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Technical Paper

Results and Analysis from Reduced Gravity Experiments of the Flexible Membrane Commode Apparatus

Two separate experimental rigs used in tests on NASA and Zero-G Corporation aircrafts flying low-gravity trajectories, and in the NASA 2.2 Second Drop Tower have been developed to test the functioning of the Flexible Membrane Commode (FMC) concept under reduced gravity conditions. The first rig incorporates the flexible, optically opaque membrane bag and the second rig incorporates a transparent chamber with a funnel assembly for evacuation that approximates the size of the membrane bag. Different waste dispensers have been used including a caulking gun and flexible hose assembly, and an injection syringe. Waste separation mechanisms include a pair of wire cutters, an iris mechanism, as well as discrete slug injection. The experimental work is described in a companion paper. This paper focuses on the obtained results and analysis of the data.
Technical Paper

Heat Transfer Characteristics of the Concentric Disk inside the WFRD Evaporator for the VPCAR Water Recovery System

We consider the heat transfer characteristics of an ideal concentric disk used in the Wiped-Film Rotating-Disk (WFRD) evaporator for the Vapor Phase Catalytic Ammonia Removal (VPCAR) water recovery system. A mathematical model is derived to predict the radial temperature distribution and its average over the surface of the disk as a function of system parameters. The model shows self-similarity of the temperature distribution and the existence of a dimensionless parameter S (ratio of heat flux to convection) that can be used as a criterion to optimize the thermal characteristics of the disk in order to approach uniform surface temperature. Comparison of the model to experimental data using global (infrared imager) and local (resistive temperature devices) measurements shows that agreement with the model depends on the ambient condition denoted by the local heat transfer coefficient.
Technical Paper

Development of a Reduced Gravity Test Rig for Waste Management

The space environment presents many challenges to the operation and functioning of life support systems. These challenges include reduced gravity, near vacuum ambient, extreme temperatures, and radiation. Proper testing and modeling of system components to account for these factors will be important for their verification. This paper describes the modeling and design of a reduced gravity test rig for waste management studies. The first investigation planned relate to the functioning of components of the Flexible Membrane Commode (FMC) currently under development at NASA Ames Research Center. The planned reduced gravity tests will be carried out in NASA's C'9 aircraft which provides approximately 25 seconds of reduced gravity per parabolic trajectory. The filling of the commode bag under the influence of a directed air flow will be studied. Simulated waste will be injected and cabin air will be used for directing the waste into the bag.
Technical Paper

Development of Waste Bag Air Flow and Drying Models for Solid Waste Management

NASA is developing a novel waste bag concept for filling, storing and drying astronaut fecal material. The three-layer bag is lined with a membrane that is impermeable to solid and liquid matter but permeable to gases. The air flow provided by a blower assists in containing the waste in the bag. After use, the bag is sealed and then connected to a vacuum manifold for drying the waste. This paper describes the development of theoretical models for analyzing the air flow patterns in the bag during the filling process as well as the parameters governing the drying rate. The models will be used to support the design and testing of the waste bag.