Rogelio Rosas
M.S. Graduate Student
Mechanical Engineering
Room: 1337 ERB
Email: rosas2@wisc.edu
Hometown: Los Angeles, CA
Thesis: Modeling a Superfluid Pulse Tube Refrigerator
Motivation
 Infrared and x-ray astrophysics missions have a need to cool
below 1 Kelvin in order to use instruments such as transition
edge sensor (TES) bolometers, microwave kinetic inductance
detectors (MKIDs), and microcalorimeters
 Refrigerators with non-moveable parts are essential in low-
gravity environments because of reliability and durability
 Continuous cooling provides for longer available time to
record data
System and Component Modeling
 A detailed numerical model of
the heat exchangers and pulse
tubes will be developed
 The final model will be
inserted into the system level
model and used to complete
the design of hardware
 The model will be used to
determine required pump
pressure ratio and volume, the
size and effectiveness of the
recuperative, cold end, and
warm end heat exchangers, the
pulse tube size, and the orifice
size
Future Work
 Once system model has been optimized the equipment
will then be assembled to test a complete unit
 Testing will include running the refrigerator with
various cycle times and with 3He-4He mixtures with
different 3He concentrations
 Maps of performance (cooling power vs cold end and
warm end temperatures) for different operating
conditions will be generated
 The data will be an analyzed and the system model will
be refined using the experimental performance data