Its the T-Class sub from GWX 2.0, I should know - I made the model, one of my first proper 3d models in fact (and im sorry to say it kinda shows)
Hopefully some one will build a better looking one in the future.
If it helps, the T-class with 10 tubes (1st group) carried 16 torpedos total, the 4 external tubes could not be reloaded, the 6 internal bow tubes had one reload each.