Unit Operation Performance Testing of Cascade Distillation Subsystem

The Cascade Distillation System (CDS) is a waste water recovery technology being developed under NASA’s Advanced Exploration System (AES) water recovery project. The Cascade Distiller (CD) is the principal component of the CDS. The CDS prototype unit was extensively tested at NASA Johnson Space Center (JSC) during 2008 and 2009. In 2012 the need for additional CD testing was identified to determine thermodynamic, hydraulic, and distillation performance through experiment at operating conditions of interest. This paper discusses this operational testing performed at Honeywell in 2012 on the prototype Cascade Distiller. The thermodynamic performance demonstrated an average specific energy for recovered water of 92 watt-hr/kg. The limiting process recovery of distilled water was 95% of the feed on a weight basis. The distillation performance was tested using a chemical analysis method that used a water soluble red dye. This new method allows qualitative and quantitative measures of the concentrations of salt in the CD and the distillation efficiency.