Applied Mechanics and Materials Vols. 90-93

Abstract: Constructed wetlands (CWs) have been applied for wastewater treatment since 1987 in Mainland China. There were about 150 public owned CWs operated to treat different types of wastewater, including urban domestic wastewater, rural sewage, effluent from secondary treatment, industrial wastewater, urban and agricultural runoff. About 44% of the CWs are designed for urban and rural sewage treatment. Hybrid CW takes a majority role for wastewater treatment in China. There are 24 full-scale hybrid CWs among the surveyed 59 systems in this paper. The most frequently used filtration media for vegetated beds are gravel and cobble. Phragmites australis is the dominate plant used in CWs in north China, while cyperus alternifolius and Typha latifolia are commonly applied in south China. The statistical average removal efficiencies of CWs for industrial wastewater treatment are the highest in terms of COD and BOD₅, followed by the efficiencies of treating urban domestic wastewater, rural sewage, effluent from secondary treatment, urban and agricultural runoff in a decline order with a revise trend of the designed hydraulic loading rates.

Abstract: The ClO₂ chemical oxidation system and ClO₂ catalytic oxidation system are studied in this paper. The results show that pH=6~8, 1000mg ClO₂/L wastewater, reacting 60min are the most efficient and economical, when treating Acid Brilliant Scarlet GR dyestuff wastewater, the COD of which is 3500mg/L, by ClO₂ chemical oxidation. The COD removal ratio exceeds 50%, and the oxidation index (COD removal amount/ ClO₂ used amount) is 2.3. When treating the wastewater by catalytic oxidation which is composed of ClO₂ and special catalyst, pH≈2, 800mg ClO₂/L wastewater, reacting 45~60min are the most efficient and economical. The COD removal ratio exceeds 80%, and the oxidation index (COD removal amount/ ClO₂ used amount) is 3.5. The cost of oxidant removing 1kg COD is ¥3.7. The effect is superior to that of ClO₂chemical oxidation apparently. The study indicates that ClO₂ catalytic oxidation is an efficient method to treat refractory wastewater and it’ll have a broad prospect.

Abstract: The effect of masss of natural diatomite, initial dye concentrations, pH and temperature on adsorption was investigated. The adsorption of reactive dye was slightly increased then decreased with rising amouts of natural diatomite that is increasing competition of natural diatomite. The removal rate of reactive black increase with the temperature because of endothermic reaction. The removal rates of reactive black from solution were decreased as the pH increase and gain the maximum in low pH. The removal rate for all concentrations were rapid at initial stages and then keep increase gradually until the progress until equilibrium reached.

Abstract: Aimed at the emergency condition under natural disaster and water pollution, this article expounds the emergency water supply system and respectively introduces the up to date development of research on the beforehand scheme of emergency water supply, the layout of emergency water sources, the emergency water supplying equipments and technologies. At last, this article gives a prospect on the developing orientation of emergency water supplying equipments and technologies.

Abstract: A computational fluid dynamics (CFD) model is proposed to simulate numerically conjugated heat transfer process of fluid washing out solid with evenly internal heat source in the pipe. Temperature field and velocity field inside the pipe and outside solid are gained by calculation. Based on numerical simulation, the varying regularity of Nusselt number between fluid and solid wall surface is obtained and analyzed. The results show that there are two symmetrical vortexes in the back of solid. The Nusselt number and heat exchange rate dramatically decrease with increasing horizontal distance of top and bottom of solid.

Abstract: In heat source ability sufficient situation, some phenomenon occurred in some central heat supply system, such as uneven heating, serious disorders, the far-end heating reliability was insufficient. To improve the heating security and reliability, this article carries on an investigation test, problem analysis, Clears the crux of the problem, Proposes the corresponding transformation plan, and carries on the effective analysis of the actual heating effect after transformation. The results show that after transformation, the actual heating network runs well, increases the heating area, improves the heating security and reliability, provide the reference for other large-scale pipe network energy conservation transformation.

Abstract: Two combined operation modes of basic heat source and distribution heat source are described, the possible values of basic heat source capacity coefficient α under these two combined operation modes in each region with heating provision are explored, the theoretical calculation formula of distribution heat source opening temperature and closing temperature is derived, and figure out distribution heat source opening temperature and closing temperature of each region with heating provision according to the recommended basic heat source capacity coefficient α, draw that if heating temperature is 5°C, distribution heat source can not only reinforce the peak, but also run the valley in these regions which are colder than Yinchuan, but distribution heat source can only reinforce the peak in other regions.

Abstract: The article reviews the basic principles of interaction between the cutting tools with the ground. Their advantages and disadvantages. It is carried out to determine the degree of relevance of the issues under research and to clarify the currently existing methods of solving them. We are especially interested in frozen soils, because the problem of the frozen soils’ development is one of the most serious to date. Most of the unexplored territories of the world lie under the snow cover in winter times. In the extreme north an acute problem of dealing with permafrost soils demands a rapid optimization of the cutting processes applied to frozen grounds. To this end, we developed a special milling and boring rig BME-2000 (Bore-Milling Equipment 2000), based on a machine excavator. It works on the principle of core drilling and is designed to develop permafrost and extremely durable surfaces such as asphalt and concrete. This article will try to formulate all the necessary questions for further research studies and to set objectives for further optimization of the cutting processes based on the BME-2000 as a comparison model. This will be done through a review of all known principles of excavation and existing machinery that deals with the development of soils/frozen soils and very durable surfaces.

Abstract: A CCHP system using LNG as the primary energy should integrate cold recovery unit to increase the total energy efficiency. A scheme of CCHP consisting of gas turbine-steam turbine combined cycle, absorption refrigeration unit, cold recovery unit and cooling media system is a system with high efficiency and operation flexibility. Three different power cycles using the cold energy of LNG is(are 或 were) presented and simulated. The results show that the cascade Rankine power cycle using ethylene and propane in the two cycles respectively has highest energy efficiency. However, the unit is most complex. The efficiency of ethylene Rankine power cycle is little lower than the cascade one, and is much higher than the traditional propane Rankine cycle. The complexity of ethylene cycle is identical to that of the propane cycle. The ethylene Rankine power cycle is the referred method of cold recovery in a CCHP system based on overall considerations.

Abstract: By using household heat metering system，people can control indoor temperature according to their economic conditions and the requirement of thermal comfort. In this paper, DeST-h is used to simulate the energy consumptions of architecture heating in different temperature, which compare to the situation that not use temperature control simulation, to analysis the heating energy saving potential in domestic architecture in Shenyang. So as to develop people’s consciousness of energy saving, and to provide the quantized datat for decision-makers to make relevant policies.