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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Sorption cryogenic refrigeration - Status and future

The operation principles of sorption cryogenic refrigeration are discussed. Sorption refrigerators have virtually no wear-related moving parts, have negligible vibration, and offer extremely long life (at least ten years), making it possible to obtain efficient, long life and low vibration cooling to as low as 7 K for cryogenic sensors. The physisorption and chemisorption systems recommended for various cooling ranges down to 7 K are described in detail. For long-life cooling at 4-5 K temperatures, a hybrid chemisorption-mechanical refrigeration system is recommended.

Jones, Jack A.↗
NASA NTRS1988

Iodine sorption study on the proposed use of Viton A in a shuttle galley water accumulator

The installation of a Viton A accumulator in the Shuttle galley has been proposed to prevent overpressurization of the hot water supply system. A laboratory study has been conducted to determine if there would be any interaction between the Viton A material and the iodine used to disinfect the water. Coupons of Viton A were exposed for 24 hours to aqueous iodine solutions similar in quality to the Shuttle's potable water. Changes in the iodine residual were monitored to determine the rate of iodine sorption by the coupon. Total organic carbon (TOC) was monitored to determine the rate of desorption of organic materials from the Viton A. The same coupons were then soaked in reagent-grade water for 24 hours, and iodine was monitored to determine the rate of iodine desorption. The coupons were again exposed to iodine solutions for 24 hours and iodine and TOC were monitored. No significant change in the iodine sorption rate was detected between the first and second exposures. A triangle taste test indicated at a 1 percent confidence level that the water exposed to Viton A had a different taste which was less acceptable to the panelists.

Gibbons, Randall E.↗
NASA NTRS1991

Mixed-Gas Sorption Joule-Thomson Refrigerator

Proposed mixed-gas sorption Joule-Thomson refrigerator provides cooling down to temperature of 70 K. Includes only one stage and no mechanical compressor. Simpler, operates without vibrating, and consumes less power in producing same amount of cooling. Same sorption principle of operation applicable in compressor that chemisorbs oxygen or hydrogen from mixture with helium, neon, and/or other nonreactive gases.

Jones, Jack A.↗
NASA NTRS1990

Regenerative sorption compressors for cryogenic refrigeration

Dramatic efficiency improvements for sorption coolers appear possible with use of compressor heat regeneration techniques. The general theory of sorption compressor heat regeneration is discussed in this paper, and several design concepts are presented. These designs result in long-life, low-vibration cryocoolers that potentially have efficiencies comparable to Stirling refrigerators for 65 to 90 K spacecraft instrument cooling applications.

Bard, Steven↗
NASA NTRS1994

Simpler Three-Stage Regenerative Sorption Cooler

Three-stage regenerative sorption cooler simpler version of one described in "Three-Stage Regenerative Sorption Cooler Reaches 65 K" (NPO-18366). In exchange for simplification, requires about 1 1/2 times input power of more-complicated version.

Bard, Steven↗
NASA NTRS2000

Design Models for the Development of Helium-Carbon Sorption Crycoolers

We have developed models for predicting the performance of helium-based Joule-Thomson continuous-flow cryocoolers using charcoal-pumped sorption compressors. The models take as inputs the number of compressors, desired heat-lift, cold tip temperature, and available precooling temperature and provide design parameters as outputs. Future laboratory development will be used to verify and improve the models. We will present a preliminary design for a two-stage vibration-free cryocooler that is being proposed as part of a mid-infrared camera on NASA's Next Generation Space Telescope. Model predictions show that a 10 mW helium-carbon cryocooler with a base temperature of 5.5 K will reject less than 650 mW at 18 K. The total input power to the helium-carbon stage is 650 mW. These models, which run in MathCad and Microsoft Excel, can be coupled to similar models for hydrogen sorption coolers to give designs for 2-stage vibration-free cryocoolers that provide cooling from approx. 50 K to 4 K.

Lindensmith, C. A.↗
NASA NTRS2000

Design Models for the Development of Helium-Carbon Sorption Cryocoolers

We have developed models for predicting the performance of helium-based Joule-Thomson continuous-flow cryocoolers using charcoal-pumped sorption compressors. The models take as inputs the number of compressors, desired heat-lift, cold tip temperature, and available precooling temperature and provide design parameters as outputs. Future laboratory development will be used to verify and improve the models. We will present a preliminary design for a two-stage vibration-free cryocooler that is being proposed as part of a mid-infrared camera on NASA's Next Generation Space Telescope. Model predictions show that a 10 mW helium-carbon cryocooler with a base temperature of 5.5 K will reject less than 650 mW at 18 K. The total input power to the helium-carbon stage is 650 mW. These models, which run in MathCad and Microsoft Excel, can be coupled to similar models for hydrogen sorption coolers to give designs for 2-stage vibration-free cryocoolers that provide cooling from approximately 50 K to 4 K.

Lindensmith, Chris A.↗
NASA NTRS2012

Reversible Ammonia Sorption for the Primary Life Support System (PLSS)

Results are presented on the development of regenerable trace-contaminant (TC) sorbent for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). Since ammonia is the most important TC to be captured, data presented in this paper are limited to ammonia sorption, with results relevant to other TCs to be reported at a later time. The currently available TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal. The sorbent is non-regenerable, and its use is associated with appreciable pressure drop, i.e. power consumption. The objective of this work is to demonstrate the feasibility of using vacuum-regenerable sorbents for PLSS application. In this study, several carbon sorbent monoliths were fabricated and tested. Multiple adsorption/vacuum-regeneration cycles were demonstrated at room temperature, as well as carbon surface conditioning that enhances ammonia sorption without impairing sorbent regeneration. Depending on sorbent monolith geometry, the reduction in pressure drop with respect to granular sorbent was found to be between 50% and two orders of magnitude. Resistive heating of the carbon sorbent monolith was demonstrated by applying voltage to the opposite ends of the monolith.

Wojtowicz, Marek A.↗
NASA NTRS2017

Kinetics of Moisture Sorption and Reverse Bias Degradation in Chip Tantalum Capacitors

Exposure of chip MnO2 tantalum capacitors to humid environments might result in increased ESR, leakage currents, and first turn-on failures. However, there is a lack of literature data on the effect of moisture on reverse bias behavior of the parts. The presence of moisture can also result in pop-corning when a high water vapor pressure develops when moisture absorbed in pores of tantalum slugs vaporizes instantly during soldering process resulting in damage to capacitors. A study of kinetics of moisture ingress to and release from active elements of capacitors would allow a better understanding of degradation mechanisms and is important for preventing failures. In this work, a technique for investigation of moisture sorption and desorption in solid chip tantalum capacitors that employs tantalum slugs as a humidity sensor have been developed and kinetics of the process analyzed for different types of capacitors at temperatures from room to 125 ºC. A model that relates diffusion characteristics of polymer cases and size of the slugs to characteristic times of moisture sorption has been developed. A strong effect of moisture on long-term degradation of reverse bias currents in MnO2 cathode capacitors has been demonstrated and physical mechanisms discussed.

Teverovsky, Alexander↗
NASA NTRS2017

Kinetics of Moisture Sorption and Reverse Bias Degradation in Chip Tantalum Capacitors

Exposure of chip MnO2 tantalum capacitors to humid environments might result in increased ESR, leakage currents, and first turn-on failures. However, there is a lack of literature data on the effect of moisture on reverse bias behavior of the parts. The presence of moisture can also result in pop-corning when a high water vapor pressure develops when moisture absorbed in pores of tantalum slugs vaporizes instantly during soldering process resulting in damage to capacitors. A study of kinetics of moisture ingress to and release from active elements of capacitors would allow a better understanding of degradation mechanisms and is important for preventing failures. In this work, a technique for investigation of moisture sorption and desorption in solid chip tantalum capacitors that employs tantalum slugs as a humidity sensor have been developed and kinetics of the process analyzed for different types of capacitors at temperatures from room to 125 C. A model that relates diffusion characteristics of polymer cases and size of the slugs to characteristic times of moisture sorption has been developed. A strong effect of moisture on long-term degradation of reverse bias currents in MnO2 cathode capacitors has been demonstrated and physical mechanisms discussed.

Teverovsky, Alexander↗
NASA NTRS1967

A study of a sorption process.

Sorption process for determining sticking probability of molecules on surface of sorbents, diffusion coefficient of molecules through sorbents and adsorption isotherms

DIFFUSION COEFFICIENT↗
NASA NTRS2002

Evaluation of hydride compressor elements for the Planck sorption cryocooler

Hydrogen sorption crycoolers are being developed for the European Space Agency Planck mission to provide nominal 19 K cooling to instruments for measuring the temperature anisotropy of the cosmic microwave background with extreme sensitivity and resolution.

sorption cryocoolers metal hydides gas gap heat sw↗
NASA NTRS2000

Performance prediction of the Planck sorption cooler and initial validation

Two continuous operation 18 K/20 K sorption coolers are being developed by JPL for the ESA Planck mission to provide about 200 mW of cooling at 18 K and 1.4 W at 20 K. A detailed performance prediction model has been developed to support the design process and to evaluate the results of a prototype testing.

sorption cryocoolers thermal model analyses metal ↗
NASA NTRS1997

Post-Flight Analysis of a 10K Sorption Cryocooler

In May 1996, the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE) was flown aboard the Space Shuttle flight STS-77 in the first space-flight demonstration of chemisorption cryocooler technology. While on orbit, BETSCE successfully met its science objectives of cooling from 70 K to 10 K in less than two minutes, sustaining a 100 mW heat load below 11 K for over then minutes, and demonstrating recycle times of approximately eleven hours.

sorption crycooler chemisorption cryocooler↗