Variable bi-directional airflow system and method for a thermal processing machine

A variable bi-directional airflow freezer system for a spiral conveyor configured in at least one spiral stack enclosed within a freezer chamber having an inlet and an outlet, the spiral conveyor entering the freezer chamber via the chamber inlet and exiting the freezer chamber via the chamber outlet, the variable bi-directional airflow freezer system comprising:

• a cooling medium supply for substantially horizontally supplying cooling medium to the freezer chamber at a target temperature and velocity;
• and
• a cooling medium directing assembly configured to divide the spiral stack into at least an infeed treatment zone, an outfeed treatment zone, and a return zone each extending along a height of the spiral stack and substantially confined within a footprint of the spiral stack, wherein the infeed treatment zone includes a portion of the spiral conveyor entering the freezer chamber via the chamber inlet, the outfeed treatment zone includes a portion of the spiral conveyor exiting the freezer chamber via the chamber outlet, and the return zone includes a portion of the spiral conveyor extending between the infeed and outfeed treatment zones;
• wherein the cooling medium supply substantially horizontally supplies cooling medium to the infeed and outfeed treatment zones and substantially horizontally withdraws cooling medium from the at least one return zone.

A spiral conveyor freezer, comprising:

• a freezer chamber having an inlet and an outlet;
• a spiral conveyor configured in at least one spiral stack enclosed within the freezer chamber, the spiral conveyor entering the freezer chamber via the chamber inlet and exiting the freezer chamber via the chamber outlet;
• a cooling medium supply for substantially horizontally supplying cooling medium to the freezer chamber at a target temperature and velocity;
• and
• a cooling medium directing assembly configured to divide the spiral stack into at least an infeed treatment zone, an outfeed treatment zone, and a return zone each extending along a height of the spiral stack and substantially confined within a footprint of the spiral stack, wherein the infeed treatment zone includes a portion of the spiral conveyor entering the freezer chamber via the chamber inlet, the outfeed treatment zone includes a portion of the spiral conveyor exiting the freezer chamber via the chamber outlet, and the at least one return zone includes a portion of the spiral conveyor extending between the infeed and outfeed treatment zones,
• wherein the cooling medium supply substantially horizontally supplies cooling medium to the infeed and outfeed treatment zones and substantially horizontally withdraws cooling medium from the at least one return zone.