Browsing by Author "Chepko, Ariane"
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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 Design, Development, and Testing of a Water Vapor Exchanger for Spacecraft Life Support Systems(46th International Conference on Environmental Systems, 2016-07-10) Izenson, Michael; Micka, Danny; Chepko, Ariane; Rule, Kyle; Anderson, MollyThermal and environmental control systems for future exploration spacecraft must meet challenging requirements for efficient operation and conservation of resources. Maximizing the use of regenerative systems and conserving water are critical considerations. This paper describes the design, development, and testing of an innovative water vapor exchanger (WVX) that can minimize the amount water absorbed in and vented from regenerative CO2 removal systems. Key design requirements for the WVX are high air flow capacity (suitable for a crew of six), very high water recovery, and very low pressure losses. We developed fabrication and assembly methods that enable high-efficiency mass transfer in a uniform and stable array of Nafion tubes. We also developed analysis and design methods to compute mass transfer and pressure losses. We built and tested subscale units sized for flow rates of 2 and 5 ft3/min. Durability testing demonstrated a stable core geometry that was sustained over many humid/dry cycles. Pressure losses were very low (< 0.5 in. H2O total) and met requirements at prototypical flow rates. We measured water recovery efficiency across a range of flow rates and humidity levels that simulate the range of possible cabin conditions. We measured water recovery efficiencies in range 80-90%, with the best efficiency at lower flow rates and higher cabin humidity levels. We compared performance of the WVX with similar units built using an unstructured Nafion tube bundle. The WVX achieves higher water recovery efficiency with nearly an order of magnitude lower pressure drop than unstructured tube bundles. These results show that the WVX provides uniform flow through flow channels for both the humid and dry streams and can meet requirements for service on future exploration spacecraft. The WVX technology will be best suited for long-duration exploration vehicles that require regenerative CO2 removal systems while needing to conserve water.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 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 Optimal Cooling Garment Design Based on Analysis, Modeling, and Testing(49th International Conference on Environmental Systems, 2019-07-07) Izenson, Michael; Bieszczad, Jerry; Chepko, ArianeThe thermal conductance of liquid cooling garments can limit the performance of future space suits that must provide thermal control and comfort in new and challenging environments. New design approaches can help design future suits for optimal performance. These approaches can build on extensive work that has been done developing and validating analysis, data, and modeling software for heat and moisture transport in garments for the design of terrestrial chemical/biological protective gear. The analysis is based on fundamental physics of heat and moisture transport in textiles and convective transport inside the garment ensemble, coupled with models of human thermoregulation characterizing metabolic heating, sweating, and respiration. The analysis and modeling methods have been validated through extensive testing of materials, fabrics, and garment components. Design models have been formulated that use the analysis methods to calculate performance of garment ensembles. Inputs to the models include garment definition (materials, fit, closures), environmental conditions, subject anatomy, activity rate and level of exertion, and mission parameters. Outputs include rates of heat and moisture transport throughout the garment system, cooling and evaporation from the wearer’s skin, and temperatures and relative humidity levels throughout the garment system. These models help designers screen and iterate design alternatives, explore “what if” scenarios, reduce the need for expensive full system testing, and lead to greater confidence that designs are optimized with respect to cost, weight, and performance. This paper describes the basic design methods, data and models; how these elements are applied to garment design; and how they can be used to improve the performance of future space suits. Use of these design methods could guide materials selection, testing, data assessment, and optimal garment design for future liquid cooling and ventilation garments. The payoff would be improved thermal conductance and comfort of future LCVGs, thus maximizing astronaut performance.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.Item Two-Stage Dust Removal System for Mars In-Situ Resource Utilization Systems: System Sizing and Trade-offs(48th International Conference on Environmental Systems, 2018-07-08) Chepko, Ariane; Swanwick, Michael; Sorensen, Paul; Modarress, DariusA two-stage dust filtration system is presented for Mars in situ resource utilization (ISRU) gas processing systems consisting of a cyclone pre-filter and an electrostatic precipitator (ESP). An inertial cyclone pre-filter upstream of the ESP offers a regenerable, passive, and robust approach to capture the larger particles and reduce the required size of the ESP stage. We present the development of a system model to estimate performance of a cyclone-ESP dust separator operating under low-pressure, Martian conditions. We compare the model to experimental cyclone tests and computational fluid dynamics (CFD) analysis, and estimate the performance and scalability of a two-stage dust separation system. We present the sizing and collection efficiency trade-offs between the stages for a validation class ISRU processing system.