FORM-2
THE PATENT ACT,1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
(As Amended)
COMPLETE SPECIFICATION (See section 10;rule 13)
"AN APPARATUS WHICH PROVIDE BETTER FLAME STRUCTURE AND FLAME STABILITY AND INCREASING THERMAL
EFFICIENCY OF LPG DOMESTIC COOKING STOVE"

FIELD OF THE INVENTION
The present invention is related to the field of LPG fuel combustion, in particular to the class of low-pressure LPG cooking stoves that utilize natural draft for the venting of the combustion products/flue gas. Furthermore, this invention is related to the phenomenon of improved combustion. This is related to the thermal efficiency improvement for use in LPG based domestic cooking stoves. This invention particularly relates to an energy efficient LPG cooking stove.
BACKGROUND OF THE INVENTION
Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
A major percentage of population continues to depend on LPG for their cooking needs. The market for LPG fuel usage is mainly dominated by cooking stove systems that typically use liquefied petroleum gas (LPG) as a fuel source. In particular, cooking stoves have redefined the cooking style and conventional kitchen setup in most of the developing nations including India and urbanized groups across the world. Such cooking stoves involve natural draft burners and usually use the energy of the gas injecting jet to pre-mix the gas with a portion of air required for combustion. This required air is called “primary air” and normally accounts for at least 50% of air required for combustion. This mixture is ignited at the burner top where additional air, called “secondary air”, is mixed into the flame, thus providing the remainder of the air required for complete combustion.
In a LPG burner, there are various design parameters such as primary air entrainment, port area and size of holes, design of drip tray and fuel jet, loading height (gap between burner top and vessel), and pan support design which play an important role in its thermal efficiency. Optimization of the above-mentioned design parameters with the help of extensive

experimentation as well as with numerical modelling helps to design the LPG cooking stove components resulting in increased thermal efficiency.
Various arrangements of such gas burners are known in the prior art. US Patent 20080213715 relates controlled, low emissions, combustion and pressurized hydrocarbon gas burners with heat exchanger. However, this burner is not related to the design of natural draft. Indian patent IN 215495 discloses a multi-purpose stove useful for cooking, baking, space heating and drying. The use of the device of this invention is that this multipurpose stove is capable of conducting many heating processes, such as cooking, baking, space heating (room heating) and drying of various materials at a time or separately as per the requirement. One of the main uses of this device is pollution free space heating along with cooking with minimal fuel consumption. However, this patent is for burning solid fuels efficiently.
US Patent 6,093,018 discloses an improved gas burner, comprising: a burner head, a receiving chamber where primary air and fuel gas are mixed. Head containing circumferentially positioned lateral apertures for issuing and uniformly distributing the mixture around the burner head to form a flame. The gas burner provides controlled feeding and admixing of the secondary air directly to the base of the flame that enables the combustion process characterized by high-elevated temperatures. Indian patent 916/CHE/2015 discloses a LPG stove with minimum radiation heat loss by integrating a characterized circular ring in the LPG stove to transfer maximum possible heat to the cooking food, thereby reducing the escape of heat to the surroundings.
Indian patent 113/CHE/2015 discloses a swirling-flow burner assembly that includes a burner tube and an oxidizer supply tube concentric with and spaced from the burner tube, defining an annular fuel gas conduit between the tubes. The burner thermal efficiency is higher by 10-30% than that of conventional burners. Indian patent 1269/KOL/2013 discloses an improved, efficient, cost effective, environmentally compatible and modified LPG stove suitable for all sizes of vessels with reduced heat wastage and enhanced efficiency compared to conventional LPG stoves.
Indian patent 3205/CHE/2010 discloses a device that reduces the consumption of LPG and also reduces the duration of cooking comprising multiple vessels having an inner vessel and an

outer vessel that creates an annular space between them, wherein the outer vessel rests in the lip of the inner vessel and the outer vessel is provided with a hole at the centre of bottom face for entry of flue gas. WO 2011/121609 discloses an apparatus for combustion of gaseous fuel from organic wastes that include biogas burner for domestic cooking purpose having improved thermal efficiency. Indian Patent 3197/DEL/2005 discloses the novel recuperative vortex LPG burner designed and developed to recuperate the exhaust heat to enhance its efficiency. In this burner, fuel and air are introduced separately creating a partially premixed vortex flame in the burner. Swirl is imparted to air to stabilize the flame over a wide range of operating conditions. The burner can be used combustor for running gas turbine engine, rocket engines heating, drying, etc. This is applicable for industrial use and does not directly correlate with use in domestic LPG cooking stoves.
210/KOL/2012 discloses an apparatus designed to overcome the drawback of less availability of air during slow cooking hence blue flame combustion is achieved throughout the entire range of cooking. It offers 55% efficiency, thus increasing the efficiency of the gas burner by 22%, for example, saves 22% LPG. The design can be implemented for CNG or biogas burners by changing the present dimensions of mixing tub, its orifice holes, and gas nozzle. The swirling motion increase the residence time of flame in contact with the cooking pot thus increasing and causing better heat transfer to the cooking pot. Approximately 22% LPG is saved in this newly designed LPG commercial cooking burner in comparison with similar capacity conventional burners at same gas burning rate. Cooking time is reduced by 20% in the new burner in comparison with typical commercial cooking burners at same gas burning rate. This is applicable for industrial use and does not directly correlate with use in domestic LPG cooking stoves.
The domestic cooking stove typically includes a metal burner body that defines a burner chamber with an inlet that receives a mixture of gas and primary air and includes burner holes where the mixture exits and burns in the presence of secondary air. In view of the above, most of the conventional domestic LPG stoves that are well known in the art have typically relied on an open combustion flame, wherein the burner top is used with predefined number of holes with a defined port orientation. The flame profile and combustion depend on the port sizes, orientation and port angles.

Referring to other embodiments, domestic cooking stoves use conventional types of burner tops for combustion underneath the vessel. Efforts have been made so far for improvement in thermal efficiency. However, the disclosed arrangement in the above embodiments may not successfully ensure an effective utilization of thermal inertia supplied from the combustion at the exit of the burner top. Hence, conventional burner tops may require improvement in design to establish an optimum flame impingement at the bottom surface of the vessels.
Furthermore, the flame patterns generated from conventional burner tops also may not be designed to have an effective contact of the flame at the bottom surface of vessels that are of different size ranges. There is also a need for improvement in conventional burner ports with regard to the orientation, port sizes, number of ports, and port angles to generate a desired flame profile for effective combustion.
Thus, there exists a need in the state of art to effectively utilize the heat from fuel and improve upon the combustion, and thereby improving thermal efficiency of LPG stove.
SUMMARY OF THE INVENTION
It is intended that all such features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiment and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
In general, the present invention provides a burner top for a LPG stove for better orientation of flame and increasing the heat flux to the vessel, thereby leading to effective utilisation of combustion heat. In a preferred embodiment, the burner top incorporates 3 circular rows of ports with defined length, inclination angle, diameter and pitch. The burner top also has a machined surface at the bottom for resting the complete burner top on a mixing tube providing a complete sealed interface. The present burner top is to be used in LPG domestic cook stoves suitable for sizes of vessels, for example, with diameter ranging from 200 mm up to 240 mm. A flow passage mixing tube is provided below the body frame for the gas to enter into the inlet port of the burner top from a LPG cylinder. A knob is placed on a predetermined position in the body frame to control gas flow rate from the LPG cylinder. A pan support is fixed on the

top of the whole of the body frame to provide the support area to the vessel used for cooking food. The present burner top is characterized with the angle provided in the ports of the burner top that are circular in shape with predetermined inner and outer diameter, port height and diameter, and a pre-defined pitch for better positioning of the ports.
A burner top for an LPG stove is disclosed here, which comprises an annular burner body, multiple inner ports, multiple outer ports, a first angular tilt of the inner ports, and a second angular tilt of the outer ports. As disclosed herein, the “outer ports” and the “inner ports” refer to inner and outer flame exit ports that are positioned in the inner and outer circumferential surfaces respectively, of the annular burner body. The annular burner body comprises circumferential surfaces of specified thicknesses, where the circumferential surfaces comprise the inner circumferential surface and the outer circumferential surface inclined in opposing directions to each other. The inner ports are uniformly distributed along the inner circumferential surface, where the inner ports are positioned to direct a flame inwardly towards a burner top central area. The inner ports are inclined at a first angle ranging between 25 degrees to 35 degrees towards a burner centre.
The outer ports are uniformly distributed along the outer circumferential surface. The outer ports are positioned to direct the flame outwardly and away from the burner top central area for optimum flame impingement at a bottom surface of a vessel. The outer ports are inclined at a second angle ranging between 125 degrees to 115 degrees towards the burner centre. Here, the second angle is greater than the first angle to define a specific flame structure. The first angular tilt of the inner ports is directed inwardly to the burner centre at an angle slightly rotated from a normal of the inner circumferential surface, wherein the first angular tilt ranges between 35 degrees to 45 degrees. The second angular tilt of the outer ports is directed away from the burner centre at an angle slightly rotated from a normal of the outer circumferential surface, wherein the second angular tilt ranges between 35 degrees to 45 degrees. A combination of the first angular tilt of the inner ports and the second angular tilt of the outer ports generate a rotating flame.
In an embodiment, the burner top is designed with optimum orientation, diameter, and number of the inner and outer ports, along with the first angular tilt of the inner ports, the second angular tilt of the outer ports to improve the thermal efficiency of the burner top. In an embodiment,

the first angle of the inner ports, the second angle of the outer ports, the first angular tilt of the inner ports, and the second angular tilt of the outer ports increase flame stability and flame residence time, which reduces LPG consumption in the LPG stove. In an embodiment, 2 rows of the outer ports are positioned on the outer circumferential surface and 1 row of the inner ports is positioned in the inner circumferential surface.
In an embodiment, a first type of the burner top with a BIS standard IS 4246: 2002 comprises:
a total port area for each of the inner and outer ports ranging between 160 mm2 and 320 mm2;
a port diameter for each of the inner and outer ports ranging between 1.8 mm and 2.2 mm;
number of the inner ports ranging between 16 and 22;
number of the outer ports in an upper row on the outer circumferential surface ranging between
16 and 22; and
number of the outer ports in a lower row on the outer circumferential surface ranging between
32 and 44.
In an embodiment, a second type of the burner top with a BIS standard IS 4246: 2002
comprises:
a total port area for each of the inner and outer ports ranging between 260 mm2 and 480 mm2;
a port diameter for each of the inner and outer ports ranging between 1.8 mm and 2.2 mm;
number of the inner ports ranging between 26 and 32;
number of the outer ports in an upper row on the outer circumferential surface ranging between
26 and 32; and
number of the outer ports in a lower row on the outer circumferential surface ranging between
52 and 64.
In an embodiment, the positioning of the inner and outer ports improves the extent of secondary air utilization from surroundings for complete combustion of gas-air mixture emerging from of the inner and outer ports. In an embodiment, jets of the flame emerge from the inner and outer exit ports to form the rotating flame over the burner top, where the rotating flame impinges on the bottom surface of the vessel to form a rotating and radially swirling flame.
BRIEF DESCRIPTION OF DRAWINGS

The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Figure 1 shows an assembled isometric view of a complete setup of existing design of a domestic LPG stove, as one of its subsystems.
Figure 2 shows an exploded view of a complete setup of existing design of a domestic LPG stove, as one of its subsystems.
Figure 3 shows an isometric view of the burner top, as an example embodiment.
Figure 4A shows a top view of the burner top, as an example embodiment.
Figure 4B shows a side view of the burner top, as an example embodiment.
Figure 5A shows a bottom view of the burner top, as an example embodiment.
Figure 5B shows a detailed view of the burner top based on the portion marked A in Figure 5A, as an example embodiment.
Figure 6A shows a partially sectioned side view of the burner top of the apparatus, according to an exemplary embodiment.
Figures 6B and 6C show detailed view of the inner and outer ports and corresponding angle of orientation of the inner and outer ports of the burner top, according to an exemplary embodiment.
Figure 7 shows the orientation of the inner ports on the inner circumferential surface and the outer ports in an upper and lower row on the outer circumferential surface.
DESCRIPTION OF THE INVENTION

The aim of the present invention is to provide an apparatus for combustion of gaseous fuel or domestic cooking purpose having improved thermal efficiency. The above aims have been achieved through improved combustion and primarily attributing to flame orientation of the combustion flame.
The foregoing advantages as well as the particular construction of the improved gas burner tops will become more noticeable and understandable from the following detail description thereof when read in conjunction with the accompanying drawings.
Figure 1 shows an assembled isometric view of the complete setup of existing design of a domestic LPG stove 100, as one of its subsystems. Figure 2 shows the exploded view of the complete setup of existing design of a domestic LPG stove 100 corresponding to the Figure 1, as one of its subsystems. As shown in the Figure 2, a nozzle holder 202 is machined and fitted to the primary tube 204. Gaseous fuel at line pressure is accelerated into the nozzles 206, and is expelled as jets into the mixing tube 208. At the throat 210 of the mixing tube 208, the air from the atmosphere (primary air) is inducted into the mixing tube 208 due to the negative pressure in the throat 210 and propagates further. The amount of air that is aspirated depends on the opening area of the throat 210, and gas flow rate at the nozzle 206 (or gas exit velocity). In another embodiment, a triangular distributor (not shown) is provided in the cup 214 of mixing tube 200 to smoothen the flow and reduce back-pressure in the side of the mixing tube 200.
The gas being injected from the nozzle 206 accelerates the inducted primary air and mixing of gas and air takes place. Due to the design of the nozzle 206, the gas expands in width as per the spray pattern. The gas and air mixture fills the throat 210 with a relatively high velocity mixture at a slight negative pressure relative to the atmospheric pressure. This high velocity mixture is then decelerated in mixing tube 208 that has a cylindrical pipe 212 attached to the cup 214, resulting in the increase in the static pressure. The straight tube of the mixing tube 208 discharges into a cup portion of the mixing tube which comprises the cup 214 with a profile for the air-gas mixture flow.

The gas at the discharge of the diffuser is at a slight positive pressure and then the air-gas mixture flows into the burner top 216 (Or reference number 102 mentioned in Figure 1). The burner top 216, in general, is a solid end cap having multiple ports on inner and an outer surfaces. The ports are of a pre-determined diameter and placed at a defined pitch. Combustion occurs on the outside of the burner top 216. Since, the LPG stove 100 is used for cooking purposes at home, hence the dip tray 218 is provided to collect the spilled substance. The legs 220 are provided at 4 corners of the burner body 222 to provide the support to the burner body 222 and for providing space for cleaning. Two knobs 224 are provided on the burner body 222 whose position is adjusted from ‘Sim to Full’ enabling the user to control the gas flow rate as per the cooking requirement. Based on the arrangement details provided above, the flame structure exiting from the burner top 216 was observed and analysed in numerical studies.
Figure 3 shows an isometric view of the burner top 300, as an example embodiment. In an embodiment, a burner top 300 is disclosed which increases the thermal efficiency of the LPG domestic cooking stove 100. The burner top 300 includes optimized port inclination angle along with the first and second angular tilt 610 and 612 respectively as shown in Figures 6B and 6C, which increases the flame residence time that effectively reduces LPG consumption in the cooking stove 100. In an embodiment, the burner thermal efficiency is higher by 1.5 ± 0.5% than that of conventional burners. The burner top 300 disclosed here comprises an annular burner body 302, multiple inner ports 304 and multiple outer ports 306 and 308. The annular burner body 302 comprises circumferential surfaces 310 and 312 of specified thicknesses. The circumferential surfaces 310 and 312 comprise an inner circumferential surface 310 and an outer circumferential surface 312 inclined in opposing directions to each other.
Figures 4A and 4B show a top view and side view respectively, of the burner top 300, as an example embodiment. The orientation of the inner ports 304 and the outer ports 306 and 308 is disclosed here in the top view. In an embodiment, 2 rows of the outer ports 306 and 308 are positioned on the outer circumferential surface 312 and 1 row of the inner ports 304 is positioned in the inner circumferential surface 310. The inner and outer ports 304, 306, and 308 are positioned at defined orientations required for a specific flame structure.
With regard to Figures 5A and 5B, Figure 5A shows a bottom view of the burner top 300, and Figure 5B shows a detailed view of the burner top 300 based on the portion marked A in Figure

5A, as an example embodiment. A detailed reference of the specific port inclination, as shown in Figure 5A, shows that the inner and outer ports 304, 306, and 308 that are inclined at an angular tilt to their respective normal surfaces, which is clearly explained in the following Figures 6B and 6C. The benefits of this embodiment of the burner top 300 includes an increased residence time of the flame in contact with the vessel and reduced heating time and LPG usage.
Figure 6A shows a partially sectioned side view of the burner top 300 of the apparatus 100, according to an exemplary embodiment. The inner ports 304 are uniformly distributed along the inner circumferential surface 310 and the inner ports 304 are positioned to direct a flame inwardly towards a burner top central area 602. The inner ports 304 are inclined at a first angle 604 ranging between 25 degrees to 35 degrees towards a burner centre 606. The outer ports 306 and 308 are uniformly distributed along the outer circumferential surface 312. The outer ports 306 and 308 are positioned to direct the flame outwardly and away from the burner top central area 602 for optimum flame impingement at the bottom surface of a vessel. The outer ports 306 and 308 are also inclined at a second angle 608 ranging between 125 degrees to 115 degrees towards the burner centre 606. Here, the second angle 608 is greater than the first angle 604 to define a specific flame structure.
Figure 6B and 6C show detailed views of the inner ports 304 and outer ports 306, and 308 respectively, and corresponding angle of orientation present on the burner top 300, according to an exemplary embodiment. Along with the first angle 604 and the second angle 608 of the inner ports 304 and outer ports 306 and 308 as described in Figure 6A, the burner top 300 also comprises a first angular tilt 610 and a second angular tilt 612 for the inner ports 304 and outer ports 306 and 308, respectively. As shown in Figure 6B, the first angular tilt 610 of the inner ports 304 is directed inwardly to the burner centre 606 at an angle slightly rotated from a normal 310a of the inner circumferential surface 310. The first angular tilt 610 ranges between 35 degrees to 45 degrees. As shown in Figure 6C, the second angular tilt 612 of the outer ports 306 and 308 is directed away from the burner centre 606 at an angle slightly rotated from a normal 312a of the outer circumferential surface 312. The second angular tilt 612 ranges between 35 degrees to 45 degrees. A combination of the first angular tilt 610 of the inner ports 304 and the second angular tilt 612 of the outer ports 306 and 308 generate a rotating flame.

In an embodiment, the burner top 300 is designed with optimum orientation, diameter, and number of the inner ports 304 and the outer ports 306 and 308, along with the first angular tilt 610 of the inner ports 304, the second angular tilt 612 of the outer ports 306 and 308 to improve the thermal efficiency of the burner top 300. The first angle 604 of the inner ports 304, the second angle 608 of the outer ports 306 and 308, the first angular tilt 610 of the inner ports 304, and the second angular tilt 612 of the outer ports 306 and 308 increase flame stability and flame residence time, which reduces LPG consumption in the LPG stove.
Figure 7 shows the orientation of the inner ports 304 on the inner circumferential surface 310, the outer ports 306 and 308 in an upper row 702 and a lower row 704 respectively on the outer circumferential surface 312. In an embodiment, a first type of the burner top 300 with a BIS standard IS 4246: 2002 comprises:
a total port area for each of the inner and outer ports 304, 306, and 308 ranging between 160 mm2 and 320 mm2;
a port diameter for each of the inner and outer ports 304, 306, and 308 ranging between 1.8 mm and 2.2 mm;
number of the inner ports 304 ranging between 16 and 22;
number of the outer ports 306 in an upper row 702 on the outer circumferential surface 312 ranging between 16 and 22; and
number of the outer ports 308 in a lower row 704 on the outer circumferential surface 312 ranging between 32 and 44.
Furthermore, this burner top 300 has an inner diameter in the range between 21mm and 31mm and an outer diameter in the range of 62mm and 72mm, for LPG flow rate of 61 to 65 LPH.
In another embodiment, a second type of the burner top 300 with a BIS standard IS 4246: 2002 comprises:
a total port area for each of the inner and outer ports 304, 306, and 308 ranging between 260 mm2 and 480 mm2;
a port diameter for each of the inner and outer ports 304, 306, and 308 ranging between 1.8 mm and 2.2 mm;
number of the inner ports 304 ranging between 26 and 32;

number of the outer ports 306 in an upper row 702 on the outer circumferential surface 312 ranging between 26 and 32; and
number of the outer ports 308 in a lower row 704 on the outer circumferential surface 312 ranging between 52 and 64.
Furthermore, this burner top 300 has an inner diameter in the range of 25 mm to 35 mm and outer diameter in the range of 73 mm and 83 mm, for LPG flow rate of 71 to 75 LPH.
In an embodiment, positioning of the inner ports 304 and the outer ports 306 and 308 improves the extent of secondary air utilization from surroundings for complete combustion of gas-air mixture emerging from of the inner ports 304 and the outer ports 306 and 308. Jets of the flame emerge from the inner ports 304 and the outer ports 306 and 308 to form the rotating flame over the burner top 300, where the rotating flame impinges on the bottom surface of the vessel to form a rotating and radially swirling flame.
Furthermore, in the embodiment, the lower row 704 of the outer ports 308 of the burner top 300 comprises substantially twice the number of inner ports 304. The burner top 300 is designed with the axes of the inner ports 304 and the outer ports 306 and 308 which are arranged, such that the inner ports 304 and the outer ports 306 and 308 make an angle toward the burner centre 606 (as shown in Figure 6A) with respect to the horizontal plane of the burner top 300, and an angle with respect to the radius of the burner top 300. Hence, the flame jets emerging from the individual inner and outer ports 304, 306 and 308 form a vertical rotating flame over the burner top 300. Then, the rotating flame impinges on the bottom surface of the vessel to be heated.
The inner diameter, pitch, and length of the inner and outer ports 304, 306 and 308, first angle 604 and second angle 608 of port inclination, and the first angular tilt 610 of the inner ports 304 and second angular tilt 612 of the outer ports 306 and 308, are critical for the effective working of the burner top 300. However, reasonable variation in manufacturing of any dimension will not materially affect overall performance. The burner top 300 works for the vessel size ranging with external diameter from, for example, 200mm to 240mm.
The experiments were conducted for thermal efficiency measurement as per IS:4246, wherein all the stipulated conditions were controlled. Upon conducting the experiments by only

replacing the preferred embodiment of the burner top 300, the thermal efficiency was observed to improve, for example, in the range of 1.5 ± 0.5 %. The increase in thermal efficiency is attributed to the reduced time and reduced LPG consumption for the end user.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore, contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

We claim:
1. A burner top for an LPG stove, comprising:
an annular burner body comprising circumferential surfaces of specified thicknesses, wherein the circumferential surfaces comprise an inner circumferential surface and an outer circumferential surface inclined in opposing directions to each other;
a plurality of inner ports uniformly distributed along the inner circumferential surface, wherein the inner ports are positioned to direct a flame inwardly towards a burner top central area, wherein the inner ports are inclined at a first angle ranging between 25 degrees to 35 degrees towards a burner centre;
a plurality of outer ports uniformly distributed along the outer circumferential surface, wherein the outer ports are positioned to direct the flame outwardly and away from the burner top central area for optimum flame impingement at a bottom surface of a vessel, wherein the outer ports are inclined at a second angle ranging between 125 degrees to 115 degrees towards the burner centre, and wherein the second angle is greater than the first angle to define a specific flame structure;
a first angular tilt of the inner ports directed inwardly to the burner centre at an angle slightly rotated from a normal of the inner circumferential surface, wherein the first angular tilt ranges between 35 degrees to 45 degrees; and
a second angular tilt of the outer ports directed away from the burner centre at an angle slightly rotated from a normal of the outer circumferential surface, wherein the second angular tilt ranges between 35 degrees to 45 degrees, and wherein a combination of the first angular tilt of the inner ports and the second angular tilt of the outer ports generate a rotating flame.
2. The burner top as claimed in claim 1, wherein the burner top is designed with optimum orientation of the inner ports and the outer ports, number of the inner ports and the outer ports, the first angular tilt of the inner ports, the second angular tilt of the outer ports, and diameter of each of the inner ports and the outer ports, to improve the thermal efficiency of the burner top.
3. The burner top as claimed in claim 1, wherein the first angle of the inner ports, the second angle of the outer ports, the first angular tilt of the inner ports, and the second angular tilt of

the outer ports increase flame stability and flame residence time, which reduces LPG consumption in the LPG stove.
4. The burner top as claimed in claim 1, wherein 2 rows of the outer ports are positioned on the outer circumferential surface and 1 row of the inner ports is positioned in the inner circumferential surface.
5. The burner top as claimed in claim 1, wherein a first type of the burner top with a BIS standard IS 4246: 2002 comprises:
a total port area for each of the inner and the outer ports ranging between 160 mm2 and 320 mm2;
a port diameter for each of the inner and the outer ports ranging between 1.8 mm and 2.2 mm;
number of the inner ports ranging between 16 and 22;
number of the outer ports in an upper row on the outer circumferential surface ranging between 16 and 22; and
number of the outer ports in a lower row on the outer circumferential surface ranging between 32 and 44.
6. The burner top as claimed in claim 1, wherein a second type of the burner top with a BIS
standard IS 4246: 2002 comprises:
a total port area for each of the inner and the outer ports ranging between 260 mm2 and 480 mm2;
a port diameter for each of the inner and the outer ports ranging between 1.8 mm and 2.2 mm;
number of the inner ports ranging between 26 and 32;
number of the outer ports in an upper row on the outer circumferential surface ranging
between 26 and 32; and
number of the outer ports in a lower row on the outer circumferential surface ranging
between 52 and 64.

7. The burner top as claimed in claim 5, wherein positioning of the inner ports and the outer ports improves the extent of secondary air utilization from surroundings for complete combustion of gas-air mixture emerging from of the inner ports and the outer ports.
8. The burner top as claimed in claim 1, wherein jets of the flame emerge from the inner ports and the outer ports to form the rotating flame over the burner top, wherein the rotating flame impinges on the bottom surface of the vessel to form a rotating and radially swirling flame.