The stationary phase is where vials spend extended time at a nearly constant temperature during freezing. This is most distinct for the engineering run at -40°C (cf. Figure )) where the vials in the core of the pallet exhibit a stationary temperature of T sp ≈ -15°C. Similarly, the simulated profiles for vials in the core of the pallet comprise a stationary phase at T sp ≈ -5°C, nearly independent of storage temperature. In section 3.3