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At least 307 records · Page 17

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NASA NTRS2018

Maturation and Status of the Lockheed Martin Micro1-2 Cryocooler

This paper describes the maturation and status of the Lockheed Martin “High Power” Micro1-2 pulse tube cryocooler. This cryocooler, which was qualified to technology readiness level 6 in 2014, is the baseline cooler for the Jet Propulsion Laboratory (JPL) Mapping Imaging Spectrometer for Europa (MISE) instrument aboard the Europa Clipper mission, and the Johns Hopkins University Applied Physics Laboratory (JHU-APL) Gamma Ray and Neutron Spectrometer (GRNS) aboard the planned Psyche asteroid mission. This paper will describe enhancements to the cryocooler made for the MISE program, specifically modifications to maximize the cooler efficiency at low heat rejection temperature (220 K) and to increase the operating frequency. The paper will also describe minor modifications for the GRNS program, specifically modification of the coldfinger for low thermal emissivity and the addition of a cold tip interface tab. Finally, the paper will describe modifications made for operation with 150 K heat rejection temperature and 35 K cold tip temperature for the Deep Space Cooling System (DSCS) project with Iris Technology.

Frohling, K.↗

NASA NTRS1991

Preliminary design of a radiator shading device for a lunar outpost

The National Aeronautics and Space Administration is designing a thermal control system for an outpost to be placed permanently on the Moon. One of the functions of the thermal control system is to reject waste heat, which can be accomplished through a radiator. At the lunar equator and during the lunar midday, an unshaded radiator absorbs more heat than it rejects. This problem can be solved by using a shading device to reduce radiation incident on the radiator. The design team was asked to develop concepts for reducing the radiation incident on the radiator and for deploying the radiator and shade system for a 10 kW and a 25 kW heat rejection system. The design team was also asked to develop the best concepts into preliminary design. From the several alternatives developed by the design team, the best one was selected using a decision matrix. Preliminary design of the best concept include support structure, stress analyses, and thermal performance. In addition, the team developed ideas for removing lunar dust from the shading device. The final design solution consisted of a winged radiator shading system with a rail support structure and a scissors mechanism for deployment. The total radiator area required was calculated to be 389 sq m for the 10 kW heat rejection system and 973 sq m for the 25 kW heat rejection system.

Barron, Carlos↗

NASA NTRS1975

Phase 1 engineering and technical data report for the thermal control extravehicular life support system

A shuttle EVLSS Thermal Control System (TCS) is defined. Thirteen heat rejection subsystems, thirteen water management subsystems, nine humidity control subsystems, three pressure control schemes and five temperature control schemes are evaluated. Sixteen integrated TCS systems are studied, and an optimum system is selected based on quantitative weighting of weight, volume, cost, complexity and other factors. The selected sybsystem contains a sublimator for heat rejection, a bubble expansion tank for water management, and a slurper and rotary separator for humidity control. Design of the selected subsystem prototype hardware is presented.

Source record↗

NASA NTRS2011

Experimental Investigation of Sublimator Performance at Transient Heat Loads

Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will summarize the effort put into understanding sublimator response under a transient heat load. The performance will be assessed by detailing the changes in feedwater utilization due to transient starts and stops during various feedwater timing scenarios. Sublimator start up utilization will be assessed as a possible relationship to transient performance of a sublimator. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

Sheth, Rubik B.↗

NASA NTRS2023

Thermal Management System Modeling in the Heat Transport System Simulation (HeaTSSPy) Package

This paper describes the development of a thermal management system (TMS) concept design and analysis software package called Heat Transport System Simulation (HeaTSSPy). Built within Python using the OpenMDAO framework, HeaTSSPy can be used to size and optimize an active (using liquid/air heat exchangers) or passive (using finned heat sinks) TMS. The package makes use of modular TMS elements that allow for the creation of different system architectures and includes components such as heat sinks, heat exchangers, liquid pumps, fans, ducts, air inlets, air nozzles, and liquid pipes. Modeling methods for these components include a combination of physics-based analytical and empirical equations that relate component sizing criteria to system performance. The HeatSSPy heat sink methods are fully detailed within this paper, while the heat exchanger methods are described and referenced from previous work. This paper also uses high-fidelity simulation to validate two different methods of calculating thermal resistance using CFD results. Once the methods are fully described, the code is exercised to compare an active TMS with that of a passive TMS. Design criteria for this study include rejected heat, system altitude, Mach number, and ambient temperature. These criteria are used to develop a TMS system with estimated performance metrics such as weight, drag, and operational power. Results of this paper show the crossover point when a passive system begins to weigh more than an active system for a given heat rejection.

Thermal management system↗

NASA NTRS1974

Electrical power generation subsystem for Space Shuttle Orbiter

The requirements, capabilities, and design of the Space Shuttle Orbiter electrical power generation (EPG) subsystem are presented. The Orbiter EPG subsystem is designed to have the flexibility to supply the basic Orbiter electrical loads and the power requirements of the payloads which, in some cases, are completely dependent on the Orbiter for both power and heat rejection. These needs are supplied by three hydrogen/oxygen fuel cell powerplants (FCPs), having the capability of providing a total of 14 kW average and up to 24 kW peak in the basic Orbiter configuration. Kits permit dedication of one FCP to the payload by providing an additional reactant tank pair for a seven-day mission and additional heat rejection capability.

Blaski, M. F.↗

NASA NTRS2026

Thermal Considerations for 2039 Opposition Class Nuclear Electric Propulsion/Chemical Propulsion Crewed Mars Mission

The high specific impulse (Isp) of Nuclear Electric Propulsion (NEP) technology offers the potential for advanced space mission capabilities. However, the five critical technology elements of NEP vehicles have yet to prove technical maturity levels for consideration into mission design. In response to the critical reviews by the NASA Engineering and Safety Center (NESC) and the National Academies of Sciences, Engineering, and Medicine (NASEM), NASA’s Space Nuclear Propulsion (SNP) project created an NEP Technology Maturation Plan (TMP) for focused development of NEP technology. The TMP called for a coordinated set of technology development efforts to meet this objective. The Modular Assembled Radiators for NEP VehicLes (MARVL) Early Career Initiative (ECI) project was initiated to develop a portion of the fifth Critical Technology Element (CTE) of the NEP vehicle: the Primary Heat Rejection Subsystem (PHRS). A target application of a 2039 human-rated Mars mission was outlined in the TMP. For the outlined mission, a NEP vehicle will experience several thermal environments which will impact the design and operation of the PHRS. To maintain radiator temperatures within the required effective temperature range, the effect of natural, induced, and NEP internally generated heat loads on the radiator panel must be well understood. Furthermore, this analysis is critical for analyzing the influence of various orientations and positions of the NEP vehicle relative to nearby celestial bodies throughout the mission. This study conducted a complete enveloping analysis of the thermal environments influencing the NEP vehicle throughout the mission. Thermal analysis was conducted for the radiator panels based on the defined mission environments. This thermal analysis concludes with the selection of ideal radiator orientations for the NEP vehicle, and the identification of worst case hot and cold environmental sink temperatures throughout the mission. For the target application, the environmental sink temperature while the reactor is powered OFF or powered ON ranges from 30 K to 353 K and 2.7 K to 243 K respectively. When considering interplanetary space, the minimum environmental sink temperature when the reactor is powered OFF and the radiators are oriented “edge to Sun” is 2.7 K. The environmental thermal models generated in this study will be used for future studies with the full vehicle system model. The environmental sink temperature curves generated will be used for future radiator and component analysis to predict transient performance in the space environment. The environmental sink temperature and heat rejection capability curves will inform the trade between commissioning orbits that are in consideration. The model may also serve as a useful tool as reference for future crewed space missions, missions involving radiators or temperature sensitive equipment, or other missions requiring analysis of natural orbital thermal environments.

Nuclear Electric Propulsion↗

NASA NTRS1990

Thermal barrier coating evaluation needs

A 0.025 cm (0.010 in) thick thermal barrier coating (TBC) applied to turbine airfoils in a research gas turbine engine provided component temperature reductions of up to 190 C. These impressive temperature reductions can allow increased engine operating temperatures and reduced component cooling to achieve greater engine performance without sacrificing component durability. The significant benefits of TBCs are well established in aircraft gas turbine engine applications and their use is increasing. TBCs are also under intense development for use in the Low Heat Rejection (LHR) diesel engine currently being developed and are under consideration for use in utility and marine gas turbines. However, to fully utilize the benefits of TBCs it is necessary to accurately characterize coating attributes that affect the insulation and coating durability. The purpose there is to discuss areas in which nondestructive evaluation can make significant contributions to the further development and full utilization of TBCs for aircraft gas turbine engines and low heat rejection diesel engines.

Brindley, William J.↗

NASA NTRSDate not supplied

Coupled Reactor Multiphysics and Mass Scalability Assessment for Crewed Megawatt-Class NEP System Architectures

Nuclear Electric Propulsion (NEP) is an in-space propulsion technology capable of enabling opposition and conjunction class crewed Mars missions. NEP subsystems include the reactor for heat generation, a power conversion system (PCS), power management and distribution, electric propulsion system, and heat rejection system. Specific mass, or α (kg/kWe), is a key performance parameter (KPP) of the propulsion system which is directly scalable with the performance and mass predictions for each individual component. To inform technology maturation planning activities, full system and component level parametric modeling is ongoing to explore the design trade space and illustrate the effect of subsystem design choices on the system KPPs. In this study, scaling of high-assay, low-enriched uranium reactor designs is assessed through coupled reactor physics and thermal hydraulics analyses. Scaling analyses evaluate the impact of system performance parameters (power level, interface temperatures) on mass for direct gas cooled, pumped liquid metal, and passively-cooled heat pipe reactor concepts. Each concept requires specific geometries, fluids, and power conversion interface conditions (temperature, pressure, flow rate) to meet desired performance and mass. The reactor assembly includes the active core (fuel, moderator, cladding, working fluid), axial and radial neutron reflectors, control drums, structural support / pressure vessel, and external radiation shielding. Each of these components are parametrically sized based on performance parameters for a megawatt-class power cycle. Results of this scaling analysis increase NEP propulsion system modeling fidelity and ultimately aim to support concept down-selection along with related technology development planning. The reactor and shield α are a function of several PCS and heat rejection system design choices, and reactor scaling with these parameters must be considered to enable an informed decision on an optimal reactor geometry and working fluid combination.

Nuclear Electric Propulsion↗

NASA NTRS2009

Investigation of Transient Performance for a Sublimator

Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode during low lunar orbit for Altair and possibly Orion, which represents a new mode of operation for sublimators. In this mission phase, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator, which represents the state of the art in sublimator technology, was used to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

Leimkuehler, Thomas O.↗

NASA NTRS2010

Investigation of Transient Performance for a Sublimator

Sheth, Rubik B.↗

NASA NTRS2010

Experimental Investigation of Transient Sublimator Performance

Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator and Contamination Insensitive Sublimator (CIS) were tested in a ground vacuum chamber to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

Sheth, Rubik B.↗

NASA NTRS2011

Investigation of Transient Performance for a Sublimator

Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode, which represents a new mode of operation for sublimators. Sublimators can be used as a topper during mission phases such as low lunar or low earth orbit. In these mission phases, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator and Contamination Insensitive Sublimator (CIS) were tested in a ground vacuum chamber to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions

Sheth, Rubik B.↗

NASA NTRS2011

An Active Broad Area Cooling Model of a Cryogenic Propellant Tank with a Single Stage Reverse Turbo-Brayton Cycle Cryocooler

As focus shifts towards long-duration space exploration missions, an increased interest in active thermal control of cryogenic propellants to achieve zero boil-off of cryogens has emerged. An active thermal control concept of considerable merit is the integration of a broad area cooling system for a cryogenic propellant tank with a combined cryocooler and circulator system that can be used to reduce or even eliminate liquid cryogen boil-off. One prospective cryocooler and circulator combination is the reverse turbo-Brayton cycle cryocooler. This system is unique in that it has the ability to both cool and circulate the coolant gas efficiently in the same loop as the broad area cooling lines, allowing for a single cooling gas loop, with the primary heat rejection occurring by way of a radiator and/or aftercooler. Currently few modeling tools exist that can size and characterize an integrated reverse turbo-Brayton cycle cryocooler in combination with a broad area cooling design. This paper addresses efforts to create such a tool to assist in gaining a broader understanding of these systems, and investigate their performance in potential space missions. The model uses conventional engineering and thermodynamic relationships to predict the preliminary design parameters, including input power requirements, pressure drops, flow rate, cycle performance, cooling lift, broad area cooler line sizing, and component operating temperatures and pressures given the cooling load operating temperature, heat rejection temperature, compressor inlet pressure, compressor rotational speed, and cryogenic tank geometry. In addition, the model allows for the preliminary design analysis of the broad area cooling tubing, to determine the effect of tube sizing on the reverse turbo-Brayton cycle system performance. At the time this paper was written, the model was verified to match existing theoretical documentation within a reasonable margin. While further experimental data is needed for full validation, this tool has already made significant steps towards giving a clearer understanding of the performance of a reverse turbo-Brayton cycle cryocooler integrated with broad area cooling technology for zero boil-off active thermal control.

Guzik, Monica C.↗

NASA NTRS1979

The role of thermal energy storage in industrial energy conservation

Thermal Energy Storage for Industrial Applications is a major thrust of the Department of Energy's Thermal Energy Storage Program. Utilizing Thermal Energy Storage (TES) with process or reject heat recovery systems is shown to be extremely beneficial for several applications. Recent system studies resulting from contracts awarded by the Department of Energy (DOE) identified four especially significant industries where TES appears attractive - food processing, paper and pulp, iron and steel, and cement. Potential annual fuel savings with large scale implementation of near term TES systems for these industries is over 9,000,000 bbl of oil. This savings is due to recuperation and storage in the food processing industry, direct fuel substitution in the paper and pulp industry and reduction in electric utility peak fuel use through inplant production of electricity from utilization of reject heat in the steel and cement industries.

Duscha, R. A.↗

NASA NTRS1981

Thermal vacuum testing of flexible radiator systems

Flexible fin radiators are being developed to meet spacecraft requirements of light weight, compact launch volume, modular growth, reusability, and the capability of an on-orbit deployment and retraction. Two prototype versions of deployable/retractable, flexible finspace radiators (soft and hard tube) were tested simultaneously under thermal vacuum conditions. A map of the heat rejection performance of each radiator panel under various environmental conditions is given. The soft tube radiator deployment system demonstrated minimal gas pressure and was capable of maintaining partial deployment; temperature control was achieved by varying the deployment length. The radiator could be recovered after an inadvertant freezing of the coolant in the Teflon tube. The hard tube radiator deployment mechanism performed adequately throughout the testing, but did exhibit some undesirable performance characteristics. The hard tube radiator pressure drop was higher than expected, but was not affected by the length of deployment. The radiator operated at less than full deployment, and the manifolds were found to have a significant effect on heat rejection. At low-load conditions, the hard tube radiator appeared to bypass its deployed area.

Rankin, G.↗

NASA NTRS1993

Space Station thermal storage/refrigeration system research and development

Space Station thermal loading conditions represent an order of magnitude increase over current and previous spacecraft such as Skylab, Apollo, Pegasus III, Lunar Rover Vehicle, and Lockheed TRIDENT missiles. Thermal storage units (TSU's) were successfully used on these as well as many applications for ground based solar energy storage applications. It is desirable to store thermal energy during peak loading conditions as an alternative to providing increased radiator surface area which adds to the weight of the system. Basically, TSU's store heat by melting a phase change material (PCM) such as a paraffin. The physical property data for the PCM's used in the design of these TSU's is well defined in the literature. Design techniques are generally well established for the TSU's. However, the Space Station provides a new challenge in the application of these data and techniques because of three factors: the large size of the TSU required, the integration of the TSU for the Space Station thermal management concept with its diverse opportunities for storage application, and the TSU's interface with a two-phase (liquid/vapor) thermal bus/central heat rejection system. The objective in the thermal storage research and development task was to design, fabricate, and test a demonstration unit. One test article was to be a passive thermal storage unit capable of storing frozen food at -20 F for a minimum of 90 days. A second unit was to be capable of storing frozen biological samples at -94 F, again for a minimum of 90 days. The articles developed were compatible with shuttle mission conditions, including safety and handling by astronauts. Further, storage rack concepts were presented so that these units can be integrated into Space Station logistics module storage racks. The extreme sensitivity of spacecraft radiator systems design-to-heat rejection temperature requirements is well known. A large radiator area penalty is incurred if low temperatures are accommodated via a single centralized radiator system. As per the scope of work of this task, the applicability of refrigeration system tailored to meet the specialized requirements of storage of food and biological samples was investigated. The issues addressed were the anticipated power consumption and feasible designs and cycles for meeting specific storage requirements. Further, development issues were assessed related to the operation of vapor compression systems in micro-gravity addressing separation of vapor and liquid phases (via capillary systems).

Dean, W. G.↗

NASA NTRS2017

Experimental Characterization of a Composite Morphing Radiator Prototype in a Relevant Thermal Environment

For future long duration space missions, crewed vehicles will require advanced thermal control systems to maintain a desired internal environment temperature in spite of a large range of internal and external heat loads. Current radiators are only able to achieve turndown ratios (i.e. the ratio between the radiator's maximum and minimum heat rejection rates) of approximately 3:1. Upcoming missions will require radiators capable of 12:1 turndown ratios. A radiator with the ability to alter shape could significantly increase turndown capacity. Shape memory alloys (SMAs) offer promising qualities for this endeavor, namely their temperature-dependent phase change and capacity for work. In 2015, the first ever morphing radiator prototype was constructed in which SMA actuators passively altered the radiator shape in response to a thermal load. This work describes a follow-on endeavor to demonstrate a similar concept using highly thermally conductive composite materials. Numerous versions of this new concept were tested in a thermal vacuum environment and successfully demonstrated morphing behavior and variable heat rejection, achieving a turndown ratio of 4.84:1. A summary of these thermal experiments and their results are provided herein.

Bertagne, Christopher L.↗