Charging and discharging transparent glass-melt solar thermal storage

Molten glass thermal storage after 6 hours of solar charging from empty = 0.

Molten glass thermal storage after 6 hours of radiant discharging from full = 250.

The two simulations above were run in Energy2D for a 10-meter depth of molten glass with a 10-meter optical absorption length, charging at 200,000 W/m2 and discharging at 100,000 W/m2. Charging produces a stable thermocline in the melt, while discharging drives natural convection that maintains a nearly uniform temperature within the convecting layer. Surprisingly perhaps, despite the high viscosity of molten glass, the natural convection during discharge is fully turbulent. The discharge simulation above had to be run at 1/10 earth gravity to keep convective turbulence at a scale the model could handle.