Design of a small solar-powered desalination system

✍ Scribed by T.E. Bowman; A.M. El-Nashar; B.H. Thrasher; A.A. Husseiny; A.J. Unione

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 701 KB
• Volume: 39
• Category: Article
• ISSN: 0011-9164
• DOI: 10.1016/s0011-9164(00)86110-x

✦ Synopsis

A design is presented for a solar/thermal system configured to power a reverse osmosis (RO) desalination unit to produce 7000 gallons of fresh water in an eight hour period. A field of line-focus tracking solar collectors is used to heat a high pressure liquid-vapor water storage tank supplying two compound reciprccating steam engines, one direct-connected to the RO high-pressure pump and the other to an electric generator for auxiliary power. An allxiliary heating loop with an oilfired boiler is also used to supply the steam engines. The system operates in either all-solar, all-oil, or mixed solar/oil modes. Primary operating mode is assumed to be a mixed solar/oil mode in which the cilfired boiler is used only to prevent shutdown of the RO system during the course of a partly sunny day. In this mode, the RO system does not come on line in the morning until the solar collector field has brought the high-pressure storage tank to a point near maximum operating pressure. Thereafter, the oil-fired boiler comes on automatically whenever the storage tank is drawn down to a pressure near minimum full-power operation (due to inadequate or intermittent insolation) and remains on. supplying the stsam engines, until the solar collectors have again brought the storage tank to the high-pressure cutoff. In the all-solar mode, the system continues to operate at reduced power as storage tank pressure drops below the point at which the oil-fired boiler would otherwise come on. A portion of the RO system is shut doLn to maintain pressure in the remainder.

The all-oil mode is used whenever fresh water is required during non-sunny periods, or to increase fresh water production in sunny periods.