Abstract: A T-junction microwave applicator and a method for making a T-junction microwave applicator with a microwave source supplying electromagnetic energy through a junction arm to a pair of collinear arms extending in opposite directions from their junction with the junction arm. The two collinear arms form a main waveguide terminated in end walls in which entrance and exit ports are formed for a conveyor to convey material to be heated through the main waveguide for exposure to electromagnetic energy. A rectangular conductive ridge in the wall of the main waveguide opposite the junction arm extends the length of the applicator. A cylindrical tuning bar spanning the junction is positioned vertically in a plane perpendicular to the axis of the main waveguide to maximize power transfer to the material to be heated.

Abstract: A microwave heating apparatus with a tubular waveguide applicator and reactive and resistive chokes to decrease leakage. Microwave-transparent centering elements maintain articles to be treated centered in the applicator. Articles, such as individual cylindrical articles or continuous cylindrical strands, advance through the applicator in a direction in or opposite to the direction of propagation of microwaves. The resistive chokes have conductive vanes coated with a dielectric material that absorbs microwave energy that leaks through the reactive chokes to allow for large openings for large-diameter articles. The waveguide applicator is operated in the TE01 mode to concentrate microwave heating energy along the outer circumferences of the articles.

Abstract: Methods and apparatuses for thermally treating flowable materials using electromagnetic radiation, and foods and materials obtained thereby. Also provided are methods of continuous flow thermal treatment of biomaterials, apparatuses for performing the same, and products prepared using the methods and/or apparatuses.

Abstract: A microwave heating apparatus with a tubular waveguide applicator forming a heating chamber and with microwave-transparent centering elements to maintain product to be treated in proximity to the centerline axis of the chamber. Product is conveyed through the chamber in a direction in or opposite to the direction of propagation of microwaves. Cylindrical chokes at product entrance and exit openings into the chamber prevent microwave leakage and allow for large openings for large products. In some versions, a low-loss inner tube in the chamber coaxial with the tubular applicator is used to confine product to be heated in proximity to the centerline axis of the chamber to be heated effectively by microwaves with a TM01 field pattern.

Abstract: A microwave heating apparatus with a tubular waveguide applicator forming a heating chamber and with microwave-transparent centering elements to maintain product to be treated in proximity to the centerline axis of the chamber. Product is conveyed through the chamber in a direction in or opposite to the direction of propagation of microwaves. Cylindrical chokes at product entrance and exit openings into the chamber prevent microwave leakage and allow for large openings for large products. In some versions, a low-loss inner tube in the chamber coaxial with the tubular applicator is used to confine product to be heated in proximity to the centerline axis of the chamber to be heated effectively by microwaves with a TM01 field pattern.

Abstract: Methods and apparatuses for thermally treating flowable materials using electromagnetic radiation, and foods and materials obtained thereby. Also provided are methods of continuous flow thermal treatment of biomaterials, apparatuses for performing the same, and products prepared using the methods and/or apparatuses.

Abstract: A microwave waveguide applicator and a method for heating, drying, or curing generally planar materials or products. The applicator comprises a waveguide having a pair of opposing broad sides perpendicular to a pair of opposing narrow sides bounding a rectangular exposure chamber. A microwave source generates and propagates microwaves through the chamber in a propagation direction and with an electric field generally directed from one broad wall to the other. Slotted openings in the narrow sides act as entrance and exit ports for a conveyor transporting a product along a conveying path through the chamber perpendicular to the propagation direction and perpendicular to the electric field. The waveguide may be ridged to focus or bend the electric field, especially for heating thin materials.

Abstract: Microwave apparatus for exposing materials on an elongated member, such as a mandrel, to microwave energy. The apparatus includes a cylindrical microwave exposure chamber (10). Elongated slots (20) spaced about the circumference of the chamber (10) are in communication with openings (50) in the walls of waveguides (28) attached to the exterior (19) of the chamber. Microwave energy fed into the waveguide (28) is coupled into the chamber (10) through the associated openings (50) and slots (20). Bars (54) spaced apart in the direction of wave propagation span the opening (50) in the waveguide for uniform or customized delivery of microwave energy into the chamber (10). A low-profile mode stirrer (38) at the rear end of the chamber further evens out the energy distribution. A front plate (62) seals to the chamber and supports a rotatable mandrel (60) on which material to be exposed to microwave energy in the chamber (10) is wrapped.

Abstract: A microwave waveguide applicator and a method for heating, drying, or curing generally planar materials or products. The applicator comprises a waveguide having a pair of opposing broad sides perpendicular to a pair of opposing narrow sides bounding a rectangular exposure chamber. A microwave source generates and propagates microwaves through the chamber in a propagation direction and with an electric field generally directed from one broad wall to the other. Slotted openings in the narrow sides act as entrance and exit ports for a conveyor transporting a product along a conveying path through the chamber perpendicular to the propagation direction and perpendicular to the electric field. The waveguide may be ridged to focus or bend the electric field, especially for heating thin materials.

Abstract: A T-junction microwave applicator and a method for making a T-junction microwave applicator with a microwave source supplying electromagnetic energy through a junction arm to a pair of collinear arms extending in opposite directions from their junction with the junction arm. The two collinear arms form a main waveguide terminated in end walls in which entrance and exit ports are formed for a conveyor to convey material to be heated through the main waveguide for exposure to electromagnetic energy. A rectangular conductive ridge in the wall of the main waveguide opposite the junction arm extends the length of the applicator. A cylindrical tuning bar spanning the junction is positioned vertically in a plane perpendicular to the axis of the main waveguide to maximize power transfer to the material to be heated.

Abstract: A method for drying coal using microwave energy to achieve a controlled aggregate moisture content target range without starting combustion or degrading the coking qualities of the coal. Coal feed stock is first separated into fine grade coal and one or more larger grades. The fine grade coal is loaded onto a conveyor as a bed of fixed depth. The fine grade coal is conveyed continuously through a microwave-energized heating chamber for drying. The fine grade coal is dried sufficiently so that when it is combined with the larger grade coals, the moisture content of the aggregate is within a target moisture content range. By volumetrically and uniformly heating the coal, the microwave heating chamber boils away the water without heating the coal itself above about 90° C. In this way, the coal does not combust or oxidize, and its coking qualities are retained.

Abstract: A microwave applicator system exposing a material flowing through multiple applicator stages to a different radial heating pattern in each stage for uniform heating. A two-stage applicator system has a pair of back-to-back applicators, each having offset, outwardly jutting walls on opposite sides of a material flow path through a microwave exposure region. The offset, cylindrical juts formed in the wide walls of the generally rectangular waveguide cause hot spots to occur in material flowing through and between the narrow walls of the waveguide at opposite radial positions on a radial line oblique to the longitudinal direction of the waveguide. Uniform product heating can be achieved by directing a material sequentially through these two applicators in opposite directions. A cascaded applicator in which each wide wall has a pair of outward juts offset from each other and from the pair of juts on the other side wall may be used.

Abstract: Heating and drying devices including generally rectangular waveguide applicators forming exposure chambers for uniformly heating materials. Material to be heated enters and exits a microwave exposure region of the chamber through entrance and exit ports at opposite ends of the chamber. Various techniques are used to achieve uniform or preferred heating effects.

Abstract: Microwave apparatus for exposing materials on an elongated member, such as a mandrel, to microwave energy. The apparatus includes a cylindrical microwave exposure chamber (10). Elongated slots (20) spaced about the circumference of the chamber (10) are in communication with openings (50) in the walls of waveguides (28) attached to the exterior (19) of the chamber. Microwave energy fed into the waveguide (28) is coupled into the chamber (10) through the associated openings (50) and slots (20). Bars (54) spaced apart in the direction of wave propagation span the opening (50) in the waveguide for uniform or customized delivery of microwave energy into the chamber (10). A low-profile mode stirrer (38) at the rear end of the chamber further evens out the energy distribution. A front plate (62) seals to the chamber and supports a rotatable mandrel (60) on which material to be exposed to microwave energy in the chamber (10) is wrapped.

Abstract: A serpentine waveguide applicator for exposing a material to microwave energy for hearing, drying, or curing. A conveyor transports the material through aligned slots formed in facing sides at consecutive waveguide passes of the serpentine array. Each pass has a ridged waveguide structure with ridges in each corner of the otherwise rectangular waveguide. The ridges make the interior cross section of the waveguide passes cruciform and direct microwave energy away from the slots to reduce arcing, crosstalk, and leakage.

Abstract: The invention uses rapid heating to effect a material property change in a biomaterial. The biomaterial is heated to a predetermined real temperature, whereas the biomaterial's total thermal treatment is described by an equivalent temperature and an equivalent time defining a point above a minimum gel set temperature line, above a reduction in bacteria line, below a water loss line, and below a maximum gel set temperature line. According to one aspect of the invention, the biomaterial is heated by exposing the biomaterial to a relatively uniform electric field. The material is heated to a predetermined temperature for a predetermined time in order to achieve a food product characterized by a preselected refrigerated shelf life of from about two weeks to about forty-two weeks. The food product may be packaged prior to the microwave exposure so as to sterilize the packaging and decrease product loss.

Abstract: Heating and drying devices including generally rectangular waveguide applicators forming exposure chambers for uniformly heating materials. Material to be heated enters and exits a microwave exposure region of the chamber through entrance and exit ports at opposite ends of the chamber. Various techniques are used to achieve uniform or preferred heating effects.

Abstract: A device for heating relatively wide planar materials is formed by at least two parallel waveguides. Each waveguide has an opening that forms a single opening for a planar material. The planar material is propelled in a direction parallel to the propagation of an electronic wave. If each waveguide is kept in TE mode, heating is uniform across the planar material. Power splitters, septums, tuning stubs, and impedance matching can be used to control the heating in each waveguide.

Abstract: An elliptical exposure chamber has an extended focal region. A plurality of cylindrical reactors (25) form the extended focal region. Reducing the size of the opening (58) to each reactor (25) reduces the amount of energy reflected and increases the overall heating. In order to efficiently deliver the electromagnetic energy to the reduced opening (58), a tapered waveguide (55) has a concave end (56). A power splitter (42) divides power from a central waveguide (52) to the plurality of reactors (25). The power that is delivered to each reactor (25) can be adjusted by adjusting the impedance of each reactor (25), the width of each reactor (25) or the width of the opening (58) to each reactor (25). The width of the opening (58) to each reactor (25) can be controlled by a movable metal plate (44). A dielectric wheel can be used to shift hot spots along the focal region.

Abstract: A device for heating a material utilizes a rectangular waveguide with an elongated opening for passing a planar material through the rectangular waveguide. A source creates an electric field between a top surface and a bottom surface of the rectangular waveguide. The electric field is controlled to compensate for attenuation of the electric field. The electric field can be controlled by, for example, using a dielectric slab along the top surface of the rectangular waveguide or a tapered dielectric slab along the top surface of the rectangular waveguide. The electric field can also be controlled by, for example, making the waveguide appear electrically wider at one end. The waveguide can be made to appear electrically wider at one end by, for example, inserting one or more tapered fins. The tapered fins can be adjusted or removed to account for the lossiness of the planar material.