Electric barbecue oven with improved convective heat transfer

Abstract

A cooking system includes: a cooking chamber having a cooking surface therein; at least one resistive heating element that provides heat to the cooking surface; the alternating current connection is used for supplying power to the resistance heating element; and a direct current source.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 343,792 filed on May 19, 2022, and such provisional application is incorporated by reference into the present disclosure as if fully set forth on this point. Technical Field

[0002] The present disclosure relates generally to electric barbecues, and more particularly to improvements in heating within such barbecues. Background Art

[0003] Current electric grills use the available alternating current (AC) grid power supplied to the house to power The heating element is energized. When voltage is applied to the resistor inside the heating element, the resistance to the current causes heat energy to be generated inside the heating element. The temperature at the surface of the heating element increases, and its outer surface begins to radiate heat. The radiant heat generated by the heating element provides heat to the cooking surface, which is typically an open cooking grate, which shares the same principle as the grate used in a convection gas grill.

[0004] Grills that generate heat from combustible fuels, such as gas grills or charcoal grills, benefit from multiple heat transfer mechanisms, including both radiative and convective transfer. Electric grills lack energy transfer into the cooking chamber via mass transfer (e.g., combustion products generated in gas grills or charcoal grills). This results in longer initial preheat times for the grill, longer recovery times, and lower temperatures and heat available for cooking inside the cooking chamber.

[0005] The lack of convection heating also contributes to the negative impact of heat losses inside the cooking chamber volume after the lid is opened during cooking. This problem cannot be solved simply by increasing the rate of energy generation or the power intensity in the heating element. In fact, in many cases, even the heat potentially available from the power grid cannot be fully utilized because the high heat generation rate in the resistors inside the heating element leads to thermal damage of the component due to the lack of sufficient heat transfer from the component surface to the surrounding air. In addition, the radiative nature of the electric heating element design causes a large portion of the generated heat to be radiated away from the cooking surface.

[0006] What are needed are systems and methods for addressing the above-referenced and related problems. Summary of the invention

[0007] The disclosed invention includes, in one aspect thereof, a cooking system comprising: a cooking chamber having a cooking surface therein; at least one resistive heating element that provides heat to the cooking surface; an AC current connection for powering the resistive heating element; and a DC current source that selectively powers the at least one resistive heating element simultaneously with the AC current connection.

[0008] In some embodiments, the DC current source comprises a chemical battery.The DC current source may comprise a capacitor.

[0009] The cooking system may also include at least one temperature probe that measures a temperature associated with the cooking chamber. The system may include a control circuit that selectively activates a DC current source based on a reading obtained from the at least one temperature probe. The at least one temperature probe may include a cooking chamber temperature probe and a resistive heating element temperature probe. The at least one resistive heating element may include at least a first resistive heating element powered by an AC current connection and at least a second resistive heating element powered by a DC current source. Prior to activating the DC current source to power the at least one resistive heating element, the control circuit may determine whether a difference between a set point temperature and a temperature from the at least one probe exceeds a boost threshold. In some embodiments, the AC current connection recharges the DC current source.

[0010] The system may have an air duct providing fluid communication from the resistive heating element to the cooking chamber. The air duct may be provided with at least one damper to selectively inhibit air flow. At least one fan may provide air flow within the air duct. At least one additional resistive heat source may be in the air duct.

[0011] The system may include a component box below the cooking surface, with at least one resistive heating element housed therein. Some embodiments include a controller that controls operation of the at least one resistive heating element and at least one damper.

[0012] The disclosed invention includes, in another aspect thereof, a cooking device comprising: a cooking cavity having a cooking surface therein; a component box below the cooking cavity; a resistive heating element in the component box; an AC current power source connection; a DC current power source; an air duct providing fluid communication between the component box and the cooking cavity; and a fan operable to move air from the component box through the air duct to the cooking cavity. The resistive heating element is powered by the AC current power connection and the DC current power source.

[0013] The apparatus may also include: a first auxiliary heating element in the element box and powered by a DC current power source; a second auxiliary heating element in the air duct; and a plurality of dampers that control air flow from the air duct into the cooking cavity. In some embodiments, the controller selectively operates the fan and opens the plurality of dampers based at least on a temperature probe reading from the cooking cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a control schematic diagram of an electric cooking grill having improved convection heating characteristics according to the present disclosure.

[0015] Figure 2 is a schematic diagram of an electric cooking grill having improved convection heating characteristics according to the present disclosure.

[0016] Figure 3 is a schematic diagram of another electric cooking grill having improved convection heating characteristics according to the present disclosure.

[0017] Figure 4 is a simplified schematic circuit diagram of an electric cooking grill having improved convection heating characteristics in accordance with the present disclosure.

[0018] Figure 5 is a simplified schematic circuit diagram of an electric cooking grill with improved convection heating characteristics utilizing supercapacitors in accordance with the present disclosure.

[0019] Figure 6 is a simplified schematic circuit diagram of an electric cooking grill with improved convection heating characteristics utilizing both batteries and supercapacitors in accordance with the present disclosure.

[0020] Figure 7 is a flow chart depicting a control method for an electric cooking grill having improved convection heating characteristics according to the present disclosure.

[0021] Figure 8 is a flow chart depicting another control method for an electric cooking grill having improved convection heating characteristics according to the present disclosure. DETAILED DESCRIPTION

[0022] According to various embodiments of the present disclosure, waste heat can be transferred to the cooking surface / volume using means of convective transfer (e.g., after the radiation is captured by an appropriate surface). Thus, there is a mechanism to compensate for energy generation through enhanced energy transfer. Such a mechanism should be able to convert the energy generated by Heat generated by the element or another electric heating element is directed / redirected as needed into the cooking surface / volume while limiting the level and impact of undesirable heat losses via ventilation (such as during periods when the lid is open during cooking). Thus, the present disclosure provides an intelligent mechanism to manage / optimize convective heat transfer (enhancing or limiting the transfer rate as needed) in order to compensate for the primarily radiant heat generation system of the electric grill.

[0023] According to an embodiment of the present disclosure, an electric grill has enhanced cooking capabilities. The enhancements include, but are not limited to, allowing the cooking system to fully utilize the available electrical power, and reducing preheating and recovery times.

[0024] In various embodiments, the improvement can be capture by at least two mechanisms. The first mechanism includes capturing all, most, or more of the available heat. This can mean eliminating heat losses (e.g., radiant heat escaping through a wide opening under the grill and / or through a fully open cooking grid similar to that used in a gas grill) and also allowing the heating element to fully utilize all of the supplied electrical energy.

[0025] A second mechanism is to couple the release of this additional energy with controlled convection (e.g., by pulsating a fan). The control system manages both the rate of heat generation and the rate of heat transfer. In addition to when and where the energy release is utilized, the control system can also manage the variation of the energy release.

[0026] In fact, some embodiments of the present disclosure provide an apparatus that operates as an electric grill using radiant heating, but also has a fan to vary the convective heat and air flow to adjust the operation of the grill for various conditions. Thus, the conditions provided by the radiant heating are enhanced by changes in the convective air flow and / or convective heating. The enhancement may be to increase or decrease the temperature and / or change other cooking parameters.

[0027] Reference now Figure 2 , an electric grill 200 according to the present disclosure may include a cooking chamber 202 including a cooking grid 204. The cooking grid 204 may be placed above an element box 206 including an electric heating element 208, which may include Heating Element. The heating element 208 alone or in combination with other components of the electric grill 200 can provide heat to the cooking grid 204 and / or the cooking cavity 202.

[0028] According to some embodiments, a measured / controlled air flow that enhances heat transfer from the heating element 208 toward the cooking surface or cooking grill 204 and the cooking cavity 202 may be provided by an electromechanical component such as a fan 210, which may be a variable speed fan. The air flow provided from the fan 210 may prevent the heating element 208 from overheating and thermal runaway.

[0029] The controlled air flow of the electric grill 200 is compensated by an arrangement that prevents heat from being lost to the surrounding atmosphere by unnecessary free convection. To achieve this, the cooking system 200 can be designed as a thermal reservoir with a fully controlled air supply. The fan 210 is placed upstream of the air channel 212 or duct that is the only passage for air to enter the cooking cavity 202 from the element box 206. When the system 200 or the cooking cavity 202 is at its desired temperature, the system 200 minimizes the flow of ambient air into the cooking grill 204 and the cooking system 200 (by pausing the fan 210). In addition, when the system 200 detects that the lid of the cooking cavity 202 is in an open position (e.g., via a lid open sensor), it can block the air flow to reduce heat loss by means of buoyancy-driven ventilation (e.g., by pausing the fan 210 or closing the damper, as discussed below). The fan 210 can also reverse direction to draw air into the heating element box (at a relatively low flow rate) to counteract buoyancy.

[0030] The system of the present disclosure may have an electronic control board 214 having the necessary relays, controls, switches and controllers to control and implement the cooking modes and other operations discussed herein. Those skilled in the art will appreciate that there may be many ways to implement a control system based on a combination of hardware and software. For simplicity, not all leads, relays, etc. are shown. The system of the present disclosure may also rely on an alternating current (AC) source 216, which may include household current. The system may also rely on a direct current (DC) source 218, which may include, for example, a battery or a capacitor.

[0031] In situations where a higher rate of energy transfer is required (e.g., when the grill 200 is just turned on in extremely cold ambient temperatures, or when several large pieces of raw meat are placed on the grill 204), the control system 214 increases the rate of electrical power delivered to the heating element 208, and after a short period of time (to account for the response time of the resistor element), it may activate and / or operate the fan 210 to compensate for the higher rate of heat generation with the higher rate of heat transfer.

[0032] Controlled air flow is the primary mechanism for enhancing heat transfer from the heating element 208 into the cooking cavity 202 and to the cooking grill 204. This is accomplished by increasing the heat transfer coefficient around the heating element 208 and by directing the transfer of radiant heat absorbed by the surface below the heating element (e.g., the bottom of the element box 206) toward the cooking surface or grill 204 as the heated air travels into the cooking area 202.

[0033] Some operations of the disclosed system rely on temperature information at various locations in the system. A temperature probe 220 may be placed within the cooking cavity 202. Another temperature probe 222 may be placed to obtain the temperature of the cooking surface 204 or another location. The temperature probes 220, 222 may be solid-state temperature probes or any suitable temperature probes known in the art. Additional temperature probes may be utilized to obtain average readings across desired locations (e.g., within the cooking cavity 202, at the cooking grid 204, and / or at various resistive heating elements used by the disclosed system).

[0034] Reference now Figure 3 , shows a schematic diagram of a barbecue grill 300 according to the present disclosure. The barbecue grill 300 shares some common components with the barbecue grill 200. The barbecue grill 300 has an auxiliary heating element 302 adjacent to the heating element 208. The heating element 302 may be The air duct 312 may provide multiple passages to allow heated air to enter the cooking chamber 202, and these passages may be openable or closed by dampers 306, 308. Similarly, one or more dampers 304, 305 may open or close the passage of air flow from the element box 206 into the air duct 312.

[0035] A separate auxiliary or compensating heating element 340 may be located somewhere within the air duct 312. An additional electric fan 350 may control air flow across the compensating heating element 340 and within the air duct 312 to facilitate air flow into the cooking cavity 202. The compensating heating element 340 may include A heating element or another heating element.

[0036] like Figure 3 , it is therefore possible to couple the small heating element 340 with a small fan 350 in the air duct 312, which blows air (fresh air from the outside or air recirculated from the cooking cavity 202) through the compensating heating element 340 and sends the hot air into the cooking cavity 202. According to some embodiments, the power consumption rate of the coupled fan 350 and the compensating heating element 340 is significantly lower than the power consumed by the main heating element(s) 208 that heats the cooking grill(s) 204.

[0037] In some embodiments, higher power supply rates may also be based on a compensating DC source 218, such as a rechargeable battery or supercapacitor. Boost power may be provided to the same primary heating element(s) 208 or to the supplemental element(s) 302. The supplemental element(s) 302 may be positioned adjacent to the primary element(s) 208 below the cooking grid 204, or at the periphery of the cooking area to provide additional heating around the periphery of the cooking grid 204 where there is heat loss to the external environment.

[0038] In some embodiments, the system 300 is equipped with an air manifold or duct 312 having different channels controlled using dampers 304, 305, 306, 308. Depending on where a higher heating rate is required (e.g., cooking grill 204 or cooking chamber 202), the control system 214 directs the hot air flow into the appropriate medium (e.g., using dampers 304, 305, 306, 308).

[0039] In some embodiments, the system 200 , 300 is equipped with a smoke box to generate complementary smoke from the solid fuel. The control system 214 can direct air flow into the smoke box to enhance smoke generation and circulate smoke into the cooking cavity 202 .

[0040] In some embodiments, the system 200, 300 is equipped with a secondary heating element placed above the cooking area (e.g., under the cover of the cooking cavity 202). The control system 214 can direct air flow over the top heating element to increase the heat transfer coefficient and thus enhance heat transfer inside the cooking cavity 202.

[0041] In various embodiments, different types of DC sources are available. For example, one may be used to enhance the heating of the cooking grill 204, and another may be used to enhance the heating of the cooking cavity 202. Such a system may have one or more fans to enhance the heat transfer from the (one or more) heating elements toward the cooking grill and / or the cooking cavity, as shown herein or otherwise. The fans according to the present disclosure may be constant speed or variable speed. The control system 214 may run the fan constantly or pulse the fan as determined by the control algorithm based on the set point and / or temperature readings. In various embodiments, the heat source or heating element may be placed entirely below the cooking grill 204 or may also be placed above the cooking cavity 202.

[0042] The air duct 212, 312 may have an outlet that is always open, or may be equipped with one or more dampers (e.g., dampers 304, 305, 306, 308 or others). The position of the damper may be adjusted manually or automatically (e.g., using an electric motor). The system 200, 300 may include multiple modular cooking subsystems to create the equivalent of a multi-burner gas grill with greater precision and more distinguishable zones.

[0043] Figures 4 to 6 Different configurations of the circuits of the present disclosure are shown, wherein Or other resistive heating elements powered by AC mains as typically used are boosted by a DC power source such as a battery or supercapacitor. Solid state components such as MOSFETs are used to boost The discharge control of the DC power source (battery, supercapacitor, capacitor, etc.) is determined by the intelligent control function described in this document.

[0044] Now return to reference Figure 1 , a control schematic 100 of an electric cooking grill with improved convection heating characteristics according to the present disclosure is shown. Figure 100 is simplified to not show relays, resistors, grounding, and other circuit components that may be required and as are readily known in the art. An AC power supply 216 as well as a DC power supply 218 may be available to the control board 214 for implementing the various functions described herein, and for powering the control board 214 itself. The control board 214 may have the functionality to use the AC source 216 and / or the DC source 218 for any controlled component depending on the power requirements or control method being implemented.

[0045] The control board 214 may include a solid-state programmable device such as a microprocessor or microcontroller with appropriate memory and instructions to perform the control methods described herein. The control board may have operational controls for the fans 210, 350 so that they can be turned on or off, or controlled for speed (if the fans 210, 350 are multi-speed fans).

[0046] Temperature information may be provided to the control board via connections to temperature probes 220, 222. Additional information regarding the current state of the system may be provided via a lid sensor 1000 (e.g., to indicate whether the lid is open or closed, thereby indicating ventilation conditions) or other sensors. The various dampers 305, 306, 307, 308 may be electronically controlled by the control board 214 (e.g., using actuators, servos, or other devices known in the art).

[0047] The resistive heating elements 208, 302, 340 and possibly others (e.g., those associated with the smoke box) may be controlled by the control board 214 according to the methods described herein. The power requirements of the resistive heating elements 208, 302, 340 and other components of the disclosed system may cause the control board 214 or controller to selectively connect them to power (e.g., AC source 216 and / or DC source 218) via relays or other devices known in the art.

[0048] Reference now Figure 7 , a flow chart 700 is shown for a control method for a system according to the present disclosure. Such a system enhances heat generation (from AC and DC sources) and heat transfer into the grill (using a variable speed fan or pulsation of the fan) based on data provided by multiple temperature probes. The probes 220, 222 may be as follows: Figures 2 to 3 as shown in or otherwise positioned.

[0049] At 702, power is sensed, including AC and DC sources. At 704, if sufficient power is not available for the requested operation, a low power signal is indicated at 706, which may pause the system at step 710 while charging the DC source at step 708. The need for pausing and charging may be indicated to the user via a control screen or other device.

[0050] If sufficient power is available, sensing of the connection may occur at step 712. This may include sensing the connection of a temperature sensor, heating element, or other device. If any connection does not exist or is faulty at step 714, an error may be indicated to the user at 716, and the system may be paused at step 718.

[0051] With proper sensing connections, the set point, grid temperature, and chamber temperature may be read at step 716. At step 718, it is determined whether the set point is above the grid temperature. If not, it may be determined at step 736 whether the difference between the set point and the chamber temperature exceeds the chamber boost limit. If not, AC and DC energization may be stopped at step 738, while DC may be charged. A time interval may be allowed to elapse at step 740 before the reading step at 716 is repeated.

[0052] On the other hand, if the difference between the set point and the chamber temperature exceeds the chamber boost limit at step 736, the AC output rate may be determined at step 732 and then the heating element may be energized with AC only at step 734. Thereafter, a time interval may be allowed to elapse at 728 before returning to the reading step at step 716.

[0053] Returning to step 718, if the set point is above the grid temperature, it may be determined at step 720 whether the difference between the set point and the grid temperature exceeds the grid lift limit. If so, the supplemental DC input rate is determined at step 722. Thereafter, the fan speed (or pulsation, or other control parameter) is determined at step 724. At step 726, the fan is operated and the heating element is energized according to the determined parameters. A time interval delay may occur at step 728 before the control returns to step and step 716.

[0054] If the difference between the set point and the grid temperature does not exceed the grid boost limit at step 720, but the difference between the chamber temperature and the set point does exceed the grid boost limit at step 730, then the DC replenishment rate is determined at step 722, and control continues as depicted in any event. If the difference between the chamber temperature and the set point does not exceed the chamber boost limit at step 730, then the AC rate is determined at step 710.

[0055] Reference now Figure 8 , another flow chart 800 illustrates another control method that may be used for a grill equipped with an adjustable air passage to direct heated air toward the cooking grill or into the cooking cavity (as determined to be more beneficial to the grilling experience), as described above. The illustrated flow chart 800 shows a scenario with one heating element. Alternatively, there may be more than one heating element, and each heating element may be energized independently of one another or in conjunction with one another.

[0056] As can be seen, flowchart 800 shares the steps described above with respect to flowchart 700. However, prior to determining the supplemental DC output rate at step 722, once it is determined at step 720 that the difference between the set point and the grille temperature exceeds the grille boost limit, the air damper is adjusted at step 802. Similarly, after it is determined at step 730 that the difference between the set point and the chamber temperature is greater than the chamber boost limit, the damper is adjusted at step 804. In either case, control then continues to step 722 to determine the supplemental DC output rate as previously described.

[0057] It should be understood that the terms "comprises", "includes", "comprising" and their grammatical variations do not exclude the addition of one or more components, features, steps or integers or groups thereof, and these terms should be interpreted as specifying components, features, steps or integers.

[0058] If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0059] It should be understood that where the claims or specification refer to "a" or "an" element, such reference should not be interpreted as there being only one of the element.

[0060] It should be understood that where the specification states a component, feature, structure, or characteristic "may," "might," "could," or "can" be included, that particular component, feature, structure, or characteristic is not required to be included.

[0061] Where applicable, although state diagrams, flow charts, or both may be used to describe embodiments, the invention is not limited to these diagrams or corresponding descriptions. For example, a flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described.

[0062] The methods of the present invention may be implemented by performing or completing selected steps or tasks manually, automatically, or a combination thereof.

[0063] The term "method" may refer to ways, means, techniques and procedures for completing a given task, including but not limited to those ways, means, techniques and procedures known to practitioners in the field to which the invention belongs or that can be easily developed from known ways, means, techniques and procedures.

[0064] The term "at least" followed by a number is used herein to indicate the beginning of a range that begins with that number (which may be a range with an upper limit or without an upper limit, depending on the variable being defined). For example, "at least 1" means 1 or greater than 1. The term "at most" followed by a number is used herein to indicate the end of a range that ends with that number (which may be a range with 1 or 0 as its lower limit, or a range with no lower limit, depending on the variable being defined). For example, "at most 4" means 4 or less than 4, and "at most 40%" means 40% or less than 40%.

[0065] In this document, when a range is given as "(first number) to (second number)" or "(first number) - (second number)", this means a range whose lower limit is the first number and whose upper limit is the second number. For example, 25 to 100 should be interpreted as meaning a range whose lower limit is 25 and whose upper limit is 100. In addition, it should be noted that where a range is given, every possible subrange or interval within that range is also specifically intended, unless the context indicates otherwise. For example, if the specification indicates a range of 25 to 100, such a range is also intended to include subranges such as 26-100, 27-100, etc., 25-99, 25-98, etc., and any other possible combination of small and large values ​​within the range, such as 33-47, 60-97, 41-45, 28-96, etc. Note that the integer range values ​​that have been used in this paragraph are for illustration purposes only, and that decimal and fractional values ​​(eg, 46.7-91.3) should also be understood to be intended as possible sub-range endpoints unless specifically excluded.

[0066] It should be noted that where this document refers to a method comprising two or more defined steps, the defined steps may be performed in any order or simultaneously (unless the context excludes this possibility), and the method may also include one or more other steps performed before any of the defined steps, between two of the defined steps, or after all of the defined steps (unless the context excludes this possibility).

[0067] In addition, it should be noted that approximate terms (e.g., "about," "substantially," "approximately," etc.) are to be interpreted according to their ordinary and customary meanings used in the relevant art, unless otherwise indicated herein. In the absence of a specific definition in the present disclosure and in the absence of ordinary and customary usage in the relevant art, such terms should be interpreted as plus or minus 10% of the base value.

[0068] Unless otherwise indicated, the term "selective" or "selectively" is taken to mean that an operation or function is capable of being performed by the referenced structure or device, but that the operation or function may occur discontinuously or uninterruptedly. In addition, a selectively or selectively performed operation may be an operation that a user or operator of a device or method may choose whether or when to perform, but the function or operation is still fully operable on or within the relevant device, machine or method, and the device, machine or method includes the necessary structure or components to perform such operation.

[0069] The present invention is therefore well adapted to carry out the objects and attain the purposes and advantages mentioned above as well as those inherent therein. While the apparatus of the present invention has been described and illustrated herein by reference to certain preferred embodiments associated with the drawings, various changes and further modifications besides those shown or suggested herein may be made by one skilled in the art without departing from the spirit of the inventive concept, the scope of which is to be determined by the claims that follow.

Claims

1. A cooking system, comprising: a cooking cavity having a cooking surface therein; at least one resistive heating element, the at least one resistive heating element providing heat to the cooking surface; an alternating current connection for powering the resistive heating element; as well as A direct current source is connected to the alternating current and selectively powers at least one resistive heating element.

2. The system according to claim 1, wherein: The direct current source comprises a chemical battery.

3. The system according to claim 1, wherein: The DC current source includes a capacitor.

4. The system of claim 1, further comprising at least one temperature probe that measures a temperature associated with the cooking cavity.

5. The system of claim 4, further comprising a control circuit that selectively activates the DC current source based on readings taken from at least one temperature probe.

6. The system according to claim 4, wherein: The at least one temperature probe includes a cooking chamber temperature probe and a resistive heating element temperature probe.

7. The system according to claim 6, wherein: At least one resistive heating element includes at least a first resistive heating element powered by the alternating current connection and at least a second resistive heating element powered by the direct current source.

8. The system according to claim 7, wherein: The control circuit determines whether a difference between a set point temperature and a temperature from at least one probe exceeds an elevated threshold before activating the DC current source to power at least one resistive heating element.

9. The system according to claim 1, wherein: The AC current connection recharges the DC current source.

10. The system of claim 1 further comprising an air duct providing fluid communication from the resistive heating element to the cooking chamber.

11. The system according to claim 10, wherein: The air duct is provided with at least one damper to selectively inhibit air flow.

12. The system of claim 11, further comprising at least one fan providing air flow within the air duct.

13. The system of claim 12, further comprising at least one additional resistive heat source in the air duct.

14. The system of claim 13, further comprising a component housing beneath the cooking surface, at least one resistive heating element housed in the component housing.

15. The system of claim 11, further comprising a controller that controls operation of the at least one resistive heating element and at least one damper.

16. A cooking device comprising: a cooking cavity having a cooking surface therein; a component box, the component box being below the cooking cavity; a resistive heating element, the resistive heating element being in the element box; AC current power source connection; DC current power source; an air duct providing fluid communication between the component box and the cooking chamber; as well as a fan operable to move air from the component box to the cooking chamber through the air duct; Wherein, the resistive heating element is powered by the AC current power connection and the DC current power source.

17. The apparatus according to claim 16, further comprising: a first auxiliary heating element, the first auxiliary heating element being in the element box and powered by the DC current power source; a second auxiliary heating element, the second auxiliary heating element being in the air duct; as well as A plurality of dampers control air flow from the air duct into the cooking cavity.

18. The apparatus of claim 17, further comprising a controller that selectively operates the fan and opens the plurality of dampers based at least on temperature probe readings from the cooking cavity.

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