Vapor compression distillation technology for phase change recovery of potable water from wastewater has evolved as a technically mature and promising approach for use aboard NASA's Space Station. A program to design, develop, fabricate and test an advanced preprototype Vapor Compression Distillation Subsystem (VCDS) was completed by Life Systems for the NASA Johnson Space Center (JSC) during 1983.
This advanced preprototype VCDS reclaims over 96 percent of the available wastewater at a nominal water recovery rate of 1.36 kg/h (3.0 lb/hr) and 303 K (85 F) condenser temperature. The unit weights, 101 kg (223 lb), occupies a volume of 0.49 m3 (17.3 ft3) and requires only 115 W electrical power.
This paper presents a summary of the design improvements implemented in the advanced preprototype VCDS compared to previous systems and discusses the results of an extensive test program with respect to performance, life and product water quality. A discussion of current efforts involving specific improvements in VCDS components and results of parametric testing is also presented. Projections are made for a flight version Phase Change Water Processing System for the Space Station consisting of a VCDS integrated with wastewater pretreatment, product water post-treatment, biocide addition and water quality monitor assemblies.