Closed Loop Waste Processing Dryer (DRYER), Phase I

The objective of this proposal is to develop a gravity-independent pasteurization and hot air drying process suitable for stabilization of ALS wet cabin waste, drying of crew laundry, and water recovery from water-reprocessing brines. This dryer will use an energy-efficient closed air-loop Heat Pump Desiccant dryer to remove moisture from wet starting material and a Porous Membrane Condensing Heat Exchanger (PMCHX) to trap condensate. Water recovered during drying should be of good quality and available for reuse with standard processing. The process is energy efficient since enthalpy released by the condensing vapor is used to reheat the drying air. Volatile organic compounds are contained throughout the drying process. The system could incorporate a photocatalytic oxidation system to remove VOCs accumulated during drying. The key objective for the PMCHX is to extend its range of application from low-load humidity control in plant growth chambers to high-load condenser duty at up to 80°C air temperature and at temperatures varying over a 40°C range during a single drying run. Since the presence of organics in the condensate, and the predicted condenser temperatures of 5-40°C are conditions favorable to biofilm growth, PMCHX membranes will need to be configured to inhibit the formation of biofilms. More »