Advanced Materials Research Vols. 383-390

Abstract: Gas hydrate is a new energy in the 21st century with the characteristics of high energy density, huge amount of resources and cleaning. It has important significances for resources development, environmental protection and global climate changing. Due to the limitations of the occurrence mode and the technical level of marine gas hydrates, at present, the development and utilization of the resources are still tentative. This article analyzed and evaluated several key technologies to develop marine gas hydrates, that is depressurization, thermal methods, chemical injection method, CO2 replacement method, and fluorine gas+microwave method.

Abstract: For the operation situation of the series-type electrostatic fabric filter precipitator, the deflectors in the inlet of the precipitator whose angle and spacing were changed to improve the air distribution characteristic and collection efficiency were assembled. The three-dimensional structural model of the series-type electrostatic fabric filter precipitator was built and meshed, then carried on the number simulation of air distribution characteristic with FLUENT. The simulation results show that when the deflector spacing is 0.7m and the incremental height is 0.15m the air distribution is more uniform. The numerical simulation result is reasonable and can be used as the reference to optimize the designing of electrostatic fabric filter precipitator.

Abstract: Using the Gidaspow model as the momentum exchange coefficient to take a full-loop simulation of miniature circulating fluidized bed gasifier (CFBG) in the lab, and taking mutual influence of different parts in consideration, it focus on the gas-solid flow structure in the riser in this paper. The heterogeneous behavior in the CFBG riser and the radial profiles of solid volume fraction under different solid inventories in simulation are showed in this paper as a replenishment of certain data which are hard to measure in experiments. The results showed it can’t form an obvious core-annulus flow because of the riser’s high height-diameter ratio and the big refeed line diameter. There are clusters growing and dissipation in a short time. A turning point of pressure drop may be seem as a separation of dense area and dilute area.The three-dimensional (3D) simulation revealed the solid flux and the pressure drop agree with the experimental data.

Abstract: A new installation style of gas-fired infrared radiant heating system for Tianjin subway NO.1LiuYuan garage was proposed in this paper. Meanwhile simulation of the temperature field was made with CFD software, the result fits temperature requirement. Based on that, energy consumption analysis was made by Energy-Plus for garage with such system; it has proven that the new form consumes less energy than the existing form.

Abstract: The main transmission route of infectious disease is the dispersion of exhaled particulate matter with pathogen attached on. Therefore, the exploration on the dispersion routine of bio-aerosol is a significant approach for researching control method of indoor infection. Based on the continuous point-source dispersion model, this article puts forward corresponding modified methods according to different airflow patterns and make it become a reasonable predicting tool for the dispersion of bio-aerosol in indoor environment. Such predicting tool is also validated by a bacteria emanating experiment whose results show a notable improvement on predicting accuracy of the modified model. Additionally, the experiment results also indicate that the under floor air supply pattern embraces preferable controlling ability on indoor infections for each occupant in an office environment.

Abstract: The aim of this study is to investigate the effect of nutrient removal process by addition of volatile fatty acids (VFAs) as external carbon sources, and how a model can be applied to a pilot test system to simulate the system. The results showed that: the effect of nutrients removal can be substantially increased with the addition of VFAs: before the addition of VFAs, the removal rate of TN and TP are 22% and 26% respectively; after the addition of VFAs, removal rates of TN and TP achieved 74% and 80% respectively. From an error analysis between simulated value and experimental value on the condition of external carbon addition, the average relative errors of CODcr, TN, NH3-N and NO3-N are 9.5%,23.4%,36% and 22% respectively, which illuminated the correctness of the model; optimum working conditions of the system established by the model are: internal reflux ratio is 200%,external reflux ratio is 75%,sludge retention time is 10d.

Abstract: Aiming at the problem of the concentrating solar cell efficiency restricted by the temperature. The closed two-phase thermosyphon could be used for heat dissipation in concentrat- ing solar cell with high heat flux, then water was selected as the working fluid. Numerical computation methods were adopted to study heat transfer performance of the finned heat pipe radiator in free convection. The temperature field, velocity field, total heat dissipating capacity of different fin pitch and side length as well as free convection heat transfer coefficient under the condition of constant temperature of parent tube were obtained. As a result, the fin side length had greater impact on the natural convection heat transfer coefficient and average total heat flux per unit area; the fin pitch had greater impact on the finned heat pipe radiator total heat dissipating capacity per unit length; the finned heat pipe radiator was the best when fin pitch was 3mm and fin side length was 90mm.

Abstract: The performance of air dehumidifier using LiCl solution as the Liquid desiccant was studied with numerical methods. A mathematical model describing heat and mass transfer performance of air dehumidifierwas set up. The numerical solution of differential equations were derived. Taking the heat and mass transfer coefficients obtained by experiments as the input parameters of the model，the parameter distribution of air and solution was described. The simulation results corresponds very well to experimental data. Simulation results indicated that the mathematical model could be used to predict the performance of air dehumidifier. The results showed that the mathematical model can be of great value in the design and improvement of air dehumidifier.

Abstract: An overall material and energy balance analysis of hydrothermal-treatment system is conducted; a model for simulating the hydrothermal-treatment process is established. The experimental hydrothermal-treatment results of lawn-grass are used to test and prove the effectiveness of the model; and a series of technical parameters are obtained including time duration, reaction temperature, content of hemicellulose, cellulose and lignin etc.. The model can be used for technical design and operation control of lignocellulose biomass hydrothermal-treatment system.

Abstract: Based on Eley-Rideal kinetic mechanism, one dimensional mathematical model for selective catalytic reduction reaction was established, in order to simulate the SCR process in the catalyst channel. The thermal effect on the reaction and the side effect of ammonia oxidation in the channel were considered simultaneously in the modeling. The model was testified to be reliable by compared with the experimental data. By the model, the concentration and temperature distributions in the channel were simulated. The effects of catalyst structure parameters, such as the pitch, the shape of catalyst channel and the monolithic catalyst type, on de-NOX efficiency were studied emphatically. The simulation results would be as an important reference for the design of SCR catalyst in the practical application.