Life Cycle Assessment of Household Water Tanks—A Study of LLDPE, Mild Steel and RCC Tanks

A case of household water tanks, 1000 L capacity, made of RCC, LLDPE and mild steel (stainless steel) was evaluated for life cycle analysis. The scope of the research comprised of the raw materials, energy inputs and corresponding emissions during all phases of product making such as extraction of raw material, it’s processing, followed by manufacturing and transport, as well as use and reuse of the product. Simapro 8 (System for Integrated environMental Assessment of PROducts), a modelling software, from Dutch PRé Consultants was used to conduct the life cycle analysis. Simapro 8 enables systematic and transparent modelling and analysis of complex life cycles based on the recommendations of the ISO 14040 series of standards. In the present study the most common method which is acceptable worldwide “Recipe Endpoint method” (ReCiPe) was employed. ReCiPe computes the impact categories and classifies them into two classes based on relevant arrays of characterization factors. Simapro addresses impact categories viz. ozone depletion, human toxicity, ionizing radiation, photochemical oxidant formation, particulate matter formation, terrestrial acidification, climate change, terrestrial ecotoxicity, agricultural land occupation, urban land occupation, natural land transformation, marine ecotoxicity, marine eutrophication, fresh water eutrophication, fresh water ecotoxicity, fossil fuel depletion, minerals depletion, fresh water depletion at the midpoint level. While at the Endpoint level, the impact categories are multiplied by corresponding damage factors and integrated to be represented as three Endpoint level categories, viz. human health, ecosystems and resource depletion. The three endpoint categories are normalized, weighted, and aggregated into a single score. LCA studies indicate that household water tanks of LLDPE have least environmental implications considering impacts on human health, ecosystems and resource depletion as compared to its counterparts viz. Household water tanks made up of mild steel and RCC. The sequence of the material with decreasing impacts is concrete tanks > mild steel tank > LLDPE tanks. The overall assessment is centred on the elements such as material inputs, energy inputs and environmental emissions.

Estimation of drift limits for different seismic damage states of RC frame staging in elevated water tanks using Park and Ang damage index

Damage to elevated water tanks in past earthquakes can be attributed to the poor performance of their supporting frame staging. In order to ascertain the performance of these elevated water tanks, it is crucial to categorize the damage in quantifiable damage states. Among various parameters to quantify the damage states, the top drift of frame staging can be conveniently correlated to the different damage levels. In literature, drift limits corresponding to different damage states of the frame staging of the elevated water tank are not available. In the present study, drift limits for RC frame staging in elevated water tanks corresponding to different seismic damage states have been proposed. Various damage states of the elevated water tank have been determined using the Park and Ang damage index. The Park and Ang damage index utilizes results of both pushover analysis and incremental dynamic analysis. Twelve models of elevated water tanks have been developed considering variation in staging height and tank capacity. Incremental dynamic analysis has been performed using the suite of twelve actual earthquake ground motions. Based on the regression analysis between damage indexes and drift, limiting drift values for each damage state are proposed.

Seismic Response Improvement of Existing Prototype School Buildings Using Water Tanks, Port Said City, Egypt

There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load or using old provisions that cannot meet the new one. The objective of this paper is to draw attention to evaluate existing reinforced concrete school buildings, then to present a proposed methodology to improve the behaviour of such schools with low cost especially in a developing country. The proposed method uses overhead water tanks as a tuned mass damper. A pushover analysis has been performed to evaluate the existing schools and perform a feasibility study to select the best solution to achieve seismic response improvement of the existing structure. Of course, the proposed methodology can be applied easily to other existing structures.

Water-Tank Experiment on the Thermal Circulation Induced by the Bottom Heating in an Asymmetric Valley

Water tank experiments were carried out to investigate the thermal convection due to the bottom heating in an asymmetrical valley under neutral and stably stratified approach flows with the Particle Image Velometry (PIV) visualization technique. In the neutral stratification approach flow, the ascending draft induced by bottom heating is mainly located in the center of the valley in calm ambient wind. However, with ambient wind flow, the thermal convection is shifted leeward, and the descending draft is located on the leeward side of the valley, while the ascending draft is located on the windward side. The descending draft is minorly turbulent and organized, while the ascending draft is highly turbulent. With the increase of the towing speed, the descending and ascending drafts induced by the mechanical elevation begin to play a more dominant role in the valley flow, while the role of the thermal convection in the valley airflow becomes limited. In the stable stratification approach flow, the thermal convection is limited by the stable stratification and no distinct circulation is formed in calm ambient wind. With ambient wind, agravity wave appears in the upper layer in the valley. With the increase of the ambient wind speed, a gravity wave plays an important role in the valley flow, and the location and intensity of the thermal convection are also modulated by the gravity internal waves. The thermal convection has difficulty penetrating the upper stable layer. Its exchange is limited between the air in the upper layer and that in the lower layer in the valley, and it is adverse to the diffusion of pollutants in the valley.

Impact of Untreated Sedimentation Tank Sludge Water Recycle on Water Quality During Treatment of Low Turbidity Water

The overall purpose of this research is to examine the impact of untreated sedimentation tank sludge water( USTSW) recycle on water quality during treatment of low turbidity water in coagulation—sedimentation processes. 950 m L of raw water and different concentrations of 50 m L USTSW are injected into six 1 000 m L beakers without coagulant.The results indicate that USTSW characterized as accumulated suspended solids and organic matter has active ingredients,which possess the equivalent function of coagulant. The optimal blended water turbidity is in the range of 10-20 NTU,within which USTSW recycle achieves the highest save coagulant rate. The mechanism of strengthening coagulation effect when USTSW recycle mainly depends on the chemical effect and physical effect. What is more,through scanning electron microscopy( SEM),it is found that the floc structures with USTSW recycle are more compact than those without USTSW recycle. Besides,the water quality parameters of color,NH3-N,CODMn,UV254,total aluminum,total manganese when USTSW recycle is better than the raw water without recycle,indicating that USTSW recycle can improve water quality with strengthening coagulation effect.

THE FREE BENDING VIBRATION OF CYLINDRICAL TANK PARTIALLY FILLED WITH-LIQUID AND SUBMERGED IN WATER

This paper studies the free bending vibration of cylindrical tank partially filled with liquid and submerged in water. The depths of liquid and water may be completely arbitrary. The exact calculating formulae of mode shape functions and inherent frequencies are deduced. The results can be gained by means of computer. The analysis shows that the effect of liquid and water on vibration of cylindrical tank is respectively equivalent to a generalized distributive mass attached to the tank.

Treatment of submerged hollow fiber ultrafiltration membrane for reuse of sludge water

To lower the costs of wastewater treatment, the submerged hollow fiber ultrafiltration membrane was employed to reuse the filter backwash water and settling tank sludge water. Experimental study indicates that the submerged hollow fiber uhrafihration membrane can condense the concentration of sludge from 0. 1% -0. 3% to 2.5%. At 20 ℃, the system can operate continuously for 80 clays with daily online backwashing with chemical additions only once, and the membrane flux can be recovered up to 97% by using NaClO and NaOH as chemical additions. The results show that the membrane flux is mainly affected by temperature,and has a positive lin- ear relation to temperature with a slope of 0. 368. After treated by submerged hollow fiber uhrafihration membrane, the effluent can reach the National Standard for Drinking Water（ GB5749 -85 ） , especially for the sludge water from sedimentation tanks and the backwashing Water from filters in water supply plants.

Influence of Ozone Injection on Corrosion Behavior of Steel in Water Ballast Tank

Ozone is the principal active substances and usually employed in ballast water management systems. In the present study, the corrosion protective effect of ozone was conducted by immersion test and electrochemical techniques. It was found that corrosion protective effect was revealed in the range of 2.0 to 2.7 ppm of ozone concentration in seawater. The ratio of the rust area of specimen became 20% in that concentration region. The rusted area is strongly influenced by the ozone concentration and the flow rate determined by FEM （finite element method）. Ozone has a good influence for ballast tanks, i.e., ozone can delay the rust of ballast tanks, provided that the suitable concentration of ozone is selected. In this case, ozone may stop the corrosion at the defects, if a part of the paint in ballast tank is peeled off. However, ozone may also promote the corrosion of steel when the ozone concentration is very high, e.g., 10 ppm. Attention should be paid to the ozone concentration, if we use ozone as an active substance for ballast water management systems.

Cooling and Optimization in the Groove of the Outer Rotor HubMotor

The external rotor hub motor adopts direct drive mode,no deceleration drive device,and has a compact structure.Its axial size is smaller than that of a deceleration-driven hub motor,which greatly reduces the weight of the vehicle and increases the cruising range of the vehicle.Because of the limited special working environment and performance requirements,the hub motor has a small internal space and a large heat generation,so it puts forward higher requirements for heat dissipation capacity.For the external rotor hub motor,a new type of in-tank watercooled structure of hub motor was proposed to improve its cooling effect and performance.Firstly,the threedimensional finite element model of the motor is established to analyze the characteristics of motor loss and temperature field distribution.Secondly,the cooling performance of different cooling structures in the tank was studied.Finally,the thermal network model and three-dimensional finite element analysis were used to optimize the water-cooled structure in the tank,and the power density of themotor was improved by improving the cooling performance under the condition of volume limitation of the hub motor.The results show that the cooling effect of the proposed water-cooled structure in the tank is significant under the condition of constant power density.Compared to natural ventilation,the maximum temperature was reduced by 33.13°C and the cooling effect was increased by about 27.7%.

A Laboratory Modeling of the Velocity Field in the Convective Boundary Layer with the Particle Image Velocimetry Technique

Based on the research of the convective boundary layer (CBL) temperature field in a convective tank, this paper studies the characteristics of the CBL velocity field in the convective tank. Aluminium powder (400 orders) is used as a tracer particle in the application of the particle image velocimetry (PIV) technique. The experiment demonstrates: the velocity distribution in the mixed layer clearly possesses the characteristics of CBL thermals; the velocity distribution in the top zone of the mixed layer shows entrainment layer characteristics; the vertical distribution of turbulent characteristic variables is reasonable, which is similar to field observations and other tank results; the error analysis demonstrates the validity of aluminium powder, which implies the reliability of the results.

A Laboratory Model for the Flow in Urban Street Canyons Induced by Bottom Heating

Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Image Visualization) technique. Fluid experiments show that with calm ambient wind, the flows in the street canyon are completely driven by thermal force, and the convection can reach the upper atmosphere of the street canyon. Horizontal and vertical motions also appear above the roofs of the buildings. These are the conditions which favor the exchange of momentum and air mass between the street canyon and its environment. More than two vortices are induced by the convection, and the complex circulation pattern will vary with time in a wider street canyon. However, in a narrow street canyon, just one vortex appears. With a light ambient wind, the bottom heating and the associated convection result in just one main vortex. As the ambient wind speed increases, the vortex becomes more organized and its center shifts closer to the leeward building.

A Laboratory Study of the Turbulent Velocity Characteristics in the Convective Boundary Layer

Based on the measurement of the velocity field in the convective boundary layer （CBL） in a convection water tank with the particle image velocimetry （PIV） technique, this paper studies the characteristics of the CBL turbulent velocity in a modified convection tank. The experiment results show that the velocity distribution in the mixed layer clearly possesses the characteristics of the CBL thermals, and the turbulent eddies can be seen obviously. The comparison of the vertical distribution of the turbulent velocity variables indicates that the modeling in the new tank is better than in the old one. The experiment data show that the thermal＇s motion in the entrainment zone sometimes fluctuates obviously due to the intermittence of turbulence. Analyses show that this fluctuation can influence the agreement of the measurement data with the parameterization scheme, in which the convective Richardson number is used to characterize the entrainment zone depth. The normalized square velocity wi^2/w＊^2. at the top of the mixed layer seems to be time-dependent, and has a decreasing trend during the experiments. This implies that the vertical turbulent velocity at the top of the mixed layer may not be proportional to the convective velocity （w＊）.

Numerical and Experimental Studies on Flow and Pollutant Dispersion in Urban Street Canyons

In this study numerical simulations and water tank experiments were used to investigate the flow and pollutant dispersion in an urban street canyon. Two types of canyon geometry were tested. The studies indicate that in a step-up notch canyon （higher buildings on the downstream side of the canyon）, the height and shape of the upstream lower buildings plays an important role in flow pattern and pollutant dispersion, while in a step-down notch canyon （lower buildings on the downstream side）, the downstream lower buildings have little influence. The studies also show that the substitution of tall towers for parailelepiped buildings on one side of the canyon may enhance the street ventilation and decrease the pollutant concentration emitted by motor vehicles.

Performance Analysis of a Solar Continuous Adsorption Refrigeration System

A study is conducted on the performances of a solar powered continuous-adsorption refrigerator considering two particular days as references cases,namely,the summer solstice(June 21st)and the autumn equinox(September 21st).The cooling capacity,system performance coefficient and the daily rate of available cooling energy are assessed.The main goal is to compare the performances of a solar adsorption chiller equipped with a hot water tank(HWT)with an equivalent system relying on solar collectors with no heat storage module.The daily cooling rates for the solar refrigerator are found to be 102.4 kWh and 74.3 kWh,respectively,on June 21st and on September 21st,using a total collector’s area of 43.47 m2.The corresponding values for the adsorption chiller equipped with a hot water tank of 2 m3(and using a total collector’s area of 72.45 m2),are 127.1 kWh and 106.13 kWh,respectively.

Comparison and Performance Analysis of Heat Storage Equipment in Solar Heating System

Solar heating system is widely used recently. Heat storage equipment is the guarantee for steady performance of solar heating system. A design of latent heat storage exchanger with submerged coil was introduced with the structure, working principle, and the main advantages. This heat exchanger was integrated into solar heating system as the heat storage equipment. Advantage comparison of the designed heat exchanger in solar heating system with hot water tank was carried out. The analysis results show that the latent heat storage exchanger is superior to hot water tank obviously. The heat exchanger performance parameters and variations of these parameters are got： （1） with the increase of phase change material （PCM） volume ratio, heat storage equipment volume ratio decreases; （2） heat storage efficiency has the same varying tendency with outdoor and air temperature; while the bigger PCM volume ratio is, the weaker the effect of outdoor air temperature on heat storage efficiency is; （3） heat storage capacity and heat storage efficiency increase together; when PCM volume ratio is big, heat storage efficiency is high and the system can begin operating effcienfly and quickly; （4） with the increase of heat storage capacity, life cyde operation cost （LCOC） of system increases gradually in high speed; but with the increase of PCM volume ratio, the difference between the two systems LCOCs becomes smaller and smaller; （5） the reasonable range of PCM volume ratio is 0.5 - 0.7. Temperature characteristic analysis shows that, with the filled PCM, heat storage medium temperature presents several segments at different time, under conditions of different heat storage capacity and different PCM state.

Microbiological quality of roof tank water in an urban village in southeastern China

Urban villages are unique residential neighborhoods in urban areas in China. Roof tanks are their main form of water supply, and water quality deterioration might occur in this system because of poor hygienic conditions and maintenance. In this study, water samples were seasonally collected from an urban village to investigate the influence of roof tanks as an additional water storage device on the variation in the microbial community structure and pathogenic gene markers. Water stagnation in the roof tank induced significant decreases in chlorine(p < 0.05), residual chlorine was as low as 0.02 mg/L in spring. Propidium monoazide(PMA)-qPCR revealed a one-magnitude higher level of total viable bacterial concentration in roof tank water samples(2.14 ± 1.81 × 105gene copies/mL) than that in input water samples(3.57 ± 2.90 × 104gene copies/mL, p < 0.05), especially in spring and summer. In addition,pathogenic fungi, Mycobacterium spp., and Legionella spp. were frequently detected in the roof tanks. Terminal users might be exposed to higher microbial risk induced by high abundance of Legionella gene marker. Spearman’s rank correlation and redundancy analysis showed that residual chlorine was the driving force that promoted bacterial colonization and shaped the microbial community. It is worth noted that the sediment in the pipe will be agitated when the water supply is restored after the water outages, which can trigger an increase in turbidity and bacterial biomass. Overall, the findings provide practical suggestions for controlling microbiological health risks in roof tanks in urban villages.

Recent Progress on Thermal Energy Storage for Coal-Fired Power Plant

With countries proposing the goal of carbon neutrality,the clean transformation of energy structure has become a hot and trendy issue internationally.Renewable energy generation will account for the main proportion,but it also leads to the problem of unstable electricity supply.At present,large-scale energy storage technology is not yet mature.Improving the flexibility of coal-fired power plants to suppress the instability of renewable energy generation is a feasible path.Thermal energy storage is a feasible technology to improve the flexibility of coal-fired power plants.This article provides a review of the research on the flexibility transformation of coal-fired power plants based on heat storage technology,mainly including medium to low-temperature heat storage based on hot water tanks and high-temperature heat storage based on molten salt.The current technical difficulties are summarized,and future development prospects are presented.The combination of the thermal energy storage system and coal-fired power generation system is the foundation,and the control of the inclined temperature layer and the selection and development of molten salt are key issues.The authors hope that the research in this article can provide a reference for the flexibility transformation research of coal-fired power plants,and promote the application of heat storage foundation in specific coal-fired power plant transformation projects.

Electroless nickel plating on optical fiber probe

As a component of near-field scanning optical microscope （NSOM）, optical fiber probe is an important factor influncing the equipment resolution. Electroless nickel plating is introduced to metallize the optical fiber probe. The optical fibers are etched by 40% HF with Turner etching method. Through pretreatment, the optical fiber probe is coated with Ni-P film by electroless plating in a constant temperature water tank. Atomic absorption spectrometry （AAS）, scanning electron microscopy （SEM）, and energy dispersive X-ray spectrometry （EDXS） are carried out to characterize the deposition on fiber probe. We have reproducibly fabricated two kinds of fiber probes with a Ni-P film： aperture probe and apertureless probe. In addition, reductive particle transportation on the surface of fiber probe is proposed to explain the cause of these probes.

The effect of free surface on cloud cavitating flow around a blunt body

In this study, the effect of the free surface on the cloud cavitating flow around a blunt body is investigated based on the water tank experiment and the CFD method. Numerical results are in good agreement with experimental data, and the mesh independence of the methods is verified. The cavity evolution process includes the cavity growth, the re-entrant jet, the cavity shedding, and the collapse, which can all be observed from the water tank experiment. The effects of the free surface on the cavity length, the thickness, and the cavity evolution period are analyzed by comparing the difference between the cavitating flows on the upper and lower sides of the body. This study also examines the effect of the distance between the free surface and the model through a series of water tank experiments and numerical simulations. The cavity stability and asymmetry, as well as the thickness and the velocity of the re-entrant jet inside the cavity, which varies with the submerged depth, are discussed with consideration of the effect of the free surface. The effect of the free surface on the cavitating flow around the blunt body is enhanced with the decrease of the submerged depth.

Lattice Boltzmann simulations for multiple tidal turbines using actuator line model

In numerical simulations of tidal current farms,large-scale computational fluid dynamic(CFD)simulations with a high-resolution grid are required to calculate the interactions between tidal turbines.In this study,we develop a numerical simulation method for tidal current turbines using the lattice Boltzmann method(LBM),which is suitable for large-scale CFD simulations.Tidal turbines are modeled by using the actuator line(ACL)model,which represents each blade as a group of actuator points in a line.In order to validate our LBM-ACL model,we perform simulations for two interacting tidal turbines,and results of turbine performance are compared with a water tank experiment.The proposed model successfully reproduces the variation of the torque due to wave effects and mean turbine performance.We have demonstrated a large-scale simulation for ten tidal turbines using 8.55×10^(8) grid points and 16 GPUs of Tesla P100 and the simulation has been completed within 9 hours with the LBM performance of 392 MLUPS per GPU.