Browsing by Author "Phillips, Scott"
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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 Development of Lithium Chloride Absorber Radiator for Flight Demonstration(47th International Conference on Environmental Systems, 2017-07-16) Izenson, Michael; Phillips, Scott; Chepko, Ariane; Daines, Gregory; Quinn, Gregory; Steele, JohnWater conservation is an essential requirement for future exploration space suits. Lithium Chloride Absorber Radiator (LCAR) technology has been developed to meet this requirement by rejecting heat without venting water from a Spacesuit Evaporator Absorber Radiator (SEAR) subsystem. Prototype LCARs have been developed and optimized through numerous thermal vacuum tests that simulate operation in space. An actual flight demonstration is a key next step needed to advance the technology readiness level of the LCAR and make it available for future exploration missions. This paper describes on-going work to enable a flight test of an LCAR as part of a subscale SEAR system that uses a space station EMU as a test bed. The twin goals of this program are to develop a prototype LCAR design that can integrate with an EMU using existing flight-qualified hardware, and to develop and demonstrate a regeneration system that is suitable for use on the space station. Significant advances in LCAR technology include: (1) an optimized design of the absorber bed enables heat rejection at higher temperature and higher rates than prior LCAR designs; (2) measurement of improved heat rejection performance of the optimized LCAR panel through several absorption/regeneration cycles; (3) demonstration of a suitable coolant/refrigerant for use in the SEAR system; (4) demonstration that the prototype panel survives impact loads required for operation on the space station without compromising containment of LiCl / water solution; and (5) demonstration that the LCAR’s thermal performance is essentially unaffected after suffering a design-basis impact.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 Integrated Oxygen Flow Meter / Heat Exchanger for Portable Life Support Systems(48th International Conference on Environmental Systems, 2018-07-08) Izenson, Michael; Servi, Amelia; Phillips, Scott; Stokes, Sheldon; Campbell, ColinSpace suits for future exploration missions will have multi-mission goals with new and challenging requirements for the portable life support system (PLSS). In particular, the space suit ventilation loop requires cooling and flow measurement components that must meet specifications that go well beyond the capabilities of the components used for the existing Extravehicular Mobility Unit. The flow meter must provide high measurement accuracy over a wide flow range, compatibility with pure oxygen, low pressure losses, and very compact size. The heat exchanger that cools the ventilation loop must be built from materials that are compatible with the liquid cooling loop, and it must provide efficient gas cooling in a small package across conditions ranging from normal suit pressure to elevated pressure. This paper describes the development of a novel device that combines the flow measurement and cooling functions in a single, compact flow meter / heat exchanger (FMHX). We have developed design methods that enable us to assess trade-offs, optimize performance, and specify the design of an FMHX that meets the requirements and constraints for operation in future PLSSs. We used computational fluid dynamics analysis to validate the pressure drop and heat transfer characteristics of the FMHX design. Data from tests of a proof-of-concept FMHX show that the system meets all design requirements. We used the results from these tests to refine the design parameters and predict performance of an optimized, prototype FMHX.Item Lithium Chloride Absorber Radiator for Mars Exploration(47th International Conference on Environmental Systems, 2017-07-16) Izenson, Michael; Phillips, Scott; Deserranno, Dimitri; Chepko, ArianeLife support systems for Mars exploration space suits will face challenging requirements for heat rejection. These systems must be light weight, compact, rugged, make minimal use of consumables, and have low impact on the Martian environment. Thermal control will be particularly challenging because water venting should be minimized. Lithium Chloride Absorber Radiator (LCAR) technology can provide thermal control with very low water venting, but earlier designs were not intended for use on the Martian surface. To reject heat to the relatively warm Martian surface, the LCAR must operate at higher vapor pressure and LiCl concentrations than prior designs. We have shown the feasibility of an innovative LCAR system that can meet requirements for operation on Mars. The system includes an innovative water vapor compressor based on proven miniature vacuum pump technology. This device will compress water vapor from the SWME and enable the LCAR to operate at temperatures up to 80°C. Compared to prior systems, the Mars LCAR will be slightly thicker with increased LiCl loading that will reduce the concentration swing during an EVA and increase its final operating temperature. We demonstrated the feasibility of this approach by producing a detailed design of the innovative two-stage vapor compressor, predicting its performance, and showing that the compressor will enable high cooling rates and high heat rejection temperatures. We demonstrated that the Mars LCAR panel can survive representative impact loads without losing containment of LiCl solution. Finally, we measured the heat rejection capability of a prototypical LCAR panel in thermal vacuum tests that simulate operation on the Martian surface and confirmed high heat rejection rates and capacity.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 Simulated cardiovascular responses in microgravity and head-down tilt(50th International Conference on Environmental Systems, 7/12/2021) Lan, Mimi; Archambault-Leger, Veronique; Phillips, Scott; Buckey, Jay; Halter, RyanIn microgravity (?G), body fluids redistribute due to the removal of hydrostatic gradients, causing fluids to move from the legs towards the chest and head. To replicate this on Earth, head-down tilt (HDT) is commonly used. However, there are fundamental differences in how ?G and HDT create headward fluid shift. In ?G hydrostatic gradients and tissue compressive forces are removed, while in HDT, hydrostatic gradients are reversed and tissue compressive forces remain intact. This subtle difference may cause some critical physiologic responses to be reproduced incorrectly. Computer modeling provides a method to simulate the removal of hydrostatic gradients caused by ?G. In this study we gathered seven experimental measurements from HDT and ?G studies in literature that included a supine baseline. These were intracranial pressure (ICP), intraocular pressure (IOP), central venous pressure (CVP), internal jugular vein (IJV) blood flow, IJV pressure, IJV cross-sectional area (CSA), and cranial arterial blood flow. We simulated these measurements in supine, HDT and ?G using a novel craniovascular lumped parameter model developed in MATLAB�. From the literature, HDT correctly reproduced ?G changes in three of the seven measures relative to a supine baseline: IOP, IJV pressure, and cranial arterial blood flow. HDT incorrectly reproduced the changes in ICP, CVP, and IJV blood flow. It is unclear from the studies in literature whether ?G induced increases or decreases in IJV CSA relative to supine. The model simulated seven measures each for HDT and ?G, as well as for supine as a baseline value. Of these 14 trends, we were unable to assess whether IJV CSA in ?G was accurately simulated because of the mixed results from literature. Of the remaining 13 trends the model correctly predicted the changes in all but one, IJV pressure. IJV pressure increased in ?G but the model predicted a decrease.