An innovative psychometric solar-powered water desalination system

At present scarcity of potable and drinking water is a pressing issue in certain parts of the Middle East region. Important advances have been made in desalination technologies but relatively high capital and running costs restrict their wide application even in cases when solar energy is used. Flat-plate solar collectors mainly have been employed in the past to distill water in compact desalination systems. Currently, it is possible to replace the above collectors by more advanced evacuated tube ones, which are available on the market at a similar price. This paper describes results of experimental and theoretical investigations of the operation of a solar still desalination system coupled with a heat pipe evacuated tube collector with the aperture area of about 1.7 m2. A multi-stage solar still water desalination system was designed to recover latent heat from evaporation and condensation processes in four stages. The variation in the solar radiation (insolation) during a typical mid-summer day in the Middle East region was simulated using an array of 110 halogen flood lights covering the area of the solar collector. The synthetic brackish lab water solution was used for experiments and its total dissolved solids (TDS), electrical conductivity and pH were measured prior to and after the distillation process. The system’s operation was numerically simulated using a mathematical model based on the system of ordinary differential equations describing mass and energy conservation in each stage of the system. The experimental and theoretical values for the total daily distillate output were found to be in good agreement. The results of tests demonstrate that the system produces about 6.5 kg of clean water per day and have the distillation efficiency equal to 76%. However, the overall efficiency of the laboratory test rig at this stage of investigations was found to be low at the level of 26% and this is due to excessive heat losses in the system. The analysis of the distilled water shows that its quality is within the World Health Organization guidelines. Further research is being performed to improve the performance of the installation.

Theoretical simulation of small scale psychometric solar water desalination system in semi-arid region

In this study we have designed and fabricated a household solar water desalination unit for the arid regions of rural areas of Sindh like Tharparkar district. Drought conditions, shortage of drinking water and relying on saline water in arid regions of Sindh is a serious problem. In areas under these tracts, it is difficult to obtain drinkable water. This study focuses on the development of a cost effective and affordable desalination unit having simple construction, easy to use, repair, maintain and can be operated by an unskilled man. The solar desalination unit comprises of a solar oven, condenser, and collector pot. In this research various water samples were collected from three arid regions of Tharparkar district i.e., Islamkot, Diplo and Mithi. The performance of solar water desalination unit was assessed by analysing the Total Dissolve Solids (TDS), pH and Electrical Conductivity (EC) of all samples. The sample collected, before treatment had maximum TDS, conductivity, and pH values as 10421 mg/L, 20842 μS/cm and 8 respectively. Those sample after treatment reduced to TDS of 230 mg/L, conductivity of 460 μS/cm and pH of 7.4. This portable solar desalination unit showed remarkable results and found as effective in the removal of TDS from all water samples. The efficiency of unit was calculated as 35.2% with maximum daily output of 5 litres. This unit was constructed at very low cost of PAKPKR 4500/- and its complete rely on solar energy which makes it quite affordable for those which cannot afford expensive treatment techniques. This unit has very minimal maintenance cost and does not require electricity. The values for pH, TDS, and EC achieved from this unit are satisfying the World Health Organization (WHO) guidelines for drinking water quality.

Desalination processes are energy consuming and it is required to apply clean energy sources for supplying them to prevent environmental issues. Solar energy is one of the attractive clean energy sources for desalination. In solar thermal desalination systems, different thermal components could be used for heat transfer purpose. In solar desalination technologies, heat pipe as efficient heat transfer mediums could be employed to transfer absorbed and/or stored thermal energy. The objective of this study is to review applications of heat pipes in solar energy desalination systems. Regarding the performance dependency of these thermal systems on the variety of factors, scholars have investigated these systems by consideration of the effect of different influential factors. Based on the results, it is concluded that use of heat pipes could lead to proper performance of solar desalination systems. Aside from direct transfer of absorbed heat from solar radiation, heat pipes can be applied in the storage units of solar desalination systems to keep the systems active in night-hours or low solar irradiation conditions. The overall performance of the solar desalinations systems with heat pipes can be influenced by some factors such as filling ratio and operating fluid that affect the performance of heat pipes.

Recent decades have seen a shortage of water, which has led scientists to concentrate on solar desalination technologies. The present study examines the solar water desalination system with inclined steps, while considering various phase change materials (PCMs). The findings suggest that the incorporation of PCM generally enhances the productivity of the solar desalination system. Additionally, the combination of nanoparticles has been used to PCM, which is a popular technique utilized nowadays to improve the efficiency of these systems. The current investigation involves the transient modeling of a solar water desalination system, utilizing energy conservation equations. The equations were solved using the Runge-Kutta technique of the ODE23s order. The temperatures of the salt water, the absorbent plate of the glass cover, and the PCM were calculated at each time. Without a phase changer, the rate at which fresh water is produced is around 5.15 kg/m2·h. The corresponding mass flow rates of paraffin, n-PCM I, n-PCM III, n-PCM II, and stearic acid are 22.9, 28.9, 5.9, 11.9, and 73 kg/m2·h. PCMs, with the exception of stearic acid, exhibit similar energy efficiency up to an ambient temperature of around 29°. However, at temperatures over 29°, n-PCM II outperforms other PCM.

PV and CSP solar technologies & desalination: economic analysis

Globally, energy is a dynamic element that makes people's major energy demands. There are a variety of energies; the one that is stupendous potential is solar. Solar energy is an efficient problem solving one to eliminate pollution from the environment and water scarcity. This review article provides the accomplishments in the progress of the solar pond, solar desalination and integration of both the systems in the recent years. The solar pool is one of the thermal energy storing systems which perform as a huge solar radiation collector to capture and store sun’s rays. The accumulated heat in the solar pool is weighed as the low category thermal energy. Hence, to enhance the performance upgrades are mandatory. Initially, use of unique salts and various additives is studied. And then, ingenious empirical works and several layers for minimizing the thermal losses from the upper and lower layers are exhibited. Heat removal techniques from the heat storage zone and mathematical model analysis are discussed. In addition, solar desalination unit is one of the possibilities for the effective production of sweet water from any form of polluted water (marine, brackish and contaminated water). Solar still is a trouble-free device utilized by condensation and evaporation processes to improve the limpidity of the water with the utilization of solar energy. This work made an attempt to classify various still designs with the greater volume of production. And also it analyzes the new innovations and thermal energy transfer process to reach at positive judgment. Desalination system performance is low for conventional approach, as desalination plant efficiency is relative to inlet water temperature, to upgrade it the solar pond coupled to desalination unit. With the exploitation of brine concentration and recovery system and multi-stage flash, fins and flat plate collector helps to elevate the beneficial solar pond and desalination output. This comprehensive review will guide the imminent researchers who desire to accelerate the performance of the pond and desalination units further.

There is interest for desalination technologies powered by solar energy as arid areas are typically bestowed with good solar potential. In response to a US DOE call for solar desalination analysis tools, we developed an open-source solar energy desalination analysis tool, sedat, for techno-economical evaluation of desalination technologies and selection of regions with the highest potential for using solar energy to power desalination plants. It is expected that this software will simplify the planning, design, and valuation of solar desalination systems in the U.S. and worldwide. Sedat uses Dash for integrating various layers of large volumes of GIS data with Python-based models of solar energy generation and desalination technologies. It derives time-series of energy generation and water production, with details of plant performance and suggestions for improving the solar-desalination coupling. This paper summarizes the various phases of the tool’s development, presents example results showing the potential, under multiple objectives, of solar desalination in parts of the U.S. southwest, and discusses method details that would be useful for future model development.

The increase in greenhouse gas and other global warming emissions makes it necessary to utilize renewable energy sources such as solar energy with high potential for heat production by means of solar thermal collectors. Among various types of solar collectors, evacuated tube solar collector (ETC) has attracted many attentions specially for the application in solar water heater systems (SWHs). However, due to the intermittence in solar intensity during the day, the ETCs may not work at their maximum functionality. There are number of studies investigating the effect of energy storage materials to eliminate the mismatch between supply and demand during peak hours. In the recent work of the authors, application of phase change materials (PCMs) integrated directly within the ETCs is studied experimentally. In this study, the computational fluid dynamics (CFD) modeling of heat pipe evacuated tube solar collector (HPETC) is performed. In order to cross-validate the obtained results to the recent experimental analysis, the boundary conditions are set as the real field-testing data. In the first part of the study, the 3D model of commercially available HPETC is simulated, while in the second part the HPETC integrated with the PCM is developed to analyze the improved thermal distribution. The selected type of PCM is Tritriacontane paraffin (C33H68), with a melting point of 72 °C and latent heat capacity of 256 kJ/kg. The simulation results show a acceptable agreement between the CFD modeling and the experimental data. The results from this study can be the benchmark for efficiency improvement of the ETCs in thermal energy storage systems.

There is an acute scarcity of potable water in many parts of the world, and especially in the Middle East region. Important advances have been made in solar desalination technology but their wide application is restricted by relatively high capital and running costs. Until recently, solar concentrator collectors have usually been employed to distill water in compact desalination systems. Currently, it is possible to replace these collectors by the more efficient evacuated tube collectors, which are now widely available on the market at a similar price.

A novel small dynamic solar thermal desalination plant with a fluid piston converter

<abstract> <p>This review is inspired by the increasing shortage of fresh water in areas of the world, and is written in response to the expanding demand for sustainable technologies due to the prevailing crisis of depleting natural water resources. It focuses on comprehending different solar energy-based technologies. Since the increasing population has resulted in the rising demand for freshwater, desalination installation volume is rapidly increasing globally. Conventional ways of desalination technologies involve the use of fossil fuels to extract thermal energy which imparts adverse impacts on the environment. To lessen the carbon footprint left by energy-intensive desalination processes, the emphasis has shifted to using renewable energy sources to drive desalination systems. The growing interest in combining solar energy with desalination with an emphasis on increasing energy efficiency has been sparked by the rapid advancements in solar energy technology, particularly solar thermal. This review paper aims to reflect various developments in solar thermal desalination technologies and presents prospects of solar energy-based desalination techniques. This paper reviews direct and indirect desalination techniques coupled with solar energy, and goes on to explain recent trends in technologies. This review also summarizes the emerging trends in the field of solar thermal desalination technologies. The use of nanoparticles and photo-thermal materials for localized heating in solar desalination systems has decreased energy consumption and enhanced the efficiency of the system. Solar power combined with emerging processes like membrane distillation (MD) has also a recent resurgence.</p> </abstract>

Solar desalination has emerged as a sustainable solution for addressing global water scarcity in the energy-water nexus, particularly for remote areas in developing countries. How to use the light spectrum through solar devices can profoundly affect the solar energy utilization, desalination rates, off-grid applicability, and water affordability. Solar photovoltaic (PV) and solar thermal (ST) respectively have enabled a variety of interesting solar desalination technologies, but the resulting applications usually limit the integration between solar and desalination to be either electrically or thermally connected. Here this review paper explores smart co-uses of heat and electricity from the sun to improve the efficiency, productivity, and independence of various solar desalination processes. It is found that coupling solar photovoltaic-thermal (PVT) with desalination could be a practical and immediately deployable route for plausibly more sustainable solar desalination than current solutions, because the combined electrical and thermal energy outputs from PVT panels could be used synergistically to catalyze the improvement on the solar energy efficiency, specific energy consumption, and specific water production, as well as the operational independence for off-grid applications. Our preliminary analysis indicated an up to 20 % lower cost of PVT-desalination than current solar PV-desalination and ST-desalination but also with challenges discussed.

Chapter 10 - Economic and environmental aspects of solar desalination with energy storage

Advances in solar desalination using 2D and biomass derived materials: A roadmap to sustainability