An Equivalent System Mass (ESM) Analysis for the Universal Waste Management System (UWMS) with and without the Torrefaction Processing Unit (TPU)



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2020 International Conference on Environmental Systems


Equivalent System Mass (EMS) is one of the metrics commonly used in the evaluation of new systems, often performed as part of trade studies. ESM is a technique that makes it possible to reduce several physical quantities describing a system, or a subsystem, to a single parameter expressed in the units of mass. ESM has the following five components: (1) mass; (2) volume; (3) power; (4) cooling; and (5) crewtime. In this paper, results of an ESM analysis are reported for the Torrefaction Processing Unit (TPU) and the Metabolic Solid Waste Storage (MSWS), both considered in conjunction with the Universal Waste Management System (UWMS). The TPU involves sterilization of human solid waste via mild non-oxidative thermal treatment (torrefaction) to produce a stable, relatively odor-free solid product. This product can be easily stored, or recycled, and TPU operation is associated with the simultaneous water recovery from the solid waste. The TPU is designed to be compatible with the UWMS, now under development by NASA. In contrast to the TPU, the MSWS involves no waste processing, which results in the need to store large amounts of unprocessed solid waste. A stand-alone TPU could be used to treat the contents of a waste canister from the UWMS, thus allowing the waste canister to be reused, which significantly reduces the number of canisters required on board. An ESM analysis was performed for the TPU and for the MSWS, and results were compared for the case of a Mars mission and a four-person crew. Results show that the use of the TPU is associated with some advantages as compared with the MSWS, even though system design is more complex.


Marek A. Wójtowicz, Advanced Fuel Research, Inc., US
Joseph E. Cosgrove, Advanced Fuel Research, Inc., US
Michael A. Serio, Advanced Fuel Research, Inc., US
Jeffrey M. Lee, National Aeronautics and Space Administration (NASA), US
ICES304: Physio-Chemical Life Support- Waste Management Systems- Technology and Process Development
The proceedings for the 2020 International Conference on Environmental Systems were published from July 31, 2020. The technical papers were not presented in person due to the inability to hold the event as scheduled in Lisbon, Portugal because of the COVID-19 global pandemic.


Equivalent system mass (ESM), Waste management, Torrefaction, Life support