Performance analysis of solar still with different energy-absorbing materials

Solar still is a simple device which can convert available waste or brackish water into potable fresh water by utilising solar energy. In the present research work, an attempt has been made to store excess heat energy in solar stills during the daytime for the continuation of the process at late evening and night hours for increment distillate output. To investigate the effect of energy storage materials on the productivity under the same climatic conditions, three same-size single-basin single-slope solar stills with an area of 1?m² made of fibre reinforced plastic (FRP) sheet were tested with 0.04?m layer of water level to investigate effects on solar still. Different energy storage materials like marble pieces and sandstones were used for easy availability and lower price. It has been found that sand stones are more productive compared with marble pieces and without materials inside solar still.     

Theoretical and experimental performance analysis of sandstones and marble pieces as thermal energy storage materials inside solar stills

The present research paper deals with the theoretical and experimental investigation of solar stills with two different thermal energy storage materials, namely, marble pieces and sandstones. To carry out this research, three solar stills of 1?m square area have been made. All solar stills have been provided with a glass cover and a cooling and dripping arrangement for reducing top heat loss and maintaining a constant level of water. It has been found that the use of sandstones as storage materials and the cooling and dripping arrangement have a remarkable effect on the distillate output of a solar still. The set-up has been used to augment the distillate output throughout the day. Theoretical results have also been compared with the experimental results and have been found to be in good agreement.     

Importance of speciation methods in analytical control of water treatment processes with application to fluoride removal from waste waters

Analytical methods of speciation for the control of water treatment processes, particularly for the removal of fluoride by aluminium hydroxide polymers as precipitant, have been discussed. It has been shown that combination of ultrafiltration with spectroscopic methods and fluoride ion-selective electrode offers a powerful means for the control of both the precipitant and pollutant, e.g. fluoride. ²⁷Al n.m.r. has been used for the identification of hydrolytic products of aluminium(III) and the ultrafiltration technique has been applied for the separation of the active polymer. The hydrolytic products were also characterized by timed spectrometric method. The interaction between aluminium hydroxide polymer and fluoride was studied by means of fluoride ion-selective electrode, ultrafiltration and atomic absorption spectrometry. The usefulness of these speciation methods for choosing the best conditions for water treatment process is discussed. By applying them for the removal of fluoride, it was found that the fluoride levels can be brought down to less than 10 mg l^?1, the limit set by Swiss regulatory body for discharge of waste water. The importance of using such speciation methods for evaluating the possible impact of the “products” of the water treatment (dissolved species in treated water, discharged solid) is also emphasized.     

Anti-corrosion performance of bridge strands consisting of steel wires galvanised with zinc–aluminium alloy

Strands consisting of 19 parallel steel wires galvanised with zinc (Zn, 90%) and aluminium (Al, 10%) alloy were produced and accelerated corrosion tests were conducted, and the anti-corrosion performance was compared with the conventional strands galvanised with Zn. The strands were placed at a relative humidity (RH) of 60%, RH of 100% and the wet condition in the thermo-hygrostat at 40°C for 150 days. The mass loss due to corrosion of the strands galvanised with Zn–Al at an RH of 60% and 100% was small, and the strands had good corrosion resistance. The corroded mass of the strands at the wet condition was 15 times larger than that at RH of 100%. The strands galvanised with Zn–Al had lesser corrosion than those galvanised with Zn under the three environmental conditions. Corroded mass was larger in the surface wire, the inside wire and the centre wire in this order. The cross-sections of corroded strands were investigated by using a microscope and an electron probe micro-analyser showing that the corrosion product of Zn was porous and coarse. By contrast, the corrosion product of Zn–Al alloy was dense and hard to exfoliate from the steel layer. This difference made Zn–Al galvanised wire strands superior to Zn galvanised wire strands.     

Axial compression of metallic spherical shells between rigid plates

Aluminium spherical shells of R/t values between 15 and 240, were axially compressed in an INSTRON machine between flat plates. The modes of their collapse, load-compression and energy-compression curves, and mean collapse loads are presented. A simple analytical model has been developed for the prediction of load-compression and energy-compression curves for the metallic spherical shells, by using the concepts of stationary and rolling plastic hinges. The results thus obtained match well with the experimental results. These results have also been compared with the solutions proposed in earlier studies. Behaviour of these shells is compared with the response of spherical shells (aluminium, mild steel and galvanised steel) of shallow depth, which were also subjected to axial compression between rigid plates. Their load-deformation curves are presented, and their energy-compression behaviour and mean collapse loads are discussed.     

Year round performance and potential of a natural circulation type of solar water heater in India

The system consists of a flat-plate collector and a storage tank. Flat-plate collector is made of galvanised steel tube and aluminium plate, with MAXORB selective surface, encased in a mild steel tray with top single glass cover, bottom has been provided with glass wool insulation. It is kept facing equator and at λ+15° tilt (λ latitude of the place).The double walled storage tank is of 100 l capacity. The inner drum is made of 18 gauge galvanised steel and outer of mild steel. Space (100 mm) between them is filled with glass wool insulation.Performance and testing of solar water heater has been carried out extensively. It has been found that the heater can provide 100 l of hot water at an average temperature of 60.6 °C at 16:00 h when tap water temperature was 23.6 °C, it can retain hot water till next day morning at an average temperature of 51.6 °C. The overall efficiency of the heater is 57%.Based on performance at Jodhpur, a model has been developed by using ambient temperature and solar radiation for the prediction of its performance at various Indian stations. The predicted performance at various Indian stations revealed that hot water is required at most places for domestic use only during winter season and it can provide 100 l of hot water at an average temperature of 50–70 °C that can be retained to 40–60 °C till next day morning use.     

General behaviour and effect of rigid and non-rigid end post in stainless steel plate girders loaded in shear. Part II: Extended numerical study and design proposal

After the deep analysis and evaluation of the experimental and numerical results obtained during the described experimental campaign [Estrada I, Real E, Mirambell E. General behaviour and effect of rigid and non-rigid end post in stainless steel plate girders loaded in shear. Part I: Experimental study. Journal of Constructional Steel Research 2005 [submitted for publication]], an extended numerical analysis in code ABAQUS [Hibbit, Karlsson and Sorensen Inc., ABAQUS/Standard, Version 6.3. User’s manual. Rhode Island (USA); 2002] has been carried out dealing with the evaluation of the postbuckling strength in stainless steel plate girders. Finally, a proposal of design expressions for predicting their ultimate shear capacity is made since current design specifications dealing with shear resistance included in Eurocode 3, Part 1-4 [European Committee for Standardisation. ENV 1993-1-4. Eurocode 3: Design of steel structures. Part 1.4: General rules—supplementary rules for stainless steel. Brussels; 1996] have been demonstrated to be overly conservative.Taking special attention of the material non-linearity and the rigid or non-rigid condition of the end post, specimens covering a wide range of slenderness and aspect ratios (a/d from 0.5 to 3.0) have been numerically tested. Austenitic and Duplex stainless steel grades, which are the most commonly used in construction, have been evaluated during the whole analysis development.Finally, a new design proposal based on the Rotated Stress Field model developed by Höglund [Höglund T. Shear buckling resistance of steel and aluminium plate girders. Thin-Walled Structures 1998;29(1-4):13-30], adequately adapted to the particular features of stainless steel is presented in order to reach a more optimum use of this relatively modern resistant material in construction.     

Study of polymeric aluminium(III) hydroxide solutions for application in waste water treatment. Properties of the polymer and optimal conditions of preparation

The optimal conditions for the preparation of polymeric aluminium(III) hydroxide species for water treatment has been described. The partially hydrolysed aluminium(III) solutions were characterized by ultrafiltration method, ferron assay, ²⁷Al n.m.r. measurements, high pressure anion exchange chromatography and precipitation of polymeric aluminium hydroxo species with sodium sulphate. The results of these tend to suggest that the polymeric aluminium(III) hydroxide species have a size between 10–20 Å; these have an average residual positive charge of 0.54, and constitute about 80% of the total aluminium in the hydrolysed solution. They are retained by UM05 membrane. ²⁷Al measurements indicate that Al₁₃O₄(OH)₂₄^7? ion are the predominant polymeric species in these solutions. In addition to these the hydrolysed aluminium(III) solutions contain low proportions of monomeric aluminium hydroxo species and inert micro-crystalline aluminium hydroxide. The effect of ageing, dilution and pH on the stability and characteristics of the aluminium hydroxide polymer were also studied in detail.     

Design and Characterization of the CLIMPAQ,Chamber for Laboratory Investigations of Materials,Pollution and Air Quality*

A test chamber has been developed in order to provide a small and simple emission testing facility capable of testing construction products in a climate where the important climatic parameters such as temperature, ventilation rate and air velocity can be varied independently around typical indoor values. The test chamber CLIMPAQ is made of panes of window glass. Other main surface materials are stainless steel and eloxated aluminium. The chamber has a volume of 50.9 litres and is designed to meet the requirements for quantifying air pollution. In this investigation human subjects acted as air pollution judges, and chemical characterization of the air pollution was carried out. Carpet, linoleum, wall paint and seal- ant were tested simultaneously in the CLIMPAQ and in four other chambers ranging from a full-scale chamber of 28 m³ to a field and laboratory emission cell of 3.5· 10^?5m³. Product ranking is the same in all chambers for the sensory measurements. Emission rates based on sensory measurements differ for all products less than 100 % except for tests in a 3-litre chamber where emission rates were higher. Chemical measurements differ up to approximately 10 times for the same product in different chambers. Deviations appear to be the result of different environmental parameters in the various chambers. Low air concentrations or high specific ventilation rates seem to increase emissions, while differences in air velocities and sink properties may also be the cause of differences in emission rates.     

Evaluation de l'impact de l'urbanisation sur la réalimentation des nappes d'eau souterraines au nord-est de Paris (France)

The plateau of Romainville which spreads over the district of Belleville in Paris (France) to the town of Fontenay-sous-Bois has a surface area of about 12?km² and constitutes a geological and hydrogeological unit because at its base there exists an almost impervious formation, known as the "Glaises Vertes" (green clays of the Sannoisien stage). Above this formation, two water tables exist in two formations: the "Marno-calcaire de Brie" (siliceous limestone) and the "Sables de Fontainebleau" (sand). These two formations are separated by a clay layer: the "Marnes à Huîtres" (marl). In the past (before significant urban development), both waters flowed out naturally from the top of the Glaises Vertes on the edges of the area. Today, most of the springs are directed to the sewer network. Because they are close to Paris, these springs have been harnessed very early, through a very difuse and developed network of drains called "pierrées" and aqueducts. The different archives that have been used for this study provide much information regarding these springs, and the flow rate in particular. The first information available dates from the Middle Ages. This type of water supply was strategically important for Paris for at least six centuries (from the fourteenth to the nineteenth centuries). Having defined the different methods of harnessing the underground water this study shows the evolution of the flow rate through over 50 measurements. These date from the Middle Ages to today. The figures relating to the nineteenth century are surprisingly precise The data have been compared to the rainfall figures where these were available. In 1998 the flow rates were computed over a period of 9?months from the only remaining spring that is in use. A study of the piezometry has also been carried out in the town of Les Lilas which is a part of the plateau of Romainville. The information is compared with a piezometric map of 1882 known as the Map Delesse, drawn up before significant urban development occurred. Comparisons of the data available show that there has been no significant decrease in the specific yields of the springs during the twentieth century, although the catchment area has been totally urbanised with up to a 90% impermeability. Analysis of the piezometric values of 1882 and 1998 leads to the same conclusion. It is considered that, apart from the remaining rain which infiltrates to the water table, there must be another supply that compensates for the loss in catchment capacity. The compensation could be attributed to leaks in different underground networks such as the drinking water supply, the sewer network and the rainfall runoff network. The extensive use of water in public areas for cleaning roads and for irrigation purposes is also likely to contribute to the water table flow rate. The compensating flow of water is assessed at 1.7 to 2?l?s^–1?km^–2 (i.e. 1.7 to 2?10^–3?m³?s^–1?km^–2), i.e. about 80% of the total flow of the aquifer.     

Bearing failure in stainless steel bolted connections

Although the mechanical behaviour of stainless steel and carbon steel differs significantly, design provisions for stainless steel connections in current standards are essentially based on the rules for carbon steel. For bolted connections, the design resistances in EN 1993-1-4 and the SCI/Euro Inox Design Manual for Structural Stainless Steel are based on those in EN 1993-1-8 and EN 1993-1-3 with only some minor modifications. In this paper, an investigation into the bearing behaviour of stainless steel connections between both thick and thin plates has been conducted. Numerical models for previously tested specimens in austenitic and ferritic stainless steel have been developed and validated. The validated models were then used to perform parametric studies to investigate the key variables affecting the bearing failure of bolted connections; these include edge distance e₂, end distance e₁ and plate thickness t. The investigation showed the deformation behaviour of stainless steel connections to be somewhat different from that of carbon steel connections, with stainless steel exhibiting pronounced strain hardening. However, the locations of fracture initiation obtained from the numerical models matched those observed during experimental studies of both carbon steel and stainless steel connections and this feature has been used as the basis for defining a consistent, strength based criterion of failure. The results of the parametric studies have been utilised as the basis for design provisions for bearing failure in stainless steel bolted connections that cover both the ultimate and the serviceability limit states and which are both more economic and more straightforward than the present EC3 provisions.     

Numerical investigation of net section failure in stainless steel bolted connections

Despite fundamental differences in the mechanical behaviour of stainless steel and carbon steel, design provisions for stainless steel connections in current standards essentially follow the rules for carbon steel with some limited modifications. For the case of net section capacity, the design rules from EN 1993-1-3 for cold-formed carbon steel have been adopted for stainless steel connections in EN 1993-1-4 and the SCI/Euro Inox Design Manual without any modification. In this paper, an investigation into the behaviour of stainless steel connections failing by net section rupture has been conducted. Numerical models for austenitic and ferritic stainless steel have been developed and validated against existing test results. The validated models were subsequently used to perform parametric studies to investigate the main parameters affecting the net section rupture of bolted connections; these include edge distance e₂ and bolt configuration. By studying the stress distribution along the net section for different edge distances and bolt arrangements, it was found that the ductility of stainless steel is sufficient to ensure extensive redistribution of stresses prior to fracture. Hence, a revised design equation (based on that given in EN 1993-1-3) for net section capacity of stainless steel connections has been proposed and its reliability demonstrated by means of statistical analysis.     

Le Pont Vasco de Gama – la démarche durabilité

From the concrete example of a large construction, this paper aims to show how the results obtained from the research work carried out on transfer in cement pastes were applied both on site during the concrete construction and in the laboratory to predict the durability of the concrete structure. This unique process, carried out in close collaboration with the constructor, is based on a new concept of High Performance Concrete. The construction concerned is the Vasco da Gama Bridge in Lisbon, which is one of the most important bridges ever constructed in Europe: it is more than 17?km long, built in the maritime zone on the Tagus river estuary. It was opened in April 1998. A guarantee of life duration of 120?years, without major maintenance, has been demanded. In addition to the criteria relative to the concrete constituents (non-reactive aggregates with regard to the alkalireaction, the nature of the cement and a formulation adapted to the direct environmental effects on the different construction parts), one of the main life duration criteria selected is a chloride concentration limit value of 0.4%, compared to the mass of the cement, measured directly at the reinforcement steel position. This value determines the initiation threshold of the corrosion process of steel. Specifications are both a diffusivity coefficient of chloride of less than 1×10^–12?m²?s^–1 determined by the TANG Luping method and an oxygen permeability of less than 1×10^–17?m². These basic criteria have been perfected by measures of porosity to water, tests of resistance to chloride penetration, chloride migration tests and also by extensive examinations of the concrete microstructure. All the measurements and tests have been undertaken both on concrete samples made in the laboratory and on samples made on site and concrete cores from parts of the structure built in 1995. Coefficients of chloride diffusivity measured or calculated from profiles of concentration in concrete cores have been used in a predictive model, using a finite element method integrating the interaction ions with cement paste and the evolution of the diffusivity coefficient in time. The various computing simulations, improved progressively with controls and after comparison with the real bridge, tend to confirm, on the one hand, the validity of the model used and, on the other hand, the accuracy of the chosen formulations. These formulations, having mechanical properties close to those of High Performance Concrete, also have special microstructural properties of diffusivity and permeability, answering the requirements of the durability of this bridge.     

Fire testing and design of stainless steel structures

Despite significant progress in recent years in the development of room temperature design guidance for stainless steel structures, fire resistant design has received relatively little attention. This paper reports on studies carried out to investigate the performance of unprotected stainless steel beams and columns in fire. Material tests were carried out on five grades of stainless steel to determine strength and stiffness retention factors at elevated temperatures; both strength and stiffness retention were shown to be superior to that of carbon steel beyond 600 ^°C. The temperature development characteristics of a range of stainless steel sections were investigated, and compared to those of carbon steel sections. Full scale fire tests were conducted on six stainless steel columns, and four stainless steel beams. Finite element modelling of the tests was carried out, and parametric studies were performed to supplement the test data. All tests were carried out as part of the European project ‘Development of the use of stainless steel in construction’. Design recommendations for stainless steel columns and stainless steel beams supporting a concrete slab, based on the ECCS model code for fire engineering, were validated against the test and finite element results. These recommendations have been incorporated into the Euro Inox/SCI Design Manual for Structural Stainless Steel, and implemented in Eurocode 3: Part 1.2, with minor adjustments for consistency with carbon steel.     

Phosphorus immobilisation in Al‐drinking water treatment sludge (Al‐DWTS) and soil under laboratory conditions

This study assessed the potential reuse of an aluminium coagulated drinking water treatment sludge (Al‐DWTS) as a main substrate in constructed wetland to replace soil for the treatment of P‐enriched wastewater. The adsorption isotherm and kinetics of phosphorus (P) removal from high‐P solution by Al‐DWTS and a local soil from Bailieborough, Ireland, were studied and compared. The P adsorption process was examined as a function of contact time, initial P concentration, pH and temperature. Data of P adsorption were well fitted to the Langmuir and the Freundlich isotherms but the Freundlich isotherm had a higher correlation coefficient. The P adsorption capacity on the Al‐DWTS and the soil tended to increase with an increase in temperature. The maximum P adsorption capacity of the Al‐DWTS and the soil was 39.4 mg P mg^?1 and 9.5 mg P mg^?1, respectively, at conditions of pH of 4.0 and temperature of 23°C. Kinetics studies show that adsorption in both cases followed pseudo‐second‐order kinetics. The fact that the Al‐DWTS exhibited a significantly higher P adsorption capacity at high P solution compared with the soil suggests that Al‐DWTS can be a ‘novel‐waste’ bioadsorbent with promising application in wastewater treatment engineering, such as constructed wetland systems.     

Estimating recharge rates for qanat-based water supply in northern Cyprus: a case study using remotely sensed and in-situ data

The qanat water supply technology, by which gravity drains mountain aquifers into valleys, is considered as a culturally appropriate and ecological sustainable design to meet freshwater development needs in northern Cyprus. This work provides a first-order analysis of the surface water budget to estimate qanat feasibility. The proposed qanat recharge area of 370 km² is in the upper elevations of the limestone dominated Five Finger Mountain Range, is analysed using technical data reports, field visits, and satellite elevation data. Satellite based tropical rainfall measuring mission (TRMM) monthly rainfall totals at a 0.25° grid were tested for complementing sparse precipitation gauge data, but TRMM underestimated gauge observations by 43% in narrow zones of high rainfall during the wet winter months. A water budget for qanat supply used 30-year average gauge records within the qanat recharge region, which set annual precipitation at 529 mm year^?1. A calibrated complementary relationship areal evapotranspiration model established atmospheric outputs at 222 mm year^?1, slightly below the island-average of 280 mm year^?1 estimated by the Cyprus Water Department. Recharge to the qanat aquifer was determined by subtracting evaporation from precipitation, and then allocating 50% of the remainder to environmental services. In the proposed qanat recharge region, this water budget yields an estimated recharge volume of 57 mm³ year^?1. At less than 25% development, this volume satisfies the 13 mm³ annual deficit in northern Cyprus and protects against saltwater intrusion. Additional freshwater conservation measures in northern Cyprus are needed to ensure ecological sustainability in northern Cyprus.     

Experimental and numerical studies of lean duplex stainless steel beams

Stainless steel is well suited to a range of engineering applications owing to its durability and favourable mechanical properties. The most widely used grades of stainless steel are from the austenitic family and typically contain around 18% chromium and 8%-11% nickel — these grades have a relatively high initial material cost, due, in part, to their high nickel content, and a nominal yield strength (in the annealed condition) of around 220 N/mm². A new, low nickel grade of stainless steel (UNS 32101/EN 1.4162), commonly referred to as ‘lean duplex’, has been developed, that offers over two times the strength of the familiar austenitic grades and at approximately half the initial cost — this lean duplex stainless steel appears well suited to load-bearing applications in construction. This paper reports material and 3-point bending tests on lean duplex stainless steel hollow sections. The 3-point bending tests were replicated by finite element (FE) analysis and, upon validation of the numerical models, parametric studies were conducted to assess the effect of key parameters such as cross-section aspect ratio, cross-section slenderness and moment gradient on the strength and deformation capacity of lean duplex stainless steel beams. Based on both the experimental and numerical results, appropriate slenderness limits and design rules, suitable for incorporation into structural stainless steel design standards, have been proposed.     

Rate constants of reactions of ozone with organic and inorganic compounds in water—I: Non-dissociating organic compounds

Rate constants of reactions of ozone with non-ionized solutes, such as aliphatic alcohols, olefins, chlorosubstituted ethylenes, substituted benzenes and carbohydrates, have been determined from the absolute rates with which ozone reacts in the presence of various concentrations of these compounds in water. They have been tested by comparison with the relative rates by which pairs of these solutes are transformed by ozone. Different experimental methods have been developed to determine such rate constants in the range from 10^?2 to 10⁵ M^?1 s^?1. Interferences between the direct reactions of ozone and reactions due to its preliminary decomposition to secondary oxidants could be eliminated. The kinetics of all the reactions studied are first order with respect to ozone and solute concentration. The rate constants of many types of organic compounds in water are of the same order of magnitude as in organic solvents. Substituted benzenes, however, react in water about 100 times faster. They obey a linear free energy relationship with p = ?3.1 when based on δ_p⁺ values. Comparisons of rate constants with chemical structures of the reacting groups show that all reactions of ozone are highly selective and electrophilic. The kinetic data allow explanation of the chemical effects of ozone observed in water treatment practice.     

Measurement of the emanation of radon-222 from danish soils

The radon-222 emanation from 70 samples of Danish soils, subsoils, and sedimentary rocks has been measured.Two methods have been employed. The first one is to follow the growth of the radon concentration in a radon-tight sample container by transferring small air samples to a scintillation flask detection system. The second one is to measure the equilibrium gamma-activities of lead-214 and bismuth-214 in the sample when the sample container is open and, subsequently, when it is closed.Based on the measured emanation rates the samples are grouped in three classes: 1) less than 5 atoms · sec^?1 · kg^?1, 2) from 5 to 10 atoms · sec^?1 · kg^?1, and 3) more than 10 atoms·sec^?1. In class 3) some diatomitic clays have shown emanation rates as large as 100 atoms·sec^?1·kg^?1.     

Experimental investigation on heat transfer enhancement in a minichannel using CuO-water nanofluid

In this work, CuO-water nanofluid with an average size of nanoparticles (24?nm) and volume concentrations of 0.1% and 0.5% is used. For the computer microprocessor cooling, an aluminium minichannel of dimension (40?×?1?×?3) mm³ is fabricated instead of an aluminium heat sink and a cooling fan. It is shown that the dispersion of nanoparticles into the distilled water has produced a considerable enhancement of the cooling of the minichannel. Experiments were conducted for Reynolds number ranging from 25 to 800 under a laminar regime. From the experiments, it is found that better heat transfer is achieved when CuO-water nanofluid is used as the working fluid.