Water Recovery By Vapor Compression Distillation

Space Station Freedom will require between 584 and 767 pounds of water per day. To lift this into space would require four or five shuttle flights per year of nothing but water and tankage at a cost of about $2 billion per year. To significantly reduce this cost, and to prevent possible cross-contamination of human, animal and experimental wastes, five different water reclamation systems will be incorporated into Space Station Freedom. Phase change technology will be used in the Urine Processor Assembly and the Water Recycle System and will probably be used in the Ultrapure Water System. The two phase change systems which are currently being considered are the Vapor Compression Distillation Subsystem and the Thermoelectrically Integrated Membrane Evaporation Subsystem. The Vapor Compression Distillation Subsystem has the advantages over the Thermoelectrically Integrated Membrane Evaporation System of producing better quality product water, higher water recovery rates, higher capacity, less likelihood of fouling and greater simplicity of design with less operational complexity. Use of the Vapor Compression Distillation Subsystem for the Urine Processor Assembly will save the Space Station Freedom Program over $40 million in the first ten years. Since the water usage in the Ultrapure Water System is expected to be considerably greater than in the Urine Processor Assembly, the Vapor Compression Distillation Subsystem can provide even greater savings.