Thomas Filburn

Development of an Amine-based System for Combined Carbon Dioxide, Humidity, and Trace Contaminant Control

A number of amine-based carbon dioxide (C02) removal systems have been developed for atmosphere revitalization in closed loop life support systems. Most recently, Hamilton Sundstrand developed an amine-based sorbent, designated SA9T, possessing approximately 2-fold greater capacity compared to previous formulations. This new formulation has demonstrated applicability for controlling C02 levels within vehicles and habitats as well as during extravehicular activity (EVA). System volume is competitive with existing technologies. Further enhancements in system performance can be realized by incorporating humidity and trace contaminant control functions within an amine-based atmosphere revitalization system. A 3-year effort to develop prototype hardware capable of removing C02, H20, and trace contaminants from a cabin atmosphere has been initiated. Progress pertaining to defining system requirements and identifying alternative amine formulations and substrates is presented.

An Improved Pyrolyzer for Solid Waste Resource Recovery in Space

Pyrolysis processing is one of several options for solid waste resource recovery in space. It has the advantage of being relatively simple and adaptable to a wide variety of feedstocks and it can produce several usable products from typical waste streams. The overall objective of this study was to produce a prototype mixed solid waste pyrolyzer for spacecraft applications. A twostage reactor system was developed which can process a maximum of about 0.5 kg of waste per cycle. The reactor includes a pyrolysis chamber where the waste is heated to temperatures above 600 °C for primary pyrolysis. The volatile products (liquids, gases) are transported by a N2 purge gas to a second chamber which contains a catalyst bed for cracking the tars at temperatures of about 1000-1100 °C. The tars are cracked into carbon and additional gases. Most of the deposited carbon is subsequently gasified by oxygenated volatiles (CO2, H2O) from the first stage. In a final step, the temperature of the first stage can be raised and the purge gas switched from N2 to CO2 and/or O2 in order to gasify the remaining char in the first stage and the remaining carbon deposits in the second stage. Alternatively, the char can be removed from the first stage and saved as a future source of CO2 or partially gasified to make activated carbon. This paper describes several improvements that were made in the original (First Generation) prototype pyrolyzer including: 1) replacement of stainless steel flanges with machineable ceramic in order to reduce weight; 2) construction of a new sample holder in order to make sample insertion and removal easier and sample heat-up more uniform; 3) replacement of a stainless steel outer shell with a double-wall quartz cylinder in order to significantly reduce weight and heat losses. In addition, experimental results are included for wheat straw and chicken manure feedstocks, primarily from the First Generation prototype.

Structural Design of Frame-Membrane Habitat Concepts Considering Life Support Requirements for Lunar Colonization

‡When designing a habitat for a long term lunar colonization mission, there are many considerations which need to be made beginning with the different environmental concerns, the required life support systems needed to sustain life in a shirt-sleeve environment, and the numerous construction and feasibility problems. The distant location of the habitat site also necessitates the need for a low mass and low volume structure. One way to reduce the mass and volume of the structural elements within this habitat is to incorporate the life support systems at an early stage of the design. Within this paper two habitat concepts are presented on the basis that a preliminary study of the required life support systems has been completed and their mass placed within the habitat. Lunar regolith is used as a shielding material to further reduce the transportation mass and use the principle of in-situ resource utilization (ISRU). One of the habitats has undergone a structural analysis using the finite element technique in order to determine the required member size and mass of each element. This early combination of the life support and structural systems helps to create an ideal lunar habitat with a low mass and transport volume.

Design of a Carbon-Carbon Finned Surface Heat Exchanger for a High-Bypass Ratio, High Speed Gas Turbine Engine

Compact heat exchanger designs are commonly used in many gas turbine engine applications. Though effective in their heat transfer function, they are often heavy, costly, and poor aerodynamic performers causing a reduction in engine efficiency. In addition, they are complex to manufacture and often prone to leakage. Finned surface heat exchangers are an attractive alternative to traditional compact designs. They can perform efficiently both aerodynamically and thermally. Such units could be mounted in the bypass fan stream of a gas turbine engine where large amounts of heat must be rejected from vital engine fluids such as oil and fuel. This research project investigated the efficiency of various fin designs applied to an oil cooler. Highly conductive materials, such as carbon composites were explored, and then compared to aerospace-quality aluminum alloys. Thermal, aerodynamic, economic, and weight performance comparisons between the carbon and aluminum fin structures were quantified. A three-dimensional numerical estimation of the final design concept was conducted using ANSYS. This research project specifically investigated the design of a finned surface air-oil heat exchanger. Design parameters included a total heat rejection of 2000 Btu/min and an oil temperature change of 100 degrees Fahrenheit with an inlet oil temperature of 300 degrees. The first design phase was conducted using an aerospace quality aluminum alloy. Internal and external flow convection theory was studied closely as well as basic heat exchanger and fin design concepts. A heat exchanger program was developed in Excel, automating the heat transfer based on basic geometric inputs. The program allowed easy iterations of fin/oil passage designs to meet the performance requirements and optimize the heat exchanger’s weight. The final iteration was then numerically modeled in ANSYS. The predicted heat transfer rate was then compared to the numerical estimation in ANSYS. The Excel program was validated by producing results within 2% of the ANSYS predicted solutions. Upon completion of the aluminum design. highly conductive materials, such as carbon composites were explored and implemented. The final designs of this project (both Aluminum and Carbon-Carbon) identified a new method of heat rejection at a significantly lower weight impact to the engine. The aluminum design had a total core weight of 25.4 lb while the carbon-carbon final design had a total core weight of 12.8 lb. In addition, both units have the potential to be incorporated within an existing engine case exposed to the bypass air stream, which may result in an additional weight savings.Copyright

An Investigation into Life Support Systems for a Lunar Habitat

Long term human habitation in the lunar environment is extremely difficult because of the many challenges present within the severe local conditions including the deep vacuum, radiation exposure, reduced gravity (1/6 earth), and extreme temperatures. To be habitable, future lunar colonies need to address the basic human survival systems and elements like breathable air, habitat pressure, food, water, waste disposal, energy, transportation, communications, temperature, and radiation protection. This paper presents a comprehensive survey and analysis of the various life support systems needed for lunar habitation and how they can be incorporated into a lunar outpost. The most vital life support issues in the lunar environment consist of isolation and insulation from the exterior atmosphere, temperature regulation, and adequate radiation shielding, most of which are addressed and investigated. These results are presented as the findings from various trade studies that looked at several layers of life support loop closure using the NASA Advanced Life Support Sizing Analysis Tool ( ALSSAT) program. This program provided information on Equivalent System Mass (ESM), actual mass, power, and thermal control requirements for a variety of scenarios. These trade studies examined crew size, habitable volume, and alternative life support technologies in order to determine an optimal (i.e. minimal) ESM for a 180 day stay on the lunar surface.

Nuclear Fuel, Cladding, and the “Discovery” of Zirconium

Zirconium cladding played an important role in both the Fukushima and TMI accidents. As nuclear reactors increased in size and power, metallic cladding materials were needed to protect fuel elements. Initially, aluminum and stainless steel were used, but neither of these materials is ideal for use in the high temperature, high radiation environments of nuclear reactors. Zirconium was identified as a potential “miracle” cladding material because it maintains its characteristics at high temperatures and is very corrosion resistant. At 0.185 b, zirconium also has a very low neutron absorbing cross-section. Unfortunately, zirconium is not perfect. At very high temperatures, zirconium reacts with steam to generate heat and to produce hydrogen gas. Both of these attributes can have major negative impacts during nuclear emergencies.

Why Boiling Water

The initial US reactor development program was led by the Atomic Energy Commission (AEC), the US Navy, and several major corporate organizations (GE, Westinghouse, and others). Together, these agencies produced the PWR reactors after they helped transition the US Navy submarine force from diesel-electric boats to nuclear powered entities. The technology developed during this time also set the stage for post-war commercial nuclear power plants. The BWR reactor advanced through various development stages at Argonne and in its early semicommercial operations at various sites throughout the US. Ultimately, the BWR became the second most popular reactor style in the US and the world.

Russian Reactor Design History

The history of the soviet RBMK reactor design, the type of reactor involved in the Chernobyl accident, traces its roots to the first reactors operated in the Soviet Union. The first built in the USSR was a graphite moderated pile, extremely similar in size and performance to Fermi’s initial unit. The second soviet reactor bore a striking resemblance to the Hanford plutonium producing reactors that supported the Manhattan project. These similarities are not surprising given the level of espionage that enabled the Russians to receive design details about both US piles. These early graphite moderated reactors were designed to directly support the Soviet Nuclear Weapons program. Transitioning these weapon producing, graphite moderated reactors into the RBMK design for electrical production was natural for the Soviets, as it obviated the need for large pressure vessels to contain the high temperature and high pressure fluids found in the Western PWR design. In addition, the RBMK design required little fuel enrichment, and could be produced en-masse within the existing industrial infrastructure available in the USSR.

Why Pressurized Water

The Navy’s need for extended use submarine power drove the initial research into nuclear reactor development. This effort produced two land-based prototypes, followed by operating reactors in Navy subs. The two designs included the PWR of the Nautilus and the Sodium cooled reactor of the Seawolf. The US Navy opted for the PWR design for general use after seeing the difficulties in working with sodium and the relatively strong operating performance of the Nautilus and its land-based prototype. The Nuclear Navy provided an enormous impetus to the development of the PWR type. Rickover used a parallel path development program to ensure that the Navy achieved a nuclear, air-independent propulsion system that would revolutionize submarine technology. By investigating both the PWR and sodium cooled reactor, Rickover managed to create an organization that produced the nuclear powered Nautilus in the 10-year period from the end of the war until the submarine’s launch in 1955. In the end PWR became the dominant, and indeed sole propulsion system adopted by the Navy. The corrosion problems associated with the sodium coolant led to it falling into disuse. Following the Navy success, the Atomic Energy Commission attempted to “seed” commercial nuclear power plant development in the US. This development program used additional commercial entities to design cores, enlist utility partners, and offer alternate reactor design concepts. The end result of this decade-long development effort was numerous sites with one of a kind reactors that had significant design or operating flaws. In the end, it was the Navy’s preferred design type, the PWR that became the design for nearly two third of the commercial operating reactors in the US.

The Great East Japan Earthquake and Its Immediate Effects on Fukushima

The March 2011, Great East Japan Earthquake and resulting tsunami, produced a total station blackout in Fukushima Units 1–4. One lone emergency diesel generator survived to support units 5 and 6. Regardless of power availability, all six units were cut off from their ultimate heat sink, the Pacific Ocean. As operators struggled to control the reactors, the inability to remove decay heat led to major failures and significant radioactive releases from breaches of several containment structures at the plant site. This electrical and containment failure produced one of the most devastating nuclear accidents in history, rivaling the Chernobyl disaster of 1986.