US3825406A

US3825406A - Radiation-convection heating system

Info

Publication number: US3825406A
Application number: US00283512A
Authority: US
Inventors: G Heath
Original assignee: INFRA RAY DIVISION SOLARONICS
Current assignee: Solaronics Inc
Priority date: 1972-08-24
Filing date: 1972-08-24
Publication date: 1974-07-23
Anticipated expiration: 1991-07-23

Abstract

Radiant heat sources are provided with aspiration devices for inducing air flow across the sources and directing it along paths paralleling the emission of radiant heat energy toward objects being heated. The heat sources are preferably arranged in pairs with an apertured compressed air header positioned between the sources of each pair to induce opposed air flow currents across the sources. Air deflector plates cooperate with the compressed air header to form an aspiration device which diverts the opposed air flow currents into a common flow of heated air directed toward the objects being radiantly heated by the sources.

Description

United States Patent 1191 11 11 3,825,406

Heath I 6 1 14 1 July 23,, 1974 [5 RADIATION-CONVECTION HEATING 3,414,708 12/1968 Maier 219/369 SYSTEM 3,492,458 1/1970 White et al. 219/216 3,529,582 9/1970 Hurkom 219/400 Inventor; George Heath, Lyndhurst, 0h10 3,614,074 10 1971 Wellford, Jr 432/176 Assignee: Infra-Ray Division Solaronics, lnc., I Cleveland, Ohio v Primary Examiner-John J. Camby Assistant Examiner-Henry C. Yuen [22] Flled' 1 7 Attorney, Agent, or Firm-Watts, Hoffmann, Fisher & [21] Appl. No.: 283,512 Heinke C0.

[52] US. Cl 432/175, 432/222, 431/328, [57] ABSTRACT 51 I t 219/377 219F100 126/92 B Radiant heat sources are provided with aspiration devices for inducing air fl across the sources and 1 2 23 recting it along paths paralleling the emission of radiant heat energy toward objects being heated. The heat 201, 202, 213, 222; 34/4, 48; 431/328, 329;

126 92 B sources are preferably arranged in pairs with an aper 92 91 219/276 .347 tured compressed air header positioned between the 9 411 sources of each pair to induce opposed air flow currents across the sources. Air deflector plates cooper- [56] References Cited ate with the compressed air header to form an aspira- UNITEDYSTATES PATENTS, v tion device which diverts the opposed air flow cur- 1,534,682 4/1925 Carmean et al. 219/377 rents into a common flow of heated air directed 2,832,580 4/1958 432/176 toward the objects being radiantly heated by the 3,077,531 2/1963 219/377 sources, 3,185,458 5/1965 ,432/222 3,358,979 12/1967 Flynn. 432/175 23 Claims, 7 Drawing Figures LQ 444,: l I I V d 20 14v 22 5b 76 26 K y, 1 i 27 PATENTED JUL 2 31974 sum 2 OF 2 RAnIA'rro -coNvEcTroN HEATING SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a radiation-convection heating-system and more particularly to methods and apparatus for heating objects wherein air is drawn byaspiration across one ora pair of radiant heaters and then directed toward the objects being heat output is required, and to dispose such heaters or heater banks in an oven.

Most radiant .heatersare designed to heat substantially by radiation alone. Such convective heating as occurs is not the result of a forced convective air flow, but is rather the result of the normal tendency of relatively warm air to rise and relatively cool air to descend. Where radiant heaters are employed in an oven enclosure to heat bbjects positioned in the oven, normal convective heating is minimal as the air inside the enclosure tends to attain a substantially uniform elevated temperature. I

It is also known to employ radiant heaters in. an oven environment to heat air'in a plenum chamber and use an aspiration device to withdraw'the heated air from the plenum and direct it toward the objects being heated. Such a system does not utilize the radiant heaters to heat the objects directly and accordingly does not utilize the radiant heaters to their fullest capability.

SUMMARY OF THE INVENTION The present invention overcomes the foregoing drawbacks of the prior art and provides a radiationconvection heating system wherein radiant heaters heat objects by radiation while an aspiration air flow system draws air across the heaters and directs it toward the objects, thereby maximizing the rate of heat transfer to the objects. 7 t

In accordance with one aspect of the present invention, a pair of radiant heater structures such as infrared heaters, are positioned in parallel spaced apart relationship with an apertured compressed air header between them. The air header is provided with openings which direct an air flow between the heaters in the shielded from radiation heat transfer. Accordingly, the objects are not only heated more rapidly but also more evenly. j

As will be apparent, the aspiration air flow system of the present invention can be used with a single radiation heater structure to induce convective air flow across the heater and to direct it toward the objects to be heated. However, the maximum benefit is achieved from a single air header where it is used to discharge air between a pair of radiation heaters thus inducing opposed air flow currents across the heaters. The opposed air flow currents are then combined into a common air flow path paralleling the path of radiation emanating from the heaters.

In accordance with another aspect of the present invention, a method of heating an object with a radiant heater is provided wherein the object is aligned with the path of radiant energy emission, and air is drawn across the heater by aspiration and directed toward th object.

In accordance with another aspect of the invention, a method of heating an object with a pair of radiant heaters is provided wherein opposed air flow currents are established across the heaters and combined to form a common stream of heated air directed toward the object. v

Accordingly, it is a general object of the present invention to provide novel and improved methods and apparatus for radiation-convection heating.

Otherobjects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawings.

same general direction as radiation emanates from maximizes the efficiency of the radiant heaters. The

heaters thereby serve not only to heat exposed surfaces of the objects by radiation, but also serve to convecvtively heat the objects even along such surfaces BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a burner assembly con structed in accordance with the present invention;

FIG. 2 is a cross-sectional view of the burner assembly as seen from the plane indicated by the line 2-2 in FIG. 1, and schematically showing the burner assembly positioned inan oven enclosure; j g FIG. 3 is an enlarged cross-sectional view of a portion of the burner assembly of FIG. 1 as seen from the same plane as FIG. 2; 7

FIG. 4 is an enlarged cross-sectional view as seen from the plane indicated bythe line 4-4 in FIG.-1;

FIG. 5 is a side elevational view of another embodiment of a burner assembly constructed in accordance with the present invention;

FIG. 6 is a bottom plan view as seen from the plane indicated by the line 6-6 in FIG. 5; and,

FIG. 7 is an enlarged side-elevational view of a por tion of the burner assembly of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, a heating system constructed in accordance with the present invention is shown generally at 10. The heating system 10 is typi cally positioned in a heat-insulated oven enclosure, shown schematically in FIG. 2 at 60. While the heater assembly 10 can be positioned along any of the walls of the oven 60, it is described here as being oriented for positioning along the top wall of the oven 60 to radiate heat downwardly.

The heating system 10 includes three parallel spacedapart elongate header tubes ll, l2, 13. A plurality of transversely extending radiant heaters such as gas-fired burners 14 are positioned beneath the tubes 11, 12, 13. Brackets 1'5 welded to the undersides of the tubes 11, 12, 13 support the burners 14. A plurality of longitudinally extending gas-fired burners 16 are positioned outwardly of the tubes 11, 12. Brackets 17 are welded to the undersides of the tubes 11, 13 and support the burners 16.

The tubes 11, 13 serve as headers to supply natural gas or other suitable fuel to the burner assembly 10. Conduits 18, 19 connect with the headers 11, 13 and with the burners 14, 16 to supply gas to the burners 14, 16.

The tube 12 serves as a header to supply compressed air to ,a plurality of transversely extending conduits 20. The conduits 20 are positioned between pairs of the burners 14. As is best seen in FIG. 3, aligned through apertures 21, 22 formed in the tube 12 and the conduits 20 in regions of their intersection to serve to supply compressed air from the tube 12 to the conduits 20.

Air is discharged from the conduits 20 through downwardly facing openings 23 formed in the lower walls of the conduits 20. The openings 23 can take the form of round or elongated holes 'or a continuous slit.

Pairs of curved air deflector plates 25, 26 are positioned beneath the conduits 20. The plates 25, 26 are secured along side regions'25a, 26a, of the pairs of burners 14. The other plate side regions 25b, 26b are I connected together by straps 27 to define openings 28 between the side regions 25b, 26b. The openings 28 are aligned with the openings 23 such that air discharging through the openings 23 from the conduits 20 is directed through the openings 28.

The deflector plates-25, 26 and the apertured conduits 20 operate together to form an aspiration system which induces a primary flow of air, as indicated by the arrows 75, 76 across the burners 14 and above the deflector plates 25, 26 to form a downwardly directed convection current of heated air. Secondary air flow currents, as indicated by the arrows 77, 78 are also established below the deflector plates 25, 26. By such an arrangement, one or more objects positioned in the path of the radiant heat energy'emitted from the burners 14 will also be heated-by convection currents. The convection currents not only decrease the-time needed to bring the objects to a desired elevated temperature, but also serve to transfer heat to regions of the objects which are shadowed from radiant heat transfer. Accordingly, the combined radiation-convection system produces a more uniform heating of the objects than is usually possible where radiation alone is the principal heat transfer medium.

Referring to FIG. 4, the burners 14, 16 are of known configuration comprising a cast metal housing 35 supporting a flame spreader plate 36 and the usual apertured heater grills 37 and protective screen 38. Such burners are sold commercially under the mark INFRA- RAY by Infra-Ray Division Solaronics, Inc., 1295 West llth Street, Cleveland, Ohio.

In the embodiment of FIGS. 1-4, the burners 14 will be seen to be arranged in pairs with greater distances between the pairs of burners than between the burners of each pair. The spaces between pairs of the burners 14 are closed by plates 40.

Referring to FIGS. -7, another heating system embodiment is shown at 50. The heating system 50 isprovided with equally spaced burners 51. Apertured compressed air headers 52 are provided between alternate pairs of the burners 51 such that each header 52 serves two separate ones of the burners 51. Deflector plates 53 are carried on both sides of each of the burners 51. The deflector plates 53 serve to guide the flow of air in primary currents indicated by the

arrows

80, 81 above the plates 53 and in secondary currents below the plates 53 as indicated by the

arrows

82, 83, toward the burners from the region surrounding the objects to be heated, across the burners and back into the heating region.

Referring to FIG. 7, the burners 51 are supported by plates 55 secured to cross members 56. The spaces between adjacent'burners are closed by plates 57. The headers 52 are secured to the plates 57.

In accordance with the methods of the present invention, air is drawn across one or more radiant heaters by means of an aspiration air flow system. The aspiration system includes one or more deflectors which direct the heated air currents toward the objects being irradiated by the heaters. Where two spaced radiant heaters are used, a single aspiration air flow system interposed between the heaters draws air across the heaters in opposed directions, and combines the opposed currents to form a stream of air directed toward the objects being irradiated by the heaters.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A radiation-convection heating system, comprismg: 1

a. a source of radiant heat for emitting radiant heat energy therefrom in a given direction;

b. aspiration means positioned beside said heat source for inducing convection air flow currents by aspiration across said source and for subsequently directing said currents along paths generally paralleling said given direction;

c. whereby objects positioned in the path of said radiant heat energy are heated both by convective air flow currents and by radiation.

2. The heating system of claim 1 wherein said aspiration means includes apertured conduit means adapted to be connected to a source of compressed air and being positioned along one side of said radiant heat source for discharging compressed air in directions generally paralleling said given direction to draw air by aspiration across said radiant heat source and direct it along paths generally paralleling said given direction.

3. The heating system of claim 2 wherein said aspiration means further includes deflector means interposed between said radiant heat source and the path of discharging compressed air to direct convective air currents passing across said radiant heat source in directions generally perpendicular to said given direction.

4. The heating system of claim 3 wherein said deflector means comprises curved plate portions providing a smooth air flow deflector structure for diverting convective air currents flowing across said radiant heat source into flow paths generally paralleling said given direction.

rents and direct the combined flow toward the objects. being radiantly heated by said .6. A radiation convection heating system comprising:

a. a pair of radiant heat sources disposed in spaced apart relationship for emitting radiant heat energy 2 therefrom in a given direction;

b. aspiration means interposed between said sources for inducing convection air flow currents by aspiration across said. solurcesand along air flow paths substantially paralleling said given direction;

7 e. whereby objects positioned in the path of said radiant heat energy are heated by convective air flow currents as-well as by radiation.

7. The heating system of claim 6 wherein said aspiration means includesapertured conduit means adapted to be. connected to a source of compressed air and being positioned between said radiant heat sources for discharging compressed air in directions generally paralleling said givendirection to draw air by aspiration across said radiant heat sources and direct it along paths generally paralleling said given. direction.

8. The heating system of claim 7 wherein said aspiration means further includes deflector means interposed between saidradiant heat sources'and definingan openingtherethrough for discharging compressed air, said deflector means being adapted to direct convective air currents passing across said radiant heat sources in directions generally perpendicular to said given direction into flow paths generally paralleling said given direction.

9. The heating system of claim 8 wherein said deflector means comprises at least one thin curved plate positioned to establish primary and secondary air flow currents along opposite sides thereof and to effect a combination'of said primary and secondary air flow currents and direct the combined flow toward the objects being radiantly heated by said sources. a

10. The heating system of claim 8 wherein. said deflectormeans comprise curved plate portions providing a smooth air flow deflector structure for diverting convective air currents flowing across said radiant heat sources into flow paths generally paralleling said given direction.

11. The heating system of claim 6 wherein said aspiration means includes deflection means for directing air away from'said radiant heat sources, for combining the airflow from each of said radiant heatsources, and for directing the combined air flow from said radiant heat sources along paths generally paralleling said given direction.

12. A radiation-convection heating system comprisin 2. at least one radiant heat source for emitting radiant energy;

b. aspiration means positioned along one side of said heat source to induce air flow acorss said source and to subsequently direct the air flow in said desired direction to effect convection heating of an object positioned within the path of said radiant energy.

13. The heating system of claim 12 wherein said aspiration means further includes air flow deflector means having one side positioned substantially adjacent said heat source and having means for discharging compressed air along the opposite side of saidf deflector means to induce convective air flow across said heat source and across said deflectormeans. 'Y

'14. The heating system of claim" 13 wherein said deflector means is curved so as to divert the convective air flow along paths parallel said desired direction. 15. In an oven, the improved heating system comprismg: V

a. a plurality of pairs of radiant heatsources;

b. said heat sources being adapted to emit radiant heat energy in given directions toward one or more objects to be heated; and

c. said heating sources of each pair having aspiration means interposed therebetween for discharging compressed air in directions generally paralleling given directions to draw air as by aspiration across said heating sources and to. direct it along paths 7 generally paralleling said given direction.

16. A radiation-convection heating system comprising a pair of radiant heaters and aspiration means interposed between said heaters for drawing air by aspiration across said heaters in generally opposed directions and for combining the opposed air flows into a common stream of air directed generally parallel to the direction of emission of radiant heat from said heaters;

17. A method'of heating an object with a source of radiant heat adapted to emit radiant heat energy along a path in a given direction, comprising the steps of:

a. aligning the object with the emission; 1

b. energizing the heat source to heat the object by means of radiant heat energy; i

0. providing an aspiration air flow inducing system near the heat source; an v d. operatingthe aspiration system in such fashion as to draw air across the heat source and direct it toward the object;

e. whereby the object is heated heated air currents.

'18. The method of claim 17 wherein the aspiration air flow system includes an air deflector positioned beside the heat source for diverting air flow currents passing across the heat source along paths directed toward an object, and the step of operating the aspiration system includes establishing a flow of air beside the air deflector which will draw air currents by aspiration across by radiation and by the heat source whereafter they are directed toward the object by said deflector.

19. A method of heating an object with a pair of spaced radiant heat sources positioned to emit radiant heat energy along paths toward the object, comprising the steps of;

a. energizing the heat sources to heat the means of radiant heat energy;

b. providing an aspiration air flow between the heat sources; and,

c. operating the aspiration system in such fashion as to draw air across both heat sources and directit toward the object;

d. whereby the object is heated by radiation and by heated air currents from the heat sources.

20. The method of claim 19 wherein the aspiration air flow system includes a pair of air deflectors, each object by inducing system path of radiant energy mary and secondary air flow currents from the region of said heaters along opposite sides of said plates and to combine the air flow so produced into a stream of air directed toward the object.

22. A method of heating an object with a pair of spaced radiant heat sources positioned to emit radiant heat energy along a path in a given direction, comprising the steps of: r

a. aligning the object with the path of radiant heat 8 emission;

b. energyizing the heat sources to heat the object by radiant heat energy;

c. discharging compressed air at locations between said heat sources to draw air flow currents by aspiration across each heat source in directions generally perpendicular to the path of radiant heat emission with the air flow currents across the heat sources being directed toware each other;

d. diverting the opposed air flow currents to form a common air stream directed toward the object;

e. whereby the object is heated by radiation and by heated air currents from the heat sources.

23. The method of claim 22 wherein the step of diverting opposed air flow currents is effected by drawing air across a an air deflector structure positioned between the heaters.

Claims

1. A radiation-convection heating system, comprising: a. a source of radiant heat for emitting radiant heat energy therefrom in a given direction; b. aspiration means positioned beside said heat source for inducing convection air flow currents by aspiration across said source and for subsequently directing said currents along paths generally paralleling said given direction; c. whereby objects positioned in the path of said radiant heat energy are heated both by convective air flow currents and by radiation.

5. The heating system of claim 3 wherein said deflector means comprises at least one thin curved plate positioned to establish primary and secondary air flow currents along opposite sides thereof and to effect a combination of said primary and secondary air flow currents and direct the combined flow toward the objects being radiantly heated by said sources.

6. A radiation convection heating system comprising: a. a pair of radiant heat sources disposed in spaced apart relationship for emitting radiant heat energy therefrom in a given direction; b. aspiration means interposed between said sources for inducing convection air flow currents by aspiration across said sources and along air flow paths substantially paralleling said given direction; c. whereby objects positioned in the path of said radiant heat energy are heated by convective air flow currents as well as by radiation.

7. The heating system of claim 6 wherein said aspiration means includes apertured conduit means adapted to be connected to a source of compressed air and being positioned between said radiant heat sources for discharging compressed air in directions generally paralleling said given direction to draw air by aspiration across said radiant heat sources and direct it along paths generally paralleling said given direction.

8. The heating system of claim 7 wherein said aspiration means further includes deflector means interposed betwEen said radiant heat sources and defining an opening therethrough for discharging compressed air, said deflector means being adapted to direct convective air currents passing across said radiant heat sources in directions generally perpendicular to said given direction into flow paths generally paralleling said given direction.

9. The heating system of claim 8 wherein said deflector means comprises at least one thin curved plate positioned to establish primary and secondary air flow currents along opposite sides thereof and to effect a combination of said primary and secondary air flow currents and direct the combined flow toward the objects being radiantly heated by said sources.

10. The heating system of claim 8 wherein said deflector means comprise curved plate portions providing a smooth air flow deflector structure for diverting convective air currents flowing across said radiant heat sources into flow paths generally paralleling said given direction.

11. The heating system of claim 6 wherein said aspiration means includes deflection means for directing air away from said radiant heat sources, for combining the air flow from each of said radiant heat sources, and for directing the combined air flow from said radiant heat sources along paths generally paralleling said given direction.

12. A radiation-convection heating system comprising: a. at least one radiant heat source for emitting radiant energy; b. aspiration means positioned along one side of said heat source to induce air flow acorss said source and to subsequently direct the air flow in said desired direction to effect convection heating of an object positioned within the path of said radiant energy.

13. The heating system of claim 12 wherein said aspiration means further includes air flow deflector means having one side positioned substantially adjacent said heat source and having means for discharging compressed air along the opposite side of said deflector means to induce convective air flow across said heat source and across said deflector means.

14. The heating system of claim 13 wherein said deflector means is curved so as to divert the convective air flow along paths parallel said desired direction.

15. In an oven, the improved heating system comprising: a. a plurality of pairs of radiant heat sources; b. said heat sources being adapted to emit radiant heat energy in given directions toward one or more objects to be heated; and c. said heating sources of each pair having aspiration means interposed therebetween for discharging compressed air in directions generally paralleling given directions to draw air as by aspiration across said heating sources and to direct it along paths generally paralleling said given direction.

16. A radiation-convection heating system comprising a pair of radiant heaters and aspiration means interposed between said heaters for drawing air by aspiration across said heaters in generally opposed directions and for combining the opposed air flows into a common stream of air directed generally parallel to the direction of emission of radiant heat from said heaters.

17. A method of heating an object with a source of radiant heat adapted to emit radiant heat energy along a path in a given direction, comprising the steps of: a. aligning the object with the path of radiant energy emission; b. energizing the heat source to heat the object by means of radiant heat energy; c. providing an aspiration air flow inducing system near the heat source; and, d. operating the aspiration system in such fashion as to draw air across the heat source and direct it toward the object; e. whereby the object is heated by radiation and by heated air currents.

18. The method of claim 17 wherein the aspiration air flow system includes an air deflector positioned beside the heat source for diverting air flow currents passing across the heat source along paths directed toward an object, and the step of operating the aspiratiOn system includes establishing a flow of air beside the air deflector which will draw air currents by aspiration across the heat source whereafter they are directed toward the object by said deflector.

19. A method of heating an object with a pair of spaced radiant heat sources positioned to emit radiant heat energy along paths toward the object, comprising the steps of; a. energizing the heat sources to heat the object by means of radiant heat energy; b. providing an aspiration air flow inducing system between the heat sources; and, c. operating the aspiration system in such fashion as to draw air across both heat sources and direct it toward the object; d. whereby the object is heated by radiation and by heated air currents from the heat sources.

20. The method of claim 19 wherein the aspiration air flow system includes a pair of air deflectors, each interposed between the heater on a separate one of the heat sources and adapted to divert air flow currents passing across its respective heat source along paths directed toward the object, and the step of operating the aspiration system incudes establishing an air flow between the deflectors which will draw air currents across both heat sources and direct such air currents toward the object.

21. The method of claim 20 wherein said deflectors comprise thin curved plates positioned to establish primary and secondary air flow currents from the region of said heaters along opposite sides of said plates and to combine the air flow so produced into a stream of air directed toward the object.

22. A method of heating an object with a pair of spaced radiant heat sources positioned to emit radiant heat energy along a path in a given direction, comprising the steps of: a. aligning the object with the path of radiant heat emission; b. energyizing the heat sources to heat the object by radiant heat energy; c. discharging compressed air at locations between said heat sources to draw air flow currents by aspiration across each heat source in directions generally perpendicular to the path of radiant heat emission with the air flow currents across the heat sources being directed toware each other; d. diverting the opposed air flow currents to form a common air stream directed toward the object; e. whereby the object is heated by radiation and by heated air currents from the heat sources.