Skip to main content Skip to navigation
Hydrogen Properties for Energy Research (HYPER) Lab Eli Shoemake’s Posts

Cryo-cycling in place – Styrofoam cups and Silly Putty to the rescue!

In this past post, we discussed using cryo-cycling  to identify and fix possible cold leaks before installing equipment in the cryostat. This prevents a lot of problems before they can happen, often saving days of cool-down and warm-up if a test has to be called off. What happens, however, when the leak opens up cold? Your experiment is happily running along at cryogenic temperatures and, all of a sudden, that last temperature cycle proves too much. A crack is allowed to widen through an epoxy joint until you have a little leak and the test has to be called off. When you warm up, the expansion of the epoxy seals the crack and the leak is gone! One option in this situation would be to disassemble the entire system, testing each possible leak location as previously discussed. If your system isn’t a simple one, this could be a serious time investment, and opens up a lot of opportunity for you to break something else, improperly re-install a component, or otherwise mess up something that was already working fine. It was for this reason we developed a system for cryo-cycling in place – using nothing more than a Styrofoam cup and some Silly Putty!

Cryo-cycling in place – Instructions based off ASTM E499/E499M – 11 Test Method A:

  • Take a Styrofoam cup and cut a hole in the bottom or side of the cup just big enough to snugly fit around the test specimen.

    Styrofoam cup photo
    A Styrofoam cup with hole cut in the bottom.
  • Wrap a thin ring of Silly Putty around the test specimen where the cup will seal against the specimen.
  • Slide the Styrofoam cup onto the test specimen, the Silly putty should extrude into the cup a little bit and form a good seal against the cup and the test specimen.

    Styrofoam cup fit around hotwire plug image.
    Styrofoam cup in place. Notice the Silly Putty sticking through at the seal.
  • Apply more Silly Putty, wrapping it around the test specimen and the inside of the cup to completely seal the bottom of the cup.

    Image of cup fitted around hotwire sensor with Silly Putty seal.
    Filling in the Silly Putty for a complete seal.
  • Fill the cup with liquid nitrogen (LN2) to start cooling down the cup and test specimen. As it cools, the Silly Putty will quickly transition through it’s glass transition temperature, first turning rubbery and then becoming a hard plastic that will be a sturdy seal.

    Image of LN2 in the Styrofoam cup
    Sealed Styrofoam cup filled with LN2
  • Sniff all fittings, welds, and solder joints with mass spectrometer by passing the sniffer probe over likely leak points. Start at the bottom of the assembly and work your way up, holding the probe on or not more than 1mm from the surface. Do not move the probe faster than 20mm/s.
  • Continue sniffing in an orderly procedure from bottom to top. Mark any leaks so they can be remedied. Be aware that helium will rise, so a leak above a previously found leak may not actually exist. It is also important to be aware of the airflow in the room, as helium can be blown around the experiment and produce small “leaks” that don’t actually exist.
  • If any leaks are identified, take corrective action and restart this procedure. You may have to let the Silly Putty warm up a while before it is soft enough to be removed.

 

Surplus: What, Why, and How

Sometimes it’s necessary to remove the junk, and here’s how we do it:

  1. #1Log in to myFacilities with your WSU Network ID
  2. #2In the list, select the link for Work Request
  3. #3 Select “Request pick-up or drop-off of Surplus items”
  4. #4 Fill out the items to be surplused, and then choose “Landeen, Gayle” in the dropdown menu for approval authority.
  5. Submit the form, and you’re done!

Slide1

Saving money (and time!) with HYPER’s wiring system – Vacuum Feedthroughs

Due to the very cold nature of our work, we find ourselves needing to design (and redesign) vacuum chambers on a regular basis. In order to do useful research, this usually means trying to pass electrical signals through a high vacuum seal, which as you may expect, takes time and money. However, we’ve come up with a few tricks to reduce our time and dollar expenditures.

First, we reduce the cost of our vacuum feedthrough components. An example of a prebuilt solution is $551 for 7 connection pins, but we can build a 26 pin passthrough for around $120. To reduce the cost of the hermetic connecter itself, we use a very common military hermetic specification, the MIL-DTL-26482 Series I MS3113 (Male) with matching a female connector MS3116F16-26S. The cheapest we’ve found this so far is through Detoronics. We will also order a KF blank through Ideal Vacuum Products or McMaster-Carr. By soldering the connector together, we save a significant amount of money.

Male side installed on a KF flange
MIL-DTL-26482 Series I MS3113 installed on a KF flange
IMG_1226
MS3116F16-26S with installed leads

Secondly, and most importantly, when we set up a vacuum feedthrough, we never solder connections directly to the hermetic connector. By putting a second, non-hermetic connector between sensors and the passthrough, we can avoid having to replace the expensive vacuum feedthrough, and instead just replace the inexpensive standard plug. For this second connector, the HYPER lab uses another inexpensive common connector, the 25 pin D-sub.

A 25 pin D sub connector installed inside CHEF
A 25 pin D sub connector installed inside CHEF

Instructions and pinout as follows:

Needed: 2 female 25 pin D-sub connectors, 1 MS3113M16-26S, 1 MS3116F16-26S, 1 KF blank (we usually use KF40, KF25 if a more compact application is required.)

25 pin D-sub to MS3113/MS3116F16-26S to 25 pin D-sub

  1. Attach MIL-DTL-26482 Series I to KF flange, as shown in the post above.
  2. Starting at Pin 25, follow pinout to connect D-sub to Hermetic
    26 pin MIL-SPEC connector pinout
    26 pin MIL-SPEC connector pinout
    25 pin D Sub pinout
    25 pin D Sub pinout
    1. Pin 25 – Pin c
    2. Pin 24 – Pin b
    3. Pin 23 – Pin a
    4. Pin 22 – Pin Z
    5. Pin 21 – Pin Y
    6. Pin 20 – Pin X
    7. Pin 19 – Pin W
    8. Pin 18 – Pin V
    9. Pin 17 – Pin U
    10. Pin 16 – Pin T
    11. Pin 15 – Pin S
    12. Pin 14 – Pin R
    13. Pin 13 – Pin P
    14. Pin 12 – Pin N
    15. Pin 11 – Pin M
    16. Pin 10 – Pin L
    17. Pin 9 – Pin K
    18. Pin 8 – Pin J
    19. Pin 7 – Pin H
    20. Pin 6 – Pin G
    21. Pin 5 – Pin F
    22. Pin 4 – Pin E
    23. Pin 3 – Pin D
    24. Pin 2 – Pin C
    25. Pin 1 – Pin B

Note: Pin A on the hermetic connector should be free.

3. Starting again at Pin 25, connect the D-Sub to the other side of the hermetic using the same pinout.

Your completed passthrough!
Your completed passthrough!

Finding Cryogenic Material Propeties

Many people don’t consider from day to day how we know properties of any given material for use in design. It seems to be common knowledge that water freezes at 0°C, and it’s easy enough to look up thermal conductivities or heat capacity of common metals, gasses, and building materials. What happens, however, when your operating conditions are hundreds of degrees below room temperature? You can’t assume the same, easily found values anymore – you have to find someone who has taken the measurements at those extreme temperatures. So where do you go? Here’s a list of some good options we’ve used in the past to find data.

  1. Engineering Equation Solver (EES)
    • The lab uses EES for much of the thermodynamic calculations we do, and one reason is that it has standard curves for thermodynamic properties of many materials across a wide range of operating conditions. Through available function calls, you can get accurate thermodynamic properties for the most common real and ideal fluids, even at cryogenic temperatures. EES also has a selection of commonly used incompressible substances. Whenever using a material for the first time, make sure you look at the substance properties and references to ensure you understand the valid operating conditions and assumptions the substance is using.
  2. NIST Cryogenic Materials Database
    • NIST has data for several common structural materials at cryogenic materials. Some of these are referenced as incompressible substances in EES, some are not. The specific properties given varies for the different substances.
  3. Researchmeasurments.com / Jack Ekin’s Experimental Techniques for Low-temperature Measurements: Cryostat Design, Materials Properties, and Superconductor Critical-Current Testing
    • This site provides supplemental information and updates for the book Experimental Techniques for Low-temperature Measurements: Cryostat Design, Materials Properties, and Superconductor Critical-Current Testing, published by Oxford University Press in 2006, 2007, and 2011. The book is a handy guide we often use for reference in building our cryogenic systems. The site has many figures and data tables from the book, including many on the varies properties of materials commonly used in cryogenic design. The book provides much further insight into design that is not available on the website, and the lab owns several copies for reference.

These are the sources we’ve used the most in the lab – please let us know if you have a favorite we haven’t listed!

Cryogenic Seals using Indium

Finding a way to seal small, mobile molecules such as hydrogen and helium at cryogenic temperatures can be quite difficult. Most common seals break down at such cold temperatures, and even a tiny leak path can be catastrophic when working with flammable gasses and temperatures that can freeze the oxygen right out of the air. Luckily, we have wonder element 49: Indium. High purity indium has a lower melting point, and hardness than lead, making it malleable enough to be an effective sealing material. In addition, at high purities, indium readily pressure welds to itself, and bonds to other metals, glass, and ceramics.

Lab member Casey Evans installing a cryogenic indium seal.
Lab member Casey Evans installing a cryogenic indium seal.

In the HYPER lab, we’re set up to extrude 0.0625 inch (1.5875 mm) and 0.1 inch (2.54 mm) diameter wire, and therefore use this wire size most often. For most seals we create, this is a usable size, and allows us to standardize seal design and indium extrusion. Although much of our wire is recycled and re-extruded, we will occasionally buy new indium wire from Indium Wire Extrusion, currently priced at $150 /oz.

A good indium vacuum seal is designed to fill a small gap around the sealed volume with pure indium through an even application of pressure, usually using a bolted flange. Making things easier for us, Indium Wire Extrusion has some helpful guidelines for proper indium seal design. Indium Wire Extrusion recommends three types of indium seals:

  1. A semicircular indium seal. This seal is created by using a ball end mill to machine out a rounded ring in one side of the sealing flange. The other side of the sealing flange should be polished smooth to provide a good sealing surface. Recommended geometry is to use a ball end mill the same diameter as the wire you’re using and machine to a depth equal to half the wire diameter.
  2. A rectangular groove seal with mating surface. This seal is created by machining a rectangular step groove into one side of the flange, and a smaller rectangular step protrusion on the other side of the flange. This geometry has the advantage of not only providing a secure effective seal, but also self aligning the flanges so the seal occurs in the same place every time. Recommended geometry is a groove the same width as the the wire being used to seal and a gap area equal to ~80% of the wire cross sectional area. The protruded step should be chamfered to allow the indium to easily flow into the gap to the sides of the protrusion.
  3. Similar to the first sealing method, you can use a single seal on the flange, but with a square step groove. This can be machined with a standard flat nosed end mill. Again, the gap area of the seal should be 80% or slightly less of the cross sectional area of the wire.

Some other general suggestions when creating / using indium seals:

  1. While HYPER lab hasn’t done this extensively in the past, it can be very helpful to include a jack screw in the flange design. Indium seals after compression and cryo-cycling can be very difficult to pull apart and a jack screw will ensure that you can get the flange back apart for the next run!
  2. When creating the indium o-ring, cut the ends at as shallow an angle as possible. Ensure these ends are overlapping, so that one end of the indium wire will crush on the other to seal the ring together. A straight 90° cut will leave a gap between the ends of the indium wire in the ring, which can allow a leak path through the seal.

Cleaning Helium Compressors

The helium compressor that drives a cryocooler has to effectively reject the heat it’s removing from the helium stream to prevent itself from overheating, and keep the cryocooler cooling efficiently. In most cases, this means running a heat exchanger with a cooled water loop to keep everything cool. This can be very effective when you’re running high purity, clean water through the heat exchanger, but dirty, rusty, or impure water can reduce performance and foul the heat exchanger tubes. In the lab, we use a cooling loop independent from the building water paired with a water filter to help keep water as clean as possible in the loop. Unfortunately, our water pump in the loop had a cast iron casing and impeller, which began to rust and dirty the water. During the process of cleaning out the water and rebuilding the system, we’ve learned a few things about our cryocoolers and keeping them clean.

Sumitomo (SHI) Cryogenics:

The heat exchanger built into the SHI HE-4 cryocooler is a 1/2″ flattened copper tube, and pretty robust. It’s unlikely for anything to get stuck in the tube, although fouling on the surface is possible. Calling Sumitomo, they recommended reversing the water flow through the heat exchanger while the compressor is off to ensure the heat exchanger is free of obstruction. Running vinegar solution through the lines will help remove fouling.

Cryomech Compressors:

Similar to the Sunitomo cryocooler above, the Cryomech cryocoolers also use copper tube in their heat exchangers. The technical representative from Cryomech recommends reversing the flow on the heat exchanger and to flush the system with a standard strength Calcium, Lime, and Rust (CLR) Remover solution. In the event of sludge build up, a 50 wt. % solution of hydrogen peroxide (H2O2) is a viable option in extreme cases.

Compressed Gas Bottle Safety

Compressed gas bottle safety is important! Follow these simple rules to ensure your gas bottle stays a container – not a rocket.

  1. Bottles should be chained at all times to prevent them from tipping over.
  2. Steel caps need to be on bottles when not in use – especially for transportation.
  3. Transport gas bottles on bottle carts.
  4. Always use pressure relief devices when attaching high pressure bottles to systems.
  5. Ensure lines are depressurized and bottle valve is shut before disconnecting the bottle from a system – even when the bottle is “empty”.
  6. Flammable gas bottles should always be grounded before use to avoid static ignition

See H2Tools.org for more information regarding gaseous hydrogen storage.

 

ME 316 Lesson 8: Technology Development (TRLs)

TechD

 

 

 

 

 

 

 

 

 

As engineers, one of the things we all need to be mindful of throughout the design and development process is our stage in technology development. It’s pretty obvious that every technology we have today is supported by a long chain of discoveries, tests, research, and development to get to the products we have in front of us. Insight into where our current efforts fit in that chain can be extremely helpful in a number of tasks:

  • Deciding on your goals for the project – What is a success and what is a failure? Early on in the process, an experiment that provides results counter to your expectations can be just as successful as getting the expected result. If you’re trying to make a product, however, a failure to achieve expected results can destroy any hopes to make it to market.
  • Knowing your audiences – You don’t want to be pitching your basic research to investors to try to start a company – it will never work! At the same time, the government is not going to fund a grant to help you move your finished product to market.
  • Communicating with your audiences – Having an effective descriptor for where in the development process you are working helps your audiences, whoever they may be, to connect to your goals and objectives. This becomes much easier if we define a standard set of descriptions for the development process.

NASA realized these points, and in the 1980s started developing a standardized system to describe their technical progress, called Technology Readiness Levels. These advance from the most basic research at TRL 1 to working products at TRL 9. This system has since been picked up by many government agencies, and is increasingly being used when issuing research grants. Industries, too, are now developing their own TRL guidelines. Each guideline is slightly different for each application, but share a very similar progression. Some examples of TRL users are listed below:

This last user in particular is important, as DOE is administering the contest! An example of a TRL system from John C. Mankins’ NASA TRL White Paper is given below:

“TRL 1

Basic principles observed and reported

This is the lowest “level” of technology maturation. At this level, scientific research begins to be translated into applied research and development. Examples might include studies of basic properties of materials (e.g., tensile strength as a function of temperature for a new fiber).

Cost to Achieve: Very Low ‘Unique’ Cost (investment cost is borne by scientific research programs)

TRL 2

Technology concept and/or application formulated

Once basic physical principles are observed, then at the next level of maturation, practical applications of those characteristics can be ‘invented’ or identified. For example, following the observation of high critical temperature (Htc) superconductivity, potential applications of the new material for thin film devices (e.g., SIS mixers) and in instrument systems (e.g., telescope sensors) can be defined. At this level, the application is still speculative: there is not experimental proof or detailed analysis to support the conjecture.

Cost to Achieve: Very Low ‘Unique’ Cost (investment cost is borne by scientific research programs)

TRL 3

Analytical and experimental critical function and/or characteristic proof-of-concept

At this step in the maturation process, active research and development (R&D) is initiated. This must include both analytical studies to set the technology into an appropriate context and laboratory-based studies to physically validate that the analytical predictions are correct. These studies and experiments should constitute “proof-of-concept” validation of the applications/concepts formulated at TRL 2. For example, a concept for High Energy Density Matter (HEDM) propulsion might depend on slush or super-cooled hydrogen as a propellant: TRL 3 might be attained when the concept-enabling phase/temperature/pressure for the fluid was achieved in a laboratory.

Cost to Achieve: Low ‘Unique’ Cost (technology specific)

TRL 4

Component and/or breadboard validation in laboratory environment

Following successful “proof-of-concept” work, basic technological elements must be integrated to establish that the “pieces” will work together to achieve concept-enabling levels of performance for a component and/or breadboard. This validation must devised to support the concept that was formulated earlier, and should also be consistent with the requirements of potential system applications. The validation is relatively “low-fidelity” compared to the eventual system: it could be composed of ad hoc discrete components in a laboratory. For example, a TRL 4 demonstration of a new ‘fuzzy logic’ approach to avionics might consist of testing the algorithms in a partially computer-based, partially bench-top component (e.g., fiber optic gyros) demonstration in a controls lab using simulated vehicle inputs.

Cost to Achieve: Low-to-moderate ‘Unique’ Cost (investment will be technology specific, but probably several factors greater than investment required for TRL 3)

TRL 5

Component and/or breadboard validation in relevant environment

At this, the fidelity of the component and/or breadboard being tested has to increase significantly. The basic technological elements must be integrated with reasonably realistic supporting elements so that the total applications (component-level, sub-system level, or system-level) can be tested in a ‘simulated’ or somewhat realistic environment. From one- to-several new technologies might be involved in the demonstration. For example, a new type of solar photovoltaic material promising higher efficiencies would at this level be used in an actual fabricated solar array ‘blanket’ that would be integrated with power supplies, supporting structure, etc., and tested in a thermal vacuum chamber with solar simulation capability.

Cost to Achieve: Moderate ‘Unique’ Cost (investment cost will be technology dependent, but likely to be several factors greater that cost to achieve TRL 4)

TRL 6

System/subsystem model or prototype demonstration in a relevant environment (ground or space)

A major step in the level of fidelity of the technology demonstration follows the completion of TRL 5. At TRL 6, a representative model or prototype system or system — which would go well beyond ad hoc, ‘patch-cord’ or discrete component level breadboarding — would be tested in a relevant environment. At this level, if the only ‘relevant environment’ is the environment of space, then the model/prototype must be demonstrated in space. Of course, the demonstration should be successful to represent a true TRL 6. Not all technologies will undergo a TRL 6 demonstration: at this point the maturation step is driven more by assuring management confidence than by R&D requirements. The demonstration might represent an actual system application, or it might only be similar to the planned application, but using the same technologies. At this level, several-to-many new technologies might be integrated into the demonstration. For example, a innovative approach to high temperature/low mass radiators, involving liquid droplets and composite materials, would be demonstrated to TRL 6 by actually flying a working, sub-scale (but scaleable) model of the system on a Space Shuttle or International Space Station ‘pallet’. In this example, the reason space is the ‘relevant’ environment is that microgravity plus vacuum plus thermal environment effects will dictate the success/failure of the system — and the only way to validate the technology is in space.

Cost to Achieve: Technology and demonstration specific; a fraction of TRL 7 if on ground; nearly the same if space is required

TRL 7

System prototype demonstration in a space environment

TRL 7 is a significant step beyond TRL 6, requiring an actual system prototype demonstration in a space environment. It has not always been implemented in the past. In this case, the prototype should be near or at the scale of the planned operational system and the demonstration must take place in space. The driving purposes for achieving this level of maturity are to assure system engineering and development management confidence (more than for purposes of technology R&D). Therefore, the demonstration must be of a prototype of that application. Not all technologies in all systems will go to this level. TRL 7 would normally only be performed in cases where the technology and/or subsystem application is mission critical and relatively high risk. Example: the Mars Pathfinder Rover is a TRL 7 technology demonstration for future Mars micro-rovers based on that system design. Example: X-vehicles are TRL 7, as are the demonstration projects planned in the New Millennium spacecraft program.

Cost to Achieve: Technology and demonstration specific, but a significant fraction of the cost of TRL 8 (investment = “Phase C/D to TFU” for demonstration system)

TRL 8

Actual system completed and “flight qualified” through test and demonstration (ground or space)

By definition, all technologies being applied in actual systems go through TRL 8. In almost all cases, this level is the end of true ‘system development’ for most technology elements. Example: this would include DDT&E through Theoretical First Unit (TFU) for a new reusable launch vehicle. This might include integration of new technology into an existing system. Example: loading and testing successfully a new control algorithm into the onboard computer on Hubble Space Telescope while in orbit.

Cost to Achieve: Mission specific; typically highest unique cost for a new technology (investment = “Phase C/D to TFU” for actual system)

TRL 9

Actual system “flight proven” through successful mission operations

By definition, all technologies being applied in actual systems go through TRL 9. In almost all cases, the end of last ‘bug fixing’ aspects of true ‘system development’. For example, small fixes/changes to address problems found following launch (through ‘30 days’ or some related date). This might include integration of new technology into an existing system (such operating a new artificial intelligence tool into operational mission control at JSC). This TRL does not include planned product improvement of ongoing or reusable systems. For example, a new engine for an existing RLV would not start at TRL 9: such ‘technology’ upgrades would start over at the appropriate level in the TRL system.

Cost to Achieve: Mission Specific; less than cost of TRL 8 (e.g., cost of launch plus 30 days of mission operations)”

Homework for Monday:

  1. Finish and polish your presentation for Jake (and the rest of the world!) to be given on Monday.
  2. Read the DOE TRL guide and try to get an understanding of where our development is taking place in the TRL system. Why might DOE be using this competition to advance TRLs?

ME 316 Lesson 5: Defining What a Design MUST and SHOULD do

For those of you curious, Jake was lucky enough to be in Florida watching the MUOS-4 launch this morning and won’t be back until Friday. This is a great example of a complex system like the one we will be designing (and uses liquid hydrogen too!).

Now that you have seen the competition requirements, talked with our customers/clients, and had a chance to read relevant literature on your specific topic, you should have a pretty good understanding of what is required and some of the specific challenges we will have to rise to meet. It’s time to start talking systems design!

No engineer, regardless of how talented or experienced, will come up with the winning design in one go. Did you think ULA designed the perfect rocket to launch MUOS-4 in their first go at it? No! As we’ve discussed, there is no algorithm you can follow to get the perfect design. Engineering systems is a iterative, heuristic process – the more iterations or potential solutions you can run through, the better your design becomes. Today, we’ll run through several iterations of the whole system, and by the end of class everyone should have a good idea of the full system design we’re moving forward with.

Initial System Designs:

  • Compressor Team:IMG_20150902_132907223
  • Container Team:ContainerSys1
  • H2 Purification Team:PurificationSys1
  • H2 Source Team:SourceSys1
  • H2 Storage Team:StorageSys1
  • Heat Exchanger and Piping Team:HXSys1
  • PLC and Sensors Team:project flow -team plc
  • User Interface Team:UISys1
  • Vacuum Chamber Team:VacSys1
  • Vortex Tube Team:VTubeSys1
  • Summer Guests Team:SummerFlow

Now that you’ve each presented a potential design, we’ll look at how to make toast. Keep this in mind as we take a few minutes to iterate to the next design!

Revised System Designs:

  • Compressor Team:
  • Container Team:ContainerSys2
  • H2 Purification Team:PurificationSys2
  • H2 Source Team:SourceSys2
  • H2 Storage Team:StorageSys2
  • Heat Exchanger and Piping Team:20150902_135704
  • PLC and Sensors Team:PLCSys2
  • User Interface Team:UISys2
  • Vacuum Chamber Team:IMG_20150902_135701
  • Vortex Tube Team:VTubeSys2

 

Vote on the winning revised design, and by sending me a Slack direct message with your top two designs.

By Friday you need to:

  1. Send your TA a direct message in Slack with the names of the teams with your top two favorite system designs. I’ll post the top designs to the announcements.
  2. Start your subsystem process flow and create an editable document that will allow you to continuously update and refine your design. I would recommend using Dia Diagram, but feel free to use Visio, Word, PowerPoint, or whatever system your team is comfortable with. Upload this to OneDrive, so everyone on your team can access.
  3. Once your subsystem process flow is complete, you should have a pretty good idea of your subsystem’s requirements. Make a list of everything your subsystem NEEDS to do, and a list of everything your subsystem SHOULD do. Upload this to OneDrive as well.

 

 

Washington State University