the decomposition of cellulose mainly occurs at the temperature range of 550–670 K. The weight loss becomes quite slow when the temperature increases further up to 680 K and the amount of residue reaches a mass percent of 14.7%. The FTIR analysis shows that free water is released first during cellulose pyrolysis, followed by depolymerization and dehydration. Glucosidic bond and carbon-carbon bond break into a series of hydrocarbons, alcohols, aldehydes, acids, etc. Subsequently these large-molecule compounds decompose further into gases, such as methane and carbon monoxide.

Dissolution rate of limestone for wet flue gas desulfurization in the presence of sulfite

Limestone dissolution rate was measured by a pH-stat method with CO(2) sparging and dissolved sulfite. The dissolution rate of limestone under these conditions was found to be controlled by mass transfer and surface kinetics. As can be seen from the results, in the presence of sulfite, limestone dissolution rate increases with increasing stirring speed, reaction temperature and CO(2) partial pressure. The crystallinity of limestone has a great impact on the dissolution rate: The lower the value of the crystallinity of limestone is, the higher the dissolution rate is. The presence of sulfite promotes the dissolution rate when pH value is below 5.5 but inhibits it when pH value is above 5.5.

Experimental study of the influence of acid wash on cellulose pyrolysis

The analysis of microstructure and polymerization degree showed that acid wash altered the cellulose morphology and decreased the polymerization degree significantly. A series of experiments were done to study the effect of acid wash on cellulose rapid pyrolysis. Experimental results showed that under acid pretreatment, the yield of bio-oil decreased while the production of gas and char increased. With an increase in acid concentration, this trend would be further enhanced. Sulphuric acid limited the formation of bio-oil more effectively than hydrochloric acid and phosphoric acid. According to the GC-MS analysis of bio-oil, high-concentration acid wash restrained the formation of levoglucosan by catalyzing dehydration process and cross linking reaction.

A dielectric multilayer filter for combining photovoltaics with a stirling engine for improvement of the efficiency of solar electricity generation

In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications. The optical performance of this 78-layer interference filter constructed by TiOx and SiO2 is presented. A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed. The calculated results show the advantages of this spectrally selective method for solar power generation.

Electrostatic Capture of PM2.5 Emitted from Coal-fired Power Plant by Pulsed Corona Discharge Combined with DC Agglomeration

How to improve ESP collection efficiency for PM2.5 is getting a matter of environmental concern. in this paper, a process capable of capturing PM2.5 efficiently was proposed, which utilizes a pulsed corona discharge combined with dc agglomeration. a laboratory-scale wire-plate electrode configuration was established. the particle electrostatic charging and number concentration distribution of PM2.5 have been measured by an electric low pressure impactor (elpi) at real time with the size range from 0.007 μm to 10 μm the particle charging and collection efficiency characteristics of PM2.5 were quantitatively investigated under different applied pulse peak voltage. the results show that for a certain given operating condition, PM2.5 collection efficiency increases with the increasing pulse peak voltage. dc voltage agglomeration is used to achieve a number reduction exceeding 90% on the submicron fraction of particles. this research may provide a new technology for efficient removal of PM2.5 from flue gas in coal-fired power plant.

Heat transfer in a large-scale circulating fluidized bed boiler

Heat transfer of a furnace in a large-scale circulating fluidized bed (CFB) boiler was studied based on the analysis of available heat transfer coefficient data from typical industrial CFB boilers and measured data from a 12 MWe, a 50 MWe and a 135 MWe CFB boiler. The heat transfer of heat exchanger surfaces in a furnace, in a steam/water cooled cyclone, in an external heat exchanger and in the backpass was also reviewed. Empirical correlation of heat transfer coefficient was suggested after calculating the two key parameters, solids suspension density and furnace temperature. The correlation approach agrees well with the data from the large-scale CFB boilers.

THE PREDICTION AND MEASUREMENT OF PARTICLE BEHAVIOR IN CIRCULATING FLUIDIZED BEDS

ABSTRACT A two-dimensional gas-particle flow numerical model is presented which accounts for particle fluctuation and particle-particle collisions in the circulating fluidized beds. This model treats fluctuation of particle movement as a random Fourier series based on gas-flow fluctuation spectrum and hence is known as the fluctuation-spectrum-random-trajectory (FSRT) model. The model is used to predict the velocity particle trajectory and concentration of the particle-phase in circulating fluidezed beds. Measurements of particle velocity and the concentration of the particle-phase in circulating fluidized bed are carried out and the predictions of the FSRT model are compared with the experimental results. Some aspects of the behavior of the particle movement in circulating fluidized beds are also predicted.

The Mechanism of Naphthalene Decomposition in Corona Radical Shower System by DC Discharge

Polycyclic aromatic hydrocarbons (PAHs) from coal-fired boilers and waste incinerators are regarded as some toxic and difficult decomposition pollutants. In this paper, it was studied how the applied voltage, the initial concentration and the catalyst affected the naphthalene decomposition characteristics using a corona discharge radical shower system. The emission spectrum of OH (A2Σ+ → X2П) was detected to understand the decomposition mechanism, of naphthalene better. In addition, the decomposition by-products and the decomposition process were also analyzed initially. The results show that the increasing applied voltage and humidity is helpful to the naphthalene decomposition because of the increasing OH radicals. High initial concentration of naphthalene can heighten the decomposition amounts and the catalyst can improve the naphthalene decomposition. The main decomposed by-product is CO2 and H2O. However, there are also little CO and small-molecule organic compounds to be found because of the incompletely oxidative reactions.

Multi-pollutants Simultaneous Removals from Flue Gas

With the stricter emission standards, more pollutants in the air need to be controlled. If the traditional mean of using a technology to treat a pollutant is adopted, there are high investment running cost and complex operation system. So the multi-pollutants simultaneous removal technology from flue gas is paid more and more attention in the recent ten years. The plasma technology and semi-dry flue gas cleaning technology are two very promising multi-pollutants simultaneous removal technologies. In our researches, a plasma technology of corona radical shower and a semi-dry flue gas cleaning technology using circulating suspension and multistage humidification were selected. A series of fundament and industry application works were done. In the paper, some current results are opened out to provide some reference.