IT201900002725A1 - MECHATRONIC BURNER OF A HOB. - Google Patents

Description

MECHATRONIC BURNER OF A HOB

The present invention refers to a mechatronic burner of a hob.

In the state of the art, gas cooking hobs comprising atmospheric induction burners are known.

Fuel and oxidizer (air) are mixed upstream of the combustion process providing a quantity of oxygen sufficient to oxidize all or part of the fuel fed.

Atmospheric induction burners mounted with hobs include valves to vary a fuel gas flow rate with the aim of varying a supplied thermal power, at least one ejector, at least one burner head, at least one flame sensor (FFD, Flame Failure Device) which it interrupts the flow of combustible gas if combustion is not detected, and at least one igniter.

The two most important components for burner performance are the ejector and the Burner Head. This last component has the function of stabilizing and anchoring the flame in the desired position and allowing the combustion process to be carried out in the desired modes to efficiently transmit heat to the container or dish to be heated.

The performance and quality of the final chemical conversion process will be strictly connected to the feed conditions upstream of the flame, and therefore to the reagent mixture obtained through the combination of ejector and burner head.

The ejector is a component that allows the energization of a low-energy fluid (secondary fluid), in this case air, by means of a jet with high kinetic energy (primary fluid) which is the combustible gas in hobs. This solution allows the exchange of momentum and mechanical energy without the use of moving parts.

Disadvantageously, the hob described in this way is unable to optimize its operation by taking into account the variations in the surrounding conditions to which it may be subject.

The object of the present invention consists in realizing a burner for a cooking hob which overcomes the disadvantages of the known art, is more energetically efficient, limits unwanted emissions, and guarantees cooking safety and precision.

In accordance with the invention, this purpose is achieved with a burner of a hob according to claim 1.

Another object of the present invention consists in realizing a mesobburner, where the term mesobburner refers to a burner of compact dimensions, which co-operates with the burner of claim 1 of a cooking hob which overcomes the disadvantages of the technique note, it is more energetically efficient, limits unwanted emissions, guarantees cooking safety and precision, and is able to adapt its operation to variations in the composition of the combustible gas.

In accordance with the invention, this other purpose is achieved with a mesobburner which cooperates with a burner of a hob according to claim 5.

A further object of the present invention consists in realizing a cooking hob which overcomes the disadvantages of the known art, is more energetically efficient, limits unwanted emissions, guarantees cooking safety and precision.

In accordance with the invention, this other purpose is achieved with a hob according to claims 12 and 13.

A still further object of the present invention consists in realizing a process for manufacturing a cooking hob which overcomes the disadvantages of the known art.

In accordance with the invention, this further object is achieved with a process for making a hob according to claim 14.

A still further object of the present invention consists in realizing a method of operation of a cooking hob which overcomes the disadvantages of the known art.

In accordance with the invention, this still further object is achieved with a method of operating a hob according to claim 15.

Other features are provided in the dependent claims.

The characteristics and advantages of the present invention will become more evident from the following, exemplary and non-limiting description, referring to the attached schematic drawings in which: Figure 1 is a diagram of the atmospheric induction burner according to the present invention;

figure 2 is a detail of figure 1 showing a diagram of an atmospheric induction burner; figure 3 is a detail of figures 1 and 2 showing a diagram of electrical connections between the control unit and sensors / actuators;

Figure 4A is a detailed diagram of the previous figures showing the burner with primary combustion air supply by sucking it under the hob. (Air from below);

Figure 4B is a detailed diagram of the previous figures showing an alternative burner with primary combustion air supply by sucking it above the hob. (Air from above);

Figures 5A, 5B, 5C, 5D are detailed diagrams of the previous figures showing alternative burner injectors and ejectors according to alternative geometries such as to integrate some of the possible types of air flow regulators;

Figure 6 is a schematic of the alternative atmospheric induction burner of the present invention comprising a mesobburner;

figure 7 is a detailed diagram of figure 6 showing the cooking hob comprising the mesobburner;

figure 8 is a detailed system diagram of figures 6 and 7 showing the compartment in which the mesobburner is located;

figure 9 is a diagram of the mesobburner of figures 6-8;

Figure 10 is a detailed diagram of Figures 6-9 showing electrical connections between the control unit and the sensors / actuators of the burner and the mesobburner;

Figure 11 is a representation of the detail relating to the introduction of the mixture of burnt gases and air near the flame front anchored to the burner, where this flow comes from the mesoburner compartment;

Figure 12 shows a graph of a stability field of the mesobburner with in the abscissa a specific load at the gates of the mesobburner and in the ordinate the primary daily fraction;

Figure 13 shows a graph showing a trend in the volumetric ratio between the intake air flow and the fuel gas flow rate when the fuel gas flow varies for certain temperature values of the fuel gas, the primary combustion air, the burner and for combustible gas with a defined molar mass; Figure 14 shows a graph describing a link between the equivalence ratio and the ionization current measured for certain values of total flow rate, temperature of the reactant mixture upstream of the burner head, burner temperature and composition of the fuel gas;

Figure 15 shows a graph that describes the trend of the volumetric ratio between the intake air flow rate compared to the fuel gas flow rate supplied as the fuel gas flow rate varies for certain temperature values of the combustible gas, of the primary combustion air, of the burner, for combustible gas with a defined molar mass and for a defined position of the air regulator;

Figures 16, 17 and 18 show a flow chart which includes operating procedure steps of the hob according to the present invention.

With reference to the aforementioned figures and in particular figures 1-5D, a cooking hob 100 is shown comprising at least one atmospheric induction burner 10.

Usually the hob 100 comprises two or more burners 10.

As shown in particular in Figure 2, the burner 10 comprises at least one ejector 20 and at least one head 30.

The ejector 20 includes an ejector duct 21, an injector 40 and an air flow regulation system 50.

The burner 10 is able to regulate its own operation by responding to variations in surrounding conditions by means of the regulator of an air flow rate 51/52, where the air is sucked in by the ejector 20. The system for regulating the air flow rate intake 50 comprises at least one electromechanical actuator 53 for regulating the primary combustion air flow rate. The hob 100 comprises at least one control unit 200 which controls and commands the at least one electromechanical actuator 53 of the air flow regulation system 50.

The control unit 200 comprises at least one processor and at least one memory.

The boundary conditions that may vary relate to the following observables: a temperature of a combustible gas Tgas supplied by the injector 40, a temperature of the air Taria drawn in by the ejector 20, a temperature Tb of the burner 10, a thermal power Pgas supplied by the head 30 of the burner 10. In addition to the variables described above, the chemical composition of the fuel xgas is also a parameter that can be subject to changes, thus influencing the operation of the burner. To take this last parameter into account, however, a compact burner must be introduced, which in this discussion has been renamed with the term mesobburner, as shown in figures 6-11.

As shown in particular in Figure 2, the head 30 of the burner 10 comprises holes 31 suitable for stably anchoring the flames generated by the combustion of the reactive mixture given by comburent and fuel.

The burner 10 comprises at least one injector 40 which supplies the ejector duct 21 with combustible gas 301 by means of one or more nozzles or orifices 41. The combustible gas 301 has a modest flow rate but by flowing through at least one orifice 41 of the injector 40 increases its own speed and the high-speed flow of the gas 301 that leaves the orifice 41 allows air 310 to be drawn from the surrounding environment, hence the term atmospheric induction burner 10.

As shown in particular in figures 2, 4A-4B, 5A-5D the orifice 41 of the injector 40 comprises a duct generally axially aligned with an axis along which the ejector duct 21 of the ejector 20 develops.

As shown in particular in Figure 2, the ejector duct 21, depending on the design chosen, can have a cylindrical or Venturi geometry. Preferably, as shown in Figures 2 and 5A-5D, the section of the ejector duct 21 comprises a converging portion that defines a head mixing zone 22 which is the inlet zone of the ejector duct 21, in which the air is drawn back. environment 310 due to the effect of the gas flow 301 coming from the orifice 41 of the injector 40, a throat section 23 and a diverging section that defines a mixing duct 24, in which the mixing between the reactants takes place, i.e. the region where the mixing between air 310 and fuel 301.

The geometry of the injector 40, the geometry of the head mixing zone 22, of the throat 23 and of the mixing duct 24 of the ejector duct 21 are the main geometric parameters that determine the ratio between the quantity of sucked air and the supplied gas.

As shown in particular in Figure 2, at one end of the mixing duct 24 there is the connection with the head 30 of the burner 10 and thus a fluid-dynamic circuit and relative pressure drops of the atmospheric induction burner 10 can be defined.

Assign the geometry of the burner 10, i.e. of the ejector 20 and head 30 of the burner 10, the thermo-fluid dynamic properties of the primary and secondary fluid, the flow rate of combustible gas and the possible boundary conditions connected to the use of the object, you can define what will be the result of the combustion process and its quality.

In order to introduce a control parameter on the process, in addition to the regulation of the gas flow rate, the air regulation system 50 is inserted, which allows to modify the geometry of the ejector 20 to reduce or increase the quantity of sucked air. Some alternative types of air regulators 52 are shown in Figures 5A-5D.

Changing the geometry of the ejector 20 means changing the air inlet section by means of the air flow regulation system 50.

Figures 5A-5D show an enlargement of the ejector 20 between the injector 40 and the ejector duct 21 and presents different types of air flow regulators 52 alternative to each other, operated by electromechanical actuators 53 as shown in Figure 1. Flow rate regulators 51, 52, operated by electromechanical actuators 53 modify the ratio between the flow rates of the fuel gas supplied 301 and the aspirated ambient air 310 which flow into the head mixing zone 22 of the ejector duct 21.

The actuator 53 automatically adjusts the ratio between the flow rates of the fuel gas 301 and the ambient air 310 that flow into the head mixing area 22, automatically responding to changes in the surrounding conditions. This actuator 53 can thus be connected to the control unit 200 which gives instructions for controlling the combustion process.

Acting on the intake air 310 it is in fact able to control the equivalence ratio of the fuel-combustive mixture, defined as the ratio between the air ratio 310 - fuel 301 that should be had in stoichiometric conditions compared to that actually achieved. This parameter is of fundamental importance since it influences the stability, temperatures and emissions of the combustion processes. It is in fact the main parameter subject to monitoring in combustion processes on a domestic, industrial scale, in transport and in the generation of electrical power.

The air drawn in 310 by the operating principle of the ejector 20 is defined as primary air (Primary Air) 310 to distinguish it from the air with which the flame generated by the combustion process will come into contact, which is instead identified as secondary air (Secondary Air) 320.

Depending on whether the primary air 310 is sucked below as shown in figure 4A or alternatively above a surface 101 of the hob 100 as shown in figure 4B we are talking about burners 10 with feed from below (Air from below) or from above (Air from above). A schematic representation of the two technologies is shown in Figures 4A and 4B. Both solutions are widespread and despite the obvious aesthetic differences, they base their operation on the same physical principles.

As shown in particular in Figure 1, the variable geometry atmospheric induction burners 10 are integrated with the surface 101 of the hob 100.

The hob 100 comprises support grids 110 for 120 pots or other kitchen tools. The support grids 110 comprise at least a portion suitable for keeping the pot 120 raised to a certain height above the burners 10.

The hob 100 comprises a means for regulating the flow of combustible gas 130 sent by means of a duct 134 of the combustible gas 301 towards the injector 40. Said means for regulating the flow of combustible gas 130 allows to control the thermal power delivered by the head 30 of the burner 10. The means for regulating the inflow of combustible gas 130, and therefore the flow of gas 301, usually comprises a knob 131 to be handled by a user, a valve or cock 132 for the combustible gas 301. The valve 132 is suitable for passing at least from an open position to a closed position. The hob 100 also comprises a position transducer 133 to indicate the position of the valve 132. For example, the transducer 133 comprises an encoder which detects the actual position of the valve 132 for regulating the gas 301. Alternatively to what is shown in Figure 1 the valve 132 could be of the electronic type and in this case the adjustment could still take place through a knob 131 or through other interfaces integrated in the hob (for example buttons). Using electronic valves, the position of the fuel gas valve 132 301 could be known without using an encoder but knowing the instructions given by the control unit 200 to the valve itself based on whether and how much to open.

The cooking hob 100 comprises a combustible gas temperature sensor 140 for detecting the temperature of the combustible gas 301. The combustible gas temperature sensor 140 is for example a thermocouple. The fuel gas temperature sensor 140 is positioned inside the fuel gas supply conduit 134 301 or inserted in the injector body 40, as shown in figure 1.

The hob 100 includes an air temperature sensor 150 to measure the primary air temperature 310. The air temperature sensor 150 is a thermocouple for example. The air temperature sensor 150 is positioned in a place suitable for measuring the primary air temperature 310, for example it is placed outside the ejector duct 21 and outside the injector 40, positioned near the inlet of the head mixing zone 22 of the ejector duct 21.

The burner 10 comprises at least one temperature sensor, for example inserted in said at least one head 30. This sensor can be, for example, a thermocouple placed in contact with the head 30 or other suitably selected parts of the burner 10. "

The burner 10 comprises the air flow rate adjustment system 50 which comprises the electromechanical actuator 53 which comprises for example an encoder and an obturator 51/52 suitable for passing from at least an open position to a closed position, so as to adjust the flow rate of air mixture 310 fuel gas 301 entering the ejector duct 21.

The at least one head 30 of the burner 10 comprises at least one igniter 36 to trigger the combustion process of the mixture and at least one flame sensor 37 (flame failure device, FFD) suitable for interrupting the supply of combustible gas 301 in the event that it is not detected the presence of flame.

Taking into account the thermo-fluid dynamics underlying the operation of the atmospheric induction burner 10, the introduction of the variable geometry and of the sensors, which are measuring means, 133, 140, 150, 35 set out above allows to adjust the ratio between volume d intake air 310 and volume of fuel gas supplied 301, assuming that the combustible gas 301 has a certain chemical composition, ideally capable of well representing the fuels actually distributed in the market in which the hob 100 is used.

This adjustment aims to impose the desired equivalence ratio for each burner 10 as the heat output supplied by the user, the temperature of the burner 10, the air 150 and the fuel gas 140 vary.

It is also possible to set a certain initial position of the air regulation system 50, suitable for a prompt ignition of the burner 10, and then modify the geometry of the ejector 20 to obtain the optimal conditions in terms of energy efficiency, limitation of emissions. unwanted, safety and breadth of the range of regulation of the delivered power based on the signals obtained.

The situation described up to now substantially involves the modification of burners 10 existing on the market or the construction of new burners to include the air regulation systems 50, the regulators 51-52, the relative actuators 53 and the various measuring means 133, 140 , 150, 35 to be connected to the burners 10 and to the fuel gas valves 132 of each of them.

The hob 100 comprises at least one electronic control unit 200, suitably positioned which is adapted to receive the signals relating to the presence of flame, the signals relating to the measured parameters pertaining to each burner 10 (opening of the gas valve 132, air temperature intake 310, temperature of the fuel gas supplied 301, temperature of the burner 10, position of the air regulation system 50) and to give instructions to the actuator 53 of the air regulator 51-52 based on algorithms implemented in the control unit 200 itself.

It is possible to foresee that the ideal position of the control unit 200 is below the surface 101 of the hob 100.

In particular, the flame failure signal FFD is a signal necessary for the control unit 200 to know if the single burner 10 of the hob 100 is at that moment off, which therefore allows the control unit 200 to know whether or not to set the system. air regulation 50 in ideal conditions for ignition without making further adjustments.

The control unit 200 is electrically connected to the sensor for detecting the burner temperature 35, to the flame sensor 37, to the air flow regulation system 50, to the fuel gas temperature sensor 140, to the air temperature sensor 150, to the means for adjust the inflow of combustible gas 130, as shown in the diagrams of figures 1 and 3, in such a way that the data: the temperature of the combustible gas Tgas, the temperature of the primary intake air Taria, the temperature of the burner Tb and the thermal power Pgas powered are data transmitted to the control unit 200.

The fuel gas supply 301 can be managed directly by the user, exactly as is the case today in the most popular hobs on the market. Alternatively it is possible, by implementing electronic valves, that the control unit 200 can act on the valve 132 of the flow regulator 130. In this way the regulation aimed at obtaining a more energetically efficient burner, which limits unwanted emissions, guarantees safety and precision of cooking could take advantage not only of the air flow regulation systems 50 but also from adjustments implemented on the combustible gas flow rate 301. It should be noted that in practice it is the user who chooses the thermal power supplied on the basis of the requirements of the cooking process that want to implement. The introduction of adjustments of the control unit 200 on the valve 132 for purposes other than those relating to the safety of use of the hob 100 should therefore be limited in their extent.

From the user's point of view, there may therefore be no difference either in the methods of use or in the appearance of the hob 100 compared to what is on the market. All the modifications and additional components can in fact be placed below the surface 101 of the hob 100 and in the case of burners 10 with suction from above below the head 30 of the burner 10.

Alternatively, as shown in Figures 6-11, it is possible to provide that the hob 100 also comprises a mesobburner 60.

The mesobburner 60 co-operates with the burner 10 of the hob 100 allowing to obtain a synergistic effect for the present invention.

Taking into account the composition of the xgas fuel requires that the hob 100 includes an additional component which we will call mesobburner 60.

The mesobburner 60 is a burner of compact dimensions and smaller than those of the other burners 10 and is used in the present invention to obtain useful measures for the purposes of a correct adjustment of the main burners 10 predisposed for cooking and mounted with the cooking hob 100.

The mesobburner 60 is placed in a compartment suitable to ensure the reliability of the measurements, is equipped with a special power supply line and ancillary components connected to its installation in the hob 100 and its operation.

The mesobburner 60 allows you to adjust the flow of air sucked in by each burner 10, advantageously optimizing its operation in terms of energy efficiency, limitation of unwanted emissions, safety and cooking precision, thanks to the detection of the following parameters: flow of combustible gas in the mesobburner 60, temperature of the combustible gas fed to the mesobburner 60, temperature of the air sucked in by the mesobburner 60, temperature of the mesobburner 60, ionization current measured on the mesobburner 60, flow rate of combustible gas fed to the single burner 10 under examination, temperature of the fuel gas fed to the single burner 10 under examination, temperature of the air sucked in by the single burner 10 under examination, temperature of the single burner 10 under examination.

The variable geometry atmospheric induction burners 10 described above, including also the mesobburner 60, can also take into account in the regulation of the combustion the variations in the composition of the combustible gas 301. It is necessary to introduce the mesobburner 60 which is a small non atmospheric induction burner. prepared directly for cooking.

The mesobburner 60 is sufficient for at least one only for the entire hob 100, as opposed to the burners 10 which can be multiple burners 10 of the hob 100. The mesobburner 60 must be inserted in a compartment to be protected from any dirt and damage. The most convenient location is below the surface 101 of the hob 100.

As shown in particular in Figure 9, the mesobburner 60 has limited dimensions. The mesobburner 60 comprises an igniter 66, an ejector duct 62, a head 63 and an electrode 64, placed above the head 63 of the mesobburner 60, a sensor for detecting the temperature of the mesobburner 65. The electrode 64 measures a current electrical defined as ionization current. It has in fact been found that hydrocarbon flames generate ions during combustion, albeit in very modest concentrations. By imposing a potential difference between two electrodes 64, connected to each other and located upstream and downstream of a flame front 106 of the mesobburner 60, the presence of these ions gives rise to the passage of a current which is measured by means of a ionization current 68 which for example is a circuit for measuring the ionization current which can also be used for detecting the FFD signal. The ionization current sensor 68 comprises an ammeter and a power supply connected to the two electrodes 64 located above and below the flame front 106. Beyond the complex chemistry underlying the empirical results found, which is still the subject of studies, in practice, the measurement of the ionization current makes it possible to evaluate the presence or absence of combustion processes (FFD signal) and to correlate the current circulating in the system to the equivalence ratio with which the burner 10 is operating in the event use of natural gas as a fuel, having methane as a largely predominant component. The possibility of correlating ionization currents and equivalence ratio for other fuels is still to be verified.

As anticipated, the measurement of the ionization currents presupposes the use of an electrode 64 positioned above the head 63 of the mesobburner 60 (downstream of the flame front 106) and another electrode 64 below the head 63 of the mesobburner 60 ( upstream of the flame front 106).

Alternatively, the function of electrode 64 upstream of the combustion process can be performed by the mesobburner 60 itself, which must be made of conductive material.

The two electrodes 64 are connected to each other, integrating the circulating current measurement system. In the following, the mesobburner 60 will no longer be mentioned as electrode 64, but this term will only indicate the one downstream of the flame front 106, immersed in the fumes of the mixture burned by the mesobburner 60.

The electrode 64 is made of metal alloys resistant to high temperatures and can have different geometries. For example, planar geometries have been studied, using a metal mesh parallel to the plane of the mesobburner 60 with sufficient extension to cover the entire surface of the head 63 of the mesobburner 60 on which the flame 106 is stabilized, and alternatively a simpler cylindrical geometry, thus positioning the electrode 64 with its axis parallel to the head 63 of the mesobburner 60. The distance between electrode 64 and mesobburner 60 as well as the potential difference imposed are important parameters since they influence the signal relating to the ionization current obtained. Without reporting further considerations, it can be briefly said that the combustion control based on ionization currents is an ideal solution from a technical and commercial point of view for products intended for large consumption, capable of providing a signal for regulation based on the generation of species. electrically charged in the flame front 106, primarily a function of the specific burner analyzed, the equivalence ratio, the flow rate of fuel or mixture fed, the geometry and position of the electrode 64 adopted and the imposed electric field.

It is thus possible to know the equivalence ratio with which the mesobburner 60 operates and consequently set the adjustment strategies to be adopted on the burners 10 specifically designed for cooking, comparing the operating conditions of the mesobburner 60 with those of the single burner 10 that is desired. regular, independently of one 10 from the other 10 of the multiplicity of burners 10 of the cooking hob 100.

In detail, the mesobburner 60 is a compact atmospheric induction burner like the one shown in figures 8 and 9 which includes, in addition to the igniter 66, which is an ignition system, also a flow meter or pressure transducer 71 for determining or validating the flow rate of combustible gas 302, a combustible gas temperature sensor 141 (for example of a thermocouple) inserted in a gas supply duct 46 or in the body of an injector, an air temperature sensor 151 (for example of a thermocouple) located near the mouth of an ejector duct 62 of the mesobburner 60, a temperature sensor of the mesobburner 65 (for example of a thermocouple) integrated in the head 63 of the mesobburner 60, one or more electrodes 64 and current measurement circuit of ionization 68.

It is envisaged that the mesobburner 60 can be preferentially covered by solid walls 81 designed to avoid secondary air flows before the fumes generated by the flame front 106 come into contact with the electrode 64.

The hob 100 also includes the control unit 200 electrically connected to the sensors and the actuators 26, 135, 66, 68, 71, 65, 151, 141, 160, 37, 130, 35, 150, 140, 50 both of the burners 10 and the mesobburner 60 as shown in particular in Figures 6 and 10.

The control unit 200 controls the opening of a gas valve 135 in the presence of the ignition of at least one of the burners 10 of the hob 100 and is therefore responsible for the ignition procedures of the mesobburner 60, safety and cooling.

As shown in particular in Figure 8, the mesobburner 60 is preferably installed in a suitable compartment 80 to protect the mesobburner from possible damage or fouling. This compartment 80 is equipped with a fan 26 (also controlled by the control unit 200) for the aspiration of an air flow 311 greater than that which in any condition may be required by the mesoburner 60. The motion of the aforesaid flow of air air 311 inside the compartment must not affect the operation of the ejector 62 of the mesobburner 60, so that the latter can behave exactly as if it were in still air. At the same time, the shape of the compartment 80 must prevent the burnt gases 330 from being sucked in together with the primary air 312 as this would affect the measurements related to the ionization current. Still referring to the measurements related to the ionization current, it may be necessary to introduce solid walls 81, made of ceramic material that prevent the mixing of burnt gases 330 with secondary air until they have come into contact with the electrode 64.

As shown in Figure 8, a grid or a cage 84 is preferably provided comprising a multiplicity of through openings 83 suitable for the passage of air, making it air as quiet as possible. The cage 84 contains within it the mesobburner 60. The multiplicity of through openings 83 of the cage 84 allows to obtain a homogeneous and stationary flow of air in the vicinity of the ejector duct 62 which will then suck in the combustion air 312 of the mesobburner 60.

At the exit of the compartment 80, since the fumes 340 from the mesobburner have an enthalpy content that cannot be released into the environment without producing a useful effect for cooking and, in addition to this, they could contain fractions of unburnt products, it is necessary that the aforementioned fumes are sent to one of the burners 10 which is lit at that moment.

To achieve this direction of the gases 340 which include the burnt gases 330 and the remaining portion of the air 311 entering the compartment 80 of the mesoburner 60, it is necessary to provide a motorized node 160 connected to the compartment 80 and to various ducts 163 which lead to the release points 165 of the fumes 340 in proximity to each burner 10, as shown in particular in figures 6, 7 and 11.

To avoid losses from the energy point of view and avoid the establishment of excessively hot regions, it is advisable for the compartment 80 of the mesobburner 60 to be thermally insulated, at least in its top, just as it is advisable for the outlet duct 85 from compartment 80 to be insulated. , the distribution node 160 and the ducts 163 which branch out towards the different burners 10.

The regulation of the combustion process takes into account the fact that the mixture of burned gas 330 and air coming from the mesobburner 60 is sent only to one or some of the burners 10 which are currently on. It follows that it is necessary to know the position in which an actuator 162 which controls the motorized node 160 is located. In this way the choice of the equivalence ratio to be achieved in each burner 10 will not only be based on the thermal power supplied by the user and on the temperature of the burner 10 but also on taking this additional flow into account. This may be important in particular in the presence of burners 10 with primary air intake 310 above the surface 101 of the hob 100.

In the eyes of the user, the only difference compared to a traditional hob 100 would therefore result in the feeding sections of the gas mixture 340 coming from the mesobburner 60 to the different burners 10.

In particular in figures 6 and 11 it is possible to note how the mixture 340 coming from the mesoburner 80 compartment is sent through the duct 85, the motorized node 160, the duct 163 to a manifold 164 positioned in proximity to the burner 10 such as to release said mixture 340 in the vicinity of the flame front 107 of the burner 10, through doors 165, mixing at the same time with the secondary air 320.

A representative diagram of the different components mentioned so far and of the variables that it is necessary to know to set up the combustion regulation strategies, identified for each of them, is shown in figure 7.

At the end of cooking, once all the burners 10 have been extinguished and consequently the control unit 200 has also turned off the mesobburner 60, it is possible to exploit the presence of the fan 26 to cool the burners 10 used in sequence. For this purpose, the number of revolutions per minute of the fan 26 can be increased so as to reduce the time required for cooling the individual burners 10.

What has been said so far allows us to summarize the task that the control unit 200 will have to perform.

First of all, the control unit 200 detects the ignition of the burners 10. When the FFD signal of at least one burner 10 signals the presence of a flame (due to the activation by the user of the hob 100), the control unit 200 starts the ignition of the mesobburner 60. It should be noted that the user's intention to ignite the hob 100 is known thanks to the position transducer 133 of the fuel gas valve 132 which, once a signal has been detected outside the region corresponding to zero flow, it can alert the control unit 200. Alternatively, it can be known thanks to the signal sent directly to the control unit if this is set up to control an electronic valve 132.

An ignition process could first see the placement of the motorized node in the suitable position to send the mixture 340 of the mesobburner 60 to the ignited burner 10. Subsequently, the control unit 200 can start the fan 26 to wash the compartment 80 and after a short period of time open the fuel gas valve 132 with simultaneous activation of the ignition circuit 66 of the mesobburner 60 and the circuit set up to detect the current. of ionization 68.

Once the circuit set up for measuring the ionization current 68 has detected the presence of a flame (FFD signal), the control unit 200 can interrupt the power supply to the ignition circuit of the mesobburner 60. If the flame is not detected within a it is possible to interrupt all activities and restart the ignition procedure for a certain period of time. After a certain number of unsuccessful attempts, the control unit 200 can interrupt the procedure and send a system block signal. Again for safety reasons, it should be noted that at the start signal the fan 26 is actually operating or that there are no obstructions to the escape of the mixture 340.

If another burner 10 is activated, the motorized node 160 can either divide the flow rate among several burners 10 or continue to send the entire flow 340 to only one.

Once cooking is complete and all burners 10 have been turned off, the control unit 200 must interrupt the flow of fuel supplied to the mesobburner 60 by closing the gas valve 135. The fan 26 can now continue to operate to wash the compartment 80 of the mesoburner 60 and to cool in sequence the burners 10 that have been used. To this end, the signal linked to the temperature of the different burners 10 can be used to identify when it is appropriate to change the position of the motorized node 160, and consequently the burner 10 to be cooled. Note that every time the user turns off a burner 10, the control unit 200 can act on the air regulator of that specific burner 10 to bring it to the optimal position for the ignition conditions.

When the mesobburner 60 is active, it is possible to use it as previously mentioned to obtain measurements relating to the actual equivalence ratio with which it is operating and adjust the burners 10 that are lit at that time accordingly.

The control unit 200 measures the flow of fuel gas fed 302 to the mesobburner 60 or verifies that the mains supply pressure is suitable for obtaining a correct measurement of the equivalence ratio. Once this is done, the control unit 200 can therefore receive the signal from the mesobburner 60 relating to the ionization current measured, the temperature of the fuel gas supplied 302, the temperature of the intake air 312, the temperature of the mesobburner 60. Received these variables at the input, it can use them , making use of suitable algorithms implemented therein, to regulate the combustion for each of the other burners once it knows for each of them the degree of opening of the gas cock 132 set by the user, the temperature of the fuel injected gas 301, the the temperature of the intake air 310, the temperature 35 of the burner 10, the position of the air regulation system 50 and if the flow rate of burned gas 330 and air 340 coming from the mesobburner 60 is sent to the specific burner 10 being analyzed.

In particular, the control unit 200 is thus able to calculate what the position of the air regulation system 50 should be, check if this coincides with the one in progress and if not, send the actuator 53 the instructions relating to how much to move the regulator. air 51, 52.

Alternatively, when the hob 100 does not include any mesobburner 60 and it is desired to make a variable geometry atmospheric induction burner 10 without mesobburner 60, the steps of the process, which will be described below, from the first phase to the eighth phase can be omitted.

Alternatively, it is possible to foresee that if only four observable Tgas, Taria, Tb, Pgas listed above were to be taken into consideration, the mesobburner 60 would not be necessary. operation in terms of energy efficiency, limitation of unwanted emissions, safety and cooking precision, assuming a certain reference composition of the fuel and thanks to the detection of the following parameters: flow rate of combustible gas fed to the single burner 10 under consideration, temperature of the fuel gas fed Tgas to the single burner 10 under examination, temperature of the air sucked in by the single burner 10 under examination, temperature Tb of the single burner 10 under examination.

Alternatively, the invention described up to now can be implemented in different ways, making use of multiple engineering and experimental approaches. One of these approaches will be reported below.

As far as the manufacturing process of the mesobburner macro-components 60 and one or more burners 10 is concerned, the manufacturing process of the hob 100 comprises twelve steps.

The chronological sequence of the phases of the procedure is not to be considered binding as is the construction method described which aims solely to prove the feasibility of the object.

The steps of the procedure for the realization of the macro-components mesobburner 60, burners, reference is made to mathematical equations.

For the sake of clarity, the symbols used in the following mathematical equations are listed below:

equivalence ratio

volumetric flow rate of fuel gas volumetric flow rate of air volumetric flow rate of the fuel air mixture

fuel gas density

air density

ratio between the density of the fuel gas fed and that of the aspirated air molar mass of the combustible gas molar mass of the air

volumetric ratio between the air sucked in by the ejector and the fuel gas supplied

mass ratio in conditions

stoichiometric air-fuel gas

passage area of the fuel gas nozzle

passage area of the burner doors

throat area of the ejector throat diameter of the ejector diameter of the fuel gas nozzle atmospheric pressure

pressure difference between upstream and downstream of the fuel gas nozzle

efflux coefficient of the fuel gas flow

ejector flow rate reduction coefficient

outflow coefficient of the burner doors

ejector pressure drop coefficient

primary air fraction

higher calorific value of the fuel expressed in mass terms

thermal power

molar flow of a species j-th molar or volumetric fraction of a given

j-th species in the mixture

chemical composition of the fuel universal constant of gases temperature of the fuel gas

powered

temperature of the air sucked in by the ejector

temperature of the fuel-air mixture

burner temperature ionization current

molar specific heat under pressure

fuel gas constant

molar specific heat under pressure

air constant

mass specific heat of the body to be heated

equivalent mass of the body to be heated difference between the initial and final temperature of the heated body for the time efficiency tests

position taken by the ejector air regulator

binary variable linked to the supply of gases from the mesobburner thermal power delivered by the burner.

In particular, the sequence of phases of a process for manufacturing the cooking hob 100 comprising the mesobburner 60 is reported.

From the first phase to the seventh phase of the procedure are phases for the realization of the mesobburner 60.

A first phase involves a choice of the nominal power of the mesobburner 60.

The nominal power of the mesobburner 60 is calculated starting from equation 1 below and is therefore given by the product of the nominal fuel gas flow rate of the combustible gas 302 taken as a reference (for example G20) for the corresponding calorific value (conventionally assumes the gross calorific value, PCS). This must be carefully chosen by the designer. In fact, this power must be the result of the compromise given by trying to minimize the thermal power supplied to the mesobburner 60, so as to make it as negligible as possible with respect to that supplied to the burners 10 predisposed to cooking, without however leading to an excessive miniaturization of the mesobburner. 60 itself, which would compromise the cost-effectiveness of the device and its reproducibility on an industrial scale.

Equation 2 below can be a useful reference from this point of view as it allows you to evaluate the diameter that the injector nozzle will have (by calculating it starting from area Ai) as the fuel gas flow rate 302 varies by setting some parameters which can be imposed or estimated starting from values reported in the literature (as in the case of the efflux coefficient,

Subsequently, making use of equation 4 above, considering an appropriate value of the flow rate reduction coefficient ω starting from what is reported in the literature, it is possible to obtain a first estimate of the throat diameter of the ejector 62 in order to have a determined value of R (equation 3) which indicates the ratio between the sucked air 312 and the injected gas 302 in volumetric terms (for example by first choosing a fairly rich mixture, which involves more stable flames and reduced throat diameters) and thus a certain Φ (equation 5 ) and a certain total volume flow under isothermal conditions (equation 6). These last two parameters are useful in turn for a first geometric sizing of the head 63 of the mesobburner 60. It should be noted that knowing the throat diameter it is possible to estimate what the length of the mixing duct of the ejector 62 should be starting from the recommendations that can be found. in technical literature. By doing so, overall a preliminary assessment of the size of the mesobburner 60 is obtained, starting from the nominal power chosen, being able to assess its suitability or not.

A second phase involves the sizing of the head 63 of the mesobburner 60.

The head 63 of the mesobburner 60 can be made with different configurations ranging from porous septa to perforated plates with doors of different geometry and size. The key aspect to consider is the cost-effectiveness of the choice made and its reproducibility on an industrial scale.

For the choice of the total section of passage of the combustible mixture through the head 63 of the mesobburner 60, where the flame 106 will be anchored, reference can be made to equation 7, obtained for isothermal conditions and hypotheses applicable in practice to atmospheric burners 10. In doing this, it is possible to estimate the coefficients related to the pressure drops

and consistently with what is reported in the technical literature. For the actual dimensions of the individual gates, their geometry and spatial distribution, reference should be made to the known concepts related to the propagation speed of the flame front 106, the quenching diameter and the empirical findings detailed in the literature.

Note that equation 4 previously adopted is reported to be valid for burners where the size of the burner doors is such as to make their effect on the sucked air negligible. In particular, it is recommended that the ratio between the outflow area from the burner doors and the area of the ejector throat section is greater than 1.5. If this is not verified for the passage sections previously obtained, you can use equation 8 to recalculate the term Dg. The choice of materials with which to make the head of the mesobburner 60 is also an important parameter and, for example, metals already commonly adopted for the production of burners can be adopted.

The design must also include those fundamental elements for the operation of the mesobburner 60 such as the igniter 66, the ionization electrode 64 and any solid walls 81 (made for example with ceramic material) designed to avoid the introduction of secondary air before of the reaching of the electrode 64 by the burnt gases 330.

Once the configuration has been chosen, the head 63 of the mesobburner 60 can be connected to a duct into which a known flow of combustible gas 302 and one of air are fed.

The supply can, for example, be performed through flowmeters connected to cylinders containing the fuel under pressure and to compressed air transport pipes. Note that the pipe upstream of the burner head must be long enough to give complete mixing of the reagents. Once the flow rate and the composition of the flows are known, it is possible to reconstruct the stability field 501 of the mesobburner 60 as shown in figure 12, which shows the specific load at the burner ports on the abscissa 912 and the fraction of primary air on the ordinates 913, identifying the regions of flash back 502, flame lift 503 and sooting 504 through observation of the flame. In detail, video recordings can be made to see how for an assigned nominal flow rate of combustible gas 302, as the primary air 312 increases, it is possible to reach conditions of instability 503 (flame lift) or, on the contrary, by reducing the primary air 312 (and therefore increasing Φ) leads to the appearance of the yellow color which in the flames of hydrocarbons 504 signals the presence of fine carbonaceous particles. Also through video footage it is possible to identify the instant in which, by reducing the flow of fuel gas 302, there will be a flash back. Therefore, moving along two coordinates (flow rate of combustible gas and fraction of primary air supplied) it is possible to obtain a graph like the one shown in figure 12.

The fraction of primary air (PA) is calculated as the ratio between the air actually fed with respect to the air that would theoretically be fed to oxidize all the fuel fed (for example G20) and is clearly a parameter linked to Φ and R (equations 5 and 9).

The specific load at the burner ports (Burner Port Loading) is instead nothing more than the ratio between the thermal power supplied (equation 1) and the total area of the burner ports.

Obtaining this graph therefore allows you to validate the design chosen as a function of the nominal power chosen or alternatively to modify the nominal power as a function of the operating range of the head 63 of the mesobburner 60 that has been characterized.

A third phase of the procedure involves the sizing of the ejector 62 of the mesobburner 60.

Once the operating range of the head 63 of the mesobburner 60 has been obtained and the nominal heat output is known, it is possible to choose the value of R which is to be achieved always in nominal conditions.

The choice of R must aim first of all at giving flammable mixtures and flames that fall within the stability range 501 previously defined as the surrounding conditions vary (composition of the combustible gas, temperatures, etc ...) and secondly to be suitable obtaining a signal as suitable as possible for obtaining the measurements related to the ionization current. The measured signal will in fact be maximum for a certain Φ (around 1.1) but working near this value can lead to signals that may not be unique and would involve the installation of additional systems to clarify doubtful situations. It would therefore be ideal to always operate with an R such as to give the highest possible current values and at the same time always in increasing or decreasing monotonic sections.

Once this R has been chosen, it is possible to proceed with the design of the ejector 62 which can be done by means of empirical expressions (equations 2, 4 and other fluid dynamics correlations) or by means of other tools such as CFD (computational fluid dynamics). For this purpose it may be useful to experimentally evaluate the head losses connected to the head 63 of the mesobburner 60, for example by evaluating the total pressure difference upstream and downstream of the head 63 of the mesobburner 60 itself as the total flow rate varies, implementing this information. in the calculation algorithms that will be used.

Once a first geometry of the ejector 62 has been obtained and made, it is possible to integrate it with the head 63 of the mesobburner 60 and carry out tests to evaluate the actual R value in nominal conditions.

To do this, it is sufficient to feed a known flow rate of combustible gas 302, of known composition, and at the same time to isolate the head 63 of the mesobburner 60 from possible inflows of secondary ambient air, by measuring the composition of the burned gases. In fact, it must be remembered that compared to the previous point, now the air flow 312 is no longer imposed but is sucked by the ejector 62, resulting in an unknown parameter, difficult to measure at the inlet of the ejector 62. To obtain the gas composition it is sufficient make use of an analyzer of the composition of the burned gases connected to a probe predisposed to take the gases directly from the exhaust of the mesobburner 60.

At this point, making use of atomic balances, known the composition of the fuel 302 and the ambient air 312 aspirated by the mesobburner 60, it is possible to obtain Φ and the actual R ratio.

For example, let's assume that we operate with G20 gas (100% CH4) in conditions where it can be assumed that all the hydrogen present in the fuel gives H2O and that the only other combustion products relevant to the definition of Φ are CO, CO2. and O2. It follows the following balance in terms of molar discharge:

The values measured by the analyzer are generally on an anhydrous basis and report the molar fractions of the measured species (in this example CO, CO2 and O2).

The mole fraction of N2 in the fumes can be obtained as the complement to one of the molar fractions reported by the analyzer:

Since the molar flow rate of fuel from an atomic carbon balance is known, we have:

Once the molar flow rate of methane is known, it is therefore immediate to have the total molar flow rate of dry gases:

Once the total molar flow rate of dry fumes has been calculated, the molar flow rate of each individual species measured by the analyzer is thus obtained:

Since the hypothesis has been made that all the hydrogen contained in methane goes to give water, which is subsequently condensed, the molar flow of the same is also obtained thanks to an atomic balance on hydrogen:

With an atomic balance on oxygen it is therefore able to determine the molar flow rate of the fed air since this can be approximated in a mixture having a chemical composition equal to 21% of O2 and 79% of N2.

Note how in the example shown, since the fuel is free of nitrogen fractions, it would have been possible to calculate the molar flow of air starting from the molar flow of nitrogen.

Once the molar flow rate of air has been obtained, we immediately have R and Φ of the mixture, as the molar and volumetric flow rates are linked by the state law of ideal gases and that both the volumetric flow rate of the supplied gas and that of the sucked air are at pressure atmospheric.

The solution model described above can of course be extended by considering the measurement or estimation of any other combustion products such as H2, unburnt hydrocarbons (HC), nitrogen oxides (NOx) or any traces of water due to incomplete dehydration of the fumes.

Similarly, the approach used is applicable to fuels of different known composition.

Once R is obtained, it is possible to evaluate whether this is close to the value you wanted to obtain or whether it is necessary to modify the geometry of the ejector 62. A fourth phase of the procedure involves obtaining the expression of Rmeso.

Once the definitive atmospheric induction mesobburner 60 has been obtained, consisting of ejector 62 and mesobburner head 63, it is possible to proceed with the definition of the expression of Rmeso, where with the subscript "meso" it is specified that it is the expression of R referred to to the mesobburner component 60.

To do this, it is possible to use the same test bench used for the validation of the geometry of the ejector 62, thus adopting a derivation of the air-fuel ratio known the flow rate and composition of the combustible gas 302 and the composition of the fumes 330 avoiding the secondary air intake.

In this case, however, systems capable of controlling certain thermo-physical parameters must be introduced. In particular, it will be necessary to evaluate the trend of Rmeso as the fuel gas flow rate 302 varies, the temperature of the fuel gas, the temperature of the air, the temperature of the mesobburner, the composition of the combustible gas.

The flow rate and composition of the combustible gas are already under control since it is possible to feed combustible gas 302 of known composition through a cylinder and adjust the flow rate using a suitable laboratory flow meter. In particular, it is important to know the molar mass of the combustible gas since for an ideal gas at a given pressure and temperature this is what allows to obtain its density.

From the application point of view, the fuel gas temperature can be measured / estimated in two ways: either by inserting a temperature sensor 141 (for example a thermocouple) in the gas supply duct itself or in the body of the injector 45 of the ejector 62. The injector is in fact the element that due to its proximity to the burner can be subject to the greatest heating and given the reduced passage section and the high circulation speeds of the combustible gas inside it, it will contribute predominantly to determining the actual temperature of the gas. fuel at the outflow.

For the arbitrary control in the experimental tests of the temperature of the fuel gas 302, for example, it is sufficient to install a fuel gas supply duct heated by an electric resistance, with thermal power supplied by the modular Joule effect, upstream of the injector 45.

The ambient air temperature can be controlled by inserting the mesobburner 60, or at least the part where the air is sucked, in an air-conditioned environment. The measurement of the air temperature can be obtained by placing a thermocouple 151 near the entrance to the ejector duct 62.

The temperature of the mesobburner can similarly be measured by inserting a thermocouple 65 inside the head 63 of the mesobburner 60, in a cavity made of the metal material of which it is composed, ensuring suitable contact between the two components.

The problem with this parameter, however, lies not in its extent but in its control. In fact, by the very nature of the mesobburner 60 this will start from an initial temperature, equal to the ambient one, and will undertake a transient heating which will bring it to temperatures close to the head 63 of the mesobburner 60 even a few hundred degrees Celsius higher.

The analysis relating to the effect of the mesobburner temperature cannot therefore be conducted in stationary conditions but the trend of R over time must be measured as the aforementioned temperature varies.

By doing this it is possible to determine curves such as those shown in Figure 13 as the various parameters initially mentioned vary.

Having experimentally obtained the different curves that link Rmeso to the thermophysical variables of interest, a function can be reconstructed which, taking for example equation 4 as a model, would result in:

Where applying the state law of ideal gases, considering air and gas at a pressure equal to the atmospheric one, we obtain:

The expression of pressure drops / flow reduction can be approached by searching for different suitable formulations.

For example, you can think of an equation such as:

Where ωrif is the flow rate reduction coefficient that would occur with all the quantities measured in reference conditions and where α, β, γ, δ indicate coefficients obtained experimentally or functions involving all or part of the other measured parameters, always obtained through analysis of empirical results.

The actual applicability of one model or another is to be verified during the re-processing of the measured data taking into account the choice that best lends itself to minimizing the uncertainties related to the formulation of Rmeso through analytical expression.

A fifth phase of the procedure involves a determination of the Φmeso-IIon bond, where the subscript "meso" specifies that it is the expression of Φ referring to the mesobburner component 60.

The determination of the equivalence ratio with which the mesobburner 60 (Φmeso) actually operates in the presence of any variation of the boundary conditions is of fundamental importance since it allows to set combustion regulation strategies that also take into account the variation in the composition of the combustible gas. if natural gas primarily composed of methane is used. The applicability of the same system to operate with other fuels such as LPG mixtures, on the other hand, has yet to be verified.

It is necessary to create the ionization current measurement circuit 68, assuming that it will be necessary to impose potential differences between electrode 64 and mesobburner 60 of about 300-400 V and that the measured currents will be of the order of nA-µA. Naturally these evaluations are based on the data found in the literature.

It is also important that the electrode 64 has been placed from the beginning of the design (second phase of the procedure) at a suitable distance (indicatively less than 10 mm) from the ports 61 of the mesobburner 60 and that it has been subjected to an aging process so that the measured signal does not vary over time.

The applied voltage can be alternating or direct and the ionization current measurement circuit can also be used as the FFD system of the mesobburner 60.

At this point it is possible to start an experimental campaign aimed at obtaining the steps of the procedure that will allow the reconstruction of curves like the one shown in the graph in Figure 14 that link the ionization current to the effective equivalence ratio. The parameters of interest will be the chemical composition of the fuel, the total flow rate of the flowing mixture, the temperature of this mixture and the temperature of the mesobburner.

The tests can be carried out with fuels having different compositions, taking as a reference the limit gases for the functioning tests of the hobs to be used in the different markets. Clearly the actual composition of the combustible gas will be unknown in commercial use but the regulation systems based today on the ionization current base their operation on being able to reconstruct curves that bind Φ-II not effectively applicable for substantial combustion adjustments taking into account the uncertainties due the lack of knowledge of the actual reactive chemical species. Therefore, carrying out tests with combustible gases of different compositions allows to quantify the uncertainties of the correlations obtained and consequently the uncertainty that will arise when the regulation strategies are adopted.

To obtain these curves it is possible to create a test bench where the head 63 of the mesobburner 60 is connected to a duct designed for the complete mixing of combustible gas and air, equipped with a heating system of this mixture by means of an adjustable electric heater for to be able to impose the temperature of the mixture upstream of the head 63 of the mesobburner 60.

The mesoburner temperature is an easily measurable parameter but not so easy to control. As already described in the fourth phase of the procedure, the burner will in fact tend to vary its temperature, warming up with respect to the initial ignition conditions.

A system commonly adopted in practice to control this phenomenon is to circulate a coolant in the burner head in order to control its temperature and evaluate its effects.

This therefore makes it necessary to design a head 63 of the mesobburner 60 which detaches itself from the one which will then be applied in the product suitable for commercial diffusion but which instead integrates a cooling circuit designed to stabilize the temperature of the mesobburner 60 at certain values, so as to be able to then apply the results obtained in the object without this thermal dissipation system.

Thus, by making use of two flowmeters predisposed to supply known flow rates of combustible gas 302 of known composition and air 312, the total flow rate of the mesobburner 60 and the equivalence ratio can be set, measuring the value of the ionization current for of the set temperature values of the mixture and of the mesobburner (figure 14).

We can therefore obtain an expression which in general terms results in:

In fact, it should be noted that the total flow rate, the temperature of the mixture and of the mesobburner are the main parameters which for an assigned equivalence ratio determine the relative distance of the flame front with respect to the head 63 of the mesobburner 60 and to the electrode 64, influencing in the at the same time the temperature of the reaction zone, thus also taking into account the non-adiabatic nature of the flame front 106 itself.

The above relationship, however, contains two terms that are not measured in the commercial application. In fact, the temperature of the mixture and the volumetric flow rate of the mixture are not parameters measured in what will be the design of the mesobburner 60 for mass distribution.

In the first place, however, it can be found that the temperature of the mixture will be close to that of the supplied air since this has a significantly higher flow rate than that of the fuel gas (remember that the stoichiometric air-fuel ratio between, for example, methane gas and air in molar terms it is equal to 9.5). It is therefore possible to obtain the temperature of the mixture by considering it to be equal to that of the air or to be more precise by weighing approximately the temperature of the combustible gas and that of the air considering a specific heat of air and suitable combustible gas and a value of Rmeso equal for example to what should be achieved under the reference conditions of the third stage of the procedure (equation 15).

As regards the total flow rate, this is linked to the expression of Rmeso obtained in the fourth phase of the process and to the flow rate of combustible gas 302 supplied to the mesobburner 60, which is a measurable parameter, as described by equation 6 for the case in which air and gas are at the same temperature.

Note how the composition of the fuel, which is unknown in the use of mesobburner 60 outside the laboratory tests, but whose predominant species can be known (for example methane for natural gas), does not perceptibly affect the flow rate. total given that:

Considering instead the case of different temperatures between combustible gas and aspirated air, equation 4 can be modified taking into account the molar volumes:

It follows that thanks to the expression of Rmeso obtained in point 4 it is possible to rewrite equation 14 taking into account how the variations in the temperature of air, combustible gas and mesobburner modify the value of the total flow rate for an assigned or measured gas flow rate fuel, thus obtaining an expression such as:

Equation 16 is therefore applicable to mesobburner 60 complete with uncooled head 63, ejector 62 and sensors designed to measure the various variables.

Since it is reasonable to expect that the predominant dependence in the expression of the equivalence ratio is that of the ionization current, it is possible that an expression in the form of equation 17 is suitable for a correct representation of this magnitude.

Where a, b, c, d indicate, as in the case of equation 13, the coefficients obtained experimentally or the functions that totally or partially incorporate the different measured variables.

A sixth step of the process provides for the construction of a gas supply line to the mesobburner 60 and of the sensors to be implemented in the atmospheric induction mesobburner 60.

The gas supply line must first of all include a solenoid valve, in particular a simple valve 135 normally closed, which opens when the hob 100 is used and the mesobburner 60 must be started to set the combustion regulation strategies accordingly. based on it.

In principle it is not necessary to provide proportional valves since the most convenient solution from the point of view of the measurements to be carried out on the mesoburner 60 is to operate possibly with a constant fuel gas flow rate. By operating with a non-proportional valve, therefore, the effective flow rate is influenced by the gas supply pressure to the hob 100 and by the composition of the combustible gas, parameters respectively related to the terms and ρgas of equation 2. As seen previously the density of the combustible gas has a negligible effect in principle in determining the total flow rate flowing in the mesobburner 60, which as seen is a parameter of fundamental importance for the correlation between Φmeso and IIon, while the variations in the network pressure are not instead negligible.

At this point it is important to consider the flow of combustible gas and the effect this has on Rmeso and the Φmeso-IIon bond.

The trend of Rmeso represented in figure 13 shows how beyond a certain flow rate of combustible gas the value of R tends to become independent of

settling on an approximately constant value.

The results obtained on the burners used in the boilers show that beyond a certain thermal power (and therefore the total flow rate fed by the power supply fan of the burner of the boiler itself) for certain Φ there are approximately constant values of IIon.

Alternatively, if these two considerations were to be applicable to the mesobburner 60, it would therefore be possible to omit the insertion of a flow meter 71, but it would be sufficient to use a pressure transducer 71 designed to validate the gas flow rate as suitable for the application of the algorithms that describe Rmeso and Φmeso previously obtained simply by verifying that the supply pressure falls within a certain range.

Alternatively, if this were not the case, a flowmeter 71 would have to be used, designed exclusively for reading the flowing flow rate, choosing the most suitable technical solution, aiming above all at the maximum reliability of the component and its cost-effectiveness.

At this point it is possible to summarize the components that are theoretically necessary for the use of the algorithms obtained so far considering the final design of the mesobburner 60 for mass production:

• Flowmeter or pressure transducer 71 for the determination or validation of

• Temperature sensor 141 inserted in the fuel gas supply duct or in the injector body 45

• Air temperature sensor 151 located near the intake duct of the ejector 62

• Temperature sensor 65 integrated in the head 63 of the mesobburner 60

• Electrode 64 and IIon measurement circuit 68. A seventh step of the procedure involves the realization of the ancillary components of the mesobburner 60.

Being a component primarily designed for a measuring function, the mesobburner 60 must be placed in a special compartment 80, protected from any damage or fouling.

The air 311 fed to the compartment is sucked through a common fan 26 (for example a fan driven by a brushless DC electric motor). The air flow 311 must be greater than that which the mesobburner 60 may possibly require in any case. The electric motor should also include systems for verifying that the start signal it receives corresponds to its actual operation and that the number of revolutions per minute is close to the expected value. The prevalence of the fan 26 must be such as to overcome the pressure drops in the compartment and in the ducts prepared for sending the mixture given by the excess air and the fumes 340 of the mesobburner 60 to the different burners 10 of the hob 100.

It is certainly easier to design the compartment 80 and the distribution pipes 163, to make these components, to evaluate the curve that links the pressure drops to the flow rate of the flowing mixture and on the basis of these results to design or select the design of the fan 26 and the relative electric motor.

The compartment 80 must be designed to ensure that the fluid flow field generated by the forced flow given by the fan 26 does not affect the operation of the mesobburner 60, causing it to operate exactly as if it were in a quiet air condition. Furthermore, it must be constructed in such a way that the burned gases 330 escaping from the mesobburner 60 cannot be sucked up by the mesobburner 60 itself, thus preventing recalls of stale air from invalidating the measurements and consequently the regulation strategies. This design can be based on theoretical or empirical approaches or on the use of CFD.

The obtained expressions of Rmeso and of the Φmeso-IIon link must in fact be unaltered. To do this, the compartment must be made in such a way that downstream of the fan 26 the kinetic term of the flow is converted into static pressure (suitable expansion) to minimize the speeds that can be found. Subsequently, it is appropriate that the air can reach the ejector 62 through, for example, a perforated grille 83, 84, such as to uniform the field of motion and minimize the actual speeds in order to recreate a situation similar to having the mesobburner 60 operating in still ambient air. Finally, it is sufficient to create solid walls or preferential paths for excess air in order to make it impossible to recirculate burnt gases 330 at the entrance to the mesobburner 60.

Since the mesobburner 60 can be unique for a whole hob 100 which on the contrary integrates several burners 10, it is necessary to ensure that the flow outgoing from the compartment 80 can be directed only to one or more of the burners 10 actually lit at that moment. To do this, it is possible to insert, downstream of the main outlet duct 85 from compartment 80, a motorized node 160 for distributing the fumes to the various channels 163 leading to the individual burners 10.

The node 160 can be made as a hollow cylinder equipped with an opening for the inlet of the flow from the other or from the bottom, and equipped with a single hole on the side surface. This, if allowed to rotate on its own axis, for example by means of a stepping motor, can be inserted in another hollow cylinder coaxial to it, fixed, provided with different holes from which the different ducts 163 of relevance depart. of the single burner 10.

In this way, depending on the burner 10 ignited, the lateral hole of the innermost cylinder can be made coaxial exclusively to the hole of the duct 163 to be fed.

There are other ways of making a node 160 of this type, but once again it is essential that they are equally economical and robust solutions like the one proposed here.

Since the need to send the gases exiting the mesobburner 60 to the various main burners 10 arises from the need to oxidize any unburnt products generated by the mesobburner 60, but above all to prevent the enthalpy content of these fumes from being dispersed into the environment without generating any effect. useful for cooking, it is advisable that the compartment 80, the distribution node 160 and the various ducts 163 are suitably insulated.

Once the cooking process is finished, all the burners 10 and the mesobburner 60 have been turned off, the fan 26 present can be used to quickly cool the different burners 10, thus reducing the time in which, due to the high temperatures present, the hob 100 can harm the user if touched

From the eighth phase to the twelfth phase of the process for making the hob 100 are phases for the construction of one or more burners 10. To make the mechatronic hob 100 it is possible to design new burners 10 or to start from models already present on the market by adding only the necessary changes.

In this embodiment, reference will be made to the latter case which allows for significant savings from the point of view of costs related to product engineering.

An eighth phase of the procedure involves the construction of the feeding sections of the gases coming from the mesobburner 60.

The gases 340 coming from the mesobburner 60 must be fed to the flames of the burners 10 so that any unburnt products are oxidized and that the enthalpy content of this mixture is not lost in the environment but goes to heat the pot 120.

The design of these inlet sections can be imagined aimed at guaranteeing rapid mixing with the secondary air 320 and at establishing a motion field at the base of the pan 120 which is optimal for heat exchange (for example by imposing thanks to this flow forced a swirl motion). To do this, it is sufficient to create the entry points 165 of the gases 340 coming from the mesobburner 60 with suitable geometry. However, it should be noted that if the burners 10 selected are of the type with primary combustion air intake 310 above the surface 101 of the hob 100, the gases 340 coming from the mesobburner 60 could also mix with this. flow. This situation should be taken into consideration in determining the optimal equivalence ratio of the burners 10 as will be seen in the ninth phase of the process for making the hob 100.

An embodiment of the supply sections is a metal crown 166 removable for cleaning operations, which wraps around the burner 10, being coaxial to it, in which holes 165 of different geometry are made, possibly inclined to generate a swirl motion or to allow the mixture produced by the mesobburner 60 to go against the flames of the burners 10 at a given angle. Below this crown there must be the annular manifold 164 into which the duct 163 coming from the distribution node 160 of the mesobburner 60 enters.

Since with the hob 100 off, the fan 26 can be used for rapid cooling of the burners 10 (cooling function), the design of the power supply sections can also be aimed primarily at this activity.

A ninth phase of the procedure involves the definition of the optimal equivalence ratio (Φnom). Once the 10 burners you want to use have been selected, it is possible to experimentally evaluate the optimal operating conditions.

By working exclusively on the head 30 of the burner 10 it is possible first of all to carry out energy efficiency tests. There are specific rules that establish how to carry out these tests so that the data found in different products are comparable to each other.

In general terms, the efficiency can be measured by evaluating the ratio between the amount of heat transferred to the water contained in the pot 120 that you want to heat with respect to the thermal power delivered by the burner 10. Then define the size of the pot 120, the material of the pot 120, the quantity of water contained in the container and the preheating times of the burner 10 of the grids 110 supporting the pot 120, it is possible to place the pot 120 above the burner 10 and by inserting a thermocouple in the water, measure the variation temperature of the same over time.

The flow rate of fuel fed and its composition is known, the thermal power delivered is known and thus the efficiency is obtained as described by equation 18:

Therefore, by feeding a known fuel gas flow rate 301 and a known air flow 310 to the head 30 of the burner 10 through special flowmeters, it is possible to find the optimal equivalence ratio which we will call Φnom of each burner 10 as the main surrounding conditions vary.

The known or measurable boundary conditions prevailing in determining the performance of the burner 10 are the flow rate of fuel gas supplied (and therefore the thermal power supplied) and the fact that the gases coming from the mesobburner are at that moment supplied or not to that burner 10. 60.

The flow rate of combustible gas is clearly known in experimental tests but it is not so in the burners 10 set up for commercial diffusion. In fact, it would not be economically possible to introduce a flow meter in all the burners 10. In the commercial burners 10 adopted for cooking, the power delivered, and therefore the flow of combustible gas, is controlled directly by the user of the hob 100 who sets the opening of the valve 132 of the fuel gas tap 301 and therefore the term

of equation 2. For this reason, it is possible to omit the direct measurement of the fuel gas flow rate but only detect the position of the gas valve, for example by applying an encoder 133 that indicates the degree of closure of the tap itself. In fact, it is reasonable to expect that the network pressure is close to nominal values and that the main pressure variations are related to the user's choices. Alternatively, if the tap 132 were of the electronic type, the position could also be calculated starting from the electrical adjustment signal sent to it.

The feeding or not of the flow 340 coming from the mesobburner 60 can affect the identification of Φnom and it is therefore advisable to carry out the tests both in the presence of this gas flow and in its absence. It should be noted how this is particularly relevant in the presence of burners 10 with air intake 310 above the surface 101 of the hob 100. This variable, defined as it can in fact be a term that admits two values, 0 and 1, depending on whether the gas flow 340 coming from the mesoburner 60 is not supplied to the burner 10 (assumed value: 0) or is (assumed value: 1).

By applying the same experimental system, it is possible to evaluate not only the efficiency but also the emissions of the main unwanted chemical species, in particular CO and NOx.

For example, by placing the pot 120 inside a conduit coaxial to it but with a larger diameter, such as to create an interspace between the pot 120 and the conduit itself, it is possible to take the gases that rise along the lateral surface of the pot and evaluate them the composition.

To compare different operating conditions, for example, an approach aimed at expressing the mole fraction of CO and NOx referred to dry gases, with respect to a determined mole fraction of oxygen, could be applied. This method is in fact convenient because it avoids introducing more complex data processing systems.

If we consider a flow containing a certain fraction of pollutants expressed in ppmvd (volumetric parts per million of dry gases) and having a certain mole fraction of oxygen (y% O2), it is possible to report this fraction by referring it to a certain mole fraction value of oxygen (x% O2) via equation 19:

Having thus the value expressed in ppmvd of the various chemical species analyzed and the mole fraction of O2 thanks to the measurement carried out by the flue gas analyzer, it is possible to obtain values that compare the emissions as the equivalence ratio fed and the variables on which you have set the search for Φnom.

In addition to energy efficiency and the content of unwanted species, the choice of Φnom can also be based on considerations regarding the cooking precision and safety of the device.

Since it has been assumed to modify burners 10 already present on the market, it is possible to assume that the operating range of the burner 10 is available without the need to carry out other tests. To improve cooking precision, it is the designer's objective to expand the possible adjustment range to the maximum and therefore the ratio between the maximum and minimum power of the burner 10. However, this can lead to conditions close to the stability limits defined by the operating range and typically such. ratio is limited in commercial burners 10, which operate with a fixed geometry, to values between 2 and 3. Taking into account that thanks to the mechatronic burner 10 it is possible to vary the geometry to respond to changes in the surrounding conditions, it is possible to try to expand this range ensuring that at critical points the Φnom is not only linked to performance parameters (and unwanted emissions) but also to the ability to have a system capable of operating stably and having time to adjust accordingly in the presence of sudden and significant variations in boundary conditions.

Since the burner 10 will undertake a thermal transient from the moment of ignition until reaching stationary conditions, it is possible to carry out tests that take this into account to possibly vary the optimal equivalence ratio as a function of the burner temperature. In particular, it is possible to start from the burner at room temperature, turn it on and monitor the emissions as the temperature rises, imposing a constant equivalence ratio thanks to the flow meters. This repeated analysis for different equivalence ratios allows you to implement any corrections of the nominal equivalence ratio previously obtained, again for different thermal powers and with or without the flow 340 coming from the mesobburner 60.

What has been described so far therefore provides the elements to define the optimal equivalence ratio that you want to achieve during cooking, keeping it constant as the surrounding conditions vary:

A tenth phase of the procedure involves the construction of atmospheric induction burners with variable geometry.

In order to make adjustments to the combustion process by varying the intake air flow 310 in order to operate with the desired equivalence ratio, it is necessary to introduce motorized systems that allow to vary the geometry of the atmospheric induction burners 10.

On the ejector 20 it is therefore necessary to install air flow regulation systems 50. These are usually adjusted manually and there are various technical solutions reported in the literature.

In order to carry out an automatic adjustment, it is necessary to introduce actuators 53 which allow the translation of the components, for example by associating a certain physical movement (for example an advance or backward movement of a shutter 51, 52 by a given value of millimeters) to the number of steps taken. by a stepping motor with respect to an assigned initial position.

The insertion of such devices is simple and economical in atmospheric induction burners 10 with primary air intake 310 below the surface 101 of the hob 100 and is more complex in burners 10 with air intake above the surface 101 of the hob 100 since the moving components can be touched by the user during the cleaning procedures and can be soiled due to the cooking process.

An eleventh phase of the procedure provides for the definition of the expression of R.

Similarly to what was done for the mesobburner 60 in the fourth phase of the procedure, it is necessary to obtain the expression of R for the different atmospheric induction burners 10 for which Φnom has been defined (as indicated in the ninth phase of the procedure) and a intake air regulation system (as indicated in the tenth stage of the procedure).

It is therefore possible to feed a known flow rate of combustible gas 301 of known composition to the burner 10 object of the experimental campaign, and by analyzing the composition of the fumes with the methods described in the fourth phase of the procedure, obtain the expression of R.

Compared to what is described in the fourth phase of the procedure, however, there is one more variable to consider in the description of the function of R since now the geometry of the ejector 20 is variable. It is thus possible to reconstruct curves such as that shown in figure 15 for each of the burners 10 that will be used in the hob 100.

Going therefore to write the expression of R we have:

Where the complex expression of the flow rate reduction coefficient can be imagined, for example, it can take a form similar to equation 13, such as:

Where ωrif is the flow rate reduction coefficient that would occur with all the quantities measured under reference conditions and where α ', β', γ ', δ', τ 'indicate coefficients obtained experimentally or functions involving all or part of the other measured parameters always obtained through analysis of the empirical results.

A twelfth phase of the procedure involves the implementation of sensors and actuators to be implemented in atmospheric induction burners.

The various atmospheric induction burners that will be installed in the hob must therefore have:

• position transducer 133 of the fuel gas cock 132. For example, you can use an encoder that allows you to detect the actual position of the valve 132 controlled by the user;

• temperature sensor 140 inserted in the fuel gas supply duct 134 or in the injector body 40;

• air temperature sensor 150 located near the intake duct 21 of the ejector 20;

• temperature sensor 35 integrated in burner 10;

• electromechanical actuator 53 (for example a stepping motor) designed to control the air regulator 51, 52 possibly equipped with an encoder.

As regards the method of operation of the hob 100 by means of the control unit 200, the method may comprise steps outlined in the flow diagrams of figures 16, 17 and 18.

In the process steps for the operation of the macro-components mesobburner 60, burners 10 and control unit 200 reference is made to mathematical equations which have the same symbols used above to describe the manufacturing process of the hob 100. In the rest of the discussion, for greater clarity, all the variables that refer to the mesobburner will be indicated with the subscript "meso" while in the absence of this subscript the variables will be linked to the single burner under consideration. The exception is the term IIon which is clearly linked exclusively to the measurements carried out on the mesobburner.

The control unit 200 has the task of receiving the various input signals coming from the sensors located in the hob 100, processing them and, thanks to the algorithms implemented therein, imparting various instructions.

These instructions cover:

• the functions related to the ignition of the mesobburner 60 (and possibly also of the other burners 10);

• the safety functions of the hob 100; • the control functions of the combustion process;

• the cooling function;

Wanting to dwell on the combustion regulation logic, figures 16-18 show examples of flow diagrams concerning this aspect and which could therefore be integrated into the control unit 200.

The details of the ignition process of the mesobburner 60, the logics concerning the "safety" of the device, and the cooling function are therefore excluded from the diagrams.

For simplicity, the output conditions from the loops shown in the diagrams have also been omitted since they are not relevant in order to immediately transmit the combustion regulation process. These exit conditions can be blocks due to safety conditions (for example a lack of flame detection) or more simply, the fact that the user has turned off the burner 10 since cooking is finished.

Furthermore, the description relating to the possibility that the control unit can also act on the degree of opening of the valve 132 has also been omitted, thus also varying the flow rate of combustible gas supplied to the single burner 10 under consideration.

The diagrams describe the operating process of the hob 100 to regulate the combustion process.

Figure 16 shows the flow chart for obtaining the Φmeso equivalence ratio.

The first step 600 connected to the regulation of the combustion process through the use of the mesobburner 60 consists in defining the actual equivalence ratio of this compact burner. A first preliminary step 604 is connected to the assessment of the suitability of the fuel gas flow rate in order to obtain correct correlations between the ionization current and and the equivalence ratio. Considerations regarding this have already been set out in the sixth phase of the manufacturing process of the hob 100 and will not be taken up here.

The procedure 600 provides for the successful ignition of at least one burner 601, the start of the ignition procedure of the mesobburner 602. A check is then carried out to verify whether the mesobburner 60 has successfully ignited 603. If the mesobburner 60 has ignited then the gas flow rate 604 of the mesobburner 60 is evaluated successfully. If the gas flow rate of the mesobburner 60 is suitable 606 then the parameters IIon 607 are measured,

611. In general terms, we wanted to report in the diagram between the input variables necessary for the definition of Φmeso also the volumetric flow rate of combustible gas in order to have a description as general as possible of the regulation algorithms. Having made this premise, it is therefore possible to understand how once the control unit 200 has received the signals relating to which are in turn measured thanks to the sensors summarized in the sixth phase of the process for manufacturing the hob 100, it is possible to obtain the value of Φmeso 612 making use of equation 16 and possibly, if the empirical findings prove its suitability, of its formulation according to equation 17 and then continue 700 in figure 17.

If the mesobburner was not successfully ignited 603, then the ignition attempts 605 would be repeated. If the attempts are less than a predetermined number N then you go back to starting the ignition procedure of the mesobburner 602. If instead the mesobburner 60 does not lights up after N attempts then proceed with phase 800 of figure 18.

If the gas flow rate 606 is not suitable, then proceed with phase 800 of figure 18.

At this point, it is convenient to rewrite the actual Φmeso value obtained by comparing it to a value that should be had in nominal conditions (for example, the design R value mentioned in the third phase of the process for manufacturing the hob 100 can be assumed. a determined composition of the combustible gas and for a determined ratio of the temperatures of air and combustible gas, corresponds to a precise Φmeso-nom).

In fact, this involves expressing a relationship between the actual equivalence ratio, which is a variable term, and a nominal equivalence ratio, which therefore results in a constant, with the aim of immediately transmitting an indication of how much the actual operating conditions have moved away from the reference conditions, thus providing with equal immediacy an idea of the extent of the regulation of the combustion process that will have to be adopted.

This relationship can be defined as:

In the procedure 700 of figure 17 the geometry necessary to obtain the desired equivalence ratio Φnom is calculated.

The process of regulating combustion 700 is to be implemented in the event that the mesobburner 60 is functioning and the surrounding conditions are suitable for the application of the algorithms connected to it, as is verified 701.

First of all it is possible to identify 712 for the generic burner 10 under consideration which is the optimal equivalence ratio, identified by the control unit known the variables and the equation number 20, i.e. measured 710, 709 and 711 For analytical convenience with respect to the definition of the term K1 described by equation 23 we can therefore write the value of Φnom obtained by relating it to the nominal equivalence ratio of the mesobburner 60 (which, as already discussed, is a constant term):

At this point it is possible to introduce another term that we will define K3 that aims to introduce a correction of the regulation linked to safety reasons. In the ninth phase of construction of the hob 100 it was described how the definition of the term Φnom if aimed at maximizing the adjustment range may, in the most extreme conditions of this range, no longer have to be based solely on considerations related to performance terms (efficiency and emissions) but also to concepts aimed at ensuring the ability of the burner 10 to operate in stable conditions in the presence of sudden variations in the surrounding conditions. To this we must also add the fact that a well-defined uncertainty corresponds to each measurement performed and correlation adopted. These uncertainties must be propagated up to the definition of the uncertainty inherent in the geometric regulation of the ejector 20. In particular, it is reasonable to expect that the uncertainty will be higher the more the regulation required by the system is relevant and the closer one is to conditions system instability.

As explained so far, it is clear that K3 can express a correction of Φnom, which we will call Φ’nom, and that it can be written as:

By doing so, it is therefore possible to obtain the equivalence ratio that the system will aim to achieve by adjusting the ejector 20.

Through simple mathematical steps we obtain:

Once K is obtained, it is therefore possible to calculate the geometric adjustment of the ejector 20 of the single burner 10 under consideration in order to obtain the desired Φnom equivalence ratio.

Omitting the analytical steps, recalling the equation of state of ideal gases, remembering that air and combustible gas are at the same pressure and that both the mesobburner 60 and any other burner 10 of the hob 100 receive a combustible gas 301, 302 of the same composition (and therefore same

same molar mass MMgas) we obtain:

From which the geometric regulation to be imposed can be obtained, known the parameters Taria-meso 702, Tgas-meso 703, Tb-

meso 704, 705, 706, Taria 707, Tgas 708, Tb 709, Pgas 710, gasmeso 711, by solving equation 29 explicitly, if possible, or iteratively:

The control unit 200 is therefore able, thanks to the correlations that describe R and Rmeso obtained in the fourth and eleventh phase of the process of making the hob 100, to calculate 712, thanks to the input variables 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, what must be the position of the air regulation system 50 to obtain the desired optimal equivalence ratio. If the actual geometry 713 is different from the calculated geometry 712, 714 then it is necessary to modify the geometry of the burner 10 i-th 715 and then return to procedure 604 of the diagram in figure 16, otherwise if the actual geometry is equal to the calculated geometry 714 then yes returns to procedure 604 of the diagram in figure 16 without making any adjustments. Therefore, as can be seen from procedure 700, it is possible to check whether the air regulation system 50 is already in the correct position and, if not, provide the electromechanical actuator 53 with instructions on how much to translate.

If the fuel gas flow rate is not suitable 606 or if the number of ignition attempts of the mesobburner is greater than a number N of attempts 605, then the operating procedure proceeds in 800 of figure 18, where the 10 i-th burner is active 801.

Process 800 calculates the geometry necessary to obtain the desired equivalence ratio Φnom.

The third flow chart 800 concerns the situation in which the mesobburner 60 is either not functioning or the measurement of the equivalence ratio through the ionization current cannot be considered reliable. However, it should be emphasized that the situation described in diagram 800 is also applicable to mechatronic hobs 100 without a mesobburner 60. In fact, the absence of the mesobburner 60 prevents adjustments that take into account the variability of the composition of the combustible gas, but hobs can still be made. mechatronic cooking 100 capable of taking into account all the other variables of interest (Pgas, Tgas, Taria, Tb) by measuring them 802, 803, 804 and 805, as envisaged in the example where the mesobburner 60 is missing.

The operating procedure 800 therefore makes it possible to operate the hob 100 even without the mesobburner 60.

In detail, it is possible to assume that the fuel has a reference composition, ideally the one that best represents the quality of the combustible gas 301, 302 distributed in the market where the hob 100 is used, and thus evaluate the actual geometry 807 and making use of the equation 21 calculate the necessary geometry 806 to have the desired equivalence ratio. If the actual geometry 807 is different from the calculated geometry 806, 808 then it is necessary to modify 809 the geometry of the i-th mesobburner and then check, if the mesobburner is present, 810 if the mesobburner 60 is on. If the mesobburner is not on then go back to measures 802, 803, 804, 805, otherwise if the mesobburner 60 is on then go back to procedure 604 of the diagram in figure 16. If the hob 100 does not use the mesobburner 60 from 808 and 809 it would always return to the reading of measures 802, 803, 804, 805.

By defining the molar mass of this reference fuel and with the corresponding stoichiometric mass air-fuel ratio, we have that by defining first the Φ'nom (thus referring to equation 20 and possibly integrating it with the corrections due to the considerations previously expressed regarding the uncertainty of measurements and correlations) we have:

From which the geometric position of the air regulation system 50 is obtained by solving, possibly by iterative way, the equation:

Finally, we note that the expressions of R have been obtained in the embodiment set out above using equation 4. As seen, this expression is reported to be valid for burners 10 having an area of the passage sections of the doors to which the flames are anchored negligible from the point of view of the effect on R and more precisely it is reported that the ratio between Ab and Ag is greater than 1.5.

If this were not verified, equation 5 can be adopted. Since this expression is obtained analytically for isothermal conditions, it can be rewritten by explaining the relationship between the density of the combustible gas and that of the air according to the law of ideal gases and making in the pressure drop coefficients the further effects linked to the variations of Tgas, Taria and Tb.

In particular, it can be written:

Hence the rewriting of equations 9 and 18 in the form:

Observing expressions 34 and 35, it is immediate to note that applying them in equation 27 does not obtain the algebraic simplification of the term MMgas (which is unknown) as was the case in the case previously discussed. It is good, however, at this point to analyze equation 5.

Equation 5 can in fact be rewritten as:

Referring to natural gas and observing that the stoichiometric molar ratio between air and methane is 9.5, it can be noted that the term A has a modest weight in the determination of R. In fact, the modulus of A is equal in the conditions mentioned above to about 1 '8% of B.

Still referring to natural gas, it can be noted that A varies little even assuming important changes in the composition such as the passage from gas G20 to gas G21 and G222 (respectively of 8% and -7%). Overall, it may therefore be legitimate to introduce a suitably chosen reference molar mass in the term A, just as it is possible to always replace this value in the terms that will multiply or divide A, without giving rise to significant errors on the regulation.

In detail, equation 29 can therefore be rewritten as:

Note that the above can also be implemented in the event that equation 4 or equation 5 are the one applicable to R and the other to Rmeso or vice versa. In fact, it is always sufficient to replace the molar mass of the combustible gas with a reference value in all terms of the final expression obtained connected to term A of equation 36.

For completeness of the discussion it is also possible to report the expression of the geometric adjustment in the event that the mesobburner 60 is not functioning or is absent, taking into account equation 35 and therefore replacing equation 31 with:

Finally, it should be noted that although use has been made so far of the equations describing R reported in the literature known to the author (equations 4 and 7), it is possible to apply the regulation based on the presence of mesobburner 60 in more general terms for expressions that , following empirical findings or a specific design, they can take the following formulations:

Where is it verified:

Yes, it is:

• rewritten the expression of R and Rmeso in general terms as the product of two independent functions (respectively f and g, and fmeso and gmeso) where the first takes into account all the physical variables of interest except the chemical composition of the combustible gas, which is instead specifically the only variable on which the second function depends.

• Assuming that variations in the composition have the same effect on the burners analyzed and on the mesobburner 60, taking into account that the fuel is the same for all the aforementioned components and as suggested by equations 4 and 7.

For what is written above, equation 27 can therefore be reformulated in general terms by applying the equation of state of ideal gases, for fuel gas and air at atmospheric pressure, in order to isolate the term f and thus obtain the geometric regulation to be implemented on the single burner examined by equation 42:

The invention thus conceived is susceptible of numerous modifications and variations, all falling within the scope of the inventive concept; furthermore, all the details can be replaced by technically equivalent elements. In practice, the materials used, as well as the dimensions, may be any according to the technical requirements.

Claims (16)

CLAIMS 1. Atmospheric induction burner (10) for a hob (100) comprising at least one head (30) and at least one ejector (20), characterized in that said at least one ejector (20) of the burner (10) comprises at least one air flow rate regulation system (50) for regulating a flow rate of air sucked in by said at least one ejector (20) and said burner (10) providing at least one control unit (200) suitable for controlling at least said at least one regulation system of air flow (50). 2. Burner (10) according to claim 1, characterized in that said at least one air flow regulation system (50) comprises at least one electromechanical actuator (53) mounted with said burner (10), to control at least one flow regulator of sucked air (51, 52) and adapted to pass from at least one open position to regulate an air passage to a closed position to prevent the passage of air towards said ejector duct (21) of said at least one ejector (20). Burner (10) according to any one of claims 1 or 2, characterized in that it provides means (140, 150, 35, 130) for measuring a temperature of a combustible gas (Tgas) fed to the ejector (20), a temperature of air (Taria) drawn in by the ejector (20), a temperature (Tb) of the burner (10), a measurement of thermal power (Pgas) delivered by the head (30) of the burner (10), where said gas temperature fuel (Tgas), said air temperature (Taria), said burner temperature (Tb) and said thermal power (Pgas) are data transmitted to said control unit (200). Burner (10) according to any one of claims 1-3, characterized in that said control unit (200) regulates a fuel gas supply (301) towards said burner (10). 5. Mesobburner (60) to co-operate with at least one burner (10) for a hob (100) according to claims 1-4, characterized in that it comprises at least one ejector (62), at least one head (63) and at least one measuring means (64, 68) of an ionization current (Iion) connected to the presence of a combustion process and providing at least one control unit (200) suitable for controlling at least said at least one air flow regulation system (50) of said at least one burner (10) to regulate a flow rate of air sucked in by at least one ejector (20) of said at least one burner (10). 6. Mesobburner (60) according to claim 5, characterized in that it is a burner of smaller dimensions than said at least one burner (10) of the hob (100). 7. Mesobburner (60) according to any one of claims 5 or 6, characterized in that said means (64, 68) for measuring said ionization current (Iion) comprises at least one electrode (64) positioned downstream of the flame front (106) and an ionization current sensor (68) connected to said at least one electrode (64). 8. Mesobburner (60) according to any one of claims 5-7, characterized in that it is installed inside a compartment (80) comprising walls, an inlet duct (25) for air (311) comprising at least one fan ( 26) and an outlet pipe (85, 163) for exhaust fumes (340). Mesobburner (60) according to any one of claims 5-8, characterized in that it comprises solid walls (81) positioned so as to contain at least the flame front (106) of said head (63) of the mesobburner (60) and avoid inflows of air other than that sucked in (312) by the at least one ejector (62) before the fumes 330 have reached the electrode (64). 10. Mesobburner (60) according to any one of claims 5-9, characterized in that it provides means (71, 141, 151, 65) for measuring a temperature of a combustible gas (Tgas-meso) fed to the ejector (62) , a temperature of air (Taria-meso) sucked in by the ejector (62), a head temperature (Tb-meso) of the head (63) of the mesobburner (60), a flow rate measurement of the combustible gas introduced into the mesobburner (60 ), where said temperature of a combustible gas (Tgas-meso), said air temperature (Taria-meso), said head temperature (Tb-meso), said fuel gas flow rate measurement are data transmitted to said control unit (200). 11. Mesobburner (60) according to any one of claims 1-10, characterized in that it is installed inside a compartment (80) connected to at least one distribution node (160) to distribute exhaust fumes (340) towards said at least one burner (10) of the hob (100). Hob (100), characterized in that it comprises at least one atmospheric induction burner (10) and at least one control unit (200) according to claims 1-4. 13. Cooktop (100) according to claim 12, characterized in that it comprises at least one mesobburner (60) according to claims 5-11. 14. Process for manufacturing a hob (100) according to any one of claims 12 or 13, characterized in that it comprises a step of manufacturing at least one burner (10) and at least one mesobburner (60) which comprises a step of definition of an optimal equivalence ratio (Φnom), a phase of definition of a volumetric ratio (R) between the air sucked in by an ejector (20, 62) of said burner (10) and mesobburner (60) and fuel gas supplied (301 , 302), a step of making said at least one burner (10) suitable for regulating a combustion process by varying an intake air flow rate by means of at least one air flow regulation system (50) suitable for maintaining said at least one burner (10) to operate under conditions of the optimal equivalence ratio (Φnom). 15. Operating method of a hob (100) according to any one of claims 12 or 13, characterized in that at least one control unit (200) of said hob (100) carries out said operating method, comprising a step of ignition detection (801) of at least one burner (10) of said hob (100), a measurement step (802, 803, 804, 805) of a temperature of a combustible gas (Tgas) fed to at least one ejector ( 20) of said at least one burner (10), a temperature of air (Taria) sucked by said at least one ejector (20), a temperature (Tb) of said at least one burner (10), a measurement of thermal power (Pgas) delivered by said at least one burner (10), a transmission step to said at least one control unit (200) of data comprising said combustible gas temperature (Tgas), said air temperature (Taria), said burner temperature (Tb ) and said thermal power (Pgas), a step of regulating an air flow rate by means of an air regulation system (50) of said hob (100) in order to obtain an optimal equivalence ratio (Φnom) previously calculated on the basis of parameters of said at least one burner (10). 16. Method of operation according to claim 15, characterized in that it comprises a step of obtaining said optimal equivalence ratio (Φnom) by means of a step of measurements obtained by means of a mesobburner (60) according to any one of claims 5 -11, comprising a measurement step (607-611), of an ionization current (IIon), of a temperature of a combustible gas (Tgas-meso) fed to at least one ejector (62) of said mesoburner (60), of a temperature of air (Taria-meso) drawn in by the at least one ejector (62), of a head temperature (Tb-meso) of the head (63) of the mesobburner (60), of a flow rate measurement of the injected combustible gas in the mesoburner (60), a transmission phase of said ionization current (IIon), of said temperature of a combustible gas (Tgas-meso), of said air temperature (Taria-meso), of said head temperature (Tb -month), of said combustion gas flow rate measurement tible a step of calculating an equivalence ratio of the mesoburner and by means of a step of measurements obtained by means of at least one burner (10) according to any one of claims 1-4, comprising a step of measuring (702-711) of a temperature of a combustible gas (Tgas) sucked by at least one ejector (20) of said at least one burner (10), a temperature of air (Taria) sucked by at least one ejector (20), a temperature (Tb) of said at least a burner (10), a measurement of thermal power (Pgas) delivered by said at least one burner (10), knowing the presence or absence of the fumes (340) coming from the mesobburner (60) during combustion (gasmeso), a phase transmission to said at least one control unit (200) of data comprising said gas temperature (Tgas), said air temperature (Taria), said burner temperature (Tb), said thermal power (Pgas), said presence of fumes of the mesobburner (gasmeso), a calculation phase of d ect optimal equivalence ratio (Φnom) by means of said control unit (200).