Cryocatalysis Hydrogen Experiment Facility (CHEF)
CHEF is a vacuum insulated cryogenic test chamber with the capability to perform tests in near space conditions. CHEF was originally funded by United Launch Alliance (ULA) to provide test data on hydrogen catalysis for rocket fuel pressurization. CHEF provides a large test space with the ability to cool to low temperatures in a variety of atmospheric conditions.
- Vacuum insulated stainless steel chamber powered by a Leybold Trivac D60A roughing pump and a Varian V-81 turbo molecular pump
- Heat extraction is provided by a Sumitomo CH-204-N cold head and a Sumitomo HC-4E Helium Compressor operating on a two-stage Gifford-McMahon cycle
- Can produce a 2.8 x 10^-7 Torr vacuum in 10 hours.
- Cold head tested to a minimum temperature of 7.8 Kelvin.
- Cold head rated at 9.0 Watts of cooling at 20 Kelvin.
- Cool down time is estimated to be 12 hours from room temperature to 8 Kelvin.
CHEF was originally developed through funding from United Launch Alliance (ULA) to provide evidence that ortho-para catalyzation could be used to enhance the performance of hydrogen vapor cooling. This kind of cooling uses hydrogen boil off to reduce boil off from liquid oxygen tanks onboard LH2 – LOX rockets. By converting from parahydrogen to orthohydrogen as the hydrogen flowed over the tank, more energy could be pulled from the system and cooling power could be increased by as much as 50%. The test reactor for this experiment is diagrammed below:
Hydrogen was liquified in CHEF, and then boiled off at a desired rate. This hydrogen boil-off was heated to the desired temperature as it was run through the catalyst bed in the reactor. At the gas exit, temperature and thermal conductivity were measured to get a final ortho-para concentration. By measuring the amount of heating done during the process, cooling capacity could be compared to conventional boil-off.