Abstract: A combination microwave and air impingement oven has two magnetrons and an air handling system that includes two or more reciprocating ducts through which air is dispensed into the oven. The rotating ducts are configured to stir microwave energy in the oven to prevent formation of hot spots and to sweep microwave radiation over the surface of the food product. A foraminous partition, configured to encircle a portion of the cooking chamber, has a central portion and extremities mounted to divide the interior of the cabinet into a cooking chamber and an air heating chamber. The partition extends around a major part of the periphery of the cooking chamber such that air is drawn along multiple paths toward side walls and toward the rear wall from the cooking chamber.

Abstract: A method and apparatus for heating a product which includes a plurality of tapered ducts in a cabinet above and below a conveyor to form streams which are directed toward the product. Spent air is drawn through return ducts which have intake openings centered between entrance and exit openings in the cabinet and centered between lateral edges of a conveyor and between the tapered ducts to provide a balanced flow of spent air in the cabinet to the return opening. Temperature controlled gas is delivered at an angle through an array of openings adjacent opposite edges of an opening through which a conveyor extends to cause most of the heated air to be drawn to the return duct opening and to maintain internal pressure in the cabinet to prevent ingress and egress of air through the opening.