WO2008076140A2

WO2008076140A2 - Energy efficient cookware

Info

Publication number: WO2008076140A2
Application number: PCT/US2007/007276
Authority: WO
Inventors: Lee Huang
Original assignee: Lee Huang
Priority date: 2006-12-13
Filing date: 2007-03-23
Publication date: 2008-06-26
Also published as: EP2136687A2; WO2008076140A3

Abstract

Energy efficient cookware is provided that includes a base (204) and a wall (206), a radial pattern of flame guide channels a radial pattern of perturbation channels (216) are connected to the base bottom. The guide channel (208) accepts a flame and guides it to the perimeter from the central region. The perturbation fin (218) generates turbulence in the guided flame to increase heat transfer from the flame to the base and the fins. An insertion plate (700) is disposed on the base top side. The plate has a pattern of boiling nucleation stubs (704) with a venting feature on one side. The stubs (704) interlay liquid input ports (706) and vapor exit ports (708). A volume of the liquid is between the stub and base top. The liquid rapidly vaporizes when the base is heated. The vapor migrates from the stub top surface and through the exit port, where the volume is refilled with liquid from the input port.

Description

PCT PATENT APPLICATION

FOR

ENERGY EFFICIENT COOKWARE

HELD OF THE INVENTION

The invention relates generally to cookware. More particularly, the invention relates to heat transfer from a heating element to cookware, especially from a flame during the cooking process.

BACKGROUND

Cookware is a basic tool used daily in human life. Regardless the different shapes of cookware, ranging from a barbecue grill to a wok and to a teapot, the basic elements of a cookware are two surfaces: one for receiving heat from heat source, the other for heating the food. Heat energy is generated either from electricity, or a burning flame.

The heat is transferred from the source to the heat-receiving surface of the cookware. conducted through the cookware and transferred to the food. Regarding a gas range, it is reported that the efficiency of transferring heat to the pot is only about 48%. This indicates a lot of gas is wasted during the cooking process, in addition to a lot of extra undesirable CO₂ being generated. Tremendous effort has been directed to optimizing the burner to have more complete combustion of the fuels. Also attention has been paid to distribute the heat evenly across the cooking area. However with respect to combustion cooking, there has been limited effort made to improving the energy receiving component of the process, especially to improve the energy transfer efficiency from the flame to the cookware. Some attempts teach concentric grooves on the bottom surface of the cookware, while coating them with radiation absorbing coating to improve the heat absorption. These approaches are considered useful for hot-plate type cooking ranges. Other attempts provide cookware with patterned features that can improve the heat transfer laterally, its primary aim is to improve electric-source heat at the center and bottom of the cookware. Another attempt has been made to improve heat conduction by using concentric rings in the cookware base, however the shallow grooves have demonstrated limited improvement on heat transfer. When used with a flame-source, the proposed concentric rings are perpendicular to the flow of the flames and impede flame contact with the bottom surface. As a result the flow of the flame will go up and down over the rings increasing the inter mixing of the cool air to the hot flame reducing the efficiency of heat transfer. Other attempts have incorporated heat transfer fins along the cookware sides and bottom, where the fins conduct heat from the flame as the flame flows between the fins. However, these heat transfer fins are known to promote a highly laminar flow of the flame along the cookware bottom and sides, thus thick boundary' layers form and reduce the flame interaction with the fins and cookware and limit the heat transfer.

It would be considered an advance in the art to provide efficient cookware, used with a combustion heat source, that promotes flame interaction with the cookware surface. It would also be considered an advance in the art to provide a means of rapid boiling of liquids held in cookware, such as water. Such advances would reduce fuel consumption, and CO₂ emissions.

SUMMARY OF THE INVENTION

The present invention provides energy efficient cookware. The cookware has a cookware body, such as a base and a wall, where the wall extends from the top side of the base and spans a perimeter of the base. The current invention has at least one radial pattern of flame guide channels connected perpendicularly to a bottom side of the base, wherein the flame guide channel is made from a pair of guide fins. The guide fins have a flame entrance end near a center region of the base, and have a flame exit end positioned towards the perimeter of the base. The invention further has at least one radial pattern of perturbation channels connected perpendicularly to the base bottom side, where the perturbation channel is made from a pair of perturbation fins. The perturbation fins have a first perturbation end positioned away from the central region and a second perturbation end positioned towards the cookware perimeter. The flame guide channel accepts a flame from a stove burner and guides it towards the perimeter from the central region. The perturbation fin generates lateral turbulence in the guided flame by interfering with an onset of laminar flow and formation of a thick boundary layer in the flame as the flame moves along the guide channel. The induced turbulence increases heat transfer from the flame to the base and fins, while minimizing mixing of the flame with ambient air. Such induced turbulence promotes conduction of the flame heat through the cookware and to food for more efficient cooking.

In one embodiment of the invention, the cookware body is a dish-shaped body, such as a wok, having a heat receiving surface a food holding surface. In one aspect of the invention, the perturbation channel interlaces the flame guide channel. In another aspect, the radial pattern may be an angled radial pattern, where the pattern angle can be up to 60-degrees from a normal radial pattern. In another aspect of the invention, the pattern may be a linear pattern, where in a further aspect, the linear pattern may be segmented.

In another aspect, the fins may be a linear-shape, S-shaped, curved-shape, or serpentine-shaped. In a further aspect, the fins may be segmented. And in yet another aspect, the perturbation fin may be at least one blunt post.

In one embodiment of the invention, the perturbation channel and the flame guide channel have substantially similar heights, or in another aspect, substantially different heights. In another aspect, the perturbation fins are angled relative to the guide fins.

In another embodiment, the height of the wall is as low as a zero height, as is common for a griddle-type cookware.

In another aspect of the invention, the bottom side of the cookware base and the fins are coated with an infrared heat absorption coating.

In a further aspect of the invention, the surface area of the guide fins, the perturbation fins and the base bottom side have a combined surface area of at least 2 times a surface area of a plain base. In another aspect of the invention, the surfaces of the guide fins, the perturbation fins and the base are textured.

In another embodiment of the invention, the top of the base has base top fins, where the base top fins provide better conduction to a food medium.

In a further embodiment of the invention, the energy efficient cookware has a cookware body that includes a base and a wall, where the wall extends from a top side of the base and about a perimeter of the base. The cookvvare body holds a volume of liquid, and an insertion boiling plate is disposed on the base top side. The insertion plate has a pattern of through-holes and a pattern of boiling nucleation stubs extending from a bottom side of the plate. The stub pattern is interposed with the through-hole pattern, where the interposition divides the through-hole pattern into a set of liquid input ports and a set of vapor exit ports. The stubs have a generally flat top surface and a venting feature on one side. The venting feature is disposed near the vapor exit port and the input ports are disposed on an opposite side and about the stub. The stub flat top surface is disposed to contact the base top side to encompass a finite volume of the liquid that exists between the stub and base top side, where the finite volume of liquid rapidly transitions to a vapor state when the base is heated. The vapor migrates from the stub flat top surface, along the venting feature and through the exit port. The finite volume is refilled with liquid from the input ports.

In one aspect of the invention, the stub flat top surface is generally parallel to the base top side. In another aspect, the stub flat top surface is sloped toward the venting feature. In a further aspect, the slope is flat or cured. In another aspect of the invention, the venting feature is a semicircular cutout from the stub and a chamfer is located at an interface of the flat top surface and the cutout

In another embodiment of the invention, the energy efficient cookvvare has a cookware body that includes a base and a wall, where the wall extends from the top side of the base and spans the perimeter of the base. At least one radial pattern of flame guide channels are connected perpendicularly to the bottom side of the base. The flame guide channel is a pair of guide fins, where the guide fins have a flame entrance end that is proximal to a center region of the base and a flame exit end positioned towards the perimeter. There is at least one radial pattern of perturbation channels connected perpendicularly to the base bottom side, where the perturbation channel is a pair of perturbation fins. The perturbation fins have a first perturbation end positioned away from the central region and a second perturbation end positioned towards the perimeter. The flame guide channel accepts a flame from a stove burner and guides it to the perimeter from the central region. The perturbation fin generates turbulence in the guided flame to increase heat transfer from the flame to the base and the fins while minimizing mixing of the flame with ambient air. This interaction promotes conduction of the heat to the base for efficient cooking. A volume of liquid is held by the a cookvvare body. A boiling insertion plate is disposed on the base top side, where the plate has a pattern of through-holes and a pattern of boiling nucleation stubs extending from the bottom side of the plate. The stub pattern is interposed with the through-hole pattern, where the interposition divides the through-hole pattern into liquid input ports and vapor exit ports. The stubs have a generally flat top surface and a venting feature on one side, where the venting feature is disposed near the vapor exit port, and the input ports are disposed on an opposite side of the stub. The stub flat top surface is disposed to contact the base top side to encompass a finite volume of the liquid that exists between the stub and base top side, The finite volume of liquid rapidly transitions to a vapor state when the base is heated and the vapor migrates from the stub flat top surface, along the venting feature and through the exit port, where the finite volume is refilled with liquid from the input ports.

Some key advantages of the invention include improved energy efficiency by using a greater portion of the flame energy for heating the cookware. The improved efficiency reduces overall cooking fuel expenditures. A further advantage of the invention is that it reduces greenhouse gas emission by requiring less cooking time to heat food, where the source of the cooking flame may be from natural gas, coal, oil or wood, to name a few.

BRIEF DESCRIPTION OF THE FIGURES

The objectives and advantages of the present invention will be understood by reading the following detailed description in conjunction with the drawing, in which: FIG. 1 shows a blunt fin inducing lateral turbulence in a laminar flow field.

FIG. 2 shows a perspective view of a piece of cookware having guide channels and perturbation channels according to one embodiment of the present invention. FIGs. 3a - 3d show a comparison of the flame flow in a guide channel without perturbation fins and a guide channel with perturbation fins according to one embodiment of the present invention. FIG. 4a - 4h show an planar views of different channel patterns according to some embodiments of the present invention. FIGs. 5a - 5b show perspective views of a cookware body having guide and perturbation channels that are the same height and different heights according some embodiments of the current invention.

FIGs. 6a - 6ά show perspective views of different embodiments of the current invention. FIG. 7 shows a planar view of a insertion nucleation boiling plate according to one embodiment of the present invention. FIG. 8 shows a perspective cutaway view of the insertion nucleation boiling plate according to one embodiment of the present invention. FIGs. 9a - 9d show planar views of nucleation bubble growth according to the present invention.

FIG. 10 shows a planar cutaway view of the insertion nucleation plate positioned in a cookware pot having guide and perturbation channels according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Although the folloλving detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will readily appreciate that many variations and alterations to the following exemplary details are within the scope of the invention. Accordingly, the following preferred embodiment of the invention is set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.

The heat transfer process in a typical cooking setup over a gas range includes cookware filled with food medium, for example water. Typically, the cookware is placed on top of the flame from a burner. The flame rises up due to pressure of the gas in the supply piping and the buoyancy of the hot air touches the base of the cookware. Heat transfer from the flame to the base occurs via convection transfer as well as radiation. The heat absorbed from the heat-receiving surface is transferred to the food surface by thermal conduction. The heat is then transfer from the food surface to the water via conduction and convection heat transfer.

The present invention provides effective heat transfer features on a cookware surface to efficiently transfer thermal energy generated from cooking flame sources to the body of the cookware. Efficient flame guide channels and perturbation channels made from fins such as parallel fins, segmented fins, offset fins, louver fins, wavy fins, posts, and pins induce a turbulence in the flame flow and increase flame interaction with the surfaces for enhanced heat exchange. The protruded features have good thermal conductivity and increase the surface area for heat exchange, and at the same time perturb the convection surface layer to increase the heat transfer. Preferably the direction of the heat exchange channels will be about in the flow direction of the flame, such as the radial direction used in most of the gas ranges. Heat transfer efficiency is improved when the flame travels through the flame guide channels and interacts with the perturbation channels to reduce the thickness of the boundary layer, where the effective exchange area is much larger as compared with conventional cookware with flat surface.

Because the perturbation fins provide a lateral perturbation to the flame, the mixing of ambient cool air in the environment with the flame is minimized to reduce heat loss. The surfaces of the channels may be roughened to further perturb the boundary layer at the surface to enhance convective heat transfer.

The invention further provides rapid heating of a volume of liquid by thermally isolating small portions of the liquid for heating to a vapor state, where the vapor is then transferred to the bulk of the liquid by mixing and cooler liquid is transferred to the isolated region. A choked convection flow cycle then exists that enables two-phased heat exchange for improved liquid heat transfer.

Referring to the figures, FIG. 1 shows laminar flow field 100 that interacts with a blunt fin 102 to induce lateral turbulent flow 104, when the flow moves around the leading edge 106 of the blunt fin 102. This effect may be further exploited when the fin 102 has features or has a roughened surface (not shown). Similarly, a blunt leading edge of other body shapes will induce turbulence 104 in the laminar flow 102. FIG. 2 shows a perspective view of a piece of energy efficient cookware 200 according to one embodiment of the present invention. The cookware 200 has a cookware body 202 that includes a base 204 and a wall 206, where the wall 206 extends from the top side of the base 204 and spans a perimeter of the base 204, The current invention has at least one radial pattern of flame guide channels 208 connected perpendicularly to the bottom side of the base 204, wherein the flame guide channel 208 is made from a pair of guide fins 210. The guide fins 210 have a flame entrance end 212 near a center region of the base 204, and have a flame exit end 214 positioned towards the perimeter of the base 204, Further shown is at least one radial pattern of perturbation channels 216 connected perpendicularly to the bottom side of the base 204, where the perturbation channel 216 is made from a pair of perturbation fins 218. The perturbation fin 218 has a first perturbation end 220 positioned away from the central region and a second perturbation end 222 positioned towards the perimeter of the base 204. The flame guide channel 208 accepts a flame from a stove burner (not shown) and guides it towards the perimeter from the central region. The perturbation fin 218 generates lateral turbulence in the guided flame by interfering with an onset of laminar flow in the flame as the flame moves along the guide channel 208. The induced turbulence increases heat transfer from the flame to the base 204 and fins (210/218), while minimizing mixing of the flame with ambient air. Such induced turbulence promotes conduction of the flame heat to cookware and ultimately to the food for more efficient cooking.

The material of the fins (210/218) can be the same as the cookware body 202 or with material of good thermal conductivity. The fins (210/218) can be tailored to the characteristics of the flame used. The height of the fins (210/218) is chosen such that they are at least the thickness of the flame when it flows along the surface of the cookvvare 200. This ensures the heat exchange to happen inside the channels (208/216) formed by the fins (210/218), minimizing the passing of the flame outside of the channels and limiting interaction with cooler ambient air. The width of the guide channels 208 and perturbation channels 216 are chosen to be optimized for flame flow turbidity while ensuring the material should not be too thick or too thin. Such heat efficiency features can be incorporated in all kinds of cookware 200 including woks, frying pans, teapots, saucepans, stockpots, broiler pans, fondue pots, barbecue grills, etc., saving energy and reducing green house gas emission.

According to known fluid dynamics, when a laminar flow passes along guide channels 208, there is a boundary layer between the flame flow and the surface or the guide fin 210, where the velocity of the flow is fastest in the center of the channel 208 and about zero right at the surface of the guide fin 210. The thickness of the boundary affects the heat transfer, where the thicker the boundary layer, the lower the heat transfer. The thickness of the boundary layer increases along the guide fins 210 after the flame first hits the guide fin entrance end 212. To reduce the laminar flow and hence thickness of the boundary layer, perturbation channels 216 are introduced in the guide channels 208. The perturbation fins 218 induce turbulent flow in the guide channels 208 and impede the onset of boundary layers on the guide fins 210 of the guide channel 208, Further, at the perturbation fin trailing edge 222, a wake flow can be formed and further turbulence can be generated.

FIGs. 3a - 3d show a comparison of the flame flow in a guide channel 208 without perturbation fins 218 and a guide channel 208 with perturbation fins 218 according to one embodiment of the present invention. FIG 3a is a perspective view of a guide channel 208 that has no other features included therein. FIG. 3b shows a planar view of flame flow 300 through an open guide channel 208, where shown is an initially turbulent flow 302 introduced to the entrance end 212 of the guide channel 208. As the guide channel 208 widens the thickness of the boundary layer (not shown) increases, thus limiting the heat transfer to the surfaces of the guide fins 210 and cookware base 204. FIG. 3c shows a perspective view of a guide channel 208 having perturbation channels 216 there in. FIG. 3d shows planar view of flame flow 300 through the guide channel 208 with the perturbation channels 216. Here, an initially turbulent flame 302 is introduced to the entrance end 212 of the guide channel 208. As the flame 300 propagates along the guide channel 208 towards the perimeter of the base 204 (see FIG. 2), it interacts with one or more perturbation fins 218 of the perturbation channel 216. where turbulent flow 320 is induced by the first perturbation end 220 of the perturbation fin 218 to impede boundary layer onset. Further shown in this embodiment of the invention are additional perturbation fins 218 inducing additional turbulent flam flow 302. It should be obvious to one skilled in the art that there can be many variations of the size, shape and orientation of the fins (210/218) on the cookware base 204, as described below, without departing from the spirit of the invention.

FIGs. 4a - 4h show an planar views of different patterns of guide channels 208 and perturbation channels 216 in addition to different shapes of the guide fins 210 and the perturbation fins 218 according to some embodiments of the present invention. Shown in FIG. 4a is a radial pattern of guide channels 208 interlaced with perturbation channels 216, where the guide fins 210 and perturbation fins 218 are straight fins. FIG. 4b shows a multi-tiered pattern of perturbation channels 216 interlaced with the guide channels 208. Here, there is one radial pattern of flame guide channels 208 and two radial patterns of perturbation channels 216, where in this embodiment, one pattern of perturbation channels 216 is interlaced with the guide pattern 208, and an additional shorter pattern of perturbation channels 216 is interlaced with both the guide channels 208 and the other pattern of perturbation channels 216. FIG. 4c shows a multi-tiered set of patterns similar to those of FIG. 4b, however the guide fins 210 and the perturbation fins 218 have a serpentine shape, where it should be obvious that an S- shape fin may also be used. FIG. 4d shows a linear pattern of guide fins 210 having a linear pattern of segmented perturbation fins 218 interlaced there between. The linear pattern is particular useful with segmented and continuous fins. The linear pattern is well suited for extrusion manufacturing, in which aluminum alloys with high thermal conductivity can be used, as compared with the aluminum alloys with lower thermal conductivity used in casting. The extruded linear pattern can be also be welded to the wall pieces to form the cookware, or impact bonded to the base of conventional cookware. FIG. 4e shows an angled array of guide channels 208 and an interlaced angled array of perturbation channels 216, where the angle 400 can be as large as 60- degrees from the radial direction shown in FIG. 4a. This configuration is useful for flame sources that burn in an angled radial pattern (not shown).

The angled flame path lengthens the flame contact with the cookware. In addition to matching the angle of the flame, the channels (208/216) may curve toward the tangential direction as they approaching the perimeter of the cookware body 202 (not shown). To further increase the path length, the width of the channels 208 and 216 can be narrowed to allow the channels (208/216) to further extend the path before reaching the perimeter of the cookware body 202. The segmented fins can be offset to further enhance the interrupting effects. It is important to have fin height bigger than the flame flow thickness. This condition helps to ensure the turbulence created by the offset fins will be in the plane that is parallel to the cookware wall, minimizing the turbulence in. the vertical direction which would otherwise increase intermixing of the ambient cool air with the hot flame. FIG. 4f shows segmented fins (210/218). The channels (208/216) can be offset to promote flame turbulence 302. Additional perturbation fins 218 along the radial direction are shown. It is advantageous to design the length of the fins (210/218) and orientation of the channels (208/216) to match the flame flow pattern and flame pattern to achieve optimum results. FIG. 4g shows segmented fins (210/218) having curved shapes. The channels (208/216) are shown here to not only be interlaced but to also alternate as the flame moves from the center outward. Further, the orientation of the fins (210/218) in this embodiment are shown in a segmented-serpentine configuration. FIG. 4h shows an alternate embodiment of the invention, where the perturbation fins 218 are patterns of blunt posts 402 interlaced with the guide channels 208.

Other embodiments include different fin heights and different cookware bodies. Shown in FIGs. 5a and 5b are perspective views of a cookware body 202 having guide channels 208 and perturbation channels 216 that are the same height (FIG. 5a) and different heights (FIG. 5b).

Other embodiments are shown in FIGs. 6a - 6d, where shown in FIGs. 6a and 6b is the cookware body 202 having a dish-shape, such as found with a wok, with the flame guide channels 208 having interlaced perturbation channels 216. Fig. 6c shows the cookware body 202 having the channels (208/216) on the surface of the bottom 204, in addition to heat transfer fins 600 on the inner surface of the cookware body 202. FIG. 6ά shows the cookware body 202 having a flat planar surface, such as found with a griddle, with the flame guide channels 208 having interlaced perturbation channels 216.

To further increase the heat transfer between the flame 300 and the fins (210/218), roughening the surface of the base 204 and the fins (210/218) can further reduce the thickness of a boundary layer (not shown). Adding a heat absorption coating, such as an infrared coating, to the respective surfaces can further improve the heat transfer.

Inside the cookware 200, heat is transferred from the wall 206 to a food medium such as water. This heat transfer takes place in form of conduction and convection. Initially, heat is transferred to the water mainly from conduction. As the water temperature rises, convective motion forces the warm water to rise and cooler water then moves down to replenish the displaced warm water. During these two types of heat transfer, there is no phase transition involved. However, a nucleation boiling process can be used to improve the energy efficiency of the cookware 200. Nucleation is the onset of a phase transition in a small region, where the phase transition for water is the formation of a bubble. In the boiling process, water undergoes phase transition from a liquid state to a vapor state after absorbing an extra amount of energy known as latent heat of vaporization. The heat transfer coefficient for water at the peak of a nucleation boiling curve is called critical heat flux. This coefficient of heat transfer is significantly higher than both the conduction and convection transfer combined. Therefore it is very advantageous to utilize boiling nucleation to enhance heat transfer to liquid. In one embodiment of the invention, and shown in FIGs. 7 - 10, a boiling insert plate 700 is used to accelerate the heat transfer to water by heating, to a boiling state, small volumes of water that are isolated from the larger bulk volume. In this embodiment, the vapor generated in the isolated regions is then allowed to mix with rest of the liquid mass. Another volume of water replaces the mixed vapor and is isolated then heated to a boiling state, where the vapor again mixes with the rest of the bulk water. The process is continued until temperature of the bulk of water is raised to a targeted temperature. In this embodiment, the isolated water portion is relatively thermally separate from the rest of the bulk water and is heated to boiling independently.

Referring to FIG. 7, where shown is a planar view of an insertion boiling plate 700 according to one embodiment of the present invention. The insertion plate 700 is a flat plate 702 that has a through-hole pattern and a pattern of boiling nucleation stubs 704 extending from a bottom side of the plate 702. The pattern of stubs 704 are interposed with the through-hole pattern, where the interposition divides the through-hole pattern into a set of liquid input ports 706 and a set of vapor exit ports 708.

FIG. 8 shows a perspective cutaway view of the insertion nucleation boiling plate 700 according to one embodiment of the present invention. The stubs 704 have a generally flat top surface 800 and a venting feature 802 on one side. The venting feature is further shown with a chamfer 804 along the edge to enable vapor to move to the exit port 708. The venting feature 802 is disposed near the vapor exit port 708 and the liquid input port 706 is disposed on an opposite side of and about the stub 704. FIGS. 9a - 9d show planar views of nucleation bubble growth according to the present invention. The stub flat top surface 800 is disposed to contact, or near contact, with the base top side 900 to encompass a finite volume of the liquid that exists between the stub 802 and base top side 900, where the finite volume of liquid rapidly transitions to a vapor state when the base 200 is heated. FIG. 9a shows the formation of nucleation site in the form of a small bubble 902. As the bubble 902 grows, as shown in FIGs. 9b and 9c, the vapor migrates from the stub flat top surface 800 and along the venting feature 802 and through the exit port 708. The finite volume is refilled with liquid from the input ports 708 (not shown). FIG. 9d shows an alternate embodiment of the invention, where the flat top surface 800 is angled toward the exit port 708. Additionally, roughening the surface of the flat top 800 and the base top side 900 will improve the boiling by increasing number of the sites for nucleation.

The plate 702 divides the cookware volume into two regions, where one region is the bulk water above the plate 702 and the other region is the nucleation boiling region below the plate 702. Once the water in the nucleation boiling region undergoes a phase change, the vapor is mixed with the bulk water. When the isolated volume at the stub flat top surface 800 is emptied through the vapor exit ports 708, the cooler water will move down the liquid input ports 706 to fill the isolated volume to be heated. After the vapor exits from the exit port 708, the tension of the liquid prevents it from moving back to the narrow gap of the isolated volume to preserve the vapor nucleate, therefore preserving the vaporizing boundary. This ensures a constant nucleate cavity for nucleate boiling. The process continues to heat the entire volume of the water. In an alternate embodiment, two different regions can be made in the plate 702. A center region where the hole size passes the water efficiently, and a ring region with holes sized to pass vapor efficiently (not shown). Such a configuration would be useful for a donut-shaped flame. In such a configuration, the majority of the heat absorption in the water is in the ring of vapor holes, where the water in that region is vaporized earlier, and the vapor passes through the vapor holes. Further, cooler water comes down from the holes into the center region to be further heated and vaporized. This forms a free convection circulation of the two phases of the material is involved. This choked convection process involves phase change from liquid phase and to vapor phase and then from vapor phase to liquid phase again. The material of the plate 702 is preferable to have high thermal resistance yet safe for using in cookware, such as Teflon, ceramic, glass, etc. The contact location of the heating surface 900 can be further coated with non-wetting material. The non-wetting material will further reduce the chance of water residing at the contact location and therefore improve the chance of vapor formation.

FIG. 10 shows a planar cutaway view of the insertion nucleation plate 700 positioned in a cookware body 202 according to one embodiment of the present invention. As shown, the guide channels 208 and the perturbation channels 216 are attached to the base 204, and the insertion nucleation plate 700 is inserted to contact the base top side 900, where a finite volume exists between the stub 802 and base top side 900.

The present invention has now been described in accordance with several exemplary embodiments, which are intended to be illustrative in all aspects, rather than restrictive. Thus, the present invention is capable of many variations in detailed implementation, which may be derived from the description contained herein by a person of ordinary skill in the art. For example the fins may include perturbation features such as bumps or protrusions that further induce turbulence in the flame flow. Additionally, the segmented perturbation fins can be arranged in random orientations to increase turbulence.

All such variations are considered to be within the scope and spirit of the present invention as defined by the following claims and their legal equivalents.

Claims

CLAIMS What is claimed:

1. Energy efficient cookware comprising: a. a cookware body, wherein said body comprising a base and a wall, whereby said wall extends from a top side of said base and spans a perimeter of said base; b. at least one radial pattern of flame guide channels connected perpendicularly to a bottom side of said base, wherein said flame guide channel comprises a pair of guide fins, whereby said guide fin comprises a flame entrance end that is proximal to a center region of said base and a flame exit end positioned towards said perimeter; and c. at least one radial pattern of perturbation channels connected perpendicularly to said base bottom side, wherein said perturbation channel comprises a pair of perturbation fins, whereby said perturbation fin comprises a first perturbation end positioned away from said central region and a second perturbation end positioned towards said perimeter; and wherein said flame guide channel accepts a flame from a stove burner and guides said flame to said perimeter from said central region, whereby said perturbation fin generates turbulence in said guided flame to increase heat transfer from said flame to said base and said fins for efficient cooking.

2. The cookware of claim 1, wherein said perturbation channel interlaces said flame guide channel.

3. The cookvvare of claim 1, wherein said body is a dish-shaped body having a heat receiving surface a food holding surface.

4. The cookware of claim 1, wherein said radial patterns are linear patterns.

5. The cookware of claim 4, wherein said linear pattern is segmented.

6. The cookware of claim 1 , wherein said perturbation channel and said flame guide channel have substantially similar heights.

7. The cookware of claim 1, wherein said perturbation channel and said flame guide channel have substantially different heights.

8. The cookware of claim 1 , wherein said fins have shapes selected from a group comprising segmented, linear, S-shaped, curved, and serpentine- shaped.

9. The cookware of claim 1, wherein said perturbation fins are angled relative to said guide fins.

10. The cookware of claim 1, wherein a height of said wall is as low as a zero height.

11. The cookware of claim 1, wherein said perturbation fin is at least one blunt post.

12. The cookware of claim 1 , wherein said bottom side and said fins are coated with an infrared heat absorption coating.

13. The cookware of claim 1, wherein a surface area of said guide fins and a surface area of said perturbation fins and a surface area of said base bottom side comprise a combined surface area at least 2 times a surface area of said base bottom,

14. The cookware of claim 1 , wherein a surface of said guide fins and a surface of said perturbation fins and said base said surface area are textured.

15. The cookware of claim 1 , wherein said radial pattern is an angled radial pattern, whereby said angled radial pattern comprises an angle up to 60- degrees from said radial pattern.

16. The cookware of claim 15, wherein said channels of said angled radial pattern further angle towards a tangential direction of said perimeter, whereby said channels become narrower at said perimeter of said cookware base.

17. The cookware of claim 1, wherein said cookware further comprises base top fins, whereby said base top fins provide better conduction to a food medium.

18. Energy efficient cookware comprising; a. a cookware body, wherein said body comprising a base and a wall, whereby said wall extends from a top side of said base and about a perimeter of said base, and wherein said cookware body holds a volume of liquid; b. an insertion plate disposed on said base top side, wherein said plate comprises: i. a pattern of through-holes in said plate; ii. a pattern of boiling nucleation stubs extending from a bottom side of said plate, wherein said stub pattern is interposed with said through-hole pattern, whereby said interposition divides said through-hole pattern into a set of liquid input ports and a set of vapor exit ports, and wherein said stubs comprise a generally fiat top surface and a venting feature on one side, whereby said venting feature is disposed near said vapor exit port and said input port is disposed on an opposite side of said stub; and c. wherein said stub flat top surface is disposed to contact said base top side to encompass a finite volume of said liquid, whereby said finite volume of liquid rapidly transitions to a vapor state when said base is heated and said vapor migrates from said stub flat top surface and along said venting feature and through said exit port, and whereby said finite volume is refilled with liquid from said input port.

19. The cookware of claim 18, wherein said stub flat top surface is generally parallel to said base top side.

20. The cookware of claim 18, wherein said stub flat top surface is sloped toward said venting feature.

21. The cookware of claim 20, wherein said slope is flat or cured.

22, The cookware of claim 18, wherein said venting feature comprises semicircular cutout from said stub and a chamfer at an interface of said flat top surface and said cutout.

23. Energy efficient cookware comprising: a. a cookware body, wherein said body comprising a base and a wall, whereby said wall extends from a top side of said base and spans a perimeter of said base; b. at least one radial pattern of flame guide channels connected perpendicularly to a bottom side of said base, wherein said flame guide channel comprises a pair of guide fins, whereby said guide fin comprises a flame entrance end that is proximal to a center region of said base and a flame exit end positioned towards said perimeter; c. at least one radial pattern of perturbation channels connected perpendicularly to said base bottom side, wherein said perturbation channel comprises a pair of perturbation fins, whereby said perturbation fin comprises a first perturbation end positioned away from said central region and a second perturbation end positioned towards said perimeter; and wherein said flame guide channel accepts a flame from a stove burner and guides said flame to said perimeter from said central region, whereby said perturbation fin generates turbulence in said guided flame to increase heat transfer from said flame to said base and said fins for efficient cooking.; d. a volume of liquid held by said a cookware body; e. an insertion plate disposed on said base top side, wherein said plate comprises: i. a pattern of through-holes in said plate; ii. a pattern of boiling nucleation stubs extending from a bottom side of said plate, wherein said stub pattern is interposed with said through-hole pattern, whereby said interposition divides said through-hole pattern into liquid input ports and vapor exit ports, and wherein said stubs comprise a generally flat top surface and a venting feature on one side, whereby said venting feature is disposed near said vapor exit port and said input port is disposed on an opposite side of said stub; and f. wherein said stub flat top surface is disposed to contact said base top side to encompass a finite volume of said liquid, whereby said finite volume of liquid rapidly transitions to a vapor state when said base is heated and said vapor migrates from said stub flat top surface and along said venting feature and through said exit port, and whereby said finite volume is refilled with liquid from said input port.