A desalination system has been designed for converting brackish water into potable water utilizing ocean thermal gradient. The desalination plant evaporates the water by flash and surface evaporation and subsequently the vapour is condensed to get potable water. An experimental plant with a capacity of 20 lph was designed for a typical ocean thermal gradient. The designed operating conditions of the plant are evaporator temperature, 30°C and condenser temperature, 10°C. Experimental performance of the system was evaluated by varying the condenser and evaporator temperatures and chamber vacuum pressure. © 2007.

A Mani

Department of Mechanical Engineering

Sivasailam Kumaraswamy

Condensers (liquefiers)

Evaporation

Evaporators

OCEAN THERMAL ENERGY CONVERSION

Potable water

thermal gradients

BRACKISH WATER

FLASH EVAPORATION

SURFACE EVAPORATION

Desalination

Drinking water

WASTE FACILITY

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

With an ever-increasing population and rapid growth of industrialization, there is a great demand for fresh water, especially for drinking. In view of this, different desalination technologies have evolved with a thrust for utilization of renewable energy sources such as solar energy, ocean thermal energy, geothermal energy, and waste heat. Flash desalination is a technology in which fresh water is produced from seawater by evaporation and subsequent condensation. One such desalination technique involves different processes like pressurization of seawater using a pump, creation and maintenance of vacuum using jet pump in a flash chamber, evaporation of seawater at reduced pressure using warm water from the sea surface and condensation of water vapour using cold water from the deep sea. A two-phase variable geometry jet pump was designed, developed and tested for the flash desalination system to create a vacuum inside the flash chamber. The area ratio of the jet pump used for the investigation was 0.25. Experimental results are reported from tests on the jet pump with a view to assessing the optimum distance between orifice exit and mixing tube entrance. Overall performance of the jet pump was assessed by plotting its characteristics. Performance of the jet pump was analyzed by plotting iso-efficiency curves on characteristics curves drawn for various primary water flow rates. The optimum orifice to mixing tube distance of the jet pump was found and corresponding maximum efficiency was reported. Maximum vacuum created by the jet pump at an optimum condition, i.e., at maximum jet pump efficiency, with respect to time was determined. © 2006 Elsevier B.V. All rights reserved.

Experimental investigations on a two-phase jet pump used in desalination systems

With ever-increasing population and rapid growth of industrialization, there is a great demand for fresh water, especially for drinking, as natural resources are becoming limited. In view of the above, different desalination technologies are evolving with a thrust for utilization of renewable energy sources like solar energy, ocean thermal energy, geothermal energy and waste heat. Vacuum desalination is one such technology in which fresh water is produced from brackish water by evaporation and subsequent condensation. This desalination technique involves different processes like pressurization of brackish water by a pump, creation and maintenance of a vacuum using jet pumps, and evaporation of brackish water at reduced pressure using waste heat from a power plant such as water from condenser. In this paper an analysis of a vacuum desalination system is presented. By applying the mass, momentum and energy balances across the various components, the governing equations are obtained for the analysis. These equations are solved using simulation. Validation of the simulated performance is made with the experimental data available in the literature. The study was carried out by varying operational parameters such as evaporator temperature, condenser temperature, evaporator flow rate, condenser flow rate and chamber pressure. Yield of fresh water obtained from the system increased as condenser temperature decreased and the evaporator temperature increased. Further, the yield increased as chamber pressure decreased. © 2005 Elsevier B.V. All rights reserved.

Analysis of a jet-pump-assisted vacuum desalination system using power plant waste heat

Energy Conversion and Management

Simulation study on a solar desalination system utilizing an evaporator/condenser chamber

A new seawater desalination process using solar energy

Vacuum desalination for water purification using waste heat

Experimental studies on desalination system for ocean thermal energy utilisation

Journal	Desalination
ISSN	00119164
Open Access	No