DynaSep’s New Aerogel Critical Point Drying System Helps NASA Engineers

Newark, Delaware, June 1, 2009

DynaSep, LLC has produced equipment to help NASA engineers develop aerogels that are stronger and more flexible than ever before.

While many people first heard the term aerogel when the National Aeronautics and Space Administration used it to trap space dust on Mars, aerogels (gels whose liquid had been replaced by gas to form a strong, foam-like substance) have interested NASA for a long time.  These materials are nearly weightless, provide excellent thermal insulation and are amazingly strong—three important qualities for a material that will be used in space. 

Over the years NASA has determined that some gels make better starting materials than others.  They have also seen that the conditions they use to turn a gel into an aerogel—such as pressure, temperature, and exposure time to certain solutions—affect the properties of the finished product.  While mass market applications such as insulation for skylights and paint thickener can tolerate a variable process, the stringent requirements for materials used in applications such as space suits or thermal shields require optimized processing conditions that can be tightly controlled.

Unfortunately, the high temperatures and pressures required for supercritical CO2 rinsing and drying (extracting of liquid) have traditionally meant that conditions were monitored indirectly making process optimization and control both difficult and imprecise. 

DynaSep’s new equipment directly measures the actual temperatures and pressures that the reactants experience and records all of the data for future analysis.  Using this information it is possible to determine the optimal process conditions for creating aerogels with the properties that NASA values.  Once the conditions are determined, operators use the sophisticated Wonderware HMI to enter recipes, control the process, and view operating parameters from a single interface allowing for tighter control of operating conditions

To provide more thorough processing and improved control in multiple modes, DynaSep’s engineers made the following design decisions:

·        Optimize the drying cycle to increase the time allowed for solvent diffusion and displacement out of the wet aerogel. 

·        Allow for the washing of the wet aerogels with supercritical CO2—a distinct advantage over systems that allow the use of only liquid CO2 for washing.

·        Utilize a Kammer valve in two modes: 

o       Closed loop mass flow control for doing controlled liquid and/or supercritical CO2 washes using a coriolis mass flow meter to provide feedback;

o       Closed loop pressure control during the transition from liquid CO2 to supercritical CO2 using feedback from a pressure transducer.

·        Utilize a Red Lion PID to control temperature loops and communicate over the Ethernet with the PLC.

·        Allow user control of process parameters (through recipes).

·        Allow the use of multiple soaks and washes to facilitate the removal of solvents before beginning the critical point drying portion of the cycle.

·        Including a 10 liter vessel to allow the collection and recycling of all the solvents used in the manufacture of the aerogels.

Unlike most equipment built for a specific application, the unit DynaSep built for NASA allows for quite a bit of flexibility. The system is designed to be easily moved; with integral casters it is simple to roll it to a new location and plug it in. With four individual, stainless steel pressure vessels, NASA can dry up to 4 types of aerogel material in a single run.  These ASME stamped vessels come in two sizes—two separate 1 liter vessels and two separate 4 liter vessels—so there samples of different sizes can be processed at the same time.  The operator can choose to use which particular vessel they want

NASA’s current goals are to determine the processing conditions that create the strongest and most flexible aerogel from candidate raw materials and then to create target aerogels for further testing.

For more information on DynaSep’s Aerogel Dryer or other equipment

Contact John Melilli at jmelilli@dynasep.com or 302-368-4540, ext.143