Cooling or Freezing Apparatus Using High Heat Transfer Nozzle

A method for reducing the temperature of items, comprising:

• introducing the items onto a conveyor;
• providing gaseous cryogen to at least one delivery nozzle positioned to deliver mixed phase cryogen to the items on the conveyor;
• accelerating the gaseous cryogen to supersonic velocity in the at least one delivery nozzle;
• providing liquid cryogen to at least one secondary nozzle disposed proximate the discharge opening of or within the at least one delivery nozzle casing;
• mixing the liquid cryogen from the at least one secondary nozzle with the gaseous cryogen to form fine liquid cryogen droplets or cryogen snow;
• and
• delivering the supersonic gaseous cryogen and fine liquid cryogen droplets or cryogen snow as a mixed phase cryogen at supersonic velocity to the surface of the food items to reduce the temperature of the food items.

A nozzle delivery system, comprising:

• at least one delivery nozzle comprising a casing, having a towpath therethrough extending axially through the at least one delivery nozzle for gaseous cryogen, the casing comprising a throat, a convergent region upstream from the throat and a divergent region downstream from the throat;
• at least one first conduit for providing the gaseous cryogen to the at least one delivery nozzle;
• at least one second conduit for providing liquid cryogen to the at least one delivery nozzle;
• and
• at least one secondary nozzle in communication with the at least one second conduit, the secondary nozzle positioned proximate a discharge opening of, or within the casing and adapted to deliver liquid cryogen or solid cryogen flashing from the liquid cryogen into the gaseous cryogen flowing from or within the at least one delivery nozzle.