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Abstract: Stability of salt gradient solar pond salinity profile is examined under transient thermal phase. The analysis is done for straight as well as parabolic salinity profile. It is observed that the stability criterion at the upper interface of salinity profile is satisfied for a thin non-convective zone. However, a thin non-convective zone is unable to provide adequate insulation. Consequently the storage zone of the pond does not warm-up to desirable high temperature. The present work proposes that in order to acquire a high temperature, maintaining the stability of salinity profile, an additional zone below the interface of upper convective zone and non-convective zone should be introduced. Higher salinity gradient can be maintained in this additional intermediate zone. Thermal performance and gradient stability analysis of such a pond is presented here. [Copyright &y& Elsevier]

Abstract: The present study deals with heat storage performance investigation of integrated solar pond and collector system. In the experimental work, a cylindrical solar pond system (CSPS) with a radius of 0.80m and a depth of 2.0m and four flat plate collectors dimensions of 1.90m×0.90m was built in Cukurova University in Adana, Turkey. The CSPS was filled with salty water of various densities to form three salty water zones (Upper Convective Zone, Non-Convective Zone and Heat Storage Zone). Heat energy collected by collectors was transferred to the solar pond storage zone by using a heat exchanger system which is connected to the solar collectors. Several temperature sensors connected to a data acquisition system were placed vertically inside the CSPS and at the inlet and outlet of the heat exchanger. Experimental studies were performed using 1, 2, 3 and 4 collectors integrated with the CSPS under approximately the same condition. The integrated solar pond efficiencies were calculated experimentally and theoretically according to the number of collectors. As a result, the experimental efficiencies are found to be 21.30%, 23.60%, 24.28% and 26.52%; the theoretical efficiencies to be 23.42%, 25.48%, 26.55% and 27.70% for 1, 2, 3 and 4 collectors, respectively. Theoretical efficiencies were compared with the experimental results and hence a good agreement is found between experimental and theoretical efficiency profiles. [Copyright &y& Elsevier]

Abstract: Solar ponds combine solar energy collection with long-term storage and can provide reliable thermal energy at temperature ranges from 50 to 90°C. A solar pond consists of three distinct zones. The first zone, which is located at the top of the pond and contains the less dense saltwater mixture, is the absorption and transmission region, also known as the upper convective zone (UCZ). The second zone, which contains a variation of saltwater densities increasing with depth, is the gradient zone or non-convective zone (NCZ). The last zone is the storage zone or lower convective zone (LCZ). In this region, the density is uniform and near saturation. The stability of a solar pond prototype was experimentally performed. The setup is composed of an acrylic tube with a hot plate emulating the solar thermal energy input. A study of various salinity gradients was performed based on the Stability Margin Number (SMN) criterion, which is used to satisfy the dynamic stability criterion. It was observed that erosion of the NCZ was accelerated due to mass diffusion and convection in the LCZ. It can be determined that for this prototype the density of the NCZ is greatly affected as the SMN reaches 1.5. [Copyright &y& Elsevier]

The experimental results prove that cobble can improve temperature of lower convective zone (LCZ) and heat storage quantity of solar pond based on small solar ponds constructed on the seaside, and can avoid augmentation of brine's turbidity in the process of adding brine. The effects of porous media on temperature of LCZ, heat storage quantity and maximum thermal extraction efficiency of solar pond are researched based on a finite difference scheme. Computational results show that proper depth of porous media in some soil conditions can significantly increase heat storage quantity and maximum thermal extraction efficiency of solar pond. The effects of ground thermal conductivity on thermal performance of solar pond are also researched. If thermal conductivity of porous media frame is bigger than that of concentrated brine, temperature of LCZ of solar pond increases with increasing porosity of porous media. However, the situation is reverse if thermal conductivity of porous media frame is smaller than that of concentrated brine. [ABSTRACT FROM AUTHOR]

Results of exergetic performance analysis of three shallow solar pond (SSP) types - the CSSP, the RASSPgc, and RASSPins - are presented for the first time. The study shows that the highest irreversibilities are encountered in the components of the RASSPgc and that better exergetic performances in SSPs may be obtained by improving the surface properties: absorptivity, reflectivity, and transmissivity. Steady-state analysis also shows that exergy 'losses' in the SSPs due to irreversibilities in their water masses are significant and result from the direct absorption of solar radiation. Transient analysis reveals that the RASSPgc achieves the highest overall exergetic efficiency (4.37%), followed by the RASSPins (3.96%) and then the CSSP (2.87%). At the end of a 24 h operation, the exergy content of the water masses in the RASSPgc and the CSSP is negligible, whereas the water mass in the RASSPins retains 0.057 MJ of the exergy accumulated during daytime heating. [ABSTRACT FROM AUTHOR]

Abstract: Heat has generally been successfully extracted from the lower convective zone (LCZ) of solar ponds by two main methods. In the first, hot brine from the LCZ is circulated through an external heat exchanger, as tested and demonstrated in El Paso and elsewhere. In the second method, a heat transfer fluid circulates in a closed cycle through an in-pond heat exchanger, as used in the Pyramid Hill solar pond, in Victoria, Australia. Based on the experiences at the El Paso and Pyramid Hill solar ponds, the technical specifications, material selection, stability control, clarity maintenance, salt management and operating strategies are presented. A novel method of extracting heat from a solar pond is to draw the heat from the gradient layer. This method is analysed theoretically and results of an experimental investigation at Bundoora East, RMIT, are presented. An in-pond heat exchanger made of polyethylene pipe has been used to extract heat for over 2months. Results indicate that heat extraction from the gradient layer increases the overall energy efficiency of the solar pond by up to 55%, compared with conventional method of heat extraction solely from the LCZ. The experimental results are compared with the theoretical analysis. A close agreement has been found. From this small-scale experimental study, convection currents were found to be localised only and the density profiles were unaffected. An experimental study using an external heat exchanger for brine extraction and re-injection at different levels within the gradient layer still needs to be conducted to determine the effect of the heat extraction from the non-convective zone (NCZ) on the stability of the salinity gradient (both vertically and horizontally) and an economic analysis needs to be conducted to determine the economic gains from increased thermal efficiency. [Copyright &y& Elsevier]

Abstract: A common problem encountered in salinity-gradient solar ponds is the growth of various types of algae and bacterial populations, which affects the brine clarity and hence reduces thermal performance. Algae and bacterial populations are enhanced by the presence of organic nutrient such as nitrogen and phosphorus. A comprehensive study was undertaken on three salinity-gradient solar ponds in Australia: a 3000m2 sodium chloride solar pond at Pyramid Hill in Northern Victoria; a 50m2 sodium chloride; and 15m2 magnesium chloride solar pond at RMIT University in Bundoora, Victoria. The experimental study involved monitoring the clarity of these three ponds and testing chemical and biological treatment methods to see their effect on the brine transparency. The sources of turbidity and their impacts on clarity and efficiency of salinity-gradient solar ponds are presented in detail in this paper. The initial observation showed that the amount of sunlight is reduced due to the heavy algal growth creating instability in the solar pond as it absorbs light. Two treatment methods were applied to these solar ponds and experiments were conducted to study the turbidity reduction in the solar ponds. In the RMIT magnesium chloride solar pond, diluted hydrochloric acid was injected in the pond to reduce the pH and turbidity levels. Algal blooms were observed and found in the pond where the pH was between 5.5 and 8. It was observed from the experimental study that pH values should be kept below 4.5 to maintain low turbidity and prevent algae growth. The introduction of brine shrimps was also found to be very effective and economical to control algae, provided the oxygen has not depleted due to advanced heavy algal growth. The investigation concluded that hydrochloric acid could be used initially as a shock treatment to kill all the algae and then brine shrimps could be introduced to control the growth of algal and maintain transparency. This analysis showed that by using a combination of chemical and biological treatment methods, the pond clarity can be maintained and the thermal efficiency of the solar pond can be improved. [Copyright &y& Elsevier]

Abstract: Brine transparency is an important part of the maintenance of a salinity-gradient solar pond as it affects the amount of solar radiation reaching the storage zone and hence has an influence on the thermal performance. There is a wide range of factors that can hinder the transmission of light in a solar pond. Algal and microbial growths are the most common problems encountered in working solar ponds and control of their densities is essential to maintain transparency. Two different chemical treatment methods for algae growth prevention are described in this paper: chlorine and a novel chemical product – copper ethylamine complex. The latter method has never been implemented previously in a working pond. This paper discusses the theory of the algae control methods used and presents the experimental results of the chemical treatments. The results showed that Cupricide is more effective than chlorine and is therefore the recommended chemical for algae control in solar ponds; it improves the water transparency especially in the upper convective zone and lower convective zone with all measurement values less than 1 NTU. Chlorine was found to be more corrosive than Cupricide due to the acidic effect it has on the pH. The preliminary cost analysis showed that granular chlorine is the cheapest chemical. A more detailed financial analysis is nevertheless required to refine these costs. [Copyright &y& Elsevier]

The effect of filling the solar pond with the residual brine after desalination which is further concentrated is studied. Evaporation model of brine in different salinity is fitted through experimental results of brine evaporation, combining local meteorological conditions and using Penman-Monteith formula. Then, the consumption of residual brine after desalination and concentrating time for different salinity needed are calculated. According to the requirements of stability caused by temperature rising, a new method is proposed in which the whole filling process of solar pond can be finished through replenishing water to the pond for several times. Heat performance of the solar pond is improved by this method. [ABSTRACT FROM AUTHOR]

Abstract: In order to enhance the productivity of single basin solar stills especially during the night, a shallow solar pond (SSP) was coupled to the still. An analytical model for the various elements of the system (the pond and the still) was performed. Numerical calculations were carried out under Tanta prevailing weather conditions. The daily productivities of the active single basin solar still (ASBS) were found to be 5.740 and 1.830 (kg/m2 day) with and without the SSP, respectively. The daily productivity P d and efficiency η d of the active still were found to decrease with increasing the thickness d w and mass flow rate of the water flowing over the basin liner of the still up to typical values of 0.030m and 0.015kg/s. Moreover, the monthly average of the daily productivity had minimum values of 3.0 and 1.570 (kg/m2 day) in December with and without the SSP, respectively. The maximum values of were found to be 6.68 and 5.29 (kg/m2 day) in July with and without the SSP, respectively. To validate the proposed mathematical models, comparisons between experimental and theoretical results had been performed. Good agreement had been achieved. [Copyright &y& Elsevier]

Abstract: Non-Convective Zone (NCZ) of salt gradient solar pond is a typical double diffusive system of salinity and temperature, and it is subjected to instable effects of adverse temperature gradient. The onset of instability may occur as an oscillatory motion because of the stabilizing effect of the salinity. In this paper, the marginal state between the steady state and the convection of the NCZ is studied. The stability of the Boussinesq approximation of the Navier–Stokes equations is analyzed by a perturbation approach. The marginal states for the onset of convection are obtained by analytical method, which is based on the linearization of the ordinary differential equations, and then numerical method is used to solve the nonlinear ordinary differential equations. Numerical results provide the trajectories of the temperature and velocity coefficients in the three-dimensional phase space, as well as the two-dimensional temperature, salinity and velocity fields in NCZ. The results demonstrate that the numerical study is in agreement with the marginal stability and the critical Rayleigh number derived from linear stability analysis. Both the linear and nonlinear studies indicate that oscillation is a narrow region above the stable region; however, the nonlinear numerical results indicate that the linear stability analysis leans to a larger upper boundary in the oscillatory regions. [Copyright &y& Elsevier]

Abstract: Solar pond was discovered as a natural phenomena around the turn of the last century in the Medve Lake in Transylvania in Hungary. In this lake, temperatures up to 70°C were recorded at a depth of 1.32m at the end of the summer season. The minimal temperature was 26°C during early spring. The bottom of this lake had a salt NaCl with concentration of 26 percent. Solar pond is artificially constructed. To prevent convection, salt water is used in the pond. Those ponds are called “salt gradient solar pond”. Nowadays, mini solar ponds are also being constructed for various thermal applications. It was concluded that the optimum value of salinity in the mini solar pond is 80g/kg of water. [Copyright &y& Elsevier]

Abstract: Laboratory and field experiments were carried out along with numerical simulations in this paper to study the effects of porous media on thermal and salt diffusion of the solar ponds. From our laboratory experiments simulating heat transfer inside a solar pond, it is shown that the addition of porous media to the bottom of a solar pond could help enhance its heat insulation effect. The experiment on salt diffusion indicates that the upward diffusion of the salt is slowed down when the porous media are added, which helps maintain the salt gradient. Our field experiments on two small-scaled solar ponds indicate that when porous media are added, the temperature in the lower convective zone (LCZ) of the solar pond is increased. It is also found that the increase in turbidity is repressed by porous media during the replenishment of the salt to the LCZ. Thermal diffusivities and conductivities of brine layers with porous media such as pebble and slag were also respectively measured in this paper based on the unsteady heat conducting principles of a semi-infinite body. These measured thermal properties were then used in our numerical simulations on the effect of porous media on thermal performance of a solar pond. Our simulation results show that brine layer with porous media plays more positive role in heat insulation effect when thermal conductivity of the ground is big. On the other hand, when the ground has a very small thermal conductivity, the performance of solar pond might be deteriorated and total heat storage quantity of solar pond might be reduced by brine layer with porous media. [Copyright &y& Elsevier]

Abstract: A salinity gradient solar pond (SGSP) is a simple and effective way of capturing and storing solar energy. The Qinghai-Tibet Plateau has very good solar energy resources and very rich salt lake brine resources. It lacks energy for its mineral processes and is therefore an ideal location for the development and operation of solar ponds. In China, solar ponds have been widely applied for aquaculture, in the production of Glauber’s salt and in the production of lithium carbonate from salt lake. As part of an experimental study, a SGSP using the natural brine of Zabuye salt lake in the Tibet plateau has been constructed. The pond has an area of 2500m2 and is 1.9m deep. The solar pond started operation in spring when the ambient temperature was very low and has operated steadily for 105days, with the LCZ temperature varying between 20 and 40°C. During the experimental study, the lower convective zone (LCZ) of the pond reached a maximum temperature of 39.1°C. The results show that solar ponds can be operated successfully at the Qinghai-Tibet plateau and can be applied to the production of minerals. [Copyright &y& Elsevier]

The gravitational stability of NCZ (non-convective zone, also called gradient layer) of solar pond subjected to temperature gradient was researched. The analysis considers solar energy absorption in the layer and assumes certain heat flux values as boundary conditions for the heat-conduction differential equation. The marginal states for the onset of convection were obtained using a Galerkin method based on a weak formulation of the governing equations. The influence of turbidity (extinction coefficient) and heat extraction on the NCZ stability was studied. The analysis of linear stability on the salt gradient layer indicates that the critical stability value Rae is not much susceptible to the turbidity of the water, and a turbid pond tends to a decreasing Rae. Synthetically considering the influence of heat extraction and water turbidity, when the heat extraction f is 0. 65-0. 70, the influence of water turbidity on stability of NCZ is the least. When f is smaller than this value, Rae increases with the increase of turbidity, and system tends stable; but when f is larger than this value, Rae decreases with the increase of turbidity, and system tends unstable. [ABSTRACT FROM AUTHOR]

The impulse approximation of pion production reactions is studied by developing a relativistic formalism, consistent with that used to define the nucleon-nucleon potential. For plane wave initial states we find that the usual one-body (1B) expression O1B is replaced by O2B = -iK(mπ/2)O1B/mπ, where K(mπ/2) is the sum of all irreducible contributions to nucleon-nucleon scattering with energy transfer of mπ/2. We show that O2B ≈ O1B for plane wave initial states. For distorted waves, we find that the usual operator is replaced with a sum of two-body operators that are well approximated by the operator O2B. Our new formalism solves the (previously ignored) problem of energy transfer forbidding a one-body impulse operator. Using a purely one pion exchange deuteron, the net result is that the impulse amplitude for np → dπ0 at threshold is enhanced by a factor of approximately two. This amplitude is added to the larger "rescattering" amplitude and, although experimental data remain in disagreement, the theoretical prediction of the threshold cross section is brought closer to (and in agreement with) the data. [ABSTRACT FROM AUTHOR]

A theoretical and numerical study of the effect of thermodiffusion on the stability of a gradient layer is presented. It intends to clarify the mechanisms of fluid dynamics and the processes which occur in a salinity gradient solar pond. A mathematical modelling is developed to describe the thermodiffusion contribution on the solar pond where thermal, radiative, and massive fluxes are coupled in the double diffusion. More realistic boundary conditions for temperature and concentration profiles are used. Our results are compared with those obtained experimentally by authors without extracting the heat flux from the storage zone. We have considered the stability analysis of the equilibrium solution. We assumed that the perturbation of quantities such as velocity, temperature, and concentration are infinitesimal. Linearized equations satisfying appropriate prescribed boundary conditions are then obtained and expanded into polynomials form. The Galerkin method along with a symbolic algebra code (Maple) are used to solve these equations. The effect of the separation coefficient y is analyzed in the positive and negative case. We have also numerically compared the critical Rayleigh numbers for the onset of convection with those obtained by the linear stability analysis for Le = 100, μa = 0.8, and f = 0.5. [ABSTRACT FROM AUTHOR]

Abstract: Although, more than two-thirds of the Earth is covered by water, shortage of potable water is a serious issue that many countries suffer from. Furthermore, the worldwide rapid growth of industry and population has resulted in a large boom in demand for fresh water. The solar still, in many respects, is an ideal source of fresh water for both drinking and agriculture; it is one of the most important and technically viable applications of solar energy. There are many types of solar still; the simplest and most proven is the basin type. Investigations showed that the basin-type solar still has been found to be of limited performance. Numerous experimental and numerical investigations on basic types of solar still have been reported in various literatures. An extensive review for solar desalination systems has been carried out in this paper. [ABSTRACT FROM AUTHOR]

Abstract: Salinity-gradient solar ponds can collect and store solar heat at temperatures up to 80°C. As a result, these water bodies act as a renewable source of low grade heat which can be utilized for heating and power generation applications. In this paper, design and test result of the combined system of thermosyphon and thermoelectric modules (TTMs) for the generation of electricity from low grade thermal sources like solar pond is discussed. In solar ponds, temperature difference in the range 40–60°C is available between the lower convective zone (LCZ) and the upper convective zone (UCZ) which can be applied across the hot and cold surfaces of the thermoelectric modules to make it work as a power generator. The designed system utilizes gravity assisted thermosyphon to transfer heat from the hot bottom to the cold top of the solar pond. Thermoelectric cells (TECs) are attached to the top end of the thermosyphon which lies in the UCZ thereby maintaining differential temperature across them. A laboratory scale model based on the proposed combination of thermosyphon and thermoelectric cells was fabricated and tested under the temperature differences that exist in the solar ponds. Result outcomes from the TTM prototype have indicated significant prospects of such system for power generation from low grade heat sources particularly for remote area power supply. A potential advantage of such a system is its ability to continue to provide useful power output at night time or on cloudy days because of the thermal storage capability of the solar pond. [ABSTRACT FROM AUTHOR]

Abstract: The efficiency and the lifetime of a solar pond depends mainly on the behavior of the gradient Non-Convective Zone (NCZ), embedded between an Upper Convective Zone (UCZ) and a Lower Convective Zone (LCZ). The NCZ is often the siege of instabilities. These instabilities can destroy the linearity and transform it to a well mixed layer leading the pond to loose its main role of storing. Series of laboratory studies have been carried out to assess the stability of a linearly salt-stratified system (simulating the NCZ of a solar pond) heated from below. An assortment of flow visualization by Shadowgraph and Particle Image Velocimetry (P.I.V) techniques was employed to provide a phenomenological description of flow convection. This experimental characterization reveals three specific stages. The first stage corresponds to the onset of a non periodic oscillation in space and time of the bottom flow. In a second stage a well mixed layer is born and an oscillatory movement appears at the free surface whereas the last stage is relative to the transition from linear stratification to non-linear one (two superimposed layers separated by a well thin interface), before the homogenization of the whole system is accomplished. Most theoretical and experimental studies in the literature, considered a gradient layer heated from below at constant heat flux, whereas in this work the free surface system is heated from below at constant temperature. In addition, we will focus on the onset and development of the first mixed layer for small values of stability parameter Λ (values that can be encountered in a real solar pond. In the vicinity of our laboratory a 3m-deep solar pond of 1500m2 area is available). To our knowledge, no investigations has been performed, on the birth and self-organization of the first layer for small values of Λ. [ABSTRACT FROM AUTHOR]

Abstract: Solar ponds provide the most convenient and least expensive option for heat storage for daily and seasonal cycles. This is particularly important for a desalination facility, if steady and constant water production is required. If, in addition to high storage capacity, other favorable conditions exist, the salt gradient solar ponds (SGSPs) are expected to be able to carry the entire load of a large-scale flash desalination plants without dependence upon supplementary sources. This paper presents a performance investigation of a SGSP coupled with desalination plant under Jordanian climatic conditions. This is particularly convenient in the Dead Sea region characterized by high solar radiation intensities, high ambient temperature most of the year, and by the availability of high concentration brine. It was found that a 3000m2 solar pond installed near the Dead Sea is able to provide an annual average production rate of 4.3Lmin−1 distilled water compared with 3.3Lmin−1 that would be produced by El Paso solar pond, which has the same surface area. Based on this study, solar ponds appear to be a feasible and an appropriate technology for water desalination near the Dead Sea in Jordan. [Copyright &y& Elsevier]

Abstract: The performance and stability of a 0.64m2 mini solar pond were experimentally and numerically studied. The experimental results showed that the daily average temperatures of the mini pond increased quickly to reach 54°C in the lower convective zone after only 20days. A 1 D numerical model to predict the temperature and the salinity in the mini pond was developed. The results obtained from the numerical calculation were compared with our experimental results and good agreement was found. Therefore a new method of heat extraction from the non convective zone was numerically investigated in order to enhance the mini pond performance. Using this new method of heat extraction, the numerical results showed that the mini pond efficiency could be considerably improved. However, the method was found to reduce the stability of the lower interface. [Copyright &y& Elsevier]

Abstract: This paper presents the results of experimental and theoretical analysis on the heat extraction process from solar pond by using the heat pipe heat exchanger. In order to conduct research work, a small scale experimental solar pond with an area of 7.0m2 and a depth of 1.5m was built at Khon Kaen in North-Eastern Thailand (16°27′N102°E). Heat was successfully extracted from the lower convective zone (LCZ) of the solar pond by using a heat pipe heat exchanger made from 60 copper tubes with 21mm inside diameter and 22mm outside diameter. The length of the evaporator and condenser section was 800mm and 200mm respectively. R134a was used as the heat transfer fluid in the experiment. The theoretical model was formulated for the solar pond heat extraction on the basis of the energy conservation equations and by using the solar radiation data for the above location. Numerical methods were used to solve the modeling equations. In the analysis, the performance of heat exchanger is investigated by varying the velocity of inlet air used to extract heat from the condenser end of the heat pipe heat exchanger (HPHE). Air velocity was found to have a significant influence on the effectiveness of heat pipe heat exchanger. In the present investigation, there was an increase in effectiveness by 43% as the air velocity was decreased from 5m/s to 1m/s. The results obtained from the theoretical model showed good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Abstract: Terminal lakes are water bodies that are located in closed watersheds with the only output of water occurring through evaporation or infiltration. The majority of these lakes, which are commonly located in the desert and influenced by human activities, are increasing in salinity. Treatment options are limited, due to energy costs, and many of these lakes provide an excellent opportunity to test solar-powered desalination systems. This paper theoretically investigates utilization of direct contact membrane distillation (DCMD) coupled to a salt-gradient solar pond (SGSP) for sustainable freshwater production at terminal lakes. A model for heat and mass transport in the DCMD module and a thermal model for an SGSP were developed and coupled to evaluate the feasibility of freshwater production. The construction of an SGSP outside and inside of a terminal lake was studied. As results showed that freshwater flows are on the same order of magnitude as evaporation, these systems will only be successful if the SGSP is constructed inside the terminal lake so that there is little or no net increase in surface area. For the study site of this investigation, water production on the order of 2.7 × 10−3 m3 d−1 per m2 of SGSP is possible. The major advantages of this system are that renewable thermal energy is used so that little electrical energy is required, the coupled system requires low maintenance, and the terminal lake provides a source of salts to create the stratification in the SGSP. [ABSTRACT FROM AUTHOR]

In this study, a solar pond with salt gradient having a surface area 1.5 × 1.5 m2 and depth of 1.5 m has been designed and made. Two covers, which are collapsible, have been used for reducing the thermal energy loses from the surface of the solar pond during the night and increasing the thermal efficiency of the pond solar energy harvesting during daytime. These covers having reflective properties can be rotated between 0° and 180° by an electric motor and they can be fixed at any angle automatically. It has been measured temperature values obtained from pond in the case of work in different angles of the cover and has been given in graphics. Thus, the value of the cover angle providing the maximum temperature to be obtained from the pond has been identified. [ABSTRACT FROM AUTHOR]

Abstract: Several chemicals are produced from brines by solar crystallization using solar ponds. The process of salt harvest consists on mechanically retiring the salts precipitated in the solar evaporation ponds and to leave them in their respective stockpile. In an industrial operation several ponds are used for the salt crystallization, and hence the harvest planning can be a nontrivial task. Therefore, the objective of this work is to plan the feeding flow to each of the solar ponds, the manipulation of brine solution between ponds, brine and solids inventories in each pond that maximizes the production and the harvest periods. All this having as input data the evaporation rate, feed concentration, pond concentration range, and the operational initial conditions. The presented model corresponds to a MINLP, which includes the mass balances in each pond, equilibrium conditions, and planning and operational restrictions. The problem was solved in two steps: firstly, the maximization of the salt harvest was determined and then, using this maximum harvest, the maximum availability of the contractor was determined. Several cases have been studied, including: ternary (NaNO3–KNO3–H2O) and quaternary systems (KCl–KNO3–K2SO4–H2O), pond systems with 3 and 4 ponds, and considering 12 and 26 operation periods per year. [Copyright &y& Elsevier]

Abstract: A fully coupled two-dimensional, numerical model that evaluates, for the first time, the effects of double-diffusive convection in the thermal performance and stability of a salt-gradient solar pond is presented. The inclusion of circulation in the upper and lower convective zone clearly shows that erosion of the non-convective zone occurs. Model results show that in a two-week period, the temperature in the bottom of the solar pond increased from 20°C to approximately 52°C and, even though the insulating layer is being eroded by double-diffusive convection, the solar pond remained stable. Results from previous models that neglect the effect of double-diffusive convection are shown to over-estimate the temperatures in the bottom of the solar pond. Incorporation of convective mixing is shown to have profound impacts on the overall stability of a solar pond, and demonstrates the need to actively manage the mixing and heat transfer to maintain stability and an insulating non-convective zone. [Copyright &y& Elsevier]

Abstract: Rankine cycles using organic fluids (as categorized into three groups: wet, dry, and isentropic fluids) as working fluids in converting low-grade energy are investigated in this study. The main purpose is to identify suitable working fluids which may yield high system efficiencies in an organic Rankine cycle (ORC) system. Efficiencies of ORC systems are calculated based on an assumption that the inlet condition of the working fluid entering turbine is in saturated vapor phase. Parameters under investigation are turbine inlet temperature, turbine inlet pressure, condenser exit temperature, turbine exit quality, overall irrversibility, and system efficiency. The low-grade energy source can be obtained from a solar pond or/and an ocean thermal energy conversion (OTEC) system. Results indicate that wet fluids with very steep saturated vapor curves in T-s diagram have a better overall performance in energy conversion efficiencies than that of dry fluids. It can also be shown that all the working fluids have a similar behavior of the efficiency-condenser exit temperature relationship. Furthermore, an appropriate combination of solar energy and an ORC system with a higher turbine inlet temperature and a lower condenser temperature (as operated deeply under sea level) would provide an economically feasible and environment-friendly renewable energy conversion system. [Copyright &y& Elsevier]

Abstract: A series of experiments were conducted to study the turbidity reduction in solar ponds utilizing seawater as salt source. The experiment on the turbidity reduction efficiency with chemicals indicates that alum (KAl(SO4)2·12H2O) has a better turbidity control property because of its strongly flocculating and also well depressing the growing of algae and bacteria in the seawater. In comparison with bittern and seawater, our experiment shows that the residual brine after desalination can keep limpidity for a long time even without any chemical in it. Experiments were also conducted on the diffusion of turbidity and salinity, which show that the turbidity did not diffuse upwards in the solution. In the experiment on subsidence of soil in the bittern and saline with the same salinity, it was found that soil subsided quite quickly in the pure saline water, but very slowly in the bittern. In this paper we also proposed an economical method to protect the solar pond from the damage of rain. Finally, thermal performance of a solar pond was simulated in the conditions of different turbidities using a thermal diffusion model. [Copyright &y& Elsevier]

Abstract: Many natural systems such as oceans, lakes, etc.…, are influenced by the effect of double-diffusive convection. This phenomenon, which is a combination of heat and mass transfer, can destroy the stability of system-flows. In the case of solar ponds the middle layer, that is linearly stratified, acts as a thermal and mass insulator for the lower layer. This middle layer, called the Non-Convective Zone (NCZ), needs special care to avoid convection and to maintain its stability. In fact, due to an excess of heat stored, a thermal gradient occurs within the NCZ. A convective movement appears at the bottom of the stratified-layers and then grows to a double-diffusive convection movement. This movement transforms the stratified-layers into a well mixed layer, reducing the storage capacity of the pond. Laboratory small-scale pond and middle-scale outdoor solar ponds were designed and built to provide both quantitative data and to study the dynamic processes in solar ponds, including the behavior of the gradient zone. Particle Image Velocimetry (PIV) visualization-experiments carried out in the mechanical and energetic laboratory in the engineering school of Tunisia and experiments in the field showed that the instability of solar ponds could be limited by using porous media placed in the lower layer of the stratification. [Copyright &y& Elsevier]

Abstract: An attempt is made to enhance the productivity of the solar stills by connecting a mini solar pond, stepped solar still and a single basin solar still in series. Experiment is also carried out by replacing the single basin solar still into a wick type solar still. For further augmentation of the yield, baffle plate, pebble, fins, wicks and sponges are added. Day and night productivity of the solar stills for these modifications is studied. Daily efficiency and percentage increase in productivity for these modifications are also studied. Industrial effluent water is used as feed. Theoretical analysis gives very good agreement with experimental results. [Copyright &y& Elsevier]

The 'reverse-side absorber-plate shallow solar pond' (RASSP), consisting of a semi-cylindrical reflector attached to the exposed base of a conventional shallow solar pond, has been conceived in two variants, viz., one with double glass covers and the other with insulation over the top. The thermal performances of these RASSPs have also been studied analytically to determine the effect of depth variation and time of the year on the maximum water temperatures and overall daily efficiencies they are able to attain. The results of the study, here presented, show that attainable water temperatures decrease while overall daily efficiencies increase as pond depth increases. And that, for a fixed pond depth, the daily peak water temperatures attainable are strongly dependent on the time of the year, while overall daily efficiencies are not. For all seasons and depths, the RASSP with double glass covers is predicted to consistently deliver higher water temperatures but lower overall daily efficiencies compared to the RASSP with top insulation. [ABSTRACT FROM AUTHOR]

Abstract: Industrial effluent was evaporated in a fin type single basin solar still and a stepped solar still separately. To preheat the saline water, a mini solar pond was integrated with these stills. Both the stills were operated with mini solar pond and tested individually. In fin type single basin solar still, maximum productivity is obtained, when it is modified with black rubber, sponge and sand. The stepped solar still was modified with fin, pebble and sponge to enhance their productivities. When mini solar pond, pebble, sponge and fin are used in stepped solar still, maximum productivity was obtained To settle the industrial effluent, a settling tank was also fabricated with five layers namely: tray for raw effluent, pebble layer, coal layer, sand layer and collection tray for settled effluent. Physical and chemical analyses were made for raw effluent, settled effluent and distilled water. Economic analysis was made. [Copyright &y& Elsevier]

Abstract: The concept of combining a salinity gradient solar pond with a chimney to produce power in salt affected areas is examined. Firstly the causes of salinity in salt affected areas of northern Victoria, Australia are discussed. Existing salinity mitigation schemes are introduced and the integration of solar ponds with those schemes is discussed. Later it is shown how a solar pond can be combined with a chimney incorporating an air turbine for the production of power. Following the introduction of this concept the preliminary design is presented for a demonstration power plant incorporating a solar pond of area 6hectares and depth 3m with a 200m tall chimney of 10m diameter. The performance, including output power and efficiency of the proposed plant operating in northern Victoria is analysed and the results are discussed. The paper also discusses the overall advantages of using a solar pond with a chimney for production of power including the use of the large thermal mass of a solar pond as a practical and efficient method of storing collected solar energy. [Copyright &y& Elsevier]

The recent exponential growth in industrial aquaculture has led to a huge increase in Artemia biomass production in order to meet increased fish production needs. The present study explores the potential use of salt gradient solar ponds (SGSPs) for production of Artemia nauplii. An SGSP is a basin of water where solar energy is trapped and collected via an artificially imposed gradient. Three zones can be identified in an SGSP: upper and lower zones, which are both convective, and a middle zone, which is intended to be non-convective. The latter acts as a transparent insulation layer and allows for storage of solar energy at the bottom, where it is available for use. The combination of salt, temperature and high transparency could make SGSPs promising bioreactors for the production of Artemia nauplii. Using particle image velocymetry (PIV) and Shadowgraph visualisation techniques, the behaviour of Artemia nauplii under critical cultivation parameters (namely, salinity, temperature and light) was monitored to determine movement velocity, and how movement of Artemia affects the salt gradient. It was observed that Artemia nauplii constantly follow light, irrespective of adverse salinity and/or temperature conditions. However, despite the substantial displacement of Artemia following the light source, the salt gradient is not disrupted. The suitability of SGSPs as bioreactors for Artemia biomass production was then tested. The results were disappointing, probably due to the lack of sufficient O2 for Artemia survival and growth. Follow-up trials were conducted aimed at using the SGSP as a green and economically attractive energy source to induce faster hatching of cysts and improved Artemia nauplii growth. The results of these trials, and a case study of Artemia nauplii production using an SGSP, are presented. The authors constructed a Solar Pond device, which they suggest as a novel way of supplying thermal energy for Artemia biomass production in an aquaculture enterprise. Finally, the authors suggest a method of producing and collecting Artemia biomass, and of heating a fish larval tank, in an ‘ideal’ Solar Pond device, profiting from the low investment costs of using a decommissioned salt works. [ABSTRACT FROM AUTHOR]

In this study, a salt gradient solar pond having a surface area of 3.5 × 3.5 m2 and depth of 2 m has been built for supplying hot water to a leather workshop on the campus area of Vocational College of Isparta/Yalvac. A cover system was used on the surface of the pond to reduce the thermal losses from the top to air and to increase the thermal efficiency of the pond. Such an arrangement is used for the very first time. The system is composed of two covers that can be rotated between 0 and 180 degrees by a controlled electric motor and has insulation and reflection properties, i.e., the covers function as insulators when closed and as reflectors when opened. The pond's thermal analysis has been carried out theoretically and experimentally for different operating conditions. Results obtained from this study show that salt gradient solar ponds can be used as a source of warm water required at the leather workshop and for suitable domestic applications. The covers were effective both for reducing the night thermal losses and for increasing the daytime performance, although the former effect is negligible. [ABSTRACT FROM AUTHOR]

Abstract: An alternative to synthetic materials for use in solar pond liners is to select clayey soils as hydraulic barriers. This option reduces the cost of construction and the risk of contamination of subsoil and groundwater by hot brines. This paper deals with the physical, chemical and hydraulic properties of different soils tested mainly as compacted clay liners. The underdeveloped nations have the option to use this type of liner, but before doing so several tests are recommended, including those for soil and water composition, permeability, plasticity and X-ray diffraction analysis. In this investigation the following samples are analyzed: native clayey soils with illite, montmorillonite and halloysite, treated and non-treated bentonites in powder and granulated form, a mixture of zeolite and sodium bentonite, and industrial minerals composed largely of halloysite, kaolinite and attapulgite selected clays. Neutral salt aqueous solutions (NaCl and KCl) at different concentrations and under temperature gradients were used for compatibility testing conducted on these specimens. Experiment setup and particular testing procedures are also discussed. [Copyright &y& Elsevier]

Abstract  In this study, the diversity of prokaryotes inhabiting crystallizer ponds of three solar salterns, located along Bengal Bay in Tamil Nadu, India was examined. Unlike other salterns studied the Tamil Nadu salterns are fed by hypersaline spring water mixed with seawater and led to the ponds from bore wells. In addition, prokaryotic community development is restricted as salterns operate only during the arid part of the year. Both culture-based and culture-independent polymerase chain reaction 16S rRNA molecular phylogenetic approaches were employed. Representatives of the family Halobacteriaceae dominated in cultivable portion of diversity encountered with members of genera Haloferax, Halorubrum, Haloarcula, Halobacterium and Halogeometricum recovered in pure culture. In contrast, members of Bacteria were recovered from only one sampling site and were represented by members of genera Salinibacter, Cytophaga and Marinococcus. Based on culture-independent sampling, the predominant members of the haloarchaeal crystallizer community belonged to the genus Natrinema. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents a 2D numerical model where the behavior of a salt gradient solar pond (SGSP) is described in terms of temperature, salt concentration and velocity with the fluid density and viscosity dependent on temperature and salt concentration. The discretization of the governing equations is based on the respective weak formulations. The rectangular geometry allows for spectral type Galerkin approximations for which the essential homogeneous boundary conditions can easily be imposed. Taking into account the variation of density and viscosity with temperature and salinity improved the agreement between the numerical and the experimental results. [Copyright &y& Elsevier]

Abstract: The paper discusses optimisation of the size of the pond and the number of stages for three different storage zone temperatures taking into account the large variation in quantity of energy supplied by the pond between summer and winter. One result is that over-sizing the pond, leading to some rejection of the heat collected during the summer (which is referred to as peak clipping), will result in a higher utilisation factor of the desalination plant and a reduction in the summer/winter yield ratio. Optimum peak clipping days, leading to the minimum product water cost, for each storage zone temperature and performance ratio is presented. The sensitivity analysis of the various factors affecting the overall water costs show that the capital costs comprise about two thirds (2/3) of the total desalinated water costs. This demonstrates and re-emphasises the inherent and basic fact that solar desalination is a capital intensive enterprise. Each 1% increase in interest rate increases solar pond thermal energy costs by about 13–15% and desalinated water costs from SP/MSF combination by about 10–13%. [Copyright &y& Elsevier]

Abstract: In case of noninsulated salt gradient solar pond, heat losses through bottom and sides are significant. The magnitude of losses depends upon the location (depth) of water table, which act as a heat sink. Simulation analysis indicates that deeper the water table, lesser are the heat losses and higher is the temperature achieved by the pond. The present analysis, however, reveals two more significant conclusions – firstly; increase in depth of water table increases the maturation temperature and highest temperature of the pond, but does not affect the time of acquiring these temperatures. Secondly, there is a significant depth of water table, below which, further depression does not have significant impact on thermal performance of pond. This conclusion is of practical significance where efforts are done to depress the water table. [Copyright &y& Elsevier]

• The ICP process shows separation of ions based on electrophoretic mobility. • Reduction of Mg2+:Li+ is demonstrated with standard divalent ion exchange membrane. • The technical feasibility is compared with well-established electrodialysis platforms. The surge of electric vehicle deployment in response to the global climate crisis has marked tremendous increase in the demand of lithium-ion batteries. Lithium brine has gained much attention as a critical primary lithium resource over mineral sources due to cheaper processing and greater abundance. However, reducing the Mg2+:Li+ ratio of brines remains a challenge, as magnesium contaminates lithium precipitates. Solar evaporation ponds are traditionally employed to concentrate Li and reduce Mg content to tackle this issue, but typically require 1–2 years to process a batch of feed solution, and require much land area disturbing the local environment near brine resources. Here we present a continuous, scalable ion separation technique for reducing the Mg2+:Li+ ratio of brine as an alternative to solar evaporation. The device utilizes ion concentration polarization to induce a locally amplified electric field. The amplified electric field separates ions into streams according to electrophoretic mobility. We demonstrate reduction of a 25:1 Mg2+:Li+ lab brine to below 10:1 Mg2+:Li+, which is an acceptable lithium production purity by industrial standards. Reduction of a 60:1 Mg2+:Li+ to ∼ 10:1 and a 100:1 Mg2+:Li+ brine to approximately 20:1 are also demonstrated. The system suffers a high specific energy consumption (8.804 kWh/g Li+ for 25:1 reduction to 9:1) due to low lithium recovery (9.9%) and microfluidic system size. However, an economic scaling analysis shows that this work is within an order of magnitude of the state-of-the-art separation technologies in the literature after various process parameters are normalized. Ultimately, this work demonstrates a potential novel process for continuous lithium extraction from brines, which is a generalizable ion separation tool utilizing differences in electrophoretic mobility. [ABSTRACT FROM AUTHOR]

The present research deals with a novel hybrid system that comprises of a salinity gradient solar pond (SGSP) integrated with a proton exchange membrane fuel cell (PEMFC) and a thermoelectric generator (TEG). The key novelty of this research is the use of PEMFC waste heat to increase the performance of the low-temperature heat source (solar pond). Also, a thermoelectric generator is employed in the proposed setup for complete waste energy recovery. In this paper, the proposed system's energy, exergy, and economic (3E) performance are investigated, as well as compared with two additional systems that were modelled by excluding TEG and PEMFC to showcase the benefits of the sub-systems in the final configuration. A parametric study is also conducted to investigate the effect of significant parameters on the overall system performance. The simulation results indicated that the integrated system's net output power is 2288.8 kW at a base case operating condition, with energy and exergy efficiency of 11.26% and 13.17%, respectively, and a system cost rate of 394 $/h. In comparison to other components in the integrated system, SGSP alone accounts for 75% of total exergy degradation and has the highest investment cost rate of 66.70 $/h. Further, to achieve the best system performance, a multi-criteria optimization is performed for the suggested system with net output power, energy efficiency, exergy efficiency, and system cost rate as objective functions. Besides, the multi-criteria decision analysis (MCDA) is also carried out on the obtained Pareto front using TOPSIS decision-maker to select the best operating condition that improves the output power, energy, and exergy efficiency by 52.6%, 49.6%, and 61.8%, respectively, at the expense of 5.2% increase in the system cost rate. The current investigation demonstrates how an appropriate optimized design of an integrated energy system using SGSP, PEMFC, and TEG can improve the overall performance with reasonable cost increment. [Display omitted] • Solar pond integrated system with fuel cell and thermoelectric generator is proposed. • 3E based multi-criteria optimization and decision analyses are presented. • Solar pond alone accounts for 75% of total exergy degradation in the integrated system. • Optimization improved the exergy efficiency of the integrated system by 61.8%. [ABSTRACT FROM AUTHOR]

The thermal performance of a solar pond is affected by the amount of heat lost to the ground through the lower convective zone (LCZ) in which the heat is stored. Studies are focused on decreasing the heat losses, to maximize the energy stored and guarantee the stability of the thermohaline system over time. Phase change materials (PCMs) can help to achieve all these goals, since they work as thermal energy storage (TES), exploiting the latent heat absorbed during the solid-liquid phase change. This paper presents an experimental application of PCMs in the LCZ of a small solar pond. The paraffin wax was enclosed in aluminium cylinders which have been arranged on the bottom. The temperature of the solution in deep is monitored both with and without the PCM. The stability of the pond is analyzed through a laser shadowgraph technique, to visualize the effect of the thermal convection on the interfaces. Results show that the LCZ of the solar pond with PCM is around 3 °C colder than the reference case after a 6-h heating period. The shadowgraph analysis proves that the thermal convection in the reference case is stronger and damage the interface until break. The monitoring of the solar pond with PCM shows an improved stability. • A solar pond integrated with PCM has been designed and built. • After the heating period, the system with PCM results colder in the LCZ. • PCM stabilized the LCZ-NCZ interfaces, as proved with the shadowgraph technique. [ABSTRACT FROM AUTHOR]

In the field of desalination powered by renewable energies, the use of solar power cycles exhibits some favorable characteristics, such as the possibility of implementing thermal energy storage systems or a multi-generation scheme (e.g., electricity, water, cooling, hydrogen). This article presents a review of the latest design proposals in which two power cycles of great potential are considered: the organic Rankine cycle and the supercritical CO2 power cycle, the latter of growing interest in recent years. The designs found in the literature are grouped into three main types of systems. In the case of solar ORC-based systems, the option of reverse osmosis as a desalination technology is considered in medium-temperature solar systems with storage but also with low-temperature using solar ponds. In the first case, it is also common to incorporate single-effect absorption systems for cooling production. The use of thermal desalination processes is also found in many proposals based on solar ORC. In this case, the usual configuration implies the cycle's cooling by the own desalination process. This option is also common in systems based on the supercritical CO2 power cycle where MED technology is usually selected. Designs proposals are reviewed and assessed to point out design recommendations. [ABSTRACT FROM AUTHOR]

• The best method of pond water isoscapes mapping is IDW interpolation. • The pond water isoscapes contains three distinct gradients by the gradient analysis. • Pond water isotope composition is significantly correlated with altitude. Isoscapes are useful tools for studies concerned with hydroclimatic processes, at multiple scales, and their effects on water resources. However, few studies have been conducted on the application of landscape ecology methods for the characterization of isoscape patterns and their impact factors. In this work, measurements of stable hydrogen and oxygen isotope composition were performed on 112 pond-water samples from the water-source forest of the Hani terraced fields. The spatial gradients of pond-water isotope compositions, and the altitude factor of these gradients, were then analysed according to the topography of the study area, using spatial interpolation and gradient analysis methods. It was found that: 1) The pond-water evaporation line (PWEL) of the study area was δD = 6.28δ18O − 5.5 (R 2 = 0.96, n = 112). The gradient and intercept of the PWEL were lower than those of the global meteoric water line (GMWL) and local meteoric water line (LMWL), indicative of intense evaporation. 2) Inverse distance weighting (IDW) interpolation, natural neighbourhood interpolation, spline interpolation, Kriging and Co-Kriging (with altitude as an auxiliary variable) were compared, and IDW interpolation was demonstrated to be the most precise of these methods. IDW interpolation demonstrated that pond-water δ18O values generally increased with decreased altitude, in E-W, S-N and SE-NW directions across the study area. 3) Gradient analysis demonstrated that δ18O generally decreased with increased altitude across the whole-region and at watershed-scales. The δ18O was significantly correlated with altitude on virtually all transects. Therefore, altitude is one of the key factors for the spatial pattern in the stable isotope compositions of the study area's pond water. This was less pronounced in the E-W transect across the study area, as its isotope compositions were affected by watershed-level patterns. In summary, this work has established a new approach for the analysis of water-body isoscapes and their altitude factor by adopting methods of pattern analysis from landscape ecology. [ABSTRACT FROM AUTHOR]

Increasing population and growing demands from both agriculture and industry in the United Arab Emirates (UAE) necessitate the need to provide inexpensive fresh water. The only feasible source of such water is desalination. The coastal area of the United Arab Emirates especially in Abu Dhabi is formed of a series of hypersaline (47%°) lagoons surrounded by salt-encrusted flat sabkhas. Such water bodies may be used as salinity gradient solar ponds (SGSPs) to generate clean electricity that can be used in desalination plants. The geologic and climatic conditions of this region are compared with El Paso, Texas, USA where there is a well-established SGSP technology. It is concluded that the water and air temperature, solar radiation, and geologic setting support the possibility of using this technology in the UAE and especially in Abu Dhabi. Cost analyses also suggest that the generation of electricity and its use in desalination plants are economically feasible. [ABSTRACT FROM AUTHOR]

Solar ponds are the systems which collect solar energy and store it for long periods of time. For effective and efficient use of these systems in the country, concepts relating economy of solar ponds which generated hot water from the sun must be known besides their physical properties. Life cycle cost analysis is a systematic analytical method that helps identify and evaluate the environmental impacts of a specific process or competing processes. In order to quantify the costs, resource consumption, and energy use, material and energy balances are performed in a cradle-to-grave manner on the operations required to transform raw materials into useful products. In this study; life cycle cost analysis of reflecting covered and non covered solar ponds are calculated for a volume of 3.5×3.5×2 cubic meters and presented. Also the energies extractable for these solar ponds in Goller Region climatic conditions are given. [ABSTRACT FROM AUTHOR]

Abstract: An experimental salt gradient solar pond having a surface area of 3.5×3.5m2 and depth of 2m has been built. Two covers, which are collapsible, have been used for reducing the thermal energy loses from the surface of the solar pond during the night and increasing the thermal efficiency of the pond solar energy harvesting during daytime. These covers having reflective properties can be rotated between 0° and 180° by an electric motor and they can be fixed at any angle automatically. A mathematical formulation which calculates the amount of the solar energy harvested by the covers has been developed and it is adapted into a mathematical model capable of giving the temporal temperature variation at any point inside or outside the pond at any time. From these calculations, hourly air and daily soil temperature values calculated from analytical functions are used. These analytic functions are derived by using the average hourly and daily temperature values for air and soil data obtained from the local meteorological station in Isparta region. The computational modeling has been carried out for the determination of the performance of insulated and uninsulated solar ponds having different sizes with or without covers and reflectors. Reflectors increase the performance of the solar ponds by about 25%. Finally, this model has been employed for the prediction of temperature variations of an experimental salt gradient solar pond. Numerical results are in good agreement with the experiments. [Copyright &y& Elsevier]