• Quest advanced vapor cooled, vacuum shell technology insulates LH2 tanks for aircraft
  • Quest Discrete Spacer Technology supports thin, lightweight vacuum shell for Mars surface operation
  • Quest IMLI insulates part of Roman Space Telescope
  • Quest IMLI enables Lunar Environmental Monitoring Station to survive cold lunar night
  • Quest IMLI insulates cryogenic receiver dewar for NASA RRM3, first in-space cryogenic fluid transfer
  • Quest IMLI insulates the detector for Lucy spacecraft heading to Jupiter Asteroids
  • Quest IMLI insulation on the NASA GPIM spacecraft
  • Quest Load Bearing Insulation helps make NASA Reduced Boil-Off test a success

NASA Large LH2 tanks Reduced Boil Off test program

Improvements in cryogenic propellant storage are needed to achieve reduced or zero boil off of cryopropellants, critical for long duration missions. Techniques for reducing heat leak into cryotanks include using passive multi-layer insulation (MLI) and vapor cooled or actively cooled thermal shields.  Large scale shields cannot be supported by tank structural supports without heat leak through the supports. Traditional MLI also cannot support shield structural loads, and separate shield support mechanisms add significant heat leak. Quest Thermal Group has developed a novel Load Bearing multi-layer insulation (LBMLI) capable of self-supporting thermal shields and providing high thermal performance.  

Quest recently completed a Phase III program called Reduced Boil-Off for Liquid Hydrogen Tanks, in conjunction with NASA centers GRC, MSFC, Ames and KSC. This program included LBMLI design, modeling and analysis, structural testing via vibe and acoustic loading, coupon calorimeter thermal testing, and Reduced Boil-Off (RBO) testing on NASA large scale cryotanks with LH2.

LBMLI uses the strength of discrete polymer spacers to control interlayer spacing and support the external load of an actively cooled shield and external MLI. Structural testing at NASA Marshall was performed to beyond maximum launch profiles without failure.  LBMLI coupons were thermally tested on calorimeters, with superior performance to traditional MLI on a per layer basis. Thermal and structural tests were performed with LBMLI supporting an actively cooled shield, and comparisons are made to the performance of traditional MLI and thermal shield supports. LBMLI provided a 56% to 74% reduction in heat leak per layer over traditional MLI with tank standoffs, a 44% reduction in mass, and was advanced to TRL5. Active thermal control using LBMLI and a broad area cooled shield offers significant advantages in total system heat flux, mass and structural robustness for future Reduced Boil-Off and Zero Boil-Off cryogenic missions with durations over a few weeks.

Programs Highlights

  • LBMLI structurally supported a Broad Area Cooled shield without tank standoffs
  • LBMLI with BAC shield survived simulated launch ascent environment
  • LBMLI reduced heat flux by 56 to 74% per layer over traditional MLI
  • LBMLI/BAC successfully demonstrated a tube-on-shield active cooling concept
  • LBMLI was matured with these ground tests to TRL5

During the NASA RBO test program, it was determined that LBMLI could successfully withstand more than the Maximum Predicted Envelop for vibe (tested at +25% above MPE) and acoustic loading (+12db), could successfully withstand rapid depressurization from the launch ascent, could successfully support the 6kg aluminum Broad Area Cooling thermal shield and 6kg external 30 layers of conventional MLI, had a 25% to 44% reduction in mass over the traditional MLI system, and provided up to 57% reduction in heat flux for 19 layers of LBMLI compared to 30 layers of traditional MLI (a 74% reduction in heat flux on a per layer basis).

Program Conclusions

Load Bearing MLI is a next generation MLI that uses discrete polymer spacers to maintain layer density, structurally support thermal shields and reduce heat leak through the insulation system. It has advantages over traditional netting MLI with improved thermal performance per layer, more predictable and repeatable performance, estimated lower fabrication and installation costs, and can be installed onto large cryotanks using modular panels.

LBMLI successfully met NASA’s program goals for certain key performance parameters (Table below).

LBMLI helped the multicenter NASA team achieve Reduced Boiloff goals for an actively cooled flight-like cryocooler system with a “tube-on-shield” Broad Area Cooled shield on a 1400L LH2 tank.

 

LBMLI key performance parameters.

Cryogenic Propellant Storage and Transfer Technology Demonstration Mission

 

Key Performance Factor Program Goal  

Specific results from this NASA test program include:

  • Quantitative data was obtained on the thermal and structural performance of LBMLI, an advanced insulation technology, with coupon and tank ground testing in simulated space thermal-vacuum environment and launch ascent environment.
  • LBMLI successfully structurally supported a 6kg BAC shield and 6kg outer MLI through launch ascent loads (acoustic loading, vibe loading and rapid depressurization).
  • LBMLI reduced heat load into the tank by 56% compared to traditional MLI on a per layer basis for operation from 20K (LH2 tank) to ca. 90K (BAC shield).
  • LBMLI reduced heat load into the tank by 74% compared to MLI on a per layer basis for operation between 77K (tank) and 160K (BAC shield).
  • LBMLI reduced mass over conventional MLI with tank supports by 44%.
  • LBMLI (and traditional MLI) heat flux at low temperatures (20K to 90K) was higher than modeled and requires additional study.
  • Benefits of LBMLI over conventional MLI were successfully demonstrated for both passive and active thermal control.
  • LBMLI was matured to TRL5.