No description available.

Solar thermal energy generated by a salinity gradient solar pond (SGSP) is one of the most promising techniques for providing heat for desalination and other applications. A solar pond is a unique, free-energy-source system for collecting, converting and storing solar energy. Saudi Arabia is one of the most solar-radiation abundant countries on the planet, but the region also has limited water resources. Studying the thermal behaviour of a SGSP under Saudi Arabian conditions for heat generation for a thermal desalination application is the aim of this study. An empirical equation is developed and a Matlab script is programmed to calculate hourly-averaged daily solar radiation (from sunrise to sunset). The results are validated through NASA's 22-year-average data for solar radiation. Mathematical models are developed to describe and simulate the thermal behaviour of a SGSP. The results are compared with a SGSP in Kuwait; the results of the steady state model are sufficiently close to the measurements. The efficiency of a solar pond depends on the salt gradient stability in the middle non-convecting zone, and the diffusion and erosion of these salt layers are considered in this study. The proposed SGSP in Riyadh, Saudi Arabia, has an area of 100 x 100m2, and the predicted temperature of the storage zone is about 100De. Higher temperatures can be reached through improved insulation and covering the surface. Additionally, an SGSP in a cold climate is suggested to compare with and test our model. The University of Surrey SGSP exceeded 80De. This renewable and sustainable heat source can be employed in desalination; the energy cost of desalinated water constitutes over 50% of operating costs. The heat removal process from the solar pond is investigated, and coupling the proposed solar pond with a Multi-Effect Evaporator (MEE) is described; the effects of various factors on the SGSP-MEE coupling are studied.

Supplies of potable water from the conventional resources are descending due to increased industrialization;' extensive irrigation and rapid population growth. In Cyprus, a country without any perennial river, fixed rainy season and depleted natural aquifers faces severe water shortage in future. Desalination along with power cogeneration certainly poses as the most suitable option in the long run to avoid any water scarcity and rationing. This dissertation introduces all the major desalination processes and is focused on the commercially employed desalination processes. The processes have been discussed in relation with their history, principle, capacity, costs, market capitalization, energy consumption, required pre treatments, future growth potential and their environmental effects. The dissertation extensively investigates Cyprus' existing water resources, water scarcity in Cyprus, the need and existing desalination including the overall power generation capacity. This dissertation is unique in the sense of covering all the major desalination processes and investigating the Cyprus water resources as a whole outlining the need for commercially viable desalination and power, cogeneration facilities. The aim of this study is to expand the existing MSF systems to a higher level for potential changes which they will help the industrial desalination in increasing the efficiency and reducing the costs. This is a new three stage distillation system which will be designed and constructed in Cyprus. The plant will be manufactured from local materials by local manpower and requires little maintenance and operating costs. Hence it offers relatively higher efficiency which enables this system to be more cost effective.

Membrane distillation process (MD) is a new process gaining research interest because of its efficiency. The main objective of this research is to investigate the feasibility of using air bubbling and vacuum MD for water desalination. In a brackish water desalination study, a tubular MD module was used for performing experiments on a hydrophobic tubular membrane. The membrane module was designed in zigzag mode to achieve high turbulence flow. The MD process performance in terms of permeate flux and thermal efficiency was monitored as the process variables were changed. The permeate flux and thermal efficiency increased by more than 4 and 2-fold, respectively, as the feed temperature increased from 40 to 70°C. The permeate flux and thermal efficiency at 70°C and 240 (L/h) were as high as 10.8 (kg/m''h) and 52% for pure water, and 5.4 (kg/nr'h) and 35% for 5000 mg/L of feed concentration, respectively. An air bubbling system was used to enhance. tubular MD module performance. Compared to the basic module, the mass transfer coefficient increased from 5 to 25% as air bubbling rate increased from 30 to 90 (L/h). Increasing air bubbling rate 3-fold, increased Reynolds number 3-fold, which enhanced the heat transfer coefficient 2- fold. The permeate flux and thermal efficiency were higher than that of the basic module by about 1.4 and 1.5- fold, respectively for 5000 (mg/L) feed concentration. I Vacuum Membrane Distillation (VMD) performance was investigated using a flat- sheet cross flow module with a new O-ring and two commercial PTFE and PVDF hydrophobic membranes. The design of membrane module provided high heat transfer coefficients and high Reynolds numbers. Heat and mass transfer coefficients were measured within the module in VMD experiments. The effect of process parameters on the permeate flux was investigated. At optimum operating conditions the permeate flux reached 43.8 and 52.6 (kg/nr'h) for PVDF and PTFE, respectively, with over 99% salt rejection for both.

No description available.

Potable water is a commodity taken for granted by many in modem society. In places where it is not naturally available, it is usually produced by adequate processing of the supply from other sources, as is the case with seawater desalination. Such processes require an energy supply, which just as well may not exist at many of these locations. In view of the above, this w~rk focuses on the study of two well-established technologies and their integration: water desalination by Reverse Osmosis (RO) and electricity generation using Wind Energy. Based on the premise that no energy backup or storage devices would be employed, two alternative wind-powered RO system configurations are proposed. Their components are individually described and modelled. Control strategies are devised for both systems, aiming at making the best possible use of the energy available. The expected performances of both systems are assessed through simulation of computer models. Based on the simulated performance results, one of the systems is chosen for further development. A prototype system is built and experimental tests carried out. The design of the prototype is detailed and the results obtained are presented. In the light of these results, the developed model is validated and the viability of the system is discussed. Finally, practical implementation issues are discussed; a case study is introduced, including performance predictions and a simplified economic analysis presented.

La salinité est un problème mondial qui retarde la croissance des plantes et ralenti la productivité à cause de la salinisation progressive des sols et de l'eau, une de ces nouvelles techniques est l'utilisation d'espèces végétales pour enlever le sel. Afin d'étudier la capacité potentielle de certaines plantes pour éliminer les sels du sol, deux espèces Portulaca oleracea et Tetragonia tetragonioides et la laitue (Lactuca Sativa L) ont été étudiées pour évaluer leurs efficacités à éliminer les sels d'un sol sableux. Les plantes ont été analysées selon certains critères de croissance et de composition minérale des feuilles et du sol. On constate, d'après les résultats obtenus, que la T. tetragonioides est le meilleur choix des espèces testés qui permet la réduction de la salinité. Il y a d'autres avantages pour l’utilisation de cette espèce comme : 1) une production élevée de biomasse; 2) plusieurs récoltes au cours de l'année (été et hiver); 3) teneurs élevés en minéraux; 4) l'importance de l'horticulture, en tant que culture de feuille végétale; 5) multiplication facile des semences; 6) tolérance à la sécheresse et des conditions arides ; 7) contrôle en raison de son excellente couverture du sol qui réduit les phénomènes d'érosion. L’espèce P. Oleracea a une tolérante élevée pour la sécheresse suivie de l’espèce T. tetragonioides. D'autre part, la laitue est une culture irriguée et par conséquent, ne suffit pas à réduire la salinité du sol. Suite aux observations, il a été montré que cette nouvelle technique de culture permet de contrôler la salinité et c’est un bon outil de remédiation pour maintenir la durabilité du paysage et des zones irriguées. / Conventional techniques used to control the soil salinization process - soil leaching or fertilization enhancing - contribute highly to soil and aquifers contamination; on the other hand, the use of salt tolerant species will be very useful to the plants, but does not solve the problem of soil or groundwater contamination. Hence, the only way to control the salinization process to maintain the sustainability of landscapes and agricultural fields is to combat the salinization problems with environmentally safe and clean techniques. One of these new techniques is the use of salt removing species. In order to study the potential capacity to remove soil salts, two horticultural species Portulaca oleracea and Tetragonia tetragonioides, and the salt sensitive crop lettuce (Lactuca Sativa L) were evaluated for their efficiency to remove salts from sandy soil. Plants were analysed relatively to total growth and mineral composition of the leaves and soil. According to the results, it was seen that T. tetragonioides is the best salt removing species and complementary, it has other benefits, which are as follows: 1) high biomass production; 2) several harvests; 3) high content of minerals; 4) horticultural importance; 5) easy multiplication; 6) easy crop management; 7) tolerance to drought conditions; 8) soil erosion control. P. oleracea is a high drought tolerant species, followed by T. tetragonioides. As concluding remarks, it was shown that this new technique to control salinity is a powerful and environmental clean tool to maintain the sustainability of the landscape and of the irrigated areas.

Ce travail a été réalisé dans le cadre d’une étude lancée par la compagnie HUTA sur ses installations de dessalement d’eau de mer. Le procédé de dessalement des eaux de mer le plus utilisé pour la production d’eau douce est l’osmose inverse (SWRO). Une station type, installée dans d’une zone industrielle, a été choisie pour mener cette étude d’optimisation du fonctionnement pour réduire les coûts d’exploitation. L’impact des rejets des rejets sur le milieu naturel a été également étudié. La station de dessalement sélectionnée pour les travaux de recherches est située dans la région Ouest de l’Arabie Saoudite à 160 km au nord de Djeddah, dans une zone industrielle pétrochimique (Raffinerie PETRO RABIGH), site ultra sécurisée, les captages des eaux de mer se font dans la zone côtière proche du site en Mer Rouge.L’étude se concentre principalement sur 3 parties : La première concerne la prise d’eau "INTAKE", différent mode captage ont été testé avec l’installation d’un ouvrage développé spécifiquement pour la station de Rabigh en s’adaptant aux règles imposées par les autorités Saoudienne. La deuxième est réservée aux procédés membranaires et l’importance des prétraitements dans la filière de désalinisation. La dernière partie concerne l’étude d’impact environnemental des rejets industriels "OUTLET" sur le milieu récepteur. / This study was carried in some seawater desalination plants of HUTA Company. The most used seawater desalination process for freshwater production is Reverse Osmosis (SWRO). A typical station, installed in an industrial zone, was selected to conduct this optimization study in order to reduce operating costs. The desalination station selected for this research work is located in the western region of Kingdom Saudi Arabia (KSA), at 160 km north of Jeddah city, in a petrochemical industrial zone (PETRO RABIGH Refinery), an ultra security site, seawater catchments occur in the coastal zone close to the site in the Red Sea.The study focuses mainly on 3 parts, the first one concerns the water intake "INTAKE", different intake mode were tested with the installation of a prototype structure developed specifically for Rabigh station in order to respect the Saudi authorities regulation. The second part is reserved to the membrane processes and the importance of pretreatments in desalination process. The last part focuses on the environmental impact of industrial waste "OUTLET" on the aquatic system. Finally the best decision and the best operation conditions have been concluded.

Η παρούσα διπλωματική εργασία έχει ως θέμα την μελέτη μιας κολόνας διύλισης και πιο συγκεκριμένα την εκτίμηση των συγκεντρώσεων του υγρού σε κάθε δίσκο της με χρήση του βέλτιστου γραμμικού φίλτρου Kalman, καθώς και τον έλεγχό της. / -

Η εξάντληση των ορυκτών καυσίμων και το ενδεχόμενο ενεργειακό αδιέξοδο σε συνδυασμό με τη δυνατότητα παραγωγής ενέργειας από ανεξάντλητες πηγές χωρίς επιβάρυνση στο περιβάλλον έχουν οδηγήσει τους τομείς έρευνας προς τις ανανεώσιμες πηγές ενέργειας. Ένα άλλο μεγάλο πρόβλημα είναι αυτό της εξάντλησης του νερού. Έτσι έχει αναπτυχθεί η έρευνα για την αξιοποίηση των αλμυρών ή υφάλμυρων αποθεμάτων νερού της Γης μέσω της τεχνολογίας αφαλάτωσης. Στην εργασία αυτή παρουσιάζεται ο σχεδιασμός και η οικονομική αξιολόγηση ενός συστήματος αφαλάτωσης το οποίο τροφοδοτείται απο υβριδικό σύστημα φωτοβολταϊκών πλαισίων και ανεμογεννητριών. Για τη διαστασιολόγηση χρησιμοποιήθηκαν γενετικοί αλγόριθμοι οι οποίοι αποτελούν εργαλεία επίλυσης προβλημάτων βελτιστοποίησης. / The depletion of mineral fuels and the potential future energy issues, conbined with the ability to produce energy from alternative sources of practically infinite capacity without causing environmental damage, has driven research towards exploring renewable energy sources. A major issue is also the issue of water depletion, driving research towards the development of desalination technologies that use seawater or brackish water. In this thesis we explore the potential and we perform the economic evaluation of a desalination system, which is powered by a hybrid system of photovoltaics and wind turbines. The parameters of the proposed implementation are optimized using genetic algorithms.