RU2739001C2 - Heat exchanger for baking ovens - Google Patents

Abstract

FIELD: heat exchange.

SUBSTANCE: group of inventions relates to a convective furnace with a heat exchanger intended for preparation of food products and operating on gas fuel or liquid types of fuel. Gas furnace consists of a baking chamber equipped with a bottom wall and a roof wall, a fan with a horizontal axis of rotation (X—X), a burner with a preliminary mixing system and a heat exchanger. Heat exchanger includes at least two bundles of tubes installed opposite to each other between place for inlet of flue gases, made with possibility of connection with gas burner of gas furnace, and outlet hole for flue gases, made with possibility of connection with exhaust manifold of said gas furnace. Each tube bundle comprises at least two pipe sections, each of which consists of at least one pipe. Said sections of tubes lie in planes parallel to each other, perpendicular to horizontal axis (X—X), and are connected to each other in series by means of at least one transfer element so that flue gases can pass through each of sections of pipes in direction opposite direction of flue gas flow in section of pipes lying in adjacent plane. Pipe sections are located overlapping each other next to each other, so that the contours of the pipe section lying in the first plane completely overlap—if viewed along horizontal axis (X—X)—contours of pipe sections located in the following planes.

EFFECT: disclosed is a heat exchanger for baking ovens.

14 cl, 32 dwg

Description

DESCRIPTION OF THE TECHNICAL SIDE OF THE INVENTION

[0001] The present invention relates to a heat exchanger improved in particular for a domestic, professional or industrial type convection oven for cooking food, fueled with gas fuel or liquid fuels, hereinafter referred to as a gas oven for short.

BASIC TECHNICAL DATA OF THE INVENTION

[0002] Convection ovens for cooking food typically consist of a box-like body with a baking chamber in which food to be cooked or heated can be accommodated. Frontal access to the baking chamber is through a door that is fixed to the body by means of hinges. In order to achieve uniform heating of the air in the cooking chamber, means for heating and air circulation are provided, which are suitably connected to the controller and the control panel.

[0003] The means for circulating air is usually provided by at least one fan, preferably bi-directional, driven by an electric motor and located in an area that communicates with the baking chamber. If we talk about heating means, it should be noted that there are mainly two types of baking ovens on the market: electric ovens and gas-fired ovens.

[0004] In electric ovens, the means for heating inside the baking chamber are electric heating elements, usually located around the fan.

[0005] In gas ovens, the heating means consists of a gas heating unit containing mainly a burner, preferably of the pre-mixing type and usually located in the lower part of the baking chamber, and a heat exchanger, usually consisting of one or more tubes located in different methods, mainly against the back wall of the chamber, or sometimes in the form of a circle around the fan and adapted to allow the flue gases generated by the burner to pass through them to provide heat exchange and influence the temperature inside the baking chamber, before the residual flue gases are discharged through the exhaust hole located in the roof of the furnace. An example of such known heat exchangers is shown in DE 4125696.

[0006] In such gas ovens, one drawback is observed, which is that the thermal energy obtained from the combustion of combustible gases is only partially used to heat the baking chamber, since the flue gases pass through the pipes at a very high speed and the heat exchange surface of the pipes the inside of the baking chamber is relatively small; from which it follows that the temperature of the flue gases in the area of the outlet is still quite high.

[0007] To overcome this drawback, it is desirable to increase the heat exchange surface of the heat exchanger tubes, for example, by increasing its length inside the baking chamber in order to increase the heat exchange efficiency; however, in this case, the size of the space required to accommodate the heat exchanger body is greatly increased, which leads to problems in the furnace structure due to the large size.

[0008] In addition, it must be borne in mind that, unlike electric heating elements, for which heat exchange is substantially constant throughout their location, in a gas heat exchanger the temperature of the combustible gases passing through it gradually decreases with distance from the burner and, consequently, the heat intended for heat exchange with the baking chamber is reduced.

[0009] As a result, elongation of the heat exchanger can lead to uneven temperature distribution within the baking chamber, which in some cases results in uneven baking of food products and, therefore, is unacceptable for cooking.

[0010] JP 2011141098 shows a furnace equipped with a heat exchanger consisting of two tube bundles arranged symmetrically around a fan. In particular, each of these two tube bundles consists of three sections of tubes that penetrate into the furnace chamber from the roof side, so that combustible gases pass through them in one direction, and a pair of return pipes that allow the passage of combustible gases in the opposite direction, and located at a greater distance from the first section of pipes relative to the fan, and connected to them by means of a transfer element located under the fan, and intended for conducting flue gases to the outlets located in the upper wall of the baking chamber, and thus ensuring the passage of flue gases in the return , the opposite direction.

[0011] However, the expansion of the structure of the above-described heat exchanger is radial with respect to the fan, since the sections of the pipes that allow the combustion gases in the opposite direction are located at a greater distance with respect to the sections of the pipes that allow the combustion gases to move in the forward direction; accordingly, this entails an increase in the dimensions of the housing required to accommodate the heat exchanger in it, and also leads to a limitation in the choice of the size of the fan to be installed in the furnace.

[0012] In addition, according to one industry expert, this configuration of the heat exchanger leads to the fact that the air supplied from the furnace fan initially passes through the air supply pipes in the forward direction, and then through the pipes through which the air passes in the opposite direction. which contributes to optimization in terms of heat transfer efficiency.

SUMMARY OF THE INVENTION

[0013] The main object of the present invention is to overcome the existing technical disadvantages by developing an improved heat exchanger for gas baking ovens, which will improve the efficiency of heat transfer between combustible gases and the temperature inside the chamber, while improving the uniformity of temperature distribution within the chamber. for baking.

[0014] Within the scope of this object, an object of the present invention is to provide an improved heat exchanger for gas furnaces focused on volume reduction through a compact heat exchanger to ensure a compact overall furnace.

[0015] The next object of this invention is to create such a compact heat exchanger that it can be placed in the body of an electric furnace powered by electric heating elements, placing the heat exchanger in the same space where the heating elements were located, in case there will be such a problem, and if it is acceptable to the oven manufacturer.

[0016] Another object of the present invention is to provide such a heat exchanger for gas ovens for cooking, which will ensure an even temperature distribution throughout the baking chamber, eliminating temperature differences, in particular along the vertical axis, so that the cooked products are baked uniformly, evenly.

[0017] Another object of the present invention is to provide an improved heat exchanger for gas ovens that will fulfill the above objectives and will meet the above purpose, at minimum production costs, so that its use also has economic benefits, and this is achievable due to the use of different types modern equipment.

[0018] The above objectives and goals, as well as goals and objectives that will appear in the future, are achieved by means of a heat exchanger, the definition of which is given in paragraph 1 of the claims of the present invention; Additional characteristics are defined in the following claims and depending on claim 1 of the claims of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

[0019] The advantages and features of the invention will become apparent from the following description, with non-limiting examples and with reference to the accompanying drawings, such as:

- Figure 1A shows a front view of the structure of a gas cooking oven in which a heat exchanger according to the invention is installed;

- Figure 1B shows the furnace structure in accordance with Figure 1A - top view;

- Figure 1C shows the furnace structure - side view indicated by the arrow Z in Figure 1A and in accordance with the previous figures;

- Figure 2 shows a main side view W, shown in Figure 1A, of a heat exchanger according to a first embodiment of the present invention;

Figure 3 shows a main side view, indicated by W in Figure 1A, of a heat exchanger according to a second embodiment of the present invention;

- Figure 4A shows a cross-sectional view of the heat exchanger along the vertical Y-Y axis shown in Figure 1C, in accordance with Figure 3 when used in the furnace design;

- Figure 4B shows a heat exchanger in accordance with Figure 3, shown in cross-section along the plane A-A of Figure 4A;

- Figure 4C shows a heat exchanger, in accordance with Figure 3, shown in section along the section line C-C of Figure 4B;

- Figure 4D shows a heat exchanger, in accordance with Figure 3, in section along the plane B-B of Figure 4A;

- Figure 4E shows a heat exchanger, in accordance with Figure 3, in section along the section line D-D of Figure 4D;

- Figure 5A in cross-section along the vertical axis Y-Y, and in accordance with Figure 1C depicts an embodiment of the heat exchanger according to this invention when applied to the design of a gas furnace;

- Figure 5B shows a heat exchanger according to an embodiment of Figure 5A, in cross-section along plane A-A of the same figure;

- Figure 5C shows a heat exchanger according to the embodiment of Figure 5A, in section along the section line C-C of Figure 5B;

- Figure 5D shows a heat exchanger according to an embodiment of Figure 5A, in cross-section along plane B-B of Figure 5A;

- In fig. 5E depicts a heat exchanger according to the embodiment of Figure 5A, in section along the plane line D-D of Figure 5D;

- In fig. 6A is a cross-sectional view along the vertical Y-Y axis shown in Figure 1C of a third embodiment of a heat exchanger according to the present invention when used in a gas furnace structure;

- Figure 6B shows the heat exchanger in accordance with Figure 6A, in section along the plane A-A of the same figure;

- Figure 6C shows a heat exchanger, in accordance with Figure 6A, in section along the plane B-B;

- Figure 7A, in section along the vertical Y-Y axis shown in Figure 1C, shows an embodiment of a heat exchanger in accordance with this invention when used in a furnace design;

- Figure 7B shows a heat exchanger according to the embodiment of Figure 7A, in section along the plane A-A of the same figure;

- Figure 7C shows a heat exchanger according to the embodiment of Figure 7A, in section along the section line C-C of Figure 7B;

- Figure 7D shows a heat exchanger according to the embodiment of Figure 7A, in section along the plane B-B in Figure 7A;

- In fig. 7E shows a heat exchanger according to the embodiment of Figure 7A, sectioned along the plane D-D in Figure 7D;

- Figure 8A shows a front view of a gas furnace structure in which a heat exchanger is installed according to a fourth embodiment of the present invention;

- Figure 8B shows a top view of the furnace structure of Figure 8A;

- Figure 8C shows a side view of the furnace structure indicated by the arrow Z in Figure 8A and in accordance with the previous structures.

Figure 9 shows a main side view, W, indicated by the arrow in Figure 8A, of a heat exchanger according to a fourth embodiment of the present invention;

- Figure 10 shows the main view of the heat exchanger according to the fifth embodiment of the present invention, intended for use in the structure of a gas furnace equipped with three fans located on top of each other;

- Figure PA is a frontal view of the heat exchanger in Figure 10;

and

- Figures 11B, 11C and 11D show the cross-sections obtained respectively along the planes A-A, B-B and C-C indicated in Figure 11A.

DESCRIPTION OF THE MOST PREFERRED EMBODIMENTS OF THE INVENTION

[0020] It should be noted that in the description below, indicative terms such as "top, bottom, vertical, horizontal, bottom and top", as well as any other similar terms, should be interpreted in relation to the heat exchanger and furnace design used, as shown in the attached figures.

[0021] In addition, it is obvious that those advantageous features that will be described with reference to a specific, specific implementation of the present invention may also be provided in other implementations, even if they are not explicitly described or illustrated.

[0022] With reference to Figures 1A, 1B and 1C, a gas cooking oven 1 is shown equipped with a heat exchanger 10 in accordance with the present invention. The specified structure of the oven 1 consists of a body-box, having in its inner part a cavity or chamber for baking 2, having the shape of a parallelepiped and consisting of a pair of side walls 2A connected to the bottom 2B and the roof 2C; the rear wall 2D covers the baking chamber 2 from the rear, while the front part can be closed by means of a door 3 hinged to the body and controlled by a special handle 3A.

[0023] From the front, the structure of the furnace 1 advantageously comprises a control panel 8 provided with automatic or manual control and monitoring means that allow the operation of the furnace to be correctly controlled.

[0024] Inside the baking chamber 2, in close proximity to one of the side walls 2A and a divided partition 4, which extends along the entire height and almost the entire width of the chamber 2, leaving open two vertical openings 4A for free temperature movement in the oven a heating and ventilation chamber 50, in which at least one fan 5 is located, preferably with a horizontal axis X-X, capable of circulating air inside the baking chamber 2, and which is driven by at least one coaxial electric motor ( not shown) installed outside the baking chamber 2.

[0025] In order to heat the air in the baking chamber 2, a burner 6 is provided, preferably a pre-mixing system, which is fed with a mixture of air and fuel gas, including a combustion chamber 6A, and a heat exchanger 10, which is expandable, preferably inside said ventilation and heating chamber 50, and is designed to communicate the above-mentioned combustion chamber 6A with the exhaust port for combustible gases 7.

[0026] In particular, said heat exchanger 10 consists of at least two bundles of tubes 11, where each of said bundles consists of at least two sections of tubes that originate from the combustion chamber 6A of said burner 6, are located in a ventilation -heating chamber 50 around the fan 5, and is connected at the end with the outlet manifold 14, which is a common cavity for both pipe sections to which 11 are connected, and which is connected to the outlet 7.

[0027] It is preferable that the pipes of each of the two pipe sections 11 are arranged so as to be in parallel planes relative to each other, and preferably perpendicular to the axis X-X of rotation of the fan 5, connected in series with each other by at least one transfer element, and are preferably located along one axis parallel to the axis X-X of rotation of the fan 5.

[0028] In particular, an advantageous characteristic for this heat exchanger is that the tube sections of both tube banks 11 are arranged in such a way that they can develop towards the center of the heat exchanger, that is, towards the axis of rotation X-X of the fan 5, so that to ensure the compactness of this heat exchanger by placing the pipes as close as possible around the fan, and therefore increasing the efficiency of heat transfer, as will be explained in more detail below.

[0029] A particular feature of the present invention is that each pipe section is arranged such that the flue gases generated by the burner 6 flow in the opposite direction to the adjacent pipe located in the adjacent plane.

[0030] As explained below in more detail, these said pipes can be of different structures - each can consist of a single pipe, or possibly a pair of pipes, or a plurality of parallel pipes, and preferably have a circular cross-sectional shape, or an oval , or perhaps any other suitable form.

[0031] In addition, the cross-sectional dimension of the pipes may remain the same for all pipes of the branch of a given 11.

[0032] As an alternative and advantageous, it is possible for the pipe section size to vary along the corresponding tube bundle 11 and, in particular, it is preferable that the pipe section size gradually decreases, downwardly, as the distance from the burner increases.

[0033] In fact, as the combustible gases move away from the burner, they cool down, their volume and hence their speed decreases; therefore, it is advantageous to modulate the pipes of the section in such a way as to maximize the heat transfer coefficients while keeping heat losses below the tolerance limit.

DETAILED DESCRIPTION OF THE FIRST EMBODIMENT OF THE INVENTION

[0034] In accordance with Figure 2, there is shown a first realizable variant of the heat exchanger 10 in accordance with the present invention, located between the combustion chamber 6A of this burner 6, located, in particular, in the lower region of the baking chamber 2, and an exhaust manifold 14 connected to the indicated outlet 7, in accordance with the vault 2C of this baking chamber 2, as shown in Figures 1A and 1C.

[0035] In this first embodiment of the invention, two bundles of tubes 11 are arranged symmetrically around the fan 5 about its diametrical axis, and preferably about the vertical axis Y-Y passing through the center of the fan 5.

Each of the two bundles of pipes 11 that make up this heat exchanger 10 contains several sections of pipes 12A, 12B, 12C, located in parallel planes relative to each other and connected in series, and where each of the pipe sections consists of one pipe.

[0036] In particular, it is provided that the first pipe section 12A is directly connected by its first end part to the combustion chamber 6A, and its second end part is directed towards the roof 2C of said baking chamber 2, the second pipe section 12B is connected by its first end part to the second end part of the above first pipe section 12A and is positioned around the fan 5 so that its second end part reaches the bottom 2B of the baking chamber 2, the third pipe section 12C is connected by its first end part with the second end part of the said second pipe section 12B, and is connected at its second end part to the outlet 7 by means of an outlet manifold 14, desirably located in a vertical position.

[0037] Said three sections of pipes 12A, 12B, 12C are located mainly along corresponding planes, parallel to each other, and perpendicular to the axis X-X of rotation of the fan 5, and are connected in sequence with each other, located relative to the specified axis of rotation X- X by means of a first transfer element and a second transfer element 13, 15, each of which is a common cavity for the passage of flue gases, to which both tube bundles 11 of the heat exchanger 10 are connected.

[0038] In addition, there is a terminal receptacle 16, connected to the second end of the third pipe section 12C of both bundles 11, and the purpose of which is to collect the flue gases coming from the pipes and conduct them into the exhaust manifold 14.

[0039] Preferably, said second transmission member 15 is located substantially coaxial with said combustion chamber 6A, and can be connected thereto by positioning a first dividing wall 61; at the same time, said terminal receiving element 16 is preferably located coaxially with respect to the first transmission element 13 and can be connected to this latter by positioning a second partition 62.

[0040] From a flue gas flow point of view, said pipes 12A, 12B and 12C are adapted to move the flue gas flow in opposite directions; in particular, as shown by the arrows in figure 2, the gases first pass through the specified first section of pipes 12A mainly in the upward direction of movement, then, upon reaching the first transfer element 13, pass into the second section of pipes 12B and pass in the opposite downward direction, and finally , returning to said second transfer element 15, they pass into the third section of pipes 12C and move upward until they reach the terminal receiving element 16, which is a common cavity for both tube bundles 1, and which should preferably be located above the fan 5 and finally the flue gases reach the outlet 7 through said outlet manifold 14.

DETAILED DESCRIPTION OF THE SECOND EMBODIMENT OF THE INVENTION

[0041] Figures 3, 4A-4E show a heat exchanger 10 in accordance with a second embodiment of the present invention, which is substantially similar to the embodiment described above, and assumes pairs of tube bundles 11 are arranged preferably symmetrically with respect to the vertical axis YY of the fan 5 between the combustion chamber 6A of the burner 6 located in close proximity to the bottom wall 2B of the baking chamber 2 and the outlet 7 located in the roof of the chamber 2C, as shown in Figures 1A and 1C.

[0042] In addition, the specified tube bundles 11 contain several sections of pipes, which are located in planes parallel to each other, and perpendicular to the axis X-X of rotation of the fan 5, connected in sequence by means of the first and second transfer elements 13, 15, and are located coaxially relative to each other and relative to the specified axis of rotation X-X.

[0043] However, unlike the previous embodiment of the present invention, each tube bundle 11 of said heat exchanger 10 consists of a first tube section 12A, consisting of a pair of tubes connected by its first end portion to the combustion chamber 6A and simultaneously respectively connected by its second end portion to the first transfer element 13, located above the fan 5 in the immediate vicinity of the roof 2C of the baking chamber 2, advantageously using the cavity of the transfer element common to both tube bundles 11 of the heat exchanger 10.

[0044] Similarly to the previous embodiment of the present invention, it is provided that the second section of pipes 12B is connected to the first transfer element 13 and the third section of pipes 12C, and the second and third sections of pipes 12B, 12C are arranged in sequence one after the other and are interconnected by a second a transfer element 15, which, as provided, is located in close proximity to the bottom 2B of the baking chamber 2, and which is a common cavity for both tubular bundles 11.

[0045] Preferably, said second transmission member 15 is disposed coaxially with respect to the combustion chamber 6A and can be connected thereto by positioning a first partition 61.

[0046] In addition, the second end portion of the third pipe section 12C of both tube bundles 11 is advantageously connected to a terminal receiving element 16, preferably located coaxially with the first transmission element 13, and separated from the latter by a second dividing wall 62,

[0047] In particular, from the point of view of the flow of combustible gases within a given heat exchanger 10, said first pipe section consists of a pair of pipes 12A, which directly communicate with the combustion chamber 6A of the burner 6, and are arranged in parallel with each other, and through them the combustible gases pass in the upward direction. The combustible gases then pass further through said first transfer element 13 into a second pipe section 12B, which, being connected in series with said first pipe section 12A, conducts combustible gases in a downward direction, then the flue gases pass through the second transfer element 15 into the pipes of the third pipe section 12C and move upward until they reach said terminal receiving element 16, which is a common cavity for both tube bundles 11 and which is located above said fan; finally, the flue gases reach the outlet 7 through said outlet manifold 14.

[0048] Figures 5A-5E show an embodiment of the above-described heat exchanger, which differs from the latter in that it can be adapted and applied to the design of the furnace 1, in which the exhaust port 7 is provided on the side wall 2A, ?? on which is installed a fan 5, which is preferably recommended to be located near the roof 2C of the baking chamber 2, and said outlet manifold 14 is connected to the terminal receiving element 16, which is a common cavity for both tube bundles 11, and is located parallel to the axis of rotation X-X of the fan 5. This embodiment of the invention is preferable if it is planned to place another furnace, a different structure, above the furnace 1.

[0049] In addition, in contrast to the embodiment described above, and in order to ensure the best compactness, each tube bundle 11 is provided with its own, separate first transfer element 13, clearly located separately from the corresponding other first transfer element 13, symmetrically located on the other pipes 11.

DETAILED DESCRIPTION OF THE THIRD EMBODIMENT OF IMPLEMENTATION OF THIS INVENTION

[0050] Figures 6A-6C show a heat exchanger 10 according to a third embodiment of the present invention. In particular, in contrast to the previously described embodiments, this heat exchanger 10 is designed to be applicable to the structure of an oven 1, where said burner 6 is located in close proximity to the roof 2C of the baking chamber 2 and is adjacent to the outlet 7.

[0051] Accordingly, each tube bundle 11 of the heat exchanger 10 contains at least two sections of tubes 12A, 12B, where each group consists of one tube, and the groups are located in parallel planes relative to each other, and mainly perpendicular to the X axis -X rotation of the fan 5, connected in sequence

and are positioned coaxially with respect to said axis of rotation X-X and by means of a transfer element 13, which advantageously forms a common cavity for both tube bundles 11, through which the flue gases pass in opposite directions, as indicated by the arrows.

[0052] When evaluating the flue gas flow passing through the heat exchanger 10, it is found that for each tube bundle 11, the flue gases pass in a downward direction through said first tube section 12A, while the flue gases pass in the opposite direction through said second tube section 12B. direction relative to said first pipe section 12A, i.e. in an upward direction, and thus the flue gases are discharged into the terminal receiving element 16, which is a cavity common to both tube bundles 11, and finally the flue gases reach the outlet 7 through the exhaust manifold 14.

[0053] Preferably, said receiving element 16 is located on the same axis with the combustion chamber 6A and can be connected to it by means of a first partition 61.

[0054] Figures 7A-7E show an embodiment of the heat exchanger 10 described just above, substantially similar to the one just described, assuming a pair of tube bundles 11 arranged symmetrically around said fan 5 between combustion chamber 6A of burner 6 located above said a baking chamber 2, and an outlet 7 located in the immediate vicinity of said burner 6. In addition, each of said tube bundles 11 consists of two sections of tubes 12A, 12B installed in parallel planes relative to each other and perpendicular to the axis of rotation X -X of the fan 5, and connected in sequence to each other by means of the transfer element 13, and through which flue gases pass in opposite directions.

[0055] However, said first pipe section 12A consists of a pair of pipes connected by its first end portion to said combustion chamber 6A, and respectively connected by its second end portion to said transfer members 13, which is a cavity common to both tube bundles 11, and to which is also attached said second section of pipes 12B, which also consists of a pair of pipes.

[0056] In particular, from the point of view of the flow of flue gases passing inside the specified heat exchanger 10, the specified pair of pipes forming the specified first section of pipes 12A directly interacts with the combustion chamber 6A of the burner 6, are arranged in parallel, and through them combustible gases are passed in a downward direction ; then the gases are redirected by the specified transfer element 13 further to the second pair of pipes of the second section of pipes 12B, also arranged in parallel with respect to each other and connected in series with respect to the first section of pipes 12A, the combustible gases pass through both pipes of the second section in the upward direction and are combined into receiving element 16, which is a cavity common to both tube bundles 11, and finally reach the outlet 7 via said outlet manifold 14.

[0057] It is preferable that the specified receiving element 16 is located coaxially with the combustion chamber 6A, and can be connected with it through the first partition 61.

[0058] A third baffle 63, as shown in Figure 7E, may be provided inside said first transfer member 13 to separate the circulating flue gases circulating in the two tube bundles 11 and also to avoid noise generation.

DETAILED DESCRIPTION OF THE FOURTH EMBODIMENT OF THE INVENTION

[0059] Figures 8A-8C show the structure of a furnace 1 within which a heat exchanger 10 is incorporated in accordance with a fourth embodiment of the present invention.

[0060] As best seen in Figure 9, said heat exchanger 10 is positioned between the combustion chamber 6A of said burner 6 located in the lower region of the baking chamber 2, laterally with respect to the vertical axis of the fan 5, and an outlet 7 located near the roof 2C of said chamber for baking 2, preferably from the opposite side with respect to the vertical axis of the fan 5, in the diametrically opposite side with respect to the location of the combustion chamber 6A of the burner 6.

[0061] In this fourth embodiment, two bundles of tubes 11 are arranged around the fan 5, arranged symmetrically about its diametrical axis; however, it should be emphasized that in this case the said tube bundles 11 are symmetrical about the inclined axis MM, which is relative to the vertical axis Y-Y passing through the center of the fan 5.

[0062] Similar to the second embodiment of the heat exchanger 10 described above with reference to Figures 3 and 4a-4E, each of the tube bundles 11 of the heat exchanger 10 comprises a first tube section 12A consisting of a pair of tubes that are connected by their first end portion to said combustion chamber 6A, and, accordingly, with their second part, are connected to the specified first transfer element 13, which is located in close proximity to the arch 2C of the baking chamber 2, in the area diametrically opposite to the fan 5 relative to the location of the specified burner 6, and, which is a cavity common to both bundles of tubes 11 heat exchanger 10.

[0063] A second section of pipes 12B is then provided connected to said first transfer member 13, and then a third section of pipes 12C, each of which 12B, 12C consists of only one pipe, and they are arranged coaxially and connected to each other in succession. about the specified axis of rotation X-X by means of a second transfer element 15 installed in close proximity to the bottom 2B of the baking chamber 2 and which is a cavity common to both tube bundles 11.

[0064] Preferably, said second transmission member 15 is aligned with the combustion chamber 6A and can be connected thereto by means of a first partition 61.

[0065] In addition, the end portions of the third tube section 12C of both tube bundles 11 are advantageously connected to a receiving member 16, which is preferably coaxial to said first transfer member 13, and is separated from the latter by a second dividing wall 62.

[0066] In particular, from the point of view of the flow of flue gases within said heat exchanger 10, said two pipes of the first section of pipes 12A are connected directly to the combustion chamber 6A of the burner 6, respectively, they are arranged in parallel with each other and they both conduct the flue gases through them in an upward direction. Then the flue gases are passed further through the first transfer element 13 and enter the pipe of the second section 12B, which is located in series with the specified first part 12A, through the pipe of the second section 12B, the flue gases are conducted in a downward direction, then pass through the second transfer element 15, then enter the pipe of the third pipe section 12C and extend in an upward direction until they reach said receiving element 16, which is a cavity common to both tube bundles 11, preferably located above said fan 5, and finally the flue gases reach the outlet 7 through the specified exhaust manifold 14.

DETAILED DESCRIPTION OF THE FIFTH EMBODIMENT OF THE INVENTION

[0067] Figures 10, 11A-11D show a heat exchanger 10 in accordance with a fifth embodiment of the present invention; the specified heat exchanger 10 is functionally identical to the heat exchanger shown in figures 6A-6C, but has a peculiarity - it is designed for such a structure of a baking oven, which is equipped with several fans 5, for example three, mounted one above the other, and having their centers aligned on the same axis with vertical axis YY.

[0068] For this purpose, therefore, the tube bundles 11 of said heat exchanger 10 can be modeled in a wave-like shape, so as to copy the profiles of said fans 5.

[0069] In this embodiment, the heat exchanger 10 is also configured to be housed in an oven structure in which said burner 6 is located in close proximity to the roof of the baking chamber and adjacent to the outlet 7.

[0070] Accordingly, each tube bundle 11 of the heat exchanger 10 contains at least two sections of tubes 12A, 12B, each of which consists of one tube installed in planes parallel to each other, and perpendicular to the axis of rotation X-X of the fan 5,

are arranged coaxially and connected to each other in sequence relative to the specified axis of rotation X-X and by means of the transfer element 13, and through them the flue gases pass in opposite directions, as indicated by the arrow in Figure 11B.

[0071] Estimating the flow of flue gases through a given heat exchanger 10, it can be argued that each tube bundle 11 is characterized by the fact that through the specified first section of pipes 12A flue gases pass in a downward direction, while through the specified second section of pipes 12B, the flue gases flow in the opposite direction to the first pipe section 12A, i.e. in an upward direction, and then enter the receiving element 16, which is a cavity common to both tube bundles 11, and finally reach the outlet 7 via the specified exhaust manifold 14.

[0072] The specified receiving element 16 is located coaxially to the combustion chamber 6A and can be connected to it by means of the first partition 61.

[0073] A third dividing wall 63 is possible within the first transfer element 13 to ensure separation of the circulating flue gases passing through the two tube bundles 11 and also to avoid the generation of noise.

[0074] Obviously, in general, the heat exchanger 10 in accordance with the present invention can be configured to adapt to the burner 6 and the outlet 7 of the baking chamber 2 of the gas oven 1, according to the desire and requirement for the number of fans 5 and their location in the design of the furnace.

[0075] For example, in the case where the oven 1 is equipped with a burner 6 located in the immediate vicinity of the bottom of the bottom wall 2B of the baking chamber 2 and laterally with respect to the vertical axis YY of the fan 5, and the outlet 7 is located in the roof of the upper wall 2C of the chamber for baking 2, but coaxially with the vertical axis YY of said fan 5, the heat exchanger 10 according to the present invention will be provided with two bundles of tubes 11 located around the fan 5, but asymmetrically with respect to each other about an imaginary axis connecting the outlet 7 and the burner 6.

[0076] In conclusion, from the foregoing, it can be seen that the heat exchanger 10 for a gas oven for cooking food 1, in accordance with any of the described embodiments of the present invention, as well as in accordance with related, derivative variants thereof, achieves the above objectives and advantages ...

[0077] In fact, it is an improved heat exchanger, which, due to its special shape, makes it possible to increase the efficiency of heat exchange between the flue gases and the baking chamber of a gas oven. In fact, due to the expanded design of the tube sections forming the two tube bundles 11, a significant increase in the heat exchange surface is achieved, and therefore a significant increase in the efficiency of the heat exchanger is achieved and, therefore, a significant increase in the overall efficiency of the furnace is achieved.

[0078] In addition, since each of the two tube bundles 11 of the heat exchanger 10 according to the present invention has at least two pipe sections allowing the flue gases to flow in opposite directions, an improved air temperature distribution within the baking chamber 2 is observed. without increasing the body space.

[0079] It should be noted that this heat exchanger assumes the expansion of the structure of said pipe sections of said tube bundles inward, deep into the heat exchanger 10, that is, towards its center, in other words, towards the axis X-X of rotation of the fan 5, and not, outward, in breadth, as suggested by the document JP 2011141098, which makes it possible to impart absolute compactness to this specified heat exchanger 10. In addition, another advantageous characteristic is that the heated air propagating radially from the fan 5 towards the baking chamber affects the heat exchange simultaneously with all sections of the heat exchanger tubes 10, thus achieving an increased efficiency of the heat exchanger 10 in comparison with others.

[0080] Another advantageous characteristic of this heat exchanger is that due to the fact that the two bundles of tubes 11 of the heat exchanger 10 are configured symmetrically about the vertical axis of the fan 5, as shown by way of example, in the first three embodiments of the invention, the temperature distribution is achieved as evenly as possible along the vertical axis to ensure optimal uniform cooking of food in the oven.

[0081] Another advantage, especially when relying on the third embodiment, is that the heat exchanger 10 is so compact that it can be modified with minimal changes in the chambers of electric furnaces, when converting them from electricity to gas, thereby minimizing the production costs associated with the production of ovens.

[0082] In addition, the heat exchanger 10 according to the fourth embodiment of the invention can be advantageously applied in such furnaces, where, for reasons of limited space, the burner 6 is located laterally with respect to the vertical axis passing through the center of the fan 5, and at the same time, an optimal performance in terms of heat exchange and acceptable uniform temperature distribution in the baking chamber 2.

[0083] In addition, it is emphasized that the heat exchanger, as defined in the appended claim 1, can be configured and expanded in the most suitable way around the fan 5 or fans 5 between the burner 6 and the outlet 7 while remaining within the protection scope of the present invention.

[0084] Of course, the present invention is open to numerous modifications, variations, variations of numerous applications, without leaving the scope of protection as defined by the appended claims. In addition, the materials and equipment used to implement the present invention, as well as the shapes and sizes of individual components, can be improved in accordance with specific requirements and objectives.

Claims (14)

1. The heat exchanger (10) of the gas furnace (1), containing at least two bundles (11) of pipes installed opposite each other between the place (6A) for the inlet of flue gases, made with the possibility of connection with a gas burner (6) of the specified gas furnace (1), and a flue gas outlet (7) configured to be connected to the exhaust manifold (14) of said gas furnace (1), each tube bundle (11) comprising at least two sections (12A, 12B , 12C, 12A ', 12B') pipes, each of which consists of at least one pipe, these pipe sections lie in planes parallel to each other, perpendicular to the horizontal axis (X-X), and are connected in series with each other by means of at least one transfer element (13, 15) so that the flue gases can pass through each of the pipe sections in the direction opposite to the direction of the flue gas flow in the pipe section lying in an adjacent plane, characterized in that said sections (12A, 12B, 12C, 12A ', 12B') of pipes are located overlapping one another next to each other, so that the contours of the pipe section (12A, 12A ') lying in the first plane completely overlap - if viewed along the horizontal axis (X -X) - contours of pipe sections (12V, 12C, 12V ') located in the following planes. 2. Heat exchanger (10) according to claim 1, wherein at least one of said pipe sections (12A, 12B, 12C) consists of a single pipe. 3. A heat exchanger (10) according to claim 1 or 2, in which at least one of said pipe sections (12A ', 12B') consists of a plurality of pipes located in parallel planes relative to each other, perpendicular to said horizontal axis (X-X). 4. Heat exchanger (10) according to any one of paragraphs. 1-3, in which the specified pipe sections (12A, 12B, 12C, 12A ', 12B') of pipes have a cross-section of a circular or oval shape. 5. Heat exchanger (10) according to any one of paragraphs. 1-4, in which the cross-sectional dimensions of the pipes, of which the specified sections (12A, 12B, 12C, 12A ', 12B') of pipes are composed, are the same along the entire length of the pipes of the corresponding tube bundle (11). 6. Heat exchanger (10) according to any one of paragraphs. 1-4, in which the cross-sectional dimensions of the pipes that make up the specified pipe sections (12A, 12B, 12C, 12A ', 12B') gradually decrease with movement along the corresponding tube bundle (11). 7. Heat exchanger (10) according to any one of paragraphs. 1-6, in which at least one transfer element (13, 15) is common to both tube bundles (11). 8. Heat exchanger (10) according to claim 7, wherein at least one transfer element (13, 15) is arranged along an axis substantially parallel to said horizontal axis (X-X). 9. Heat exchanger (10) according to any one of paragraphs. 1-8, wherein said at least two tube bundles (11) are arranged symmetrically between said flue gas inlet (6A) and said flue gas outlet (7). 10. Gas oven (1), containing a baking chamber (2), equipped with a wall (2B) of the bottom and a wall (2C) of the roof, a fan (5) with a horizontal axis (X-X) of rotation, a burner (6) with a system of preliminary mixing, outlet manifold (14) and heat exchanger (10) in accordance with any of the preceding paragraphs. 11. Gas furnace (1) according to claim 10, in which said burner (6) is located near said wall of the roof (2C), said heat exchanger (10) comprises a first section (12A, 12A ') of pipes made in such a way that flue gases passed through it in the downward direction, and the second section (12B, 12B ') of pipes, designed in such a way that flue gases pass through them in an upward direction, and the said first and second pipe sections are connected in series with each other by means of a transfer element (13) ... 12. Gas furnace (1) according to claim 10, in which said burner (6) is located in close proximity to said bottom wall (2B), said heat exchanger (10) comprises a first section (12A, 12A ') of pipes, designed in this way so that flue gases pass through them in an upward direction, a second section (12B, 12B ') of pipes, designed in such a way that flue gases pass through them in a downward direction, and said first and second pipe sections are connected in series with each other by means of a first transfer element (13), and a third pipe section (12C), designed so that flue gases pass through them in an upward direction, connected to said second pipe section (12B, 12B ') in series by means of a second transfer element (15). 13. Gas oven (1) according to any one of paragraphs. 10-12, in which said burner (6) is located laterally with respect to said fan (5), said heat exchanger (10) contains a pair of tube bundles (11) arranged symmetrically with respect to said fan (5). 14. Gas oven (1) according to any one of paragraphs. 10-12, in which said burner (6) is located laterally with respect to said fan (5), said heat exchanger (10) contains a pair of bundles (11) of tubes located asymmetrically relative to the fan (5).

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