FRESH WATER FOR ARID LANDS—JENKINS 291 
square foot per °F. could be maintained in a system utilizing forced 
circulation and drop-wise condensation in vapor-compression distilla- 
tion processes. Similar and complementary research was conducted 
by the British Admiralty [17] under the program of the Organiza- 
tion for European Economic Cooperation (OEEC.) Several pri- 
vate organizations in the United States and Europe are experiment- 
ing with drop-wise promoters for various types of heat exchanger 
surfaces. 
The flash type of distillation process is now receiving increasing 
commercial application. In this process, warm salt water enters an 
evaporation chamber in which the pressure has been reduced below 
the boiling point of the salt water, thereby inducing a portion of 
liquid to vaporize (flash) into steam. As with most of the present 
types of commercial evaporation equipments, the flash units have been 
primarily developed for marine use. However, Westinghouse Corp. 
of Pittsburgh, Pa., completed one of the largest distillation plants in 
the world at Kuwait (pl. 1, fig. 2), making use of the multistage flash 
process. That installation consists of four 4-stage flash evaporators 
with a total capacity of 214 m.g.p.d. Other companies are also offer- 
ing multistage flash evaporators, and other land installations are 
presently being considered for this type of equipment. The Office of 
Saline Water is developing improved multistage flash distillers for 
potential combinations with nuclear-process [18] steam reactors, as 
this type of evaporator will make use of very large amounts of steam 
in civilian-type applications. 
There are also locations where waste heat is currently available or 
where ocean temperature differences are sufficient to induce flash evap- 
oration [19]. Therefore, low-temperature flash evaporation was 
recently studied by Griscom-Russell Co. [20] for Massillon, Ohio, 
for the Office of Saline Water, as adapted to a single-stage flash 
evaporator using the energy of a stream of warm waste water from 
a power station of an industrial plant, or from natural sources. Esti- 
mates showed that, given a temperature difference of 30° F. between 
the warm and the cold water, plants of 100,000 and 10,000,000 gallons 
output capacity would produce fresh water from sea water at over-all 
costs of $1.28 and $0.71 per 1,000 gallons respectively, using the 
Office of Saline Water standardized cost estimating procedure [21] 
as modified for this process. 
SOLAR DISTILLATION 
Distillation by means of solar heat has the advantage of eliminating 
the cost of the fuel energy otherwise required. However, the diffuse 
nature of solar energy makes necessary the use of large areas for 
collection. The major problem in solar distillation is reduction of 
