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Wrapped MLI

Multilayer insulation (MLI) for cryogenic propellant feedlines has much higher heat flux than MLI tank insulation, with heat leak into spiral wrapped MLI on pipes up to ten times higher than conventional tank MLI. Quest Thermal's Wrapped MLI (WMLI) is a high performance multilayer insulation using innovative patented discrete spacer technology and nested low emissivity shells specifically designed to reduce heat flux in cryogenic piping.

Better cryogenic feed line insulation is an important enabling technology to meet cryogenic propellant storage and transfer requirements, and improved insulation for Ground Support Equipment would reduce cryogen losses during vehicle loading.  The poor performance of MLI wrapped on feed lines is due to compression of the MLI layers, with increased interlayer contact and heat conduction. WMLI uses patented polymer spacers, formed from Triple Orthogonal Disks, that maintain precise layer spacing, with a unique design to minimize contact area/length ratio and reduce solid heat conduction.

 

WMLI offers superior performance to traditional MLI installed on cryogenic pipe, with 2.2 W/m2 heat flux compared to 26.6 W/m2 for traditional spiral wrapped netting MLI (5 layers, 77K to 295K). WMLI as inner insulation in Vacuum Jacketed Pipe can offer heat leaks as low as 0.09  W/m, compared to industry standard VJP with 0.31 W/m. WMLI enables improved spacecraft cryogenic feedlines, and industrial hot/cold transfer piping, with lower heat leak.

 

Wrapped MLI measured performance versus spiral wrapped & clamshell conventional netting MLI
Wrapped MLI

Table: Comparison of WMLI/VJP and industry standard Vacuum Jacketed Pipe
Wrapped MLI

 

WMLI is a high performance, next generation cryogenic feedline insulation system, with applications for spacecraft cryogenic piping, Vacuum Jacketed Pipe, and improved insulation for industrial hot/cold transfer piping.