3
With the emplacement process successfully finished,
the next step was to test the heat transmission from the
container to the host rock and backfill depending on trench
depth. Since the dummies were not fitted with a heating
system, it was necessary to develop another experimental
setup. Moreover, due to handling capabilities the dummies
were constructed with fiber glass material, which would
not work for a realistic thermal transmission experimental
setup.
Therefore, a small-scale model was developed on a 1:30
ratio. It consisted of an aluminum cylinder that was fitted
with a heating bullet on its inside. The heating bullet was
connected to a control and logging system, that enables the
user to change the temperature. In order to determine the
spatial heat distribution around the cylinder, conventional
stainless-steel Thermocouple K sensors have been used.
They were connected to a Sparkfun microcontroller with
amplifiers and a multiplexer.
The cylinder was then placed into a miniature trench
in one of the test drift floors. The trench was created with
manual labor by a stone mason since mechanical creation is
not accurate enough on such a small-scale.
It was then covered with rock salt and the sensors were
put in place in approximately 5 cm distance from each
other. The full setup is visible in Figure 4. Heating was ini-
tiated and conducted for 7 days. In total 3 of such heating
cycles have been completed in the underground test site.
For each cycle the trench depth was increased.
The trench depth was chosen respective to the alumi-
num cylinders diameter (Figure 5). It was capped at 30%
depth due to considerations than deeper entrenching could
possibly damage the POLLUX in a real-life scenario because
of creeping and resulting uneven convergence pressure.
Figure 2. Placement of the POLLUX container dummy
(Schaarschmidt, 2022)
Figure 3. Emplaced POLLUX container dummy
(Schaarschmidt, 2022)
Figure 4. In-Situ testing of heat transmission (Schaarschmidt, 2023
With the emplacement process successfully finished,
the next step was to test the heat transmission from the
container to the host rock and backfill depending on trench
depth. Since the dummies were not fitted with a heating
system, it was necessary to develop another experimental
setup. Moreover, due to handling capabilities the dummies
were constructed with fiber glass material, which would
not work for a realistic thermal transmission experimental
setup.
Therefore, a small-scale model was developed on a 1:30
ratio. It consisted of an aluminum cylinder that was fitted
with a heating bullet on its inside. The heating bullet was
connected to a control and logging system, that enables the
user to change the temperature. In order to determine the
spatial heat distribution around the cylinder, conventional
stainless-steel Thermocouple K sensors have been used.
They were connected to a Sparkfun microcontroller with
amplifiers and a multiplexer.
The cylinder was then placed into a miniature trench
in one of the test drift floors. The trench was created with
manual labor by a stone mason since mechanical creation is
not accurate enough on such a small-scale.
It was then covered with rock salt and the sensors were
put in place in approximately 5 cm distance from each
other. The full setup is visible in Figure 4. Heating was ini-
tiated and conducted for 7 days. In total 3 of such heating
cycles have been completed in the underground test site.
For each cycle the trench depth was increased.
The trench depth was chosen respective to the alumi-
num cylinders diameter (Figure 5). It was capped at 30%
depth due to considerations than deeper entrenching could
possibly damage the POLLUX in a real-life scenario because
of creeping and resulting uneven convergence pressure.
Figure 2. Placement of the POLLUX container dummy
(Schaarschmidt, 2022)
Figure 3. Emplaced POLLUX container dummy
(Schaarschmidt, 2022)
Figure 4. In-Situ testing of heat transmission (Schaarschmidt, 2023