Search

A plume in an atmospheric cross flow from a power generating solar chimney is investigated using a three-dimensional numerical simulation model. The simulation model is validated by comparing the data calculated using our model with the numerical simulated results for one-dimensional buoyancy-driven compressible flow in a proposed 1500 m high solar chimney. In this paper, the parametric performances including static pressure, static temperature, density, streamline, and relative humidity field of the flow at the symmetry plane, at the cross plane 2700 m high and at the cross plane 750 m high in the geometry are simulated. It is found that relative humidity of the plume is greatly increased due to the jet of a plume into the surroundings colder than the plume. In addition to a great amount of tiny granules in the plume originating from the ground as effective condensation nuclei of moisture, a condensation would occur, a cloud system and precipitation e.g. rainfall, snow and hail would be formed around the plume when vapor is supersaturated. It is also found that with an increase in chimney height or relative humidity of atmosphere, or a reduction in wind velocity, relative humidity is increased, and increases the probability of precipitation and the potential precipitation areas. Furthermore, the latent heat released from the condensation of supersaturated vapor can aid the plume to keep on rising.

A large quantity of red mud (RM) has been disposed to form hills from the Chinese sintering alumina process. These storage areas are generally bare of vegetation and subject to wind and water erosion, posing serious threats to the environment. Numerous sintered products made from RM have been developed, such as ceramics, burnt bricks, cements etc., however, such sintered products have seldom been applied because of the higher energy consumption and costs. Unsintered brick was developed from RM, cured at ambient conditions. The optimal proportions of RM brick are suggested as the following: 25–40% RM, 18–28% fly ash, 30–35% sand, 8–10% lime, 1–3% gypsum, and about 1% Portland cement. Samples of RM bricks with standard Chinese brick dimension were prepared. The results show that the RM brick product reaches the Chinese criterion of the 1st-class brick. Microstructure characteristics of the RM brick were investigated by XRD and SEM. C–S–H gel and ettringite are the main hydrated products, which might contribute to the strength of brick. No sintering, drying or grinding pre-treating process, and no emission of polluting gases are some of the benefits of such an unsintered product, and which may have a huge application in the market of construction materials.

A simple thermal model is developed for solar chimney thermal power system and validated by the comparison between the simulated results and those simulated by Schlaich et al. Based on a proposed 200 MW power plant in a desert in western China a special climate, which is formed around the giant solar chimney power plant by the volume of warm air flowing from the chimney outlet to a high altitude, is simulated and analyzed. An atmospheric circulation and rainfall are formed. It is found that the solar chimney power plant increases the chance of rainfall, especially for low-humidity air in the desert region, supporting the agriculture in the local area and promoting a part of the desert region to be reformed to fertile soil. Further, the effects of many factors on the rainfall area around a commercial solar chimney thermal power plant are also analyzed. It is concluded that by keeping other conditions equal, solar radiation of more than 706 W∕ m2 , a collector area of more than 10.45 km2 , a chimney height ...

The feasibility of recycling red mud and fly ash in the aluminium industries by producing glasses and glass-ceramics has been investigated. The crystallization behavior of glass-ceramics mostly produced from red mud and fly ash was studied by DTA, XRD, optical microscopy techniques. According to DTA curve, nucleation experiments were carried out at various nucleation temperatures at the same crystallization temperature of 900 °C for 2 h, and crystallization experiments were performed at the same nucleation temperature of 697 °C for 2 h followed by crystallization at various temperatures. The nucleation results show that optimum nucleation temperature is near 697 °C, and the crystallization experiments show that the crystallization at a high temperature of over 900 °C results in denser grain size. The major crystallized phases were gehlenite (Ca2Al2SiO7), and augite (Ca(Fe,Mg)Si2O6). The XRD results show that with the increase of crystallization temperature, the amount of gehlenite increases, and augite decreases, which is the result of augite transformation into gehlenite.

To study the relaxation mechanisms of neferine (Nef) on the corpus cavernosum smooth muscle (CCSM), the CCSM cells from New Zealand White rabbits were cultured in vitro. [Ca(2+)](i) was measured by fluorescence ion digital imaging system (FIDIS), using Fluo-2/AM as a Ca(2+)-sensitive fluorescent indicator. Nef (0.1, 1 and 10 micromol l(-1)) had no effect on the resting [Ca(2+)](i) (P0.05). In the presence of extracellular Ca(2+) (2.5 mmol l(-1)), Nef (0.1, 1 and 10 micromol l(-1)) inhibited [Ca(2+)](i) elevation induced by high K(+) and phenylephrine (PE) in a concentration-dependent manner (P0.05). In calcium free solution containing egtaic acid (EGTA), Nef (0.1 micromol l(-1)) had no inhibitory effects on [Ca(2+)](i) elevation induced by PE (P0.05). However, Nef (1 and 10 micromol l(-1)) inhibited [Ca(2+)](i) elevation induced by PE (P0.05). These data suggest that Nef inhibited [Ca(2+)](i) in CCSM cells via blocking voltage-dependent Ca(2+) channel, alpha(1)-adrenoceptor-operated Ca(2+) channel and Ca(2+) release from intracellular Ca(2+) pool. This inhibitory action on [Ca(2+)](i) might be one of the relaxation mechanisms of Nef on the CCSM.

A pilot experimental solar chimney thermal power generating equipment was set up in China. A simulation study was carried out to investigate the performance of the power generating system based on a developed mathematical model. The simulated power outputs in steady state were obtained for different global solar radiation intensity, collector area and chimney height. By intercomparison, it is found that the simulated power outputs are basically in agreement with the results calculated with the measurements, which validates the mathematical model of the solar chimney thermal power generating system. Furthermore, based on the simulation and the specific construction costs at a specific site, the optimum combination of chimney and collector dimensions can be selected for a required electric power output.

A pilot experimental solar chimney power setup consisted of an air collector 10 m in diameter and an 8 m tall chimney has been built. The temperature distribution in the solar chimney power setup was measured. Temperature difference between the collector outlet and the ambient usually can reach 24.1 °C, which generates the driving force of airflow in the setup. This is the greenhouse effect produced in the solar collector. It is found that air temperature inversion appears in the latter chimney after sunrise both on a cool day and on a warm day. Air temperature inversion is formed by the increase of solar radiation from the minimum and clears up some time later when the absorber bed is heated to an enough high temperature to make airflow break through the temperature inversion layer and flow through the chimney outlet.

The porous ceramisites for wastewater treatment were made from red mud, which is the industrial waste discharged from the production of Al2O3. The sintering process and the degreasing experiments with porous ceramisites have been finished. The results show that the sintering temperature control is dominant for the preparation of the porous ceramisites. The optimal sintering temperature is between 1 110–1 120°C, a narrow range. The surface of ceramists is distributed with a lot of coarse holes with diameters of about 1–10 μm. Moreover, the sintering temperatures have a great influence on the efficiency of degreasing, and the curve between the sintering temperature and the efficiency of degreasing is like a parabola.

Conditioning sewage sludge with Fenton's reagent could effectively improve its dewaterability. However, drawbacks of conditioning with Fenton's reagent are requirement of acidic conditions to prevent iron precipitation and subsequent neutralization with alkaline additive to obtain the pH of the filtrate close to neutrality. In this study, roles of pH were thoroughly investigated in the acidification pretreatment, Fenton reaction, and the final filtrate after conditioning. Through the response surface methodology (RSM), the optimal dosages of H2SO4, Fe(2+), H2O2, and lime acted as a neutralizer were found to be 0 (no acidification), 47.9, 34.3 and 43.2 mg/g DS (dry solids). With those optimal doses, water content of the dewatered sludge cakes could be reduced to 55.8 ± 0.6 wt%, and pH of the final filtrate was 6.6 ± 0.2. Fenton conditioning without initial acidification can simplify the conditioning process and reduce the usage of lime. The Fe(3+) content in the sludge cakes showed a close correlation with the dewaterability of conditioned sludge, i.e., the water content of sludge cakes, SRF (specific resistance to filtration), CST (capillary suction time), bound water content, and specific surface area. It indicated that the coagulation by Fe(3+) species in Fenton reaction could play an important role, compared to traditional Fenton oxidation effect on sludge conditioning. Thus, a two-step mechanism of Fenton oxidation and Fe(III) coagulation was proposed in sewage sludge conditioning. The mechanisms include the following: (1) extracellular polymeric substances (EPS) were firstly degraded into dissolved organics by Fenton oxidation; (2) bound water was converted to free water due to degradation of EPS; (3) the sludge particles were disintegrated into small ones by oxidation; (4) Fe(3+) generated from Fenton reaction acted as a coagulant to agglomerate smaller sludge particles into larger dense particles with less bond water; (5) finally, the dewatered sludge cakes were obtained, with less small pores (1-10 nm) that contributed to water affinity, but with more large pores (>10 nm) that contributed to a permeable, rigid lattice structure. Morphology of the Fenton-conditioned sludge cake exhibited a porous structure. The estimated cost of the composite conditioner, Fenton's reagent and lime, is USD$ 43.8/t DS, which is less than that of ferric chloride and lime (USD$ 54/t DS). Furthermore, pH of the final filtrate using this composite conditioner is about 6.6. Comparatively, that using ferric chloride and lime is as high as 12.4.

Mature aerobic granular sludge (AGS) was inoculated for the start-up of a pilot-scale sequencing batch reactor for the treatment of high concentration solvent recovery raffinate (SRR). The proportion of simulated wastewater (SW) (w/w) in the influent gradually decreased to zero during the operation, while volume of SRR gradually increased from zero to 10.84 L. AGS was successfully domesticated after 48 days, which maintained its structure during the operation. The domesticated AGS was orange, irregular, smooth and compact. Sludge volume index (SVI), SV30/SV5, mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSS/MLSS), extracellular polymeric substances, proteins/polysaccharides, average particle size, granulation rate, specific oxygen utilization rates (SOUR)H and (SOUR)N of AGS were about 38 mL/g, 0.97, 0.52, 39.73 mg/g MLVSS, 1.17, 1.51 mm, 96.66%, 47.40 mg O2/h g volatile suspended solids (VSS) and 8.96 mg O2/h g VSS, respectively. Good removal effect was achieved by the reactor. Finally, the removal rates of chemical oxygen demand (COD), total inorganic nitrogen (TIN), NH4+-N and total phosphorus (TP) were more than 98%, 96%, 97% and 97%, respectively. The result indicated gradually increasing the proportion of real wastewater in influent was a useful domestication method, and the feasibility of AGS for treatment of high C/N ratio industrial wastewater.

A loop system was used to investigate flow-assisted corrosion (FAC) of AZ91D magnesium alloy at an elbow based on array electrode technology by potentiodynamic polarization, computational fluid dynamics, simulation and surface analysis. The experimental results demonstrate the fluid hydrodynamics plays a significant role in the FAC of AZ91D magnesium alloy. The corrosion rate increases from the outer wall to the inner wall of the elbow, with the higher corrosion rate corresponding to the higher flow velocity and larger shear stress at the elbow. The maximum corrosion rate appears at the innermost wall of the elbow, the location with the maximum flow velocity and shear stress.

Phosphogypsum-based composite binder (PGCB) has been made from autoclaved phosphogypsum (PG), fly ash, lime, Portland cement and a chemical activator. The influence of autoclaved pretreatment on the properties of PG and PGCB has been investigated. It was found that the crystalline phases of original PG could be transformed, the impurities of original PG also could be effectively removed by the autoclaved pretreatment process. Under the optimum autoclaved pretreatment conditions (autoclaving at 180 °C for 6 hours), the dry compressive strength of PGCB mortars after 28 days was 31.8 MPa and the ratio of the compressive strength in wet-saturated state to that in dry state (W/D) was 0.59. PGCB mortars show good properties and water resistance with the suitable autoclaved pretreatment.

Aerobic granular sludge which had good performance to pollutants removal was successfully cultivated within 18 days in a pilot scale sequencing batch reactor, about 25% mature aerobic granular sludge was inoculated when the setting time of activated sludge was reduced to 10 min. Anaerobic biological selector was implemented to inhibit filamentous bacteria overgrowth, where the maximum COD could reach to 1703.74 mg/L. The cultivated aerobic granular sludge was irregular and pale yellow, average particle size, SVI, SV₃₀/SV₅, PN/PS, EPS and water content were 1.58 mm, 67.64 mL/g, 0.91, 2.17, 268.90 mg EPS/g MLVSS and 98.16% on the 18th day. Mechanism of rapid granulation mainly included crystal nucleus hypothesis and selection pressure hypothesis. The inoculated aerobic granules could maintain stable under short setting time environment, making it directly as the crystal nucleus and the carriers for new particles without obvious disintegration, which eventually shortened the granulation time greatly.

This paper presents a real time vehicle detection framework using learning method. This framework combines offline multiclass support vector machine and online boosting method for vehicle detection. Compare to tradition approaches, the proposed method can robust deal with multiclass vehicles and unfamiliar environment. Experiments with the city vehicle database are used to evaluate this method. The experimental results demonstrate the consistent robustness and efficiency of the proposed method.

This paper presents a real time multiclass vehicle tracking method. The method uses a combination of machine learning and feature analysis to track the vehicles on the road. Multiclass SVM are trained using train samples to achieve detection and classification of vehicles in video sequences of traffic scenes. The detection results provide the system used for tracking. Each class vehicle is tracked by SIFT method. Experimental results from highway scenes are provided which demonstrate the effectiveness of the method.

Reactive magnesium oxide (magnesia, MgO) was produced by calcining magnesite at comparatively low temperature, less than 800 ℃C. The reactive MgO and fly ash were used as additives to cementitious binder. The reactive MgO-ordinary Portland cement-fly ash is referred to as MgO-OPC-FA cement in further. The hydration expansion effect of active magnesia on the properties of cementitious binder in different mixing ratio was investigated. It is known that the “dead burnt” MgO reacts with water very slowly, which causes the expansion after the solidification of cement. Therefore, the MgO content in ordinary cement is commonly restricted to less than 5%. Effects of reactive MgO on the expansion properties of the cementitious binders were studied. Hydrated products of reactive MgO cements were investigated by X-ray diffraction (XRD) and Scanning electron microscope (SEM) analysis. The MgO-OPC-FA cement was sound, although the content of reactive MgO in cement was about 8 wt. %. Reactive MgO was hydrated at early age in 24 hours, thus causing rapid expansion. Mg(OH)2appeared on initial stage of cement hydration for active magnesia. The hydration rate of active magnesia was not equal to that of the dead burnt magnesia. The hydration of reactive MgO has a negative effect on the mechanical properties of reactive MgO-ordinary Portland cement-fly ash system, in spite of the inhibitive effect of the expansion of MgO hydration produced by fly ash. Our results shed light on the potential utilization of reactive MgO in the manufacturing of cementitious binders.

Red mud is a solid waste residue from the caustic soda leaching of bauxite ores to produce alumina by the Bayer process. Red mud contains large quantity of alkali and aluminosilicate, so it is potentially available to prepare inorganic polymeric materials by geopolymerisation process. However, the activity or dissolubility of the aluminosilicate phases in red mud is significantly poor, which constraints the geopolymerisation process. Therefore, some pretreatment process for red mud is necessary to improve the adhesive property and dissolubility of Bayer red mud. In this study, mineral phase transformation and dissolubility of a typical red mud sample were studied under different thermal treatment processes. The thermal behavior of the red mud was studied by TG-DTA. The crystalline phases of the samples calcined at 200-1000 °C for different hours were determined by XRD, and the dissolubility was determined by alkaline leaching test. The TG-DTA pattern shows no obvious endothermic or exothermic peaks, and the weight loss increases continuously as the temperature rises, which indicates that the crystalline phases transform continuously as the temperature rises, consistent with the XRD results. As the calcination temperature rises from 200 to 800 °C, several kinds of crystalline phase in original red mud, including gibbsite, katoite, muscovite, natrodavyne disappeared in succession, accompanied with the formation of nepheline, gehlenite, sodium aluminum silicate, and some amorphous aluminosilicate. The calcined products are more likely to dissolve. But when it rises over than 800 °C, the content of gehlenite increases, and the phase of which is stable. As the calcination temperature rises from 200 to 1000 °C, the dissolubility of aluminosilicate in the red mud under high alkaline conditions increases firstly and then decreases after over 800 °C. Therefore, the optimum temperature of thermal treatment for red mud is about 800 °C. This study could contribute to the following preparation of geopolymeric material made from red mud, especially the pretreatment process of red mud.

As part of contribution for developing a green recycling process of spent lead acid battery, a nanostructural lead oxide was prepared under the present investigation in low temperature calcination of lead citrate powder. The lead citrate, the precursor for preparation of this lead oxide, was synthesized through leaching of spent lead acid battery paste in citric acid solution. Both lead citrate and oxide products were characterized by means of thermogravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The results showed that the lead citrate was sheet-shape crystal of Pb(C6H6O7)·H2O. When the citrate was calcined in N2 gas, β-PbO in the orthorhombic phase was the main product containing small amount of Pb and C and it formed as spherical particles of 50–60 nm in diameter. On combusting the citrate in air at 370 °C (for 20 min), a mixture of orthorhombic β-PbO, tetragonal α-PbO and Pb with the particle size of 100–200 nm was obtained, with β-PbO as the major product. The property of the nanostructural lead oxide was investigated by electrochemical technique, such as cyclic voltammetry (CV). The CV measurements presented the electrochemical redox potentials, with reversibility and cycle stability over 15 cycles.

A novel approach to prepare glass–ceramics from molten steel slag (MSS) was proposed. In laboratory, the water-quenched steel slag was melted at 1350 °C to simulate the MSS. A mixture of additive powders in wt.% (55 quartz powder, 5 Na 2 O, 16 emery powder, 15 CaO, 8 MgO, 1 TiO 2 ) were melted into liquid at 1350 °C separately. Then the MSS and the molten additives were mixed homogeneously in order to obtain parent glass melt. The proportion of MSS in the melt was 50 wt.%. The melt was subsequently cast, annealed, heat-treated and transformed into glass–ceramics. Their microstructure and crystallization behavior were analyzed. The samples exhibited excellent properties and displayed bulk crystallization. The major crystallized phase was diopside ((Fe 0.35 Al 0.20 Mg 0.44 )Ca 0.96 (Fe 0.08 Si 0.70 Al 0.20 ) 2 O 6.12 ), which was uniformly distributed in the microstructure. The novel approach may help iron and steel industry achieve zero disposal of steel slag with utilization of the heat energy of the MSS.

The operating condition of an oxidation ditch (OD) has significant impact on energy consumption and effluent quality of wastewater treatment plants (WWTPs). An experimentally validated numerical tool, based on computational fluid dynamics (CFD) model, was proposed to optimize the operating condition by considering two important factors: flow field and dissolved oxygen (DO) concentration profiles. The model is capable of predicting flow pattern and oxygen mass transfer characteristics in ODs equipped with surface aerators and submerged impellers. Performance demonstration and comparison of two operating conditions (existing and improved) were carried out in two full-scale Carrousel ODs at the Ping Dingshan WWTP in Henan, China. A moving wall model and a fan model were designed to simulate surface aerators and submerged impellers, respectively. Oxygen mass transfer in the ditch was predicted by using a unit analysis method. In aeration zones, the mass inlets representing the surface aerators were set as one source of DO. In the whole straight channel, the oxygen consumption was modeled by using modified BOD-DO model. The following results were obtained: (1) the CFD model characterized flow pattern and DO concentration profiles in the full-scale OD. The predicted flow field values were within 1.98 ± 4.28% difference from the actual measured values while the predicted DO concentration values were within -4.71 ± 4.15% of the measured ones, (2) a surface aerator should be relocated to around 15m from the curve bend entrance to reduce energy loss caused by fierce collisions at the wall of the curve bend, and (3) DO concentration gradients in the OD under the improved operating condition were more favorable for occurrence of simultaneous nitrification and denitrification (SND).

In order to optimize the flow field in a full-scale Carrousel oxidation ditch with many sets of disc aerators operating simultaneously, an experimentally validated numerical tool, based on computational fluid dynamics (CFD), was proposed. A full-scale, closed-loop bioreactor (Carrousel oxidation ditch) in Ping Dingshan Sewage Treatment Plant in Ping Dingshan City, a medium-sized city in Henan Province of China, was evaluated using CFD. Moving wall model was created to simulate many sets of disc aerators which created fluid motion in the ditch. The simulated results were acceptable compared with the experimental data and the following results were obtained: (1) a new method called moving wall model could simulate the flow field in Carrousel oxidation ditch with many sets of disc aerators operating simultaneously. The whole number of cells of grids decreased significantly, thus the calculation amount decreased, and (2) CFD modeling generally characterized the flow pattern in the full-scale tank. 3D simulation could be a good supplement for improving the hydrodynamic performance in oxidation ditch designs.

Extracting polybrominated biphenyls (PBB) from electronic and electrical equipment is of high concern due to RoHS directive. PBBs were so toxic for human and environment, they are applied largely in electronic and electrical equipment as flame retardant. In this thesis, a new method was developed to predict the optimal conditions of semivolatile organic polybrominated biphenyls (PBB) extraction from plastic for Enviromental protection. A feed forward type of artificial neural network (ANN) model design was used to investigate the effects of four independent variables, namely, the ratio of solvent, stirring speed (rpm), extraction temperature (°C), extraction time (h) on the response, the acquired ratio of PBB. The independent variables were coded at four levels and their actual values selected on the basis of results of single-factor experiment. The model was initially trained by the analytical data with function approximation principle in MATLAB environment to reveal the real engineering world of extract process. Then dimensions of the trained result were reduced from n-D to 2D, In which, a visual contour plot and simulated curve were displayed, an optimal extract processing is achieved with 9.654% maximal acquired ratio of PBB. In order to validate the method, at the optimal point, the simulated result generated by proposed model was checked with the real experiment, it founded they kept a good agreement with each other. Thus proves that the mathematical model developed for resolving the PBB extraction from plastics is very effective and accurate. It is also a useful tool to reveal the real parameters effect on productivity. Modern computational and experimental tools have matured to a stage where they can provide substantial insight into engineering processes involving extracting some contents from herbs, vegetable oil, rubber, plastics etc, and the successful application of optimization design can help to improve the process productivity. Extracting the flame retardant as polybrominated biphenyls (PBBs) from electronic and electrical equipment is of high concern due to RoHS directive [1]. PBBs were so toxic for human and environment, it is applied in electronic and electrical equipment as flame retardant. When the EE wastes disposed unsoundly at the end of life, some hazardous substances emit into air, water, soil which are a strict threaten to human. So to determine such substances for EE industries has a profound meaning. Many methods to determine such hazardous substance such as GC-MS, ICP-OES, AES, IC etc. are developed[2–4], however, there is a very high requirement for sample preparation. Soxhlet extraction is a good digest technology to prepare samples, in this thesis, a new method was developed for predicting the optimal digest conditions of semivolatile organic compounds PBB in plastic with soxhlet extrat technology. During experiment, Uniform design is accepted to array data due to the uniformation consideration. Conventional optimization design was to hold one but all other variables as constant while methodically changing one at a time which is called one variable at a time or OVAT [5]. But the major pitfall in this procedure is that it cannot quantitatively explore the interaction among all variables and does not describe the net effect of the various combined conditions on the response [6]. The rapid and continuous development in processing design will require a new proposal to meet goals for increased performance, robustness and visualization. To date, the majority of efforts in optimization of extraction process have relied on gradient-based search algorithms, polynomial-based response surface methodologies (RSM), local gradient-based method and so on [7]. However, the challenge of these approaches are that it renders to search insufficiently due to the objective functions discontinuous over the broad design space or too resource-intensive due to unrestricted “brute force” search schemes. So here, based on global optimization problems especially for multidisciplinary ones, a matrix method was developed to predict the extract process of PBB from plastics which are compositions of packaging, sealed, adiabatic, insulating materials in electronic and electrical equipment (EEE). By establishing a functional artificial neural network (ANN) which maps the relationship between the response and variables, using a global optimization line-up competing algorithm (LCA) to train the network [8], simulation curve and the optimal contour plots were produced in 2-D plane. The model would not only serve as a visual aid to have a clearer picture about the effect of different variables on the responses in the form of animation but also enable to locate the region where the properties are optimized. It is also possible to predict the combination of independent variables which will result in optimal acceptance. It helps to understanding how the result is achieved and increases the reliability to the result.

Red mud is a solid waste produced in the process of alumina extraction from bauxite. In this paper, recovery iron from Bayer red mud was studied with direct reduction roasting process followed by magnetic separation, and then building materials were prepared from alumosilicate residues. After analysis of chemical composition and crystalline phase, the effects of different parameters on recovery efficiency of iron were carried out. The optimum reaction parameters were proposed as the following: ratio of carbon powder: red mud at 18:100, ratio of additives: red mud at 6:100, roasting at 1300 degrees C for 110min. With these optimum parameters, total content of iron in concentrated materials was 88.77%, metallization ratio of 97.69% and recovery ratio of 81.40%. Then brick specimens were prepared with alumosilicate residues and hydrated lime. Mean compressive strength of specimens was 24.10MPa. It was indicated that main mineral phase transformed from nepheline (NaAlSiO4) in alumosilicate residues to gehlenite (Ca2Al2SiO7) in brick specimens through X-ray diffraction (XRD) technology. The feasibility of this transformation under the experimental conditions was proved by thermodynamics calculation analysis. Combined the recovery of iron with the reuse of alumosilicate residues, it can realize zero-discharge of red mud from Bayer process.

This paper estimates the potential solar power for the solar photovoltaic Roof Integration System (RIS) using the Geographic Information System (GIS) method, taking into account the geographic distribution of solar irradiation and the estimate of costs for the RIS and identifies the distribution of potential solar energy radiating on the RIS and power. The total urban roof area is estimated to be 2957 million square metres by assuming five-story buildings. Based on the conversion efficiency of the RIS from solar energy to electric power that reached about 14%, the total potential power of this system in the urban regions of China can attain about 1.9 × 1018 J, thus lessening the cumulative emission at approximately 5.3 × 108 tons of carbon dioxide (CO2). Also, the results show that the west is the most suitable region for the RIS, where the highest electricity cost can be reached owing to the most intense irradiation. However, this large need of power will counteract the high cost induced by low irradiation to promote the application of the RIS in eastern China, where the cost of electricity is the highest.

An alternative method of heat extraction from salt gradient solar ponds to solar collector is investigated with the aim of night operation for solar chimney power system. Some details of the combined power system integrated with solar ponds and solar chimney power system are also provided. Using a developed mathematical model, theoretical analyses are carried out to investigate the performance of the combined system without considering weak solar radiation effects in the early morning. It is found from steady-state analyses that the combined solar system comprising of a daytime 5 MW solar chimney power plant and solar ponds with proper dimension is able to produce more than 2.21 MW power during night. In addition, the power output for the combined system increases with the temperature of the collector entering hot brine and its mass flow, which is directly proportional to the plastic film height and the brine velocity. It is found from non-steady-state analyses that the combination of the daytime 5 MW solar chimney power plant and 1,400,000 m² solar ponds is a good choice, considering its performance and cost factor. This would make the day before performance of solar ponds be renewed by next day.