Abstract:
An outdoor firepit comprises a vessel adapted to contain a combustible material. A plurality of conduits are within the vessel and are positioned to be in thermal communication with the combustible material. An air source forces air through the plurality of conduits and into an area surrounding the firepit. An apparatus for heating an outdoor area comprises a vessel adapted to contain a combustible material having an inner bowl and an outer bowl and a space therebetween. A plurality of conduits are within the vessel adjacent the inner bowl and are positioned to be in thermal communication with the combustible material. An air source forces air through the plurality of conduits and into the outdoor area surrounding the vessel.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    This invention relates to apparatus and method for heating an outdoor area. 
         [0003]    2. Description of the Related Art 
         [0004]    Outdoor patio fireplaces, heaters, and firepits are used to heat ambient air in selected outdoor areas. These units commonly use radiant heating to heat the area surrounding such a heater. Any convective heating is primarily due to wind currents. As such, the heating effect is primarily limited to areas in close proximity to the heater. 
         [0005]    There is a demonstrated need for an outdoor firepit that provides an enhanced heating area around the firepit. 
       SUMMARY 
       [0006]    The following presents a general summary of several aspects of the present invention. This summary is not an extensive overview of the invention. It is not intended to identify key or critical elements of the invention or to limit the scope of the claims. The following summary merely presents some concepts of the invention in a general form as a prelude to the more detailed description that follows. 
         [0007]    In one aspect, an outdoor firepit comprises a vessel adapted to contain a combustible material. A plurality of conduits is located within the vessel and is positioned to be in thermal communication with the combustible material. An air source forces air through the plurality of conduits and into an area surrounding the firepit. 
         [0008]    In another aspect, an apparatus for heating an outdoor area comprises a vessel adapted to contain a combustible material having an inner bowl and an outer bowl and a space therebetween. A plurality of conduits is located within the vessel adjacent the inner bowl and is positioned to be in thermal communication with the combustible material. An air source forces air through the plurality of conduits and into the outdoor area surrounding the vessel. 
         [0009]    In yet another aspect, a method of heating an outdoor area comprises disposing a plurality of conduits in a vessel. A combustible material is combusted in thermal contact with the plurality of conduits in the vessel. Air is forced through the plurality of conduits such that the air exiting the plurality of conduits heats an area surrounding the vessel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    For detailed understanding of the illustrative embodiments, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein: 
           [0011]      FIG. 1  is a cross-section view of one embodiment; 
           [0012]      FIG. 2A  is a perspective view of one illustrative example of the present invention; 
           [0013]      FIG. 2B  is an exploded perspective view showing a flow manifold and bowl of the firepit of  FIG. 2A ; 
           [0014]      FIG. 3A  is a section view of one illustrative example of a flow conduit for use in one embodiment of the present invention; 
           [0015]      FIG. 3B  is a side view of an exit nozzle of a flow conduit of  FIG. 3A ; 
           [0016]      FIG. 3C  is a top view of an exit nozzle of a flow conduit of  FIG. 3A ; 
           [0017]      FIG. 4A  is a section view of another illustrative embodiment of the present invention; 
           [0018]      FIG. 4B  is a perspective view of an example flow conduit of  FIG. 4A ; 
           [0019]      FIG. 5  is a sketch showing a non-limiting example of an air deflector in a nozzle in one embodiment; 
           [0020]      FIG. 6  is a sketch of a dual-walled vessel having a flow conduit assembly according to one embodiment; 
           [0021]      FIG. 7  is a sketch showing one non-limiting example of a firepit having an air-motor driven fan; 
           [0022]      FIGS. 8A-8D  show non-limiting examples of flow conduits at least partially formed in at least one wall of a firepit; 
           [0023]      FIG. 9  shows a non-limiting example of a flow conduit arrangement; 
           [0024]      FIG. 10  shows another non-limiting example of a flow conduit arrangement; and 
           [0025]      FIG. 11  shows yet another non-limiting example of a flow conduit arrangement. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Described below are several illustrative embodiments of the present invention. They are meant as examples and not as limitations on the claims that follow. For purposes of this disclosure, the terms firepit, outdoor fireplace, patio heater, outdoor space heater, and outdoor heater are intended to mean the same. 
         [0027]    According to one embodiment of the present invention, see  FIGS. 1 ,  2 A,  2 B, a firepit  1  comprises a vessel such as bowl  4  suitable for containing a combustible material  10 . As used herein, the term bowl includes any concave vessel suitable for containing the combustible material  10 . Such shapes include, but are not limited to, rectangular vessels, square vessels, circular vessels, portions of oblate spheroids, and hemispherical vessels. Bowl  4  may be made of any suitable material for containing combusting materials. Such materials include but are not limited to, steel, stainless steel, copper, copper alloys, aluminum, aluminum alloys, ceramic, ceramic coated metal. Stone, masonry, and cement. The term combustible material includes, but is not limited to: wood, charcoal, coal, paper products, liquid and/or gas hydrocarbons, and any other suitable combustible material. In one embodiment, a thermal insulating material  9  is applied to the bottom surface of bowl  4  to reduce the heat loss through the bottom of bowl  4 . Insulating material  9  may be applied by painting, spraying, dipping or any other suitable technique. Insulating material  9  may be made of a fibrous material, a cementitious material, or any other suitable material. 
         [0028]    An inlet tube  12  is located in the bottom surface of bowl  4 . Attached to inlet tube  12  is an air source  7  suitable for providing air at a positive pressure to inlet tube  12 . In one embodiment, air source  7  is a squirrel cage fan providing an air flow  8  upward through inlet tube  12 . As used herein, the term fan is intended to mean any bladed air moving device including, but not limited to, an axial fan, a centrifugal fan, an axial blower, a centrifugal blower, and any other suitable air moving device. A motor  11  is used to power air source  7 . In one embodiment, motor  11  may be an electric motor powered by AC or DC current. Alternatively, motor  11  may be an air driven motor powered by a suitable air supply. 
         [0029]    Air flow  8  from air source  7  is routed through flow conduits  6  placed within bowl  4 . The flow conduits  6  may be part of a manifold assembly  15  (see  FIGS. 2A and 2B ). In one embodiment, as shown in  FIGS. 1 ,  2 A, and  2 B, manifold assembly  15  is removable from inlet tube  12  for ease of cleaning of the firepit and for replacement of a worn and/or damaged manifold. Conduits  6  may be manufactured out of any suitable material, such as, for example, steel, stainless steel, copper, copper alloys, aluminum, aluminum alloys, ceramic, and ceramic coated metal. Heat generated by the combustion of combustible material  10  in bowl  4  is conducted through the walls of conduit  6  and is heats the air flow  8  by thermal conduction and convection. Air flow  8  exits conduit  6  at nozzle  19 . 
         [0030]    In one embodiment, see  FIGS. 3A-3C , nozzle  19  may be shaped to accelerate air flow  8  as it exits nozzle  19 . The accelerated air flow provides an enhanced heating effect at a substantial distance from the firepit. In one example, see  FIG. 3  B, the top side  32  of conduit  19  converges toward the bottom side  33  by an angle α creating a reduced area nozzle causing the air flow  8  to accelerate at the exit of conduit  19 . The angle α may be in the range of about 5 degrees to about 20 degrees. Alternatively, both top side  32  and bottom side  33  may converge. 
         [0031]      FIG. 3C  shows a top view of nozzle  19  where the sides  34  of nozzle  19  diverge at an angle β to spread the flow out to a larger horizontal zone in the vicinity of firepit  1 . The angle β may be in the range of about 5 degrees to about 20 degrees. The angles α and β may be selected such that the net cross sectional area of conduit nozzle  19  reduces toward the exit such that the air flow  8  is accelerated as it flows toward the exit of conduit nozzle  19 . Conduit nozzle  19  may be designed such that the exit velocity may be in the range of about 5 to about 40 feet per second. 
         [0032]    In one illustrative embodiment, a deflector  30  is moveably attached by pin  31  near the exit to conduit nozzle  19  such that air flow  8  may be deflected by deflector  30  as air flow  8  exits conduit nozzle  19 . Any suitable air deflector and attachment method is suitable for the present invention. 
         [0033]      FIGS. 4A and 4B  present another illustrative example of an embodiment of the present invention. As shown therein, firepit  25  has a dual-walled vessel  26  comprising an inner bowl  22  and an outer bowl  20  with a space  27  between the two bowls  22  and  20 . The space between the bowls may be filled with an insulating material  24 . Each bowl  22 ,  20  may be made of a material such as the materials previously described with respect to bowl  4  of  FIG. 1 . Each bowl  22 ,  20  may be made from a different material or both bowls may be made from the same material. 
         [0034]    In one non-limiting example, insulation  24  may be a mineral material, including but not limited to: vermiculite, perlite, sand, and any mixture of these minerals. Alternatively, insulating material  24  may be crushed fiberglass. In yet another alternative, a gas such as air and/or nitrogen may be used as an insulator. In another alternative, the space  27  between the bowls may be evacuated such that a vacuum exists between the bowls  22 ,  20 . 
         [0035]    As shown in  FIG. 4A , air flow  8  is directed through flow channels  23  along the surface of inner bowl  22  and out through conduit nozzle  19 . One non-limiting example of flow channel  23  is shown in  FIG. 4B . Flow channel  23  may have a flange  29  attached to each side. Flange  29  facilitates attachment of flow channel  23  to inner bowl  22 . Such attachment technique may include, but is not limited to, seam welding, tack welding, brazing, soldering, riveting, any combination of these techniques, and any other suitable attachment method. Any number of flow channels  23  may be attached to inner bowl  22 . Alternatively, flow channel  23  may be attached to a single walled vessel as described with reference to  FIG. 1 . 
         [0036]      FIG. 6  presents yet another non-limiting example in which the manifold assembly  15  previously described in  FIG. 2A  is combined with the dual-walled vessel described with respect to  FIG. 4A . 
         [0037]      FIG. 7  presents another non-limiting example wherein an air source  50  supplies a suitable volume of air through supply line  51  to motor  11 . As previously indicated, motor  11  may be an air-driven motor. Any suitable air source may be used including, but not limited to a refillable and/or replaceable storage tank and a compressor. 
         [0038]      FIGS. 8A-8D  illustrate non-limiting examples wherein firepit  85  has a dual-walled vessel  86  having an inner bowl  81  and an outer bowl  83 . Inner bowl  81  has a flow channel  82  formed therein. Flow channel  82  may be formed using any suitable manufacturing technique. In  FIG. 8  B, flow channel  82  has a plate  88  forming the remaining side to form a closed flow conduit. In another example,  FIG. 8  C shows a modified inner bowl  83 ′ having a formed section  89  such that channel  82  and section  89  form a flow conduit. In yet another example,  FIG. 8  D shows inner bowl  81 ′ formed with a channel  82 ′ that extends to outer bowl  83  such that they form a flow conduit for air flow  8 . Edges  84  and  84 ′ may be firmly attached to outer bowls  83 ′ and  83  respectively by welding, brazing, soldering, or any other suitable technique. 
         [0039]    In another non-limiting example, see  FIG. 9 , firepit  95  has curvilinear flow conduits  90  shaped to provide additional heat transfer area for air flow  8  to pass through. This additional area provides enhanced heating of flow  8  as it passes through conduits  90 . 
         [0040]    In even another non-limiting example,  FIG. 10  shows firepit  105  with flow conduits  101  having a vertically elongated cross-section as compared to the conduits described previously. Such a geometry may provide additional heat transfer area as compared to conduits having a substantially horizontally elongated cross-section as shown in  FIGS. 1-9 . 
         [0041]    In another non-limiting example,  FIG. 11  shows firepit  115  with curved vertically elongated conduits  110  that project through the walls of bowl  111  and stand  112 . Such an arrangement may reduce the flow frictional losses in conduits  110  and provide enhanced heated area coverage. 
         [0042]    While various embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the scope of the invention. Accordingly, it is to be understood that the examples of this disclosure have been presented by way of illustrations and not limitation.