Patent Application
20060000467
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.
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.
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:
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.
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,
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.
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
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.
