Browsing by Author "Bue, Grant"
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Item Design of a Lithium Chloride Absorber Radiator for Flight Testing on an Extravehicular Mobility Unit(46th International Conference on Environmental Systems, 2016-07-10) Izenson, Michael; Phillips, Scott; Chepko, Ariane; Quinn, Gregory; Steele, John; Bue, GrantThermal control systems for exploration space suits and spacecraft will need to meet critical requirements for water conservation and durability. Spacesuit Evaporator Absorber Radiator (SEAR) technology offers a non-venting thermal control approach. A SEAR system combines a lithium chloride absorber radiator (LCAR) with a spacesuit water membrane evaporator (SWME). To prove operation of a SEAR system in a space environment, we are currently designing and demonstrating a subscale SEAR system that is designed to meet requirements for a flight test as part of an EMU on the International Space Station. The flight-test system must meet critical requirements for safety, impact resistance, ease of use, durability/lifetime, and simplicity of operation. To meet these requirements, we have developed and demonstrated a new design for the LCAR housing that increases durability dramatically compared to prior prototypes. We have also developed new concepts for integrating the LCAR with the EMU that use existing spacesuit interface components. The overall SEAR system includes controls that will enable operation during EVA with minimal direct intervention by the crew. We have formulated plans for controlling water chemistry to prevent corrosion and growth of microbes in the system. Finally, we have developed a concept for regenerating the LCAR on orbit using existing ISS experimental accommodations. The regeneration system will enable multiple absorption/regeneration cycles while on orbit while also demonstrating critical features of SEAR operation in microgravity.Item Experimentally Determined Overall Heat Transfer Coefficients for Spacesuit Liquid Cooled Garments(45th International Conference on Environmental Systems, 2015-07-12) Bue, Grant; Watts, Carly; Rhodes, Richard; Anchondo, Ian; Westheimer, David; Campbell, Colin; Vogel, Matt; Vonau, Walt; Conger, Bruce; Stein, JamesA Human-In-The-Loop Portable Life Support System (PLSS) 2.0 test has been conducted at NASA Johnson Space Center in the PLSS Development Laboratory from October 27, 2014, to December 18, 2014. These closed-loop tests of the PLSS 2.0 integrated with human subjects in the Mark III Suit at 3.7 psi to 4.3 psi above ambient pressure performing treadmill exercise at various metabolic rates from standing rest to 3000 BTU/hr (880 W). The bulk of the PLSS 2.0 was at ambient pressure, but effluent water vapor from the Spacesuit Water Membrane Evaporator and the Auxiliary Membrane Evaporator, and effluent carbon dioxide from the Rapid Cycle Amine were ported to vacuum to test performance of these components in flight-like conditions. One of the objectives of this test was to determine the overall heat transfer coefficient (UA) of the liquid cooling garment (LCG). The UA, an important factor for modeling the heat rejection of an LCG, was determined in a variety of conditions by varying inlet water temperature, flowrate, and metabolic rate. Three LCG configurations were tested: the Extravehicular Mobility Unit LCG, the Oceaneering Space Systems LCG, and the Oceaneering Space Systems auxiliary LCG. Other factors influencing accurate UA determination, such as overall heat balance, LCG fit, and the skin temperature measurement, will also be discussed.Item Gas Trap Plug Design, Function and Performance(51st International Conference on Environmental Systems, 7/10/2022) Bue, Grant; Phillion, James; Rivas, AmandaThe cooling loops of the Internal Active Thermal Control System (IATCS) on the Node 3, Node 2 and US Laboratory (USL) Modules of the International Space Station (ISS) have been serviced by Gas Traps (GTs) since the onset of operations. These traps serve to protect the pumping function of the cooling loops by eliminating free gas that would otherwise impact the impellers and cause a loop shutdown. Gas Trap Plug Assemblies (GTPAs) have been designed, manufactured and tested, to permit function of the IATCS in the event of a loss of cabin atmosphere and long term decrew event. The GTPA also serve to give the crew additional time to evacuate the United States Operating Segment (USOS) in the unlikely event of an Ammonia breach of an Interface Heat Exchanger (IFHX). These GTPAs have been installed on the ISS IATCS since May 2019. This paper will address purpose, design and testing of the GTPA. The paper will also provide analyses showing residual trapping capability and free gas elimination of the GTs even while tightly plugged, for both the GTs and the Alternate Gas Trap Assemblies (AGTAs) ground spares.Item High-Capacity Spacesuit Evaporator Absorber Radiator (SEAR)(45th International Conference on Environmental Systems, 2015-07-12) Izenson, Michael G.; Chen, Weibo; Phillips, Scott; Chepko, Ariane; Bue, Grant; Quinn, GregoryFuture human space exploration missions will require advanced life support technology that can operate across a wide range of applications and environments. Thermal control systems for space suits and spacecraft will need to meet critical requirements for water conservation and multifunctional operation. This paper describes a Spacesuit Evaporator Absorber Radiator (SEAR) that has been designed to meet performance requirements for future life support systems. A SEAR system comprises a lithium chloride absorber radiator (LCAR) for heat rejection coupled with a space water membrane evaporator (SWME) for heat acquisition. SEAR systems provide heat pumping to minimize radiator size, thermal storage to accommodate variable environmental conditions, and water absorption to minimize use of expendables. We have built and tested a flight-like, high-capacity LCAR, demonstrated its performance in thermal vacuum tests, and explored the feasibility of an ISS demonstration test of a SEAR system. The new LCAR design provides the same cooling capability as prior LCAR prototypes while enabling over 30% more heat absorbing capacity and regeneration in only half the time. Studies show that it should be feasible to demonstrate SEAR operation in flight by coupling with an existing EMU on the Space Station.Item Multifunctional Cooling Garment for Space Suit Environmental Control(45th International Conference on Environmental Systems, 2015-07-12) Izenson, Michael; Chen, Weibo; Phillips, Scott; Chepko, Ariane; Bue, Grant; Ferl, Janet; Cencer, DanielFuture manned space exploration missions will require space suits with capabilities beyond the current state of the art. Portable Life Support Systems for these future space suits face daunting challenges, since they must maintain healthy and comfortable conditions inside the suit for long-duration missions while minimizing weight and water venting. We have demonstrated the feasibility of an innovative, multipurpose garment for thermal and humidity control inside a space suit pressure garment that is simple, rugged, compact, and lightweight. The garment is based on a conventional liquid cooling and ventilation garment that has been modified to directly absorb latent heat as well as sensible heat. This hybrid garment will prevent buildup of condensation inside the pressure garment, prevent loss of water by absorption in regenerable carbon dioxide removal beds, and conserve water through use of advanced lithium chloride absorber/radiator technology for nonventing heat rejection. We have shown the feasibility of this approach by sizing the critical components for the hybrid garment, developing fabrication methods, building and testing a proof-of- concept system, and demonstrating by test that its performance is suitable for use in space suit life support systems.Item Performance of a Multifunctional Space Evaporator- Absorber-Radiator (SEAR)(44th International Conference on Environmental Systems, 2014-07-13) Izenson, Michael G.; Chen, Weibo; Phillips, Scott; Chepko, Ariane; Bue, Grant; Quinn, GregoryThe Space Evaporator-Absorber-Radiator (SEAR) is a nonventing thermal control subsystem that combines a Space Water Membrane Evaporator (SWME) with a Lithium Chloride Absorber Radiator (LCAR). The LCAR is a heat pump radiator that absorbs water vapor produced in the SWME. Because of the very low water vapor pressure at equilibrium with lithium chloride solution, the LCAR can absorb water vapor at a temperature considerably higher than the SWME, enabling heat rejection sufficient for most EVA activities by thermal radiation from a relatively small area radiator. Prior SEAR prototypes used a flexible LCAR that was designed to be installed on the outer surface of a portable life support system (PLSS) backpack. This paper describes a SEAR subsystem that incorporates a very compact LCAR. The compact, multifunctional LCAR is built in the form of thin panels that can also serve as the PLSS structural shell. We designed and assembled a 2 ft2 prototype LCAR based on this design and measured its performance in thermal vacuum tests when supplied with water vapor by a SWME. These tests validated our models for SEAR performance and showed that there is enough area available on the PLSS backpack shell to enable rejection of metabolic heat from the LCAR. We used results of these tests to assess future performance potential and suggest approaches for integrating the SEAR system with future space suits.Item Space Evaporator Absorber Radiator (SEAR) for Thermal Storage on Manned Spacecraft(45th International Conference on Environmental Systems, 2015-07-12) Izenson, Michael G.; Chen, Weibo; Chepko, Ariane; Bue, Grant; Quinn, GregoryFuture manned exploration spacecraft will need to operate in challenging thermal environments. State-of-the-art technology for active thermal control relies on sublimating water ice and venting the vapor overboard in very hot environments, and or heavy phase change material heat exchangers for thermal storage. These approaches can lead to large loss of water and significant mass penalties for the spacecraft. This paper describes an innovative thermal control system that uses a Space Evaporator Absorber Radiator (SEAR) to control spacecraft temperatures in highly variable environments without venting water. SEAR uses heat pumping and energy storage by LiCl/water absorption to enable effective cooling during hot periods and regeneration during cool periods. The LiCl absorber module has the potential to absorb over 500 kJ, compared to phase change heat sink systems that typically achieve ~50 kJ/kg. This paper describes analysis models to predict performance and optimize the size of the SEAR system, estimated size and mass of key components, and an assessment of potential mass savings compared with alternative thermal management approaches. We also describe a concept design for an ISS test package to demonstrate operation of a subscale system in zero gravity.