The condensator/evaporator drum, which was rotated by a brushless DC motor via a hermetically sealed magnetic coupling to maintain the evaporator fluid liquid/vapor interface in zero gravity, produced water vapor that was compressed to raise the condensation temperature and pressure. The compressed vapor was directed to the outer surface of the evaporator drum (the condenser portion of the drum), where the vapor gave up latent heat and condensed. The latent heat produced by condensation was then conducted through the thin metallic wall of the evaporator drum to provide the latent heat for evaporation. VCDS product water (condensate) was pumped from the distillation unit by the fourth section of the fluids pump after which the conductivity was measured with a conductivity sensor. The conductivity measurement served as a control to determine if the water was acceptable for delivery to post-treatment and storage or if it should be reprocessed by the VCDS. The VCDS operated at a temperature range of 75 to 100ºF with a fluid pump speed range of 7.0 to 8.0 rpm.
The VCDS contained a Control/Monitor Instrumentation (C/M I) (model 340 series), which provided automatic mode and mode transition control, automatic shutdown for self-protection, monitoring of the subsystem parameters and interfacing with the operator through a display unit. There were five modes, four operational, defined for the VCDS - normal mode, shutdown mode, reprocessing mode, partial drydown mode, and unpowered mode. The normal mode was the normal mode of operation for the VCDS and was the mode where wastewater was being processed. The shutdown mode was when the VCDS was not processing and wastewater and all rotating components were shut off. Power was still supplied to the VCDS under this mode. The reprocessing mode occurred when wastewater was being processed in the distillation unit, but the product water was reprocessed due to a high conductivity reading and did not leave the VCDS. The partial drydown mode took place due to a high liquid level in the evaporator. Operation of the VCDS was characterized with the wastewater remaining the distillation unit being processed while the product water was reprocessed. Wastewater was continually removed from the distillation unit and recirculated to the urine supply tank until the liquid level in the evaporator returned to a low value. The unpowered mode was defined with no electrical power being supplied to the VCDS and no wastewater being processed.
Experiment + Water Chemistry Monitoring (LMLSTP4.2)