Sorption characterization and actuation of a gas-gap heat switch

Martins, D.; Ribeiro, Laura; Lopes, Diogo Pereira; Catarino, I.; Esteves, Isabel A. A. C.; Mota, José P. B.; Bonfait, G.

doi:10.1016/j.sna.2011.08.017

Cited by 12 publications

(5 citation statements)

References 12 publications

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“…Since the initial amount of gas in the reference volume before expansion is known, the amount adsorbed in the cell can be determined from a material balance coupled to the equation of state for the adsorptive gas: Here, V m and V R are the volumes of the measuring and calibrated cells, respectively, m s and v s = 1/ρ s are the mass and specific skeletal volume of the adsorbent (ρ s is the skeletal density), n ex is the excess adsorbed concentration at the equilibrium pressure P and temperature T , n g is the gas concentration at ( P , T ) conditions, and P 0 the initial pressure in the calibrated volume (before expansion) regulated at temperature T R .…”

Section: Materials and Experimental Setupmentioning

confidence: 99%

Structural Transitions in the MIL-53(Al) Metal–Organic Framework upon Cryogenic Hydrogen Adsorption

et al. 2017

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The energetics and phase behavior of the MIL-53(Al) metal–organic framework upon low-temperature (15–260 K), subatmospheric H2 adsorption are studied experimentally using a volumetric technique and theoretically by grand canonical Monte Carlo simulation. The adsorption equilibrium data are recorded for a fixed amount of H2 in the system at stable increasing temperature steps starting from 15 K while recording the equilibrium pressure attained at each step. The adsorption isotherms are generated by repeating the experiments for different fixed amounts of adsorbate in the system and connecting the equilibrium points obtained at the same temperature. The solid–fluid interactions are modeled using the TraPPE-UA force field and the fluid–fluid interactions using a parametrization consistent with the same force field; quantum effects on H2 adsorption are taken into account via a quartic approximation of the Feynman–Hibbs variational approach. The use of a consistent force field with proven transferability of its parameters provides an accurate description of the experimental adsorption equilibria and isosteric heats of adsorption. Because of the weak solid–fluid interaction, the Henry constant for H2 adsorption in the large-pore (LP) form of MIL-53(Al) surpasses that for H2 adsorption in the narrow-pore (NP) form at a temperature lower than that at which the dehydrated structure of the material collapses. However, the saturation capacity of the LP form is always higher than that of the NP phase. The phase behavior of MIL-53(Al) upon temperature-induced H2 desorption is interpreted in terms of the osmotic thermodynamic theory. For the conditions spanned in the experiments MIL-53(Al) exhibits at most a single structural transition and its phase behavior depends not only on pressure and temperature but also on the thermal history of the bare material.

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Section: Materials and Experimental Setupmentioning

confidence: 99%

Structural Transitions in the MIL-53(Al) Metal–Organic Framework upon Cryogenic Hydrogen Adsorption

et al. 2017

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“…Among the devices used to accomplish these needs, thermal switches have been at the forefront. Gas-gap, paraffin, and differential thermal expansion thermal switches have been developed and used [1][2][3][4][5][6]; however, these devices usually depend on external resources (e.g., sensors, power, pumps and heaters) which increase system footprints and mass, in addition to mission cost. By replacing the switching mechanisms with solid-state 'smart' actuators, considerable improvements in overall system performance can be achieved.…”

Section: Introductionmentioning

confidence: 99%

Design and development of a shape memory alloy activated heat pipe-based thermal switch

Benafan

Notardonato

Meneghelli³

et al. 2013

Smart Mater. Struct.

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This work reports on the design, fabrication and testing of a thermal switch wherein the open and closed states were actuated by shape memory alloy (SMA) elements while heat was transferred by a two-phase heat pipe. The motivation for such a switch comes from NASA’s need for thermal management in advanced spaceport applications associated with future lunar and Mars missions. As the temperature can approximately vary between −233 and 127 ° C during lunar day/night cycles, the switch was designed to reject heat from a cryogen tank into space during the night cycle while providing thermal isolation during the day cycle. A Ni47.1Ti49.6Fe3.3 (at.%) alloy that exhibited a reversible phase transformation between a trigonal R-phase and a cubic austenite phase was used as the sensing and actuating elements. Thermomechanical actuation, accomplished through an antagonistic spring system, resulted in strokes up to 7 mm against bias forces of up to 45 N. The actuation system was tested for more than thirty cycles, equivalent to one year of operation. The thermal performance, accomplished via a variable length, closed two-phase heat pipe, was evaluated, resulting in heat transfer rates of 13 W using pentane and 10 W using R-134a as working fluids. Experimental data were also compared to theoretical predictions where possible. Direct comparisons between different design approaches of SMA helical actuators, highlighting the effects of the helix angle, were carried out to give a layout of more accurate design methodologies.

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“…In other words, the working pressures considered in this study ensure that the ON/OFF conductance ratio of the heat switch will not be limited by the gas pressure. Second, 10 –4 Pa also satisfies the requirement of the pressure in the OFF state for several helium-based GGHSs operated near 4 K in the literature. , …”

Section: Methodsmentioning

confidence: 83%

“…The heat transfer coefficient in the transition region can be derived by connecting the thermal resistances of the viscous and molecular regions in series h normale normalf normalf = 1 1 h normalv + 1 h normalm …”

Section: Methodsmentioning

confidence: 99%

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Exploring the Potential of Metal–Organic Frameworks for Cryogenic Helium-Based Gas Gap Heat Switches via High-Throughput Computational Screening

Qin,

Cao

2024

ACS Appl. Mater. Interfaces

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With the advantages of a long lifetime and high reliability, gas gap heat switches (GGHSs) are attractive in many thermal management applications, especially in space-borne cryogenic systems. The performance of a GGHS is significantly affected by the adsorption characteristics of the adsorbent in the sorption pump. Compared with the commonly used adsorbent in the GGHSs (activated carbon), metal−organic frameworks (MOFs) have larger surface areas, higher pore volumes, and exceptional tunability, which motivates this study to explore their potential for application in cryogenic GGHSs. To this end, two performance metrics, the required volume of adsorbent (v sor ) and total input heat (q tot ), were computed for about 6000 MOFs via molecular simulations and compared with those of activated carbon. It is found that over 2300 MOFs possess a smaller v sor than activated carbon, and the smallest v sor of MOFs is about 12.7% of that of activated carbon. v sor and q tot generally change in the same direction, which implies it is possible to reduce both parameters simultaneously by choosing a suitable MOF. Structure− performance analysis reveals that 1/v sor consistently increases first and then decreases with pore limiting diameter, largest cavity diameter, available pore volume, accessible surface area, helium void fraction, and bulk density. Descriptor ranges corresponding to high-performing MOFs were identified based on Precision-Recall analysis. Notably, Zr-containing MOFs are particularly likely to have smaller v sor values than activated carbon. It is anticipated that the promising MOFs identified by this study will motivate further experimental investigations, and the insights into structure−performance relationships can serve to guide the rational design of novel MOF candidates for GGHSs.

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Sorption characterization and actuation of a gas-gap heat switch

Cited by 12 publications

References 12 publications

Structural Transitions in the MIL-53(Al) Metal–Organic Framework upon Cryogenic Hydrogen Adsorption

Structural Transitions in the MIL-53(Al) Metal–Organic Framework upon Cryogenic Hydrogen Adsorption

Design and development of a shape memory alloy activated heat pipe-based thermal switch

Exploring the Potential of Metal–Organic Frameworks for Cryogenic Helium-Based Gas Gap Heat Switches via High-Throughput Computational Screening

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