Currently, the two dominant desalination methods are reverse osmosis (RO) and multi-stage flash (MSF). RO requires large capital investment and maintenance, whereas MSF is too energy intensive. An innovative vapor-compression desalination system is developed in this study. A comprehensive mathematical model for the heat exchanger/evaporator is described. The literature indicates that extraordinarily high overall heat transfer coefficients for the evaporator are possible at selected operating conditions that employ dropwise condensation in the steam side and pool boiling in the liquid side. A smooth titanium surface is chosen to promote dropwise condensation and to resist corrosion. To maximize energy efficiency, a combined-cycle cogeneration scheme is employed composed of a gas turbine, a heat recovery boiler, and a steam turbine that drive a compressor. The combined-cycle power source is oversized relative to the needs of the compressor. The excess power is converted to electricity and sold to the open market. A three-effect evaporator is employed. It is fed with seawater, assumed to be 3.5% salt. Boiling brine (7% salt) is in the low pressure side of the heat exchanger and condensing steam is in the high-pressure side of the heat exchanger. The condensing steam flows at 1.52 m/s (5 ft/s), which maximizes the heat transfer coefficient. The plant is sized to produce 37,854 m3/d (10 mill gal/day) and is assumed to be financed with a 5%, 30-yr municipal bond. Two economic cases were emphasized: the United States and the Middle East. For the United States, the fuel costs $5/GJ ($5.27/mill Btu) with the latent heat exchanger at ( ) 1.11 K 2.00 F T Ä = ° . The required compressor energy is 14 MJ/m3 (14.7 kW h/thous gal). The capital cost for the U.S. is $884 d/m3 ($3,342/thous gal) and the delivered water selling price is $0.47/m3 ($1.79/thous/gal). For the Middle East, the fuel costs $0.5/GJ ($0.53/mill Btu) with the latent heat exchanger at K T 33 . 3 = Ä ( ) F 00 . 6 ° . The required compressor energy is 26 MJ/m3 (27.3 kW h/thous gal). ). The capital cost for the Middle East is $620 d/m3 ($2,344/thous gal), and the delivered water selling price is $0.25/m3 ($0.95/thous/gal). In all cases, the water selling price is attractive relative to competing technologies.

<p>Wind Power desalination for Tunisian markets.</p>

Wind Power desalination for Tunisian markets.

Please read the abstract in the section 00front of this document / Thesis (PhD)--University of Pretoria, 2008. / Physics / unrestricted

There are two basic needs globally and that is the control and supply of reliable electricity and clean water. However, one of the biggest challenges the world is facing today is the lack of fresh water resources. Lower rainfall, together with population and industry growth, are only a few factors contributing to the fast increasing strain on existing water supplies around the world. This fast increasing need therefore necessitates the investigation into finding alternative sources. One such option is that of desalination. In the last 50 years desalination technologies have been applied to produce high quality fresh water from brackish and seawater resources. In the 1980's a breakthrough was made with the introduction of the membrane desalination technology, known as the reverse osmosis (RO) process. Today newly developed technologies are improving the competitiveness of the reverse osmosis process against the traditional distillation processes. There are a number of options to increase the efficiency of a reverse osmosis plant and one option is to use warm industrial waste water as the feed water to the desalination plant. It is known that the viscosity of water is inversely proportional to its temperature. Therefore, if the feed water temperature of a reverse osmosis plant is increased the membranes will become more permeable. This will result in a higher production volume or in a lower energy demand. South Africa is on the edge of building the first fourth generation nuclear power plant, called the Pebble Bed Modular Reactor (PBMR) at Koeberg. The PBMR will produce a cooling water outlet temperature of 40°C which can be used as feed water to a reverse osmosis plant. In this study design guidelines of a reverse osmosis plant are given in nine steps. These steps were then used during a basic component design of a reverse osmosis plant coupled to the waste water stream of a PBMR nuclear power plant. Furthermore design software programs were used to simulate the coupling scheme in order to validate the outcome of the design guidelines. The results of the two design approaches compared well to one another. It furthermore showed that by using the waste water from the PBMR nuclear power plant the efficiency of the RO plant is increased and the operating cost is decreased. Fresh water can be produced at a cost of R 5.64/m3 with a specific electricity consumption of 2.53 kWh/m3. / Thesis (M.Ing. (Nuclear Engineering)--North-West University, Potchefstroom Campus, 2009.

There are two basic needs globally and that is the control and supply of reliable electricity and clean water. However, one of the biggest challenges the world is facing today is the lack of fresh water resources. Lower rainfall, together with population and industry growth, are only a few factors contributing to the fast increasing strain on existing water supplies around the world. This fast increasing need therefore necessitates the investigation into finding alternative sources. One such option is that of desalination. In the last 50 years desalination technologies have been applied to produce high quality fresh water from brackish and seawater resources. In the 1980's a breakthrough was made with the introduction of the membrane desalination technology, known as the reverse osmosis (RO) process. Today newly developed technologies are improving the competitiveness of the reverse osmosis process against the traditional distillation processes. There are a number of options to increase the efficiency of a reverse osmosis plant and one option is to use warm industrial waste water as the feed water to the desalination plant. It is known that the viscosity of water is inversely proportional to its temperature. Therefore, if the feed water temperature of a reverse osmosis plant is increased the membranes will become more permeable. This will result in a higher production volume or in a lower energy demand. South Africa is on the edge of building the first fourth generation nuclear power plant, called the Pebble Bed Modular Reactor (PBMR) at Koeberg. The PBMR will produce a cooling water outlet temperature of 40°C which can be used as feed water to a reverse osmosis plant. In this study design guidelines of a reverse osmosis plant are given in nine steps. These steps were then used during a basic component design of a reverse osmosis plant coupled to the waste water stream of a PBMR nuclear power plant. Furthermore design software programs were used to simulate the coupling scheme in order to validate the outcome of the design guidelines. The results of the two design approaches compared well to one another. It furthermore showed that by using the waste water from the PBMR nuclear power plant the efficiency of the RO plant is increased and the operating cost is decreased. Fresh water can be produced at a cost of R 5.64/m3 with a specific electricity consumption of 2.53 kWh/m3. / Thesis (M.Ing. (Nuclear Engineering)--North-West University, Potchefstroom Campus, 2009.

This project was carried out to develop a better understanding of "Electrochemical Chloride Removal (also known as Desalination), a relatively new technique for rehabilitating reinforced concrete structures suffering from chloride induced corrosion. The factors influencing chloride removal were investigated and a mathematical model for predicting the spatial distribution of chloride in the concrete at the end of the treatment was developed. To investigate the factors influencing chloride removal, concrete prisms containing varying levels of admixed sodium chloride and number of steel bars were tested. The amount of chloride removed during the treatment was assessed by analysing the anolyte. It was found that chloride removal increased with increasing applied potential, number of reinforcing bars at a particular depth, water/cement ratio, chloride contamination depth and initial chloride content. Chloride removal was unaffected by concrete strength but decreased with increasing percentage of cement replacement material. A greater percentage of chloride was removed from prisms where the thickness of the chloride bearing layer of concrete was less than the depth of cover to the reinforcement. Where the thickness of the chloride bearing layer exceeded the cover to the reinforcement, the use of an external cathode significantly increased the total amount of chloride removed. Chloride removal from a face remote from the source of the chloride contamination (soffit desalination) was shown to be feasible. In prisms containing 2, 3 and 4% Cl (by weight of cement), it was found that the amount of chloride remaining in the prisms reached a limiting value irrespective of the initial admixed chloride content. This value was believed to be approximately equal to the amount of bound chloride in the concrete. Analysis of ground samples of concrete showed, however, that in a few cases bound chloride was removed locally to the reinforcing bars. Even though significant amounts of chloride remained in the concrete after completion of the treatment, the reinforcement remained passive for periods exceeding 30 months. Towards the second aim of predicting the spatial chloride distribution in the concrete, a mathematical model for electrochemical chloride removal from concrete based on the Nernst-Planck and Laplace equations was developed. The model relies on experimentally derived chloride transport number profiles. The predicted quantities of chloride removed into the anolyte and chloride remaining in concrete correlate well with data obtained by testing prisms containing one bar and dosed with 2, 3 and 4% Cl. The model shows that all parts of the concrete prisms undergo chloride removal albeit at different rates. Concrete directly between the anode and cathode undergoes the highest rate of chloride removal while concrete below the cathode, the lowest. It would appear, therefore, that there are no 'dark spots' in the concrete where chloride removal is prevented.

No description available.

Growth of population, affluence, industrialization and urbanization drive both the demand for fresh water and the demand for electric energy upwards. China and India with their large and growing populations and quick industrialization are markets with large unmet demand for electric energy and fresh water. Literature often suggests that fresh water crisis is a major threat to sustainable development in 21st century. Nuclear desalination systems are power plants based on small nuclear power generating units connected to a desalination unit. Nuclear desalination systems are capable of cogenerating electricity and fresh water at low cost. This paper identifies market opportunities for nuclear desalination systems and forecasts the demand for nuclear desalination systems in China and India from 2008 to 2030.

<p>One of the main problems our actual society faces is the shortage of water. Despite the great effort made by authorities and researchers, multiple countries with poor economic resources are experiencing serious difficulties derivative of water scarcity. Desalination provides a feasible solution for inland and coastal areas. Through literature and reviewed articles analysis the reader will meet the actual issues regarding designing a desalination plant, and more over with reverse osmosis (RO) processes, which are the main arguments of this work. One of the big deals is the environmental concern when handling the concentrate disposal. Another important point about desalination processes is the increasingly interest in coupling the units with renewable energy sources (RES). The results point out that regardless of the efforts made until today, additional achievement is required in fields such as membrane’s structure materials for RO method, concentrate disposal systems, governmental water policies review and update, and greater distinction researches between brackish water and seawater RO desalination processes. Taking into consideration the previous outcomes it is finally concluded that some particular steps must be accomplished when beginning a desalination plant design.</p>