Heat Transfer Study for Estimating Temperature Distribution inside the Sample Environment of a Helium Gas Cryocooler
superconductive character of a material is mainly dependent on three factors, one of
which is temperature. The exceptional feature about superconductors is that once current
is setup in them, it can persist in superconducting loops virtually for several years
without decay given the adequate conditions of temperature, current density and magnetic
field. In this thesis we discuss ... read morethe thermal characteristics inside the cryocooler
utilized in testing High Temperature Superconducting (HTS) materials. The test sample is
cooled to temperatures as low as 4.2 K in a space filled with helium gas. Prior
experiments were conducted using liquid nitrogen and therefore only tested to 77 K. The
opportunity to use helium gas instead of liquid cryogens such as liquid nitrogen and
helium, offers a more flexible and safer environment. The cooling in a cryocooler system
is mainly driven by conduction and convection heat transfer through the helium gas,
therefore it is generally not as good as a cryogenic liquid in removing heat produced
during an experiment. To verify that the system can be properly utilized for the planned
experiments, it became necessary to estimate the temperature distribution in the
cryostat when a typical thermal load such as the test rig hardware is placed in the
sample area of the cryocooler. An analysis using finite element model was sought to
provide answers regarding the temperature profile. The results demonstrated that the
amount of mass and material properties of the test rig elements can affect the
temperature distribution. These finding can help in designing test hardware adequate for
a given test requirements.
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Mechanical Engineering.
Advisor: Luisa Chiesa.
Committee: Behrouz Abedian, and Makoto Takayasu.
Keyword: Mechanical engineering.read less