Patent Publication Number: US-2006000467-A1

Title: Gas cooking burner with enhanced air entrainment and system and method incorporating same

Description:
BACKGROUND  
      The invention relates generally to gas cooking systems and, more particularly, to gaseous fuel-air mixing techniques in a gas burner of gas cooking systems.  
      Conventional gas cooking systems, such as those found in households, have one or more burners in which gas is mixed with air and burned at a cooktop. To improve combustion and reduce undesirable emissions, these gas burners often mix the gas with air in a primary air entrainment region and a secondary air entrainment region. The primary air entrainment region typically comprises a gas orifice that directs a gas stream into a venturi assembly, such that air is pulled into the gas stream in the space between and surrounding the gas orifice and the venturi assembly. In addition, a fan may blow the air into the gas stream to enhance the primary air entrainment. The resulting gas-air mixture subsequently flows to a plurality of burner ports, which exhaust the gas-air mixture to the cooktop for combustion. The secondary air entrainment region resides directly downstream of these burner ports, where additional air is pulled into the exhausted gas-air mixture. Thus, the primary and second air entrainment regions supplement one another to provide the overall entrainment of air into the gas supplied to the gas burners.  
      Unfortunately, the existing techniques for primary and secondary air entrainment do not sufficiently entrain air into the gas stream, thereby leading to poor combustion and undesirable emissions. This limitation of existing air entrainment techniques is even more apparent for higher gas flow rates. As a result, the flames that burn the gas-air mixture from the gas ports can be characterized as relatively long flames, which may not satisfy the industry standards for fabric ignition at these higher gas flow rates. Accordingly, at the expense of heat output, existing gas cooking systems typically limit the maximum gas flow rate to meet industry standards for fabric ignition and emissions.  
      Accordingly, it would be desirable to develop a gas cooking system that has enhanced burner performance achieved through improved air entrainment into the gas in the gas burner, while satisfying industry standards for emissions and fabric ignition.  
     BRIEF DESCRIPTION  
      In accordance with certain embodiments, the present technique has a gas cooking system including a gas cooking burner that includes a gas line, a first gas port coupled to the gas line, and a second gas port disposed downstream from the first gas port, wherein at least one of the first and second gas ports comprises a non-circular geometry adapted to increase air entrainment, the second gas port further being non-rectangular if the first gas port has a circular geometry.  
      In accordance with certain embodiments, the present technique has a method of operating a gas cooking burner. The method includes receiving a gas from a gas feed line, flowing the gas out through a first gas port for primary air entrainment and passing the gas into a venturi section. The method includes exhausting the gas through a second gas port for secondary air entrainment, wherein at least one of the first and second gas ports comprises a non-circular geometry, the second gas port further being non-rectangular if the first gas port has a circular geometry.  
      In accordance with certain embodiments, the present technique has a method of manufacturing a gas cooking burner including, providing a venturi section, positioning a first gas port directing a gas stream into the venturi section, and disposing a second gas port downstream from the venturi section, wherein at least one of the first and second gas ports comprises a non-circular geometry, the second gas port further being non-rectangular if the first gas port has a circular geometry. 
    
    
     DRAWINGS  
      These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:  
       FIG. 1  is a block diagram illustrating a gas burner system with a gas burner in accordance with embodiments of the present technique;  
       FIG. 2  is a diagrammatical representation of a circular gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 3  is a diagrammatical representation of a multiple opening gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 4  is a diagrammatical representation of a triangular gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 5  is a diagrammatical representation of a rectangular gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 6  is a diagrammatical representation of a pipe elliptical nozzle gas port a gas burner system in accordance with embodiments of the present technique;  
       FIG. 7  is a diagrammatical representation of a linear converging elliptical gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 8  is a diagrammatical representation of a lobed gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 9  is a diagrammatical representation of a daisy shaped gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 10  is a diagrammatical representation of a ring shaped gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 11  is a diagrammatical representation of a chevron shaped gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 12  is a diagrammatical representation of a trip wire across a gas port of a gas burner system in accordance with embodiments of the present technique;  
       FIG. 13  is a flow chart illustrating a process for operating a gas burner system having at least one non-circular gas port in accordance with embodiments of the present technique; and  
       FIG. 14  is a flow chart illustrating a process for manufacturing a gas burner system having at least one non-circular gas port and/or a gas/air temperature differential mechanism in accordance with embodiments of the present technique. 
    
    
     DETAILED DESCRIPTION  
      As discussed in detail below, embodiments of the present technique function to enhance the entrainment of air into gas in a gas burner. In the various embodiments described in detail below, gas comprises a gaseous fuel, such as natural gas, methane, propane, liquefied petroleum gas (LPG), butane, and so forth.  FIG. 1  illustrates a gas cooking system  10 , according to an embodiment, for use in a gas operated cooking appliance, such as, but not limited to, gas stoves, gas cookers, gas hobs, and gas ovens. In the embodiment illustrated in  FIG. 1 , gas cooking system  10  comprises a gas burner unit  12  that receives a supply of combustible gas from a gas line  14  via a pressure regulator  16 . A conduit, such as tubing  18 , then delivers the gas to a first gas port  20 . The gas is then passed into a venturi section  22  and is finally exhausted via the gas burner  24  at the second gas port  26 . In this embodiment, the venturi section  22  comprises a converging-diverging section. Alternatively, the venturi section  22  may comprise a converging section without the subsequent divergent section. The second gas port  26  comprises a plurality of burner ports for secondary air entrainment to generate flames for cooking at the gas burner  24 . The gas burner  24  also comprises a burner cap  28  that is disposed over the gas burner  24 .  
      In operation, the gas burner unit  12  mixes the gas with air in a primary air entrainment region  30  adjacent the first gas port  20  and in a secondary air entrainment region  32  adjacent the second gas port  26 . Specifically, the primary air entrainment region  30  is located around and between the first gas port  20  and the venturi section  22 . In this primary air entrainment region  30 , the abrupt ejection of gas from the first gas port  20  and the venturi section  22  functions to entrain air into the gas flow, thereby providing a preliminary gas-air mixture that collectively flows toward the second gas port  26  further downstream. At the second gas port  26 , the gas-air mixture exits into environmental air at the secondary air entrainment region  32 , which promotes further air entrainment. In this region  32 , the gas burner unit  12  also ignites the gas-air mixture to create a flame for cooking. In the illustrated embodiment, the first gas port  20  comprises a non-circular geometry to increase air entrainment at the primary air entrainment region  30 , while the second gas port  26  may have a variety of circular, rectangular, or non-circular/non-rectangular geometries. In some embodiments, the second gas port  26  may comprise a non-circular/non-rectangular geometry to increase air entrainment at the secondary air entrainment region  32 , while the first gas port  20  may have a variety of circular or non-circular geometries. Moreover, certain embodiments have non-circular or non-circular/non-rectangular geometries for both the first and second ports  20  and  26 . As discussed in further detail below, the non-circular geometry may comprise openings that are oval, elliptical, square, rectangular, triangular, lobed (e.g., cross, daisy), ring-shaped, converging channel, diverging channel, serrated, crown, chevron, split (e.g., by trip wire), or other shapes. Moreover, the non-circular geometry may include a pattern of multiple openings. These non-circular geometries induce turbulence, which substantially increases the entrainment of air into the gas flow.  
      In the presently contemplated embodiment, the gas cooking system  10  comprises a gas/air temperature differential mechanism  36  that is operatively coupled to the primary air entrainment region  30 . The gas/air temperature differential mechanism  36  is adapted to increase a gas/air temperature differential adjacent the first gas port  20 . The increase in the gas/temperature differential is achieved by increasing a density ratio of entrained air relative to the gas by controlling a temperature of the gas and/or the ambient air.  
      In certain embodiments, the gas/air temperature differential mechanism  36  comprises a gas heating mechanism  38  adapted to heat gas flowing through the gas burner  24 . The gas heating mechanism  38  may comprise a variety of active or passive heating mechanisms, such as heat generated by the operation of the gas cooking system  10 . For example, an embodiment of the gas cooking system  10  may be configured such that the gas line  14  passes through an operationally heated region of the gas cooking system  10 . In operation of this embodiment, the heat generated by the gas burner  24  at least partially transfers to the gas line  14 , thereby increasing the gas/air temperature differential. Moreover, certain embodiments of the gas/air temperature differential mechanism  36  have an air cooling mechanism  40  that is adapted to decrease the temperature of air entrained at the first gas port  20 . For example, the air cooling mechanism  40  may comprise a variety of active or passive cooling mechanisms, such as environmental air drawn into the primary air entrainment region  30 . More specifically, embodiments of the air cooling mechanism  40  may include an environmental air channel with an inlet to environmental air remote from the gas burner  24  and having an exit adjacent the first gas port  20 . As will be appreciated by those skilled in the art, a number of variations may be devised for heating and cooling mechanisms  38  and  40  for the gas cooking system  10  performing the function as described above.  
      By way of example,  FIGS. 2-12  diagrammatically illustrate various configurations that may be implemented for the first and/or second gas ports  20  and  26  for the gas cooking system of  FIG. 1 . As illustrated in  FIG. 2 , one configuration  42  comprises a gas port  44  having a circular opening  46  that may be used at one of the first gas port  20  and the second gas port  26  in combination with at least one non-circular configurations of the first and second gas ports  20  and  26 . Alternatively, other embodiments may have non-circular configurations of the first and/or second gas ports  20  and  26 . For example,  FIG. 3  illustrates one exemplary configuration  48  having a plurality of openings  50 , which may serve as the first gas port  20  and/or the second gas port  26 . Further,  FIG. 4  illustrates an alternative configuration  52  having a triangular opening  54 , and  FIG. 5  illustrates an alternative configuration  56  having a rectangular opening  58 .  
       FIGS. 6 and 7  diagrammatically illustrate elliptical configurations for the first gas port  20  and/or the second gas port  26 . For example,  FIG. 6  illustrates an elliptical nozzle  60  having a major diameter (A) 62  and a minor diameter (B) 64 . The elliptical nozzle  60  also may span a length (L) 66 . Alternatively,  FIG. 7  illustrates a converging elliptical nozzle  68  with a tapering section  70  having a circular section  72  at the first end  76  and having an elliptical section  74  at the second end  78 . As illustrated, the circular section  72  has a diameter (D) 80 , which tapers over a length (L) 82  to a major diameter (A) 84  and a minor diameter (B) 86  of the elliptical section  74 . In other embodiments, the first and/or second gas ports  20  and  26  may simply have an elliptical opening, rather than a nozzle structure as illustrated in  FIGS. 6 and 7 .  
       FIG. 8  diagrammatically represents an exemplary lobed configuration  88  that may be employed in one or both of the first and second gas ports  20  and  26 . The illustrated configuration  88  has a nozzle or head  90  with a lobed opening  92 . As shown, the lobed opening  92  comprises a plurality of lobes  94  extending from a core  96 . Specifically, the illustrated lobes  94  extend in four directions from the core  96 , thereby forming a cross-shaped or X-shaped lobed opening  92 . Alternatively, certain other embodiments of the lobed opening  92  may comprise different numbers and configurations of lobes. For example, the lobed opening  92  may comprise one lobe that forms a slot configuration. Further, the lobed opening  92  may comprise a cloverleaf shape or a daisy shape.  FIG. 9  diagrammatically represents an exemplary configuration  98  of a lobed nozzle in a daisy shape. Specifically, the illustrated nozzle  98  has a nozzle  100  with a plurality of lobes  102  extending from a core  104  in a daisy shape.  
      It should be noted that a variety of other non-circular geometries may be employed for the first and/or second gas ports  20  and  26 , thereby enhancing primary and secondary air entrainment. Some other examples of such non-circular ports include a ring shaped opening, a port having a trip wire or a turbulent stimulator that causes a flow of gas to become turbulent and a port having a chevron nozzle with triangular openings at periphery of the nozzle to enhance air entrainment.  FIG. 10  diagrammatically illustrates an exemplary ring shaped configuration  106  for the first gas port  20  and/or the second gas port  26 . The illustrated configuration  106  has a nozzle  108  with an annular ring shaped opening  110 .  FIG. 11  illustrates an exemplary configuration  112  with a nozzle  114  having a chevron  116  to enhance air entrainment. The illustrated configuration has a plurality of triangular protrusions  118  extending from the center  120  of the nozzle  114 .  FIG. 12  illustrates an exemplary configuration  122  of a nozzle  124  having a trip wire  126  attached to the gas port  128  of the nozzle  124 .  
       FIG. 13  illustrates an exemplary process  130  for operating a gas burner system having at least one non-circular gas port in accordance with embodiments of the present technique. The process  130  begins with receiving a gas from a gas feed line (block  132 ). Typically, the gas feed line receives a gas flow from a supply, for example, a gas supply network, gas cylinder, gas tank, and so forth. At block  134 , the process  130  proceeds by flowing the gas from the gas feed line through a first circular/non-circular gas port to achieve primary air entrainment of gas. The first gas port may comprise various non-circular geometries, such as a triangular geometry, a rectangular geometry, a ring-shaped geometry, an elliptical geometry, a lobed geometry, and so forth.  
      Next, at block  136 , the process  130  then proceeds by passing gas flowing out of the first port into a venturi section. The process  130  then proceeds to exhaust the gas through a second circular/non-circular gas port for secondary air entrainment (block  138 ). Again, the geometry of this port may comprise various non-circular, non-rectangular geometries, such as a triangular geometry, a ring-shaped geometry, an elliptical geometry, a lobed geometry, and so forth. Moreover, the process  130  may combust the gas-air mixture to create flames that may be used for cooking activities by a user of the gas cooking system.  
      Moreover, the process  130  described above may comprise the act of increasing a gas/air temperature differential between gas and air adjacent the first gas port via a gas/air temperature differential mechanism (block  140 ). As will be apparent to one skilled in the art, increasing the gas/air temperature differential may comprise heating the gas. Alternatively, increasing the gas/air temperature differential may comprise cooling air entrained at the first gas port.  
      Referring now to  FIG. 14 , an exemplary process  142  for manufacturing a gas burner system having at least one non-circular gas port and/or a gas/air temperature differential mechanism in accordance with embodiments of the present technique is illustrated. The process  142  begins at block  144  by providing a venturi section in the gas burner system. The venturi section may be provided in a vertical setup. At block  146 , the process  142  proceeds by positioning a first circular/non-circular gas port directing a gas stream from a gas line into the venturi section. Next, the process  142  proceeds by disposing a second circular, rectangular, or non-circular/non-rectangular gas port downstream from the venturi section (block  148 ).  
      The process  142  as described above comprises providing non-circular port geometry for at least one of the first and second gas ports to increase the primary and secondary air entrainment, respectively. The process  142  may also include positioning a gas/air temperature differential mechanism adjacent the first gas port (block  150 ) to increase a gas/air temperature differential adjacent the first gas port. The gas/air temperature differential mechanism may comprise a gas heating mechanism to heat gas flowing through the gas burner. Alternatively, the gas/air temperature differential mechanism may comprise an air cooling mechanism to decrease an air temperature of air entrained at the first gas port.  
      The various aspects of the method described hereinabove have utility in gas operated cooking appliances for example, gas cooktops, gas cookers, gas hobs, and gas ovens. As noted above, the method described here may be advantageous for such systems for enhancing primary and secondary air entrainment of gas while satisfying industry standards for emissions and fabric ignition.  
      While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.