Engineering topics

Stapleton, Thomas J.

Publications and source records attributed to Stapleton, Thomas J..

4 records

NASA NTRS2016

Torrefaction Processing for Human Solid Waste Management

This study involved a torrefaction (mild pyrolysis) processing approach that could be used to sterilize feces and produce a stable, odor-free solid product that can be stored or recycled, and also to simultaneously recover moisture. It was demonstrated that mild heating (200-250 C) in nitrogen or air was adequate for torrefaction of a fecal simulant and an analog of human solid waste (canine feces). The net result was a nearly undetectable odor (for the canine feces), complete recovery of moisture, some additional water production, a modest reduction of the dry solid mass, and the production of small amounts of gas and liquid. The liquid product is mainly water, with a small Total Organic Carbon content. The amount of solid vs gas plus liquid products can be controlled by adjusting the torrefaction conditions (final temperature, holding time), and the current work has shown that the benefits of torrefaction could be achieved in a low temperature range (< 250 C). These temperatures are compatible with the PTFE bag materials historically used by NASA for fecal waste containment and will reduce the energy consumption of the process. The solid product was a dry material that did not support bacterial growth and was hydrophobic relative to the starting material. In the case of canine feces, the solid product was a mechanically friable material that could be easily compacted to a significantly smaller volume (approx. 50%). The proposed Torrefaction Processing Unit (TPU) would be designed to be compatible with the Universal Waste Management System (UWMS), now under development by NASA. A stand-alone TPU could be used to treat the canister from the UWMS, along with other types of wet solid wastes, with either conventional or microwave heating. Over time, a more complete integration of the TPU and the UWMS could be achieved, but will require design changes in both units.

Serio, Michael A.↗

NASA NTRS2015

Concentric Split Flow Filter

A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

Stapleton, Thomas J.↗

NASA NTRS2014

Contaminate Control Device

A contaminate control device for filtering contaminates from a gas such as air is provided. The device includes a housing having a first inlet and a first outlet. An axial flow filter is fluidly coupled between the first inlet and the first outlet, the axial flow filter has a second inlet and a second outlet. A second filter disposed about the axial flow filter and is fluidly coupled between the first inlet and the first outlet, the second filter having a third inlet on an inner diameter and a third outlet disposed on an outer diameter. A flow restrictor is fluidly coupled between the second inlet and the first inlet.

Howe, Robert H.↗

NASA NTRS2013

Development of a Universal Waste Management System

NASA is working with a number of commercial companies to develop the next low Earth orbit spacecraft. The hardware volume and weight constraints are similar to or greater than those of the Apollo era. This, coupled with the equally demanding cost challenge of the proposed commercial vehicles, causes much of the Environmental Control and Life Support System (ECLSS) designs to be reconsidered. The Waste Collection System (WCS) is within this group of ECLSS hardware. The development to support this new initiative is discussed within. A WCS concept - intended to be common for all the vehicle platforms currently on the drawing board - is being developed. The new concept, referred to as the Universal Waste Management System (UWMS), includes favorable features from previous designs while improving on other areas on previous Space Shuttle and the existing International Space Station (ISS) WCS hardware, as needed. The intent is to build a commode that requires less crew time, improved cleanliness, and a 75% reduction in volume and weight compared to the previous US ISS/Extended Duration Orbitor WCS developed in the 1990s. The UWMS is most similar to the ISS Development Test Objective (DTO) WCS design. It is understood that the most dramatic cost reduction opportunity occurs at the beginning of the design process. To realize this opportunity, the cost of each similar component between the UWMS and the DTO WCS was determined. The comparison outlined were the design changes that would result with the greatest impact. The changes resulted in simplifying the approach or eliminating components completely. This initial UWMS paper will describe the system layout approach and a few key features of major components. Future papers will describe the UWMS functionality, test results, and components as they are developed.

Stapleton, Thomas J.↗