5.5 Further Issues
369
Fig. 5.109 Transient particle temperature at center line predicted by the macroscopic conduction
equation
Fig. 5.110 The particle packing in the TF-PBEC experiment (a) and the radial particle temperature
distribution of the conduction at steady state (b)
temperature with the time is shown in Fig. 5.109. The hot wall heats the cold particles
without heat. It shows that all particle temperatures increase gradually and tend to
the hot wall at t = 220 s.
For the large-scale nuclear pebble bed [1], the thermal conductivity ratio of the
pebble to the coolant is about 550 at 500 K and in the range of 150–600 at operation conditions. Thus, the point contact mode is applied to calculating the contact area. In the TF-PBEC experiment [35], the pebble bed of helium gas is filled
with about 70,000 graphite spheres of 60mm in diameter, and the DEM packing
369
Fig. 5.109 Transient particle temperature at center line predicted by the macroscopic conduction
equation
Fig. 5.110 The particle packing in the TF-PBEC experiment (a) and the radial particle temperature
distribution of the conduction at steady state (b)
temperature with the time is shown in Fig. 5.109. The hot wall heats the cold particles
without heat. It shows that all particle temperatures increase gradually and tend to
the hot wall at t = 220 s.
For the large-scale nuclear pebble bed [1], the thermal conductivity ratio of the
pebble to the coolant is about 550 at 500 K and in the range of 150–600 at operation conditions. Thus, the point contact mode is applied to calculating the contact area. In the TF-PBEC experiment [35], the pebble bed of helium gas is filled
with about 70,000 graphite spheres of 60mm in diameter, and the DEM packing