A device for uniform heating of the bottom of a pot

Abstract

The application discloses a pot bottom uniform heating device and belongs to the technical field of cookers. The device comprises a profiled cover body which is matched with the outer contour of the pot bottom. The profiled cover body is a whole porous gas-permeable structure. The cover body is fixed to the outer side of the pot bottom and forms a semi-open uniform heating cavity between the cover body and the pot bottom. The device effectively prevents direct contact of the open fire with the pot bottom through the cooperation of the cavity back pressure and the flame quenching effect of the porous gas-permeable structure. The device realizes uniform heating of the pot bottom in combination with high-temperature radiation heat exchange, flue gas convection heat exchange and flameless combustion heat release. The device can effectively solve the problem of local overheating of the pot bottom, slow down the burning of food materials due to sticking to the pot, and has small thermal inertia and fast firepower response, and is suitable for Chinese frying, stir-frying and explosive frying scenes.

Description

Technical Field

[0001] This invention relates to the field of cookware technology, and more specifically to a bottom-mounted heat equalization device adapted to open-flame cooking pots. Background Technology

[0002] Existing open-flame heating methods for pots generally suffer from the problem of flames concentrating in the center of the pot bottom, leading to localized overheating and food easily sticking and burning. To address this issue, various heat-distributing plates, composite-bottom pot bodies, and heat-concentrating covers have emerged on the market, but all have significant drawbacks:

[0003] Traditional cast iron heat spreaders use a thick metal plate structure and rely on the thermal conductivity of the metal itself to achieve uniform heat. However, they have high thermal inertia, slow heating, and sluggish heat response, making them unsuitable for cooking scenarios that require rapid temperature control, such as Chinese frying and stir-frying. In addition, they have low thermal efficiency, increase gas consumption, and have poor radiant heat exchange effect, resulting in insufficient uniform heat distribution.

[0004] The composite bottom pot body adopts a multi-layer composite structure of "stainless steel-aluminum-stainless steel", which is complex and has high manufacturing cost. After long-term high-temperature use, due to the difference in thermal expansion coefficients of different metals, problems such as composite layer detachment and pot bottom deformation are prone to occur, resulting in a short service life. Moreover, it still cannot fundamentally solve the problem of local overheating caused by direct exposure of the pot bottom to an open flame.

[0005] A flame concentrator on a gas stove can only concentrate the flame and reduce heat loss, but it cannot change the way the open flame directly hits the bottom of the pot. The effect of evenly distributing the flame is limited, and some flame concentrators can lead to incomplete combustion, increase CO emissions, and pose safety hazards.

[0006] Existing technologies guide the design of open flame blocking applications based on the premise that "the aperture must be smaller than the static critical flame quenching diameter to achieve open flame blocking." They do not consider the pressure difference between the two ends of the vent. In most high-temperature applications, the aperture is limited to an extremely narrow range. In cookware applications, this makes processing difficult, prone to clogging, and practically difficult to implement.

[0007] The metal fiber combustion plate technology that has emerged in recent years is only applied inside the burner of a gas stove as a flame outlet. The gas burns directly on the plate and is then sprayed onto the bottom of the pot. There is no secondary heating space, so the problems of concentrated flame and large temperature difference at the bottom of the pot still exist. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned defects of the prior art and provide a pot bottom uniform flame device. Based on the flame quenching effect of the porous and breathable structure of the cover and the open flame impact prevention achieved by the cavity back pressure, combined with multiple heat exchange methods, it effectively solves the problem of local overheating caused by the open flame directly hitting the bottom of the pot.

[0009] To facilitate understanding of this invention, the following terms are defined:

[0010] In this invention, the "equivalent pore size" refers to the characteristic dimension used to characterize the air permeability of the air passage: for through holes on solid plates, the equivalent pore size refers to its hydraulic diameter, and the formula for calculating the hydraulic diameter is Dh=4A / P, where A is the cross-sectional area of ​​the through hole and P is the inner circumference of the through hole; for three-dimensional porous materials such as metal fiber sintered felt, metal powder sintered board, porous foam metal, and porous ceramics, the equivalent pore size refers to the average pore size measured by the bubble method.

[0011] In this invention, the "air permeability" refers to the ability of the contoured hood to allow smoke to pass through, which can be characterized or adjusted by at least one of the following parameters: equivalent pore size, porosity, and thickness. The change in air permeability can be achieved by altering the distribution of at least one of the above parameters from the central region to the edge region of the contoured hood.

[0012] In this invention, the "semi-open uniform heating cavity" refers to the space between the contoured cover and the bottom of the pot body that allows for the lateral flow of flue gas. Its core function is to buffer the flue gas, evenly distribute the pressure, and force the flue gas to spread laterally to achieve uniform heating. This space can be achieved in various ways, such as a macroscopic gap reserved between the contoured cover and the bottom of the pot body, or microchannels formed by guiding grooves or protrusions, columns, or reinforcing ribs processed on the outer surface of the bottom of the pot body or the inner surface of the contoured cover facing the pot body. When the contoured cover is made of a continuous porous material with a rough surface, such as metal fiber sintered felt or porous foam metal, after the cover is directly attached to the bottom of the pot, due to the large number of micron-level protrusions on the material surface, the contact surface occupies only a very small part of the surface area, and the remaining area naturally forms tiny gaps that allow for the lateral flow of flue gas. These tiny gaps are functionally equivalent to the macroscopic semi-open uniform heating cavity and should be understood as one implementation of the "semi-open uniform heating cavity" described in this invention.

[0013] In this invention, the "thickness of the semi-open uniform heating cavity" refers to the maximum vertical distance between the two opposing surfaces of the cover and the bottom of the pot, allowing for the lateral flow of flue gas. When there is a macroscopic gap between the two surfaces, this distance is the vertical distance between the two surfaces; when any one or both surfaces are machined with guide grooves, protrusions, columns, or reinforcing ribs, this distance is the maximum vertical distance between the two surfaces, including the bottom of the grooves, protrusions, columns, or reinforcing ribs; when the gap between the two surfaces is only formed by the microscopic morphology of the porous material surface, without macroscopic gaps or microstructures, the macroscopically measured distance is zero, but the microscopic gap still exists, functionally equivalent to a semi-open uniform heating cavity. The thickness range of 0.2 mm to 8.0 mm in this invention is a preferred embodiment and should not be construed as a limitation on the thickness of the semi-open uniform heating cavity.

[0014] In this invention, for continuous porous materials with rough surfaces such as metal fiber sintered felt, porous foam metal, and metal powder sintered plate, the "thickness" refers to the overall thickness of the material measured using the GB / T 24218.2 standard, with a presser foot of 25 square centimeters and a pressure of 1 kPa, rather than the height of a single fiber tip or particle protrusion.

[0015] In this invention, the "breathable support frame" refers to a breathable layer in a composite structure that provides structural support and / or protection for the continuous porous material, arranged within the porous material and / or on the side facing the flame. The breathable support frame needs to be used in conjunction with the porous material layer, and its pore size can be relatively large to significantly reduce obstruction to airflow. The breathable support frame can be a perforated metal plate, metal wire mesh, metal honeycomb, or other rigid breathable structure.

[0016] In this invention, the term "static critical flame quenching diameter" refers to the maximum diameter of an infinitely long straight circular orifice that can prevent flame propagation under static conditions where there is no external airflow disturbance and the wall temperature is the same as the ambient temperature (room temperature). When the orifice diameter is smaller than this diameter, the flame cannot pass through; when the orifice diameter is larger than this diameter, the flame can pass through. The value of this diameter depends on the type of combustible mixture, the stoichiometry, and the ambient temperature. For example, for a methane-air premixed flame (stoichiometry), the static critical flame quenching diameter at room temperature and pressure is approximately 2.0 mm to 3.0 mm. It should be noted that this value varies with factors such as wall temperature, airflow velocity, and orifice length. Under high-temperature conditions (e.g., 800°C), this critical diameter will significantly decrease to approximately 0.3 mm to 0.8 mm. It should be noted that the critical quenching diameter under the above-mentioned high-temperature conditions is a reasonable estimate based on the generally accepted principle that the quenching Pecklet number is approximately constant, and is not a precise measurement under specific experimental conditions. Its purpose is to illustrate the trend that the critical quenching diameter decreases significantly with increasing temperature, rather than to limit the scope of protection of this invention.

[0017] To achieve the above objectives, the present invention adopts the following technical solution:

[0018] A heat equalization device for the bottom of a pot includes a contoured cover that conforms to the outer contour of the bottom of the pot; the contoured cover is a porous and breathable structure; the contoured cover is used to fix to the outside of the bottom of the pot and form a semi-open heat equalization cavity between it and the bottom of the pot.

[0019] This device uses the stabilizing back pressure formed by the combination of the uniform heating chamber and the porous ventilation structure, along with the flame quenching effect of the porous ventilation structure, to prevent the open flame from directly contacting the bottom of the pot. At the same time, it utilizes the radiative heat exchange of the contoured cover, the flameless combustion heat release in the uniform heating chamber, and the convective heat exchange of the high-temperature flue gas to achieve uniform heating of the bottom of the pot.

[0020] The flame quenching effect, combined with the cavity's stabilizing back pressure, allows the equivalent pore size of the porous, permeable structure to be larger than the static critical flame quenching diameter under corresponding operating conditions, reducing processing difficulty and the risk of blockage. For solid plate solutions and porous ceramic solutions with larger pore sizes, since the equivalent pore size of some permeable holes is larger than the static critical flame quenching diameter, the physical obstruction of the stabilizing back pressure is key to flame arrest. For continuous porous materials with smaller pore sizes, such as metal powder sintered plates and porous foam metals, their three-dimensional porous structure itself has extremely strong flame quenching capabilities. In this case, the stabilizing back pressure of the heat equalization cavity mainly plays the role of uniform airflow distribution, avoiding excessively strong central airflow and excessively weak edge airflow, while further enhancing the flame quenching effect and achieving more stable open flame isolation.

[0021] The thickness of the contoured cover ranges from 0.5 mm to 4.0 mm; for solid sheet metal, the thickness is preferably 0.8 mm to 1.5 mm, balancing the machinability of opening holes and structural strength; for continuous porous materials and composite structures, the thickness is preferably 1.0 mm to 3.0 mm, balancing air permeability and quenching effect; for continuous porous materials and composite structures in large-size, high-rigidity scenarios, the thickness can preferably be 3.0 mm to 4.0 mm to improve structural stability and thermal shock resistance.

[0022] The porous breathable structure includes, but is not limited to, the following implementation methods: a number of densely distributed through holes in a solid sheet; sintered metal fiber felt; sintered metal powder board; porous foam metal; porous ceramic material. All of the above-mentioned porous breathable structures can also be directly formed using 3D printing processes adapted to their material systems.

[0023] The equivalent pore size of the through holes on the solid plate ranges from 0.3 mm to 5.0 mm, preferably from 0.5 mm to 3.0 mm; the metal fiber sintered felt is preferably iron-chromium-aluminum alloy fiber sintered felt, with an equivalent pore size of 20 μm to 150 μm and a porosity of 50% to 90%; the equivalent pore size of the metal powder sintered plate is 0.5 μm to 100 μm, with a porosity of 30% to 60%; the equivalent pore size of the porous foam metal is 40 μm to 250 μm, with a porosity of 70% to 95%; and the equivalent pore size of the porous ceramic is 0.5 mm to 3.0 mm, with a porosity of 30% to 60%.

[0024] The permeability of the porous ventilated structure can gradually change from the central region to the edge region of the contoured hood to achieve a more uniform heating effect. It should be noted that the choice of the permeability gradient direction depends on the flow resistance characteristics of the porous ventilated structure itself: when the flow resistance of the porous ventilated structure is sufficient to establish global back pressure without additional throttling structures, it is preferable that the permeability of the central region is less than that of the edge region; when the flow resistance of the porous ventilated structure is insufficient to establish global back pressure, it is preferable that the permeability of the central region is greater than that of the edge region. For different types of porous ventilated structures, the preferred gradient direction is as follows: for solid plates with through-hole structures and porous ceramics, it is preferable that the permeability of the central region is greater than that of the edge region to ensure sufficient high-temperature flue gas can enter the central region, while simultaneously utilizing the throttling effect of the small holes at the edges to establish back pressure; for continuous porous materials with small pore sizes, such as metal fiber sintered felt, metal powder sintered plates, and porous foam metal, it is preferable that the permeability of the central region is less than that of the edge region to actively intercept excess flue gas in the central region using the material's high resistance, forcing it to diffuse towards the edges. The change in air permeability can be achieved by gradually varying at least one parameter, such as equivalent pore size, porosity, or thickness, from the central region to the edge region. When a breathable support frame is used, the gradient distribution of air permeability can also be achieved by changing the width of the frame ribs, the opening area, or the frame thickness.

[0025] The conformal cover can be made of any material with good catalytic activity, high temperature resistance, and corrosion resistance, including but not limited to metal materials, ceramic materials, and composite materials. As a preferred embodiment, the solid sheet is preferably at least one of stainless steel (such as 310S stainless steel, 253MA stainless steel), nickel-based alloy (such as Alloy 330 nickel-based alloy, Alloy 601 nickel-based alloy), and iron-chromium-aluminum alloy; the metal fiber sintered felt is preferably 0Cr. 27 Al7Mo2 iron-chromium-aluminum alloy (such as Kanthal APM fiber felt); the metal powder sintered plate is preferably at least one of iron-chromium-aluminum alloy powder sintered plate, stainless steel powder sintered plate, or nickel-based alloy powder sintered plate; the porous foam metal material is preferably at least one of stainless steel foam, nickel-chromium-based high-temperature resistant alloy foam, or iron-chromium-aluminum foam; the porous ceramic material is preferably at least one of silicon carbide porous ceramic, cordierite porous ceramic, or alumina porous ceramic. The material of the breathable support skeleton can be at least one of stainless steel, nickel-based alloy, or iron-chromium-aluminum alloy. When the porous material is metal, materials with the same alloy system as the porous material layer are preferred to ensure consistent thermal expansion coefficients. It should be noted that the specific grades mentioned above are only preferred embodiments and are not limitations on the present invention. Those skilled in the art can select other materials with similar properties according to actual needs.

[0026] The contoured enclosure can be configured to have asymmetric radiation characteristics, such that the thermal emissivity of its inner surface facing the bottom of the pot is higher than that of its outer surface. The outer surface includes the flame-facing side of the enclosure's bottom and the peripheral surface exposed to the high-temperature flue gas environment. This asymmetric radiation characteristic design enhances radiative heat transfer from the inner surface of the enclosure to the bottom of the pot while suppressing radiative heat loss from the outer surface, thereby further improving the overall thermal efficiency of the device. Methods for achieving this asymmetric radiation characteristic include, but are not limited to: generating a high-emissivity film on the inner surface through in-situ chemical transformation; forming a high-emissivity coating on the inner surface through external coating; maintaining a low emissivity on the outer surface of the enclosure through pre-oxidation passivation or material selection; or a combination of the above methods. It should be noted that while reducing the emissivity of the outer surface of the contoured enclosure will simultaneously reduce its absorption rate of flame radiation according to Kirchhoff's laws, under open flame heating conditions, convective heat transfer is the dominant mode of heat transfer from the flame to the enclosure and is unaffected by surface emissivity. When the enclosure operates at high temperatures, its heat loss through radiation is significant. The energy efficiency gain from suppressing this heat loss outweighs the reduction in heat gain from flame radiation due to decreased absorptivity. Therefore, the low emissivity design of the outer surface of the enclosure contributes to improving the overall net thermal efficiency of the device.

[0027] The thickness of the semi-open uniform heating cavity ranges from 0.2 mm to 8.0 mm, preferably from 1.0 mm to 3.0 mm. This range balances the smooth lateral flow of flue gas and the radiative heat transfer efficiency from the hood to the bottom of the pot. When the thickness is less than 0.2 mm, the resistance to lateral flue gas flow increases, which is not conducive to the uniform spread of flue gas within the cavity; when the thickness is greater than 8.0 mm, the radiative heat transfer efficiency between the hood and the bottom of the pot decreases significantly, affecting the overall thermal efficiency. Within the preferred range of 1.0 mm to 3.0 mm, the lateral flow of flue gas is smooth, and the radiative heat transfer efficiency remains at a high level, achieving a good balance between the two. The thickness of the uniform heating cavity can decrease uniformly or gradually to the edge where the hood connects to the pot body. Preferably, the thickness is greater in the central area and less in the edge area. This gradient design can better match the distribution characteristics of the stove flame, which is strong in the center and weak at the edge: the greater thickness in the central area helps to accommodate more high-temperature flue gas, while reducing the direct radiative impact of the cover on the center of the pot bottom and avoiding local overheating; the smaller thickness in the edge area helps the flue gas to flow faster and be discharged, while enhancing the radiative heat exchange of the cover to the edge of the pot bottom and compensating for insufficient heat at the edge.

[0028] This device does not have a solid heat-conducting interlayer covering the main heat exchange area of ​​the heat-uniforming cavity, and does not rely on solid heat conduction as the primary heat-uniforming method, thus solving the problems of high thermal inertia and slow fire response in traditional heat-uniforming devices. It should be specifically noted that this invention does not exclude the inclusion of any local solid structures within the conformal cover or heat-uniforming cavity, including but not limited to reinforcing ribs, connecting columns, positioning structures, and sealing structures. As long as these local solid structures do not cover the main area of ​​the heat-uniforming cavity and do not constitute the primary heat-uniforming method, they still fall within the protection scope of this invention.

[0029] The core of this invention lies in abandoning the traditional design concept of "using solid heat conduction as the main heat-uniformation method" in heat-uniformation devices, and instead adopting a multi-synergistic heat-uniformation method of "radiation + convection". At the same time, porous materials are applied to the heat-uniformation device at the bottom of the cookware, and combined with the secondary mixing effect of the heat-uniformation cavity, a unity of low thermal inertia, fast response, high heat uniformity and high anti-clogging is achieved.

[0030] The contoured cover can be fixed to the outer bottom of the pot body by any suitable means, including but not limited to welding, snap-fit ​​connection, magnetic connection, clamping, etc.

[0031] The working principle of this invention relies on the process of "high-temperature flue gas entering through holes—back pressure stabilizing the cavity + quenching and flame arresting through porous structure—radiation from the enclosure + flameless combustion + synergistic heat exchange through high-temperature flue gas convection—exhaust through the edge ventilation channel" to achieve uniform heating of the pot bottom, as detailed below:

[0032] Basic power source: High-temperature flue gas through-hole intake. The high-temperature flue gas generated by combustion in the stove gains upward thermal buoyancy due to its lower density than the surrounding air. This thermal buoyancy drives the mixed airflow formed by the high-temperature flue gas and incompletely burned components to overcome the combined resistance of the porous ventilation structure and the stagnant back pressure within the heat equalization chamber. The airflow penetrates the porous ventilation structure on the contoured cover and enters the semi-open heat equalization chamber between the cover and the bottom of the pot. The high-temperature mixed airflow entering the chamber, together with the high-temperature cover directly impacted by the flame below, provides the foundation for subsequent heat exchange and combustion.

[0033] Key to flame suppression: the synergistic effect of stagnant back pressure and flame quenching. High-temperature flue gas and a mixture of incompletely burned components continuously flow into the narrow homogenizing chamber. The gas within the chamber can only escape through a porous, permeable structure. This structure itself provides some throttling damping, and the small chamber volume prevents rapid gas escape. These two factors combine to create stagnant back pressure. This stagnant back pressure is in the opposite direction to the flame propagation, providing continuous reverse resistance to the flame and combustion free radicals attempting to penetrate the permeable channel, thus hindering the upward propagation of the flame. Simultaneously, the homogenizing chamber also serves to uniformly distribute and pressurize the airflow. The porous, breathable structure's wall surface possesses excellent thermal conductivity and catalytic properties: For solid plates with through-hole structures, as the flame propagates along the venting channels, active free radicals in the flame collide with the pore walls and undergo catalytic recombination. Simultaneously, the pore walls rapidly remove heat from the flame through thermal conduction, weakening or interrupting the combustion chain reaction. For continuous porous materials, the flame undergoes multiple refractions and collisions within the three-dimensional porous structure. The extremely large specific surface area of ​​the three-dimensional porous structure can more efficiently capture active free radicals and promote their recombination. Simultaneously, it rapidly removes heat from the flame through thermal conduction, interrupting the combustion chain reaction and achieving flame quenching. The combined effect of physical back pressure blocking and chemical flame quenching ensures that even if the equivalent pore size of the porous, breathable structure is larger than the static critical flame quenching diameter under corresponding operating conditions, it can still effectively prevent open flame from penetrating the venting channels and entering the cavity, avoiding direct contact between the open flame and the bottom of the pot, alleviating localized overheating problems, while not affecting the shape-following cover's absorption of heat from the open flame and radiative heat exchange.

[0034] Airflow circulation and heat exchange: Synergistic heat exchange through radiant heating of the enclosure, flameless combustion, and high-temperature flue gas convection. The contoured enclosure, uniformly heated by the open flame below, forms a high-temperature planar radiator, emitting uniform radiant heat towards the bottom of the pot. This radiant heat is buffered by the air gaps in the homogenizing chamber, becoming more gentle and uniform, preventing localized overheating. The high-temperature flue gas and unburned component mixture entering the homogenizing chamber undergoes initial convection heat exchange with the bottom of the pot within the confined space, while the gas inside the chamber is continuously heated, increasing in temperature and decreasing in density. Simultaneously, the high-temperature flue gas and unburned component mixture entering the channels and homogenizing chamber, containing unburned hydrocarbon components and residual active groups, along with a certain amount of primary mixed air (oxygen), undergoes a flameless oxidation reaction (flameless combustion) in the confined high-temperature environment. For solid sheet metal with through-hole structures and porous ceramics, flameless combustion mainly occurs on the inner surface of the heat-uniforming chamber. For porous materials with smaller pore sizes, such as sintered metal fiber felt, sintered metal powder plates, and porous foamed metal, flameless combustion mainly occurs in the three-dimensional channels inside the material, with the inner surface of the heat-uniforming chamber playing a supplementary role. This flameless combustion has no obvious flame and a uniform combustion temperature, which can further improve the completeness of gas combustion, reduce energy waste and pollutant emissions, and generate high-temperature heat. The high-temperature gas relies on the overall thermal buoyancy to naturally convection upwards and outwards, forming a uniform convective flow field, allowing the hot gas to evenly cover the entire bottom of the pot. The synergistic effect of radiant heat from the chamber, heat generation from flameless combustion, convective heat transfer from high-temperature flue gas, and thermal buffering of the heat-uniforming chamber further improves the heating uniformity of the pot bottom, weakens local hot spots, and makes the temperature tend to be uniform over a large area of ​​the pot bottom. After heat exchange, the gas temperature decreases and the density increases. Driven by thermal buoyancy convection, it is discharged outward through the ventilation channels at the edge of the cover, realizing a complete through-flow airflow cycle of "intake-heat exchange-exhaust". There is no need to set up separate air inlets or exhaust outlets, and all gas exchange is completed by relying on the full-area porous ventilation structure.

[0035] Negative Feedback Mechanism: Ensuring Operating Stability. This device employs a unique negative feedback mechanism that enables flame isolation across a wide aperture range, preventing direct flame impact on the pot body. When the aperture of the venting channel is large, the air intake of a single channel is greater, but the stagnant back pressure within the homogenizing chamber also increases, increasing the reverse resistance to flame penetration and thus compensating for the weakened quenching caused by the increased aperture. When the aperture of the venting channel is small, the material's own flame quenching ability is strong, effectively blocking open flames even with relatively low back pressure. This dynamic balance between aperture and back pressure allows the device to operate stably across a wide aperture range. Even if a small amount of open flame passes through the venting channel, it is buffered by the homogenizing chamber, significantly reducing localized overheating.

[0036] The present invention has the following beneficial effects:

[0037] Innovative Flame-Arresting Mechanism: Breaking through the limitations of traditional designs that rely solely on single-flame quenching, this invention proposes a flame-arresting mechanism that combines cavity back pressure with flame quenching via a porous, permeable structure. This mechanism creates back pressure through the porous, permeable structure and the uniformly heated cavity, which, together with the flame quenching effect of the porous, permeable structure, forms a double flame-arresting barrier. This ensures that even under high-temperature conditions, when the equivalent pore size of the permeable channel is larger than the static critical flame quenching diameter, it can still effectively prevent open flame penetration, significantly expanding the range of pore size selection for the porous, permeable structure.

[0038] Improved heating uniformity and physical non-stick effect. Thanks to the synergistic effect of the stabilizing back pressure and the porous breathable structure, the flue gas entering the semi-open uniform heating chamber can spread evenly within the chamber, effectively avoiding local hot spots and uneven heating. Improved heating uniformity helps form a stable oil film on the bottom of the pot, thus achieving a beneficial physical non-stick effect without relying on chemical coatings. Furthermore, when the thickness of the uniform heating chamber gradually decreases from the central region to the edge region, reaching the edge where the cover connects to the pot body, the larger thickness in the central region helps to accommodate more high-temperature flue gas and reduce local radiative overheating, while the smaller thickness in the edge region facilitates faster flue gas exhaust and enhances radiative heat transfer in the edge region. This gradient design further enhances the uniformity of the pot bottom temperature, allowing the oil film to reach the ideal temperature simultaneously in all areas of the pot bottom, thereby achieving a more stable physical non-stick effect.

[0039] Improved thermal response speed. Compared to traditional solid pot bottom heating methods, this invention eliminates the solid heat-conducting jacket structure covering the main heat exchange area of ​​the uniform heating cavity, resulting in lower overall thermal inertia and faster heating speed. Furthermore, the continuous porous material used in this invention has a very large specific surface area, enabling it to absorb and transfer flame heat more quickly, making the pot's temperature response to changes in heat intensity more sensitive and rapid.

[0040] Improved thermal efficiency and reduced harmful emissions. In traditional cookware, the flame directly impacts the relatively cold bottom of the pot (usually 200-300°C), resulting in a "quenching" effect—the flame front is forced to stop due to contact with the cold wall surface, and some fuel is carried away by the flue gas before it is fully oxidized, causing incomplete combustion and generating harmful substances such as carbon monoxide (CO) and benzene. At the same time, the low temperature of the pot bottom means that heat transfer between the flame and the pot bottom mainly relies on convection, which limits the overall heat transfer efficiency. This invention simultaneously improves thermal efficiency and reduces harmful emissions through the following mechanisms: the high-temperature enclosure reduces the "quenching" effect, allowing the combustion reaction to continue at a high temperature, thus reducing the formation of precursors for harmful substances such as CO and benzene at the source; the high-temperature enclosure and the uniform heating chamber provide a secondary reaction space for unburned combustible components, enabling flameless combustion and releasing some of the chemical energy lost in traditional cookware due to quenching, while simultaneously promoting the oxidation and decomposition of intermediate products such as CO and benzene in a high-temperature, oxygen-rich environment; the combination of high-temperature radiation from the enclosure and convection heat transfer from the flue gas forms a radiation-convection dual-mode heat transfer mechanism, improving heat transfer efficiency; the uniform heating chamber extends the flue gas residence path, reducing exhaust heat loss. Furthermore, the metal oxide surfaces of the enclosure material (such as chromium oxide and aluminum oxide) have catalytic oxidation activity for hydrocarbons, further accelerating the oxidation and decomposition of CO and trace harmful substances, while promoting more complete fuel combustion. Furthermore, when metal fiber sintered felt is used, its three-dimensional porous structure forms an approximate "blackbody cavity" radiation effect, and the high emissivity oxide film on the surface of the iron-chromium-aluminum alloy further enhances the radiation heat transfer capacity and catalytic activity, thereby greatly improving thermal efficiency and further reducing harmful emissions.

[0041] The structure is safe and reliable. There is no risk of gas accumulation in the device. Even if a small amount of unburned gas escapes from the heating chamber, it will be immediately ignited by the open flame below. The device has a simple structure, low manufacturing cost, and requires less modification to the shape and processing technology of conventional pots, making it easy to mass-produce and widely adaptable to various open-flame pots.

[0042] High resistance to clogging. Due to the synergistic effect of stagnant back pressure and flame quenching, the equivalent pore size of the porous ventilated structure can be larger than the static critical flame quenching diameter, reducing the risk of pore blockage due to carbon deposits or oil stains; the continuous porous material has extremely high porosity and a large specific surface area, so even if some pores are blocked, there are still a large number of redundant pores to ensure air permeability; in high-temperature working environments, the porous ventilated structure of the contoured cover has self-cleaning ability, and the oil stains and carbon deposits adhering to the surface of the cover and in the pores are continuously oxidized and burned off at high temperatures, further reducing the possibility of blockage, while eliminating the need for frequent cleaning and reducing maintenance costs. Attached Figure Description

[0043] Figure 1This is a partial sectional view (including a partially enlarged view) of the cookware with a uniform heat distribution device in Embodiment 1 of the present invention, which is an exemplary embodiment of the scheme of using a solid plate with through holes;

[0044] Figure 2 This is a partial sectional view (including a partially enlarged view) of the cookware with a uniform heat distribution device in Embodiment 2 of the present invention, which is an exemplary embodiment of the porous material solution;

[0045] Figure 3 This is a partial sectional view (including a partially enlarged view) of the cookware with a uniform heat distribution device in Embodiment 3 of the present invention, which is an exemplary embodiment of the composite scheme of porous material and breathable frame;

[0046] Figure 4 This is a bottom view of the pot with a uniform heat distribution device in Embodiment 3 of the present invention.

[0047] Explanation of reference numerals in the attached drawings: 1-Pot body; 2-Shaped cover; 3-Through hole (only in Example 1); 21-Porous material layer (only in Example 3); 22-Ventilable support frame (only in Example 3); 4-Heating chamber; 5-Connecting flange (connecting structure). Detailed Implementation

[0048] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the porous permeable structure of the present invention is not limited to a specific form. When using continuous porous materials such as sintered metal fiber felt or porous foam metal, additional through-holes can be made on the material as needed to further adjust the permeability or enhance flue gas circulation. Regardless of whether additional through-holes are made, as long as the contoured cover as a whole is permeable and forms a semi-open uniform heating cavity with the bottom of the pot, it falls within the protection scope of the present invention. It should also be noted that the above-mentioned method for measuring thickness using the GB / T 24218.2 standard is applicable to defining the thickness of materials on planar samples. When the contoured cover is an irregular structure and cannot directly accommodate a standard pressure foot, the thickness value can be obtained through the following equivalent method: using a planar accompanying sample manufactured with the same material and process as the cover, and measuring its thickness under the same conditions; this thickness value represents the nominal thickness of the batch of materials; or selecting a locally flat area on the cover that can accommodate a standard pressure foot for measurement. The thickness values ​​obtained by the above equivalent methods are equivalent to those of the standard method and both fall within the scope of "thickness" described in the present invention.

[0049] In all the following embodiments, the contoured cover 2 is fixed by pressing together with the metal flange 5 on the edge of the pot body 1. It should be noted that the pressing connection is only one embodiment, and those skilled in the art can choose other fixing methods such as welding, snap-fit ​​connection, magnetic connection, clamping, etc., according to actual needs.

[0050] It should be noted that the following embodiments are all described with reference to the heat equalization device at the bottom of the pot body 1 of the present invention. As a preferred method for use in conjunction with it, the outer surface of the bottom of the pot body 1 can also be treated with high radiation absorptivity to improve its thermal radiation absorptivity. When the heat equalization device of the present invention is fixed to the bottom of the pot body 1 after such treatment, the thermal radiation emitted by the inner surface of the contour cover 2 can be efficiently absorbed by the outer surface of the bottom of the pot body 1, thereby forming a highly efficient and synergistic radiative heat exchange pair in the heat equalization cavity, further improving the heating uniformity and overall thermal efficiency of the pot body 1. The high radiation absorptivity treatment at the bottom of the pot body 1 is a preferred method for use in conjunction with this device and does not constitute a limitation on the structure of the heat equalization device itself. Its specific implementation can be carried out using processes known in the art, such as high-temperature oxidation, coating with high-radiation coatings, etc.

[0051] Example 1

[0052] like Figure 1 As shown, this embodiment is designed for natural gas cooking. The contoured cover 2 is made of 253MA stainless steel sheet, with several densely packed through holes 3. The hole diameter is 1.0 mm to 1.5 mm, using a gradient distribution with larger diameters at the center and smaller diameters at the edges. For example, the hole diameter in the central area is 1.5 mm, gradually decreasing to 1.0 mm at the edge. The hole spacing is 3.0 mm to 8.0 mm, with smaller spacing in the central area and larger spacing at the edge, and the opening ratio decreasing from the center to the edge. The thickness of the contoured cover 2 is 1.5 mm. The thickness of the air gap in the heating chamber 4 is 3.0 mm at the center, gradually decreasing to the edge where the cover connects to the pot body. The edge of the pot body 1 is fixed to the contoured cover 2 by pressing together with a connecting flange 5.

[0053] In this embodiment, the contoured cover 2 employs an asymmetric radiation characteristic design: a high-emissivity coating is formed on the inner surface of the contoured cover 2 using an external coating method; the outer surface of the contoured cover 2 (i.e., its fire-facing surface and outer peripheral side) utilizes the high-temperature oxidation resistance of 253MA stainless steel itself, and a dense and bright protective oxide film is formed through pre-oxidation passivation treatment, maintaining a low surface emissivity. This enhances radiative heat transfer to the bottom of the pot body 1 while suppressing outward heat dissipation.

[0054] In this embodiment, the diameter of the through hole is larger than the static critical flame quenching diameter of methane at 800°C, calculated based on generally accepted combustion principles. Through the synergistic effect of the quenching effect and the stabilizing back pressure of the heat-uniforming cavity, this embodiment effectively prevents the open flame from penetrating the through hole and impacting the pot body, thus suppressing localized high-temperature hotspots, even though the through hole is larger than the static critical flame quenching diameter.

[0055] Example 2

[0056] like Figure 2As shown, this embodiment is designed for natural gas cooking conditions. The contoured cover 2 is made of a continuous porous material, 0Cr. 27 Al7Mo2 iron-chromium-aluminum alloy fiber sintered felt (such as the Kanthal APM series commercial fiber felt) has an equivalent pore size range of 100μm to 120μm and a porosity range of 50% to 80%. It employs a radial gradient thickness design, with a central thickness of 3.0 mm, gradually thinning to 1.5 mm towards the edges. This enhances structural rigidity, reduces weight, and achieves a gradient distribution of air permeability that gradually increases from the center to the edges. This gradient distribution utilizes the material's high resistance to actively intercept excess flue gas in the central area, forcing it to diffuse towards the edges for a more uniform heating effect. The air gap thickness in the uniform heating chamber 4 is 2.0 mm at the center, gradually decreasing to the edge where the cover connects to the pot body. The edge of the pot body 1 is fixed to the contoured cover 2 by pressing together with a connecting flange 5.

[0057] In this embodiment, the metal fiber sintered felt, designed with a gradient thickness of 3.0 mm gradually decreasing to 1.5 mm towards the edge, possesses sufficient structural rigidity. Simultaneously, the radial variation in thickness creates a matching back pressure distribution. The material's three-dimensional porous structure provides strong flame quenching capability, which, combined with the auxiliary effect of the heat-uniforming cavity in resisting back pressure, effectively blocks open flame penetration. The high emissivity and low thermal conductivity of the metal fiber sintered felt enhance thermal efficiency and improve uniform flame distribution.

[0058] In this embodiment, the contoured cover 2 adopts an asymmetric radiation characteristic design: the fibers of the inner and outer surface areas of the contoured cover 2 are subjected to differentiated oxidation treatment, so that the fibers of the inner surface area generate a thicker high emissivity oxide film, and the fibers of the outer surface area generate a thinner dense and bright oxide film, thereby enabling the inner surface area to obtain a higher thermal radiation emissivity than the outer surface area, enhancing the net radiation output towards the pot body, while suppressing heat dissipation outward.

[0059] As an alternative implementation, the contoured cover 2 can also use a metal powder sintered plate, porous foam metal, or porous ceramic to replace the metal fiber sintered felt. The overall effect of open flame isolation is based on the synergistic effect of the back pressure stabilizing the heat uniform cavity and the flame quenching of the porous structure. The relative weights of these two effects vary depending on the type of breathable structure.

[0060] When using iron-chromium-aluminum or stainless steel powder sintered plates, the equivalent pore size ranges from 0.5 μm to 100 μm, and the porosity ranges from 30% to 60%. The flame quenching is mainly achieved by the flame quenching of the material's own three-dimensional pores, supplemented by the back pressure of the uniform heating cavity.

[0061] When using iron-chromium-aluminum porous foam metal, the equivalent pore size ranges from 40 μm to 250 μm, and the porosity ranges from 70% to 95%. The flame quenching effect is mainly due to the flame quenching effect of its own three-dimensional skeleton, while the heat uniform cavity plays a synergistic role in resisting back pressure.

[0062] When using silicon carbide or cordierite porous ceramics, the equivalent pore size ranges from 0.5 mm to 3.0 mm, and the porosity ranges from 30% to 60%. The fire-retardant mechanism is consistent with the through-hole scheme of solid plates, with the heat uniform cavity mainly resisting back pressure and the pore wall quenching as a supplement.

[0063] The cover shape, air permeability gradient design, heat equalization cavity structure, and fixing assembly method of the metal powder sintered plate and porous foam metal scheme are consistent with those of the aforementioned metal fiber sintered felt embodiment. The cover shape, heat equalization cavity structure, and fixing assembly method of the porous ceramic scheme can be set with reference to Embodiment 1. The air permeability gradient design is consistent with the solid plate with through holes scheme, and the cover thickness can be set to 3.0 mm. Further details are omitted here.

[0064] All of the above alternative implementation methods can be further combined with asymmetric radiation characteristics. For example, iron-chromium-aluminum powder sintered plates and iron-chromium-aluminum foam metals can achieve a higher emissivity in the inner surface area than in the outer surface area through differentiated oxidation treatment; stainless steel powder sintered plates can have a high-emissivity coating applied to the inner surface area and pre-oxidized and passivated to the outer surface area; porous ceramics can have a high-emissivity coating impregnated on the inner surface and a low-emissivity glaze applied to the outer surface.

[0065] In addition, the aforementioned metal fiber sintered felt, metal powder sintered plate, or porous foam metal scheme can also adopt a gradient material structure, in which the inner layer region uses a high emissivity material and the outer layer region uses a low emissivity material, and is made by co-sintering or one-time molding process, so that the thermal radiation emissivity of the inner surface region is higher than that of the outer surface region.

[0066] Example 3

[0067] like Figure 3 , Figure 4 As shown, this embodiment is designed for natural gas cooking conditions. The porous material layer 21 is made of 0Cr. 27Al7Mo2 iron-chromium-aluminum alloy fiber sintered felt (such as Kanthal APM series commercial fiber felt) has an equivalent pore size range of 100 μm to 120 μm, a porosity range of 50% to 80%, and a thickness of 1.0 mm with uniform distribution. An additional 0.8 mm breathable support frame 22 is added. The porous material layer 21 and the breathable support frame 22 are stacked and sintered to form the contoured cover 2 (marker 2 points to the interface between the porous material layer 21 and the breathable support frame 22, indicating the overall structure formed by the two). The breathable support frame is preferably a perforated plate made of iron-chromium-aluminum alloy sheet. The breathable support frame protrudes from the metal fiber sintered felt layer towards the flame side to protect the metal fiber sintered felt from mechanical impact from the stove support. The air gap thickness of the uniform heating chamber 4 is 2.0 mm at the center, gradually decreasing to the edge where the cover connects to the pot body. The edge of the pot body 1 is fixed to the contoured cover 2 by pressing together with a connecting flange 5.

[0068] In this embodiment, the opening area of ​​the breathable support frame gradually increases from the center area to the edge area. For example, the opening area of ​​the center area accounts for about 30% to 50%, and the opening area of ​​the edge area accounts for about 60% to 80%, so that the air permeability gradually increases from the center area to the edge area to achieve a uniform flow effect.

[0069] This embodiment achieves the decoupling of structural support, protection and thermodynamic functions through a composite structure of a breathable support frame and a metal fiber sintered felt. While retaining the high radiation efficiency and high quenching ability of the metal fiber sintered felt, it significantly improves the overall rigidity and impact resistance of the cover.

[0070] In this embodiment, the contoured cover 2 adopts an asymmetric radiation characteristic design: the inner surface of the inner sintered felt 21 is deeply oxidized to form a thicker, high-emissivity oxide film on its fiber surface; for the exposed sintered felt at the opening of the ventilated support frame and the outer surface of the ventilated support frame, a pre-oxidation passivation treatment is performed to maintain a low surface emissivity, so that the thermal radiation emissivity of the inner surface is higher than that of the outer surface, thereby enhancing the radiative heat transfer to the bottom of the pot. In addition, the ventilated support frame can also be made of a different metal material than the inner sintered felt (such as a nickel-based alloy), utilizing its self-generating low-emissivity oxide film characteristic to obtain a greater difference in emissivity between the inner and outer surfaces.

[0071] The general working process of this device is as follows: The combustion gas burns below the contoured cover 2, and the resulting high-temperature flue gas and incompletely combustible gas form a mixed gas. This mixed gas flows into the semi-open uniform heating cavity 4 between the contoured cover 2 and the pot body 1 through the porous permeable structure on the contoured cover 2. The mixed gas is restricted by the throttling damping of the porous permeable structure and the narrow cavity volume, forming a stagnant back pressure in the uniform heating cavity 4. This, together with the flame quenching effect of the porous permeable structure, prevents the open flame from contacting the bottom of the pot body 1. After being heated by the open flame below, the contoured cover 2 becomes a high-temperature radiator, emitting uniform radiant heat to the bottom of the pot body 1. This synergizes with the flameless combustion and convective heat transfer of the high-temperature gas in the uniform heating cavity 4. The flue gas, after being cooled by heat exchange with the pot body, is discharged outward through the porous permeable structure at the edge of the cover 2, forming a complete through-flow airflow circulation.

[0072] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A heat equalization device for the bottom of a pot, comprising a contour-following cover adapted to the outer contour of the bottom of the pot, characterized in that, The contoured cover is a porous and breathable structure. The contoured cover is used to fix the outer side of the bottom of the pot body and form a semi-open uniform heating cavity between the pot body and the bottom of the pot body. The uniform heating cavity and the porous and breathable structure work together to form a stagnant back pressure when the combustion flue gas continues to enter. The stagnant back pressure works in conjunction with the flame quenching effect of the porous and breathable structure to prevent open flame from penetrating the porous and breathable structure and directly contacting the bottom of the pot body. The contoured cover is heated to form a high-temperature radiator that radiates heat to the bottom of the pot, and the uniform heating cavity contains high-temperature flue gas to form convective heat transfer.

2. The pot bottom heat equalization device according to claim 1, characterized in that, The thickness of the contoured cover ranges from 0.5 mm to 4.0 mm.

3. The pot bottom heat equalization device according to claim 1, characterized in that, The thickness of the semi-open uniform heating cavity ranges from 0.2 mm to 8.0 mm. The thickness of the uniform heating cavity is uniform, or gradually decreases from the central region to the edge region to the edge where the cover and the pot body are connected.

4. The pot bottom heat equalization device according to claim 1, characterized in that, Without setting a solid heat-conducting interlayer covering the main heat exchange area of ​​the uniform heating cavity, the thermal radiation of the contoured cover and the convective heat exchange of the flue gas in the uniform heating cavity directly act on the bottom of the pot body.

5. The pot bottom heat equalization device according to claim 1, characterized in that, The porous breathable structure includes a number of densely distributed through holes formed on a solid plate, wherein the equivalent pore diameter of the through holes ranges from 0.3 mm to 5.0 mm.

6. The pot bottom heat equalization device according to claim 5, characterized in that, The solid sheet is made of metal material, which is selected from stainless steel, nickel-based alloy, and iron-chromium-aluminum alloy.

7. The pot bottom heat equalization device according to claim 1, characterized in that, The porous breathable structure is made of a continuous porous material and has continuous interconnected pores; the porous breathable structure includes at least one porous material layer, or includes at least one porous material layer and at least one breathable support skeleton.

8. The pot bottom heat equalization device according to claim 7, characterized in that, The continuous porous material is at least one of metal fiber sintered felt, metal powder sintered plate, porous foam metal, or porous ceramic.

9. The pot bottom heat equalization device according to claim 8, characterized in that, The metal fiber sintered felt is an iron-chromium-aluminum alloy fiber sintered felt with an equivalent pore size of 20 μm to 150 μm and a porosity of 50% to 90%; the metal powder sintered plate is at least one of an iron-chromium-aluminum alloy powder sintered plate, a stainless steel powder sintered plate, or a nickel-based alloy powder sintered plate with an equivalent pore size of 0.5 μm to 100 μm and a porosity of 30% to 60%; the porous foam metal is at least one of an iron-chromium-aluminum alloy foam metal, a nickel-chromium alloy foam metal, or a stainless steel foam metal with an equivalent pore size of 40 μm to 250 μm and a porosity of 70% to 95%; the porous ceramic is a silicon carbide, cordierite, or alumina porous ceramic with an equivalent pore size of 0.5 mm to 3.0 mm and a porosity of 30% to 60%.

10. The pot bottom heat equalization device according to claim 1, characterized in that, The air permeability of the porous breathable structure gradually changes from the central region to the edge region of the contoured cover; the change in air permeability is achieved by gradually changing at least one of the parameters of equivalent pore size, porosity, and thickness from the central region to the edge region.

11. The pot bottom heat equalization device according to claim 1, characterized in that, The contoured cover has asymmetrical radiation characteristics, with its inner surface facing the bottom of the pot having a higher thermal radiation emissivity than its outer surface; the outer surface includes the flame-facing side surface and the peripheral side surface exposed to the high-temperature flue gas environment.

12. A cookware, characterized in that, It includes a pot body and a pot body bottom heat equalization device according to any one of claims 1 to 11.

Images