DESC:TECHNICAL FIELD
[0001] The present disclosure relates to the field of ovens, particularly to fuel fired indirect type cyclothermic tunnel ovens.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Ovens have been used for heating, baking and roasting food since prehistoric times. The earliest ovens were found in Central Europe, and dated to 29,000 BC. In Ukraine from 20,000 BC they used pits with hot coals covered in ashes. The food was wrapped in leaves and set on top, then covered with earth. In camps found in Mezhirich, each mammoth bone house had a hearth used for heating and cooking. Ovens are also used for making bricks, for example as in a kiln. Some of the designs used for ovens have withstood the test of time and are used even now, for example the traditional Indian “tandoor”.
[0004] Commercial ovens for baking food have important considerations of automation and speed of manufacture, over and above safety of operating personnel and fitness for human consumption for the food being baked. Several mechanisms and controls are used to achieve these purposes. Typically such ovens are fueled by natural gas; diesel oil etc. and so require means wherein such fuels as well as the flue gas generated when such fuels burn does not come in contact with the food being baked.
[0005] Cyclothermic ovens are very flexible ovens and a wide variety of foods can be baked therein in commercial volumes. Hence they find wide applicability in the baking industry. These ovens are suitable for baking different products ranging from biscuits and cookies to bread and pastries. A cyclothermic oven uses combustion to heat air, which is then passed around the walls of the cooking chamber in heat exchangers that include radiation tube bundles therein. Heat transfer in these ovens is mainly by radiation due to the temperature difference between the walls and the products being baked. The combustible products produce heat while they burn and are never in contact with the product being baked. This is required to take care of food safety considerations and also to ensure that final baked product is as required and fit for human consumption.
[0006] Fuel fired indirect type cyclothermic tunnel ovens have heat exchangers comprising radiation tubes in which the hot flue gas is used to bake the food, heat transfer to the food taking place mainly by radiation. The fuel or the flue gas never comes into contact with the food being baked. The oven has a tunnel on which, via conveyer belts, the food traverses from one zone to the other zone of the oven. Each zone is configured for a certain temperature and humidity environment in line with the requirement of the product being made. Some such ovens may also have another heat exchange system in which heat transfer may also be made by convection.
[0007] Most ovens used for baking food include heat exchangers, which in turn include bundles of tubes through which a hot fluid passes which can in turn be used to heat the product being baked either by radiation or by convection. The heat exchangers are the heart of the oven and any increase in their heat exchange efficiency increases that of the oven itself with associated benefits such as lowered fuel consumption, more economical operation and lowered air pollution.
[0008] Present heat exchangers used in ovens are inefficient, which in turn leads to uneconomical operation. In case such ovens employ natural gas or diesel, consumption of such fuels increases in turn also increasing the air pollution.
[0009] There is therefore a need in the art for a device that can increase the efficiency of heat exchange in baking ovens with its concomitant benefits such as lowered fuel consumption and less air pollution.
[0010] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0011] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0012] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

OBJECTS OF THE INVENTION
[0013] It is an object of the present disclosure to provide a device for optimized heat exchange in ovens used for baking different kinds of foods.
[0014] It is an object of the present disclosure to provide a device that facilitates decreased fuel consumption in ovens used for baking different kinds of foods.
[0015] An additional object of the present disclosure is to provide a device that reduces air pollution caused by fuel in ovens used for baking different kinds of foods.
[0016] Yet another object of the present disclosure is to provide a device that can be retrofitted for optimizing heat exchange in ovens used for baking different kinds of foods.
[0017] Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figure, which is not intended to limit the scope of the present disclosure.

SUMMARY OF THE INVENTION
[0018] The present disclosure generally relates to the field of ovens, particularly to fuel fired indirect type cyclothermic tunnel oven.
[0019] In an aspect, fuel fired indirect type cyclothermic tunnel oven (also interchangeably referred to as “oven” hereinafter) of the present disclosure can be configured to have a plurality of zones of different lengths, each zone having a common width as per requirement. Such zones can also be called as baking zones hereinafter. In an aspect, total length and width of the oven can be configured to be in accordance with its production capacity. In another aspect, the oven can be so configured that the baking time can vary with the type of product being baked from say 3 minutes to 20 minutes.
[0020] In an aspect, the oven can be configured to have very flexible control of temperature in various baking zones in the oven in order to have uniformity of baking to products of any size and shape. Each baking zone can include the product being baked on conveying racks, which can travel from one end of the baking zone to the other. In another aspect the conveying rack can be so configured that the convection air can come into desired contact with the product being baked. In an embodiment the zone can be configured to have bundles of radiating tubes at its top and bottom. In an aspect, the zone can have attached a combustion chamber that can burn a fuel via burners, wherein the zone and the combustion chamber can be so configured together that the flue gas generated in the combustion chamber can enter only the radiating tube bundles not be dispersed anywhere else in the zone. This can take care of food safety considerations and can also ensure that final baked product is as required and fit for human consumption.
[0021] In an aspect, the zone can be configured with two types of heat exchangers, wherein one such type of heat exchanger can be a forced flue gas system (also called radiating type heat exchanger herein) having a combustion chamber, one or more burners, radiating tube bundles, heat recovery zone, radiation heat exchanger circulating fan, header and associated control systems, valves and piping, among other components, all of which are well within the scope of the present disclosure. This radiating type heat exchanger can be so configured that the fuel being combusted and/or the flue gas does not come in contact with the product being baked.
[0022] In an aspect, the combustion chamber can be configured to consume a fuel that can include heavy fuel oil, diesel oil, natural gas, petroleum gas etc. The burners of the combustion chamber can be so configured in accordance with the fuel being burnt. In an aspect, the fuel used in the combustion chamber can be liquid (heavy fuel oil, diesel oil etc.) or gas (natural gas, petroleum gas etc.). In an aspect the burners of the combustion chamber can be configured so as to achieve the closest possible stoichiometric values. In an aspect, combustion of fuel can occur within the combustion chamber generating hot flue gas.
[0023] In an aspect, the hot flue gas can be isolated from contact with the product being baked and can be bifurcated in a controlled fashion into the radiating tube bundles. In such a fashion, the radiating tube bundles at the top and the bottom of the zone can be heated.
[0024] In another aspect, such hot radiating tube bundles and can transfer such heat to the zone by radiation, thereby heating the product being baked. In an aspect, the flue gas from which heat has been extracted while heating the radiation tubes can be discharged from the radiation tube bundles into a special receiver s a header. This flue gas can be called used up flue gas.
[0025] In an aspect, the used up flue gas can be collected in header and can then be re-circulated back into the combustion chamber using the circulating fan, where it can be heated again and then can again be used for heating the top and bottom radiating tube by the same process as explained above.
[0026] In another aspect, any excess used up flue gas can be exhausted. In an aspect, the excess used up flue gas can be exhausted through a heat recovery zone which can recover any excess heat from this excess used up flue gas. In another aspect, this heat recovered can be added to the baking zone by suitable arrangement of heat exchangers thereby making the whole system still more efficient.
[0027] In an aspect, on an average, heat from the radiation type heat exchanger can contribute about 60% of that required for the baking process. In an aspect, forced internal air circulation system or the convection type heat exchanger can be incorporated, wherein in an aspect, the heat exchanger of the type forced internal air circulation system (also called convection type heat exchanger herein), can be so configured that convectional hot air currents can be created within the zone. Such convectional hot air currents can be called convection air, which convection air can always be in contact with the product being baked.
[0028] In an aspect, convection type heat exchanger can include lower and upper ducts, moisture removal system, convection heat exchanger circulating fan, and associated control systems, valves and piping.
[0029] In an aspect, the convection air can be sucked into the convection type heat exchanger via the lower duct due to the airflow pressure created by the convection heat exchanger circulation fan. This convection air can be forced through the bottom radiating tube bundle, which can be made hot by operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle the convection air can become hot and by convection can transfer this heat to the product being baked and can also carry some moisture away from the zone .
[0030] In an aspect, the moisture laden convection air can further be made to pass through the top radiating tube bundle and can be further sucked into the upper duct due to the airflow pressure created by the convection heat exchanger circulation fan. The moisture from this moisture laden convection air can be discharged to atmosphere through flaps. In another aspect, the moisture from this moisture laden convection air can be removed by a moisture removal system.
[0031] In an aspect, the convection air after removal of such moisture can then be fed back into the lower duct due to airflow pressure created by the convection heat exchanger circulation fan and then recirculated over the bottom radiant tube bundle and can be reheated. This reheated convection air can then again be recirculated over the product being baked and the top radiant tube bundle. In this fashion, the convection type heat exchanger can circulate hot convection air over the product being baked, can heat the product being baked via convection currents and can remove moisture from the zone.
[0032] In another aspect, during this process of circulation, this convection air can also create turbulence within the zone to displace stagnant hot convection air layers and further help in removal of moisture from the zone.
[0033] In an aspect, on an average, heat from the convection type heat exchanger can contribute about 40% of that required for the baking process.
[0034] While the above exemplary embodiment can be understood with a reference to a cyclothermic oven with both a radiation type heat exchanger as well as a convection type heat exchanger; it can be readily understood by those well versed in the art that one or both systems or a combination of those or a combination of any plurality of those can be employed in any oven required for baking food.
[0035] In an aspect, the radiating tube bundles of the present disclosure can include spiral finned type radiating tubes (also called as the device herein), wherein the spiral finned type radiating tube can include a tube along the length of which can be coiled a spiral fin. In this fashion, the radiating tube can have a plurality of spiral fins coiled along its length.
[0036] In an aspect, the spiral finned type radiating tube can have a larger surface area than those of the non-spiral finned type, the additional surface area being provided by the two sides of the spiral fin. Due such increase in the surface area, the spiral finned type radiating tube can radiate more heat and so, the heat transfer by radiation in the radiating type heat exchanger can be increased. Accordingly the radiating tube can have a larger surface area to radiate the heat so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0037] In another aspect, the larger surface area of the spiral finned type radiating tube due to the plurality of spiral fins can also contact more of the convection air being circulated per unit time in the convection type heat exchanger and can cause the convection air to remain in contact with the spiral finned type radiating tube for a longer time. Due such increase in the surface area of the spiral finned type radiating tube and the more time the convection air remains in contact with the spiral fins, the heat transfer by convection in the convection type heat exchanger can be increased. Accordingly the radiating tube bundles can have a larger surface area to increase heat transfer by convection so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0038] Spiral finned type radiating tubes as described herein above can facilitate optimized heat exchange and can improve the efficiency of the system.
[0039] In an embodiment, the spiral finned type radiating tubes of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes of the present disclosure can be made of a combination of metals.
[0040] The device of the present disclosure can be used for manufacturing biscuits, bread, cookies, buns and a lot of other bakery products in the indirect type fuel fired oven. The consistent and efficient temperature control on account of the optimized heat exchange can provide a gentle texture development and distinctive characteristics on the surface of the product being baked.
[0041] The device of the present disclosure can be used in food processing ovens such as tunnel ovens, rack ovens and other types of ovens where tubes are used for heat transfer in indirect cyclotherm ovens.
[0042] Although the present disclosure is directed to baking in fuel fired indirect type cyclothermic tunnel oven, it can be understood that the device described can be used for various other heat exchange applications including heating, drying and curing a variety of products for various industries by implementing the device suitably.
[0043] The device as disclosed herein above can enhance heat exchange and thereby the efficiency of any heat exchange system.
[0044] The device as described herein above can be retrofitted in existing indirect fuel fired cyclothermic tunnel ovens. The device can also be retrofitted in existing heat exchangers where suitable, and particularly for ovens for baking food.
[0045] Other features of embodiments of the present disclosure will be apparent from accompanying drawings and from detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is an exemplary representation of the schematic of a zone of the fuel fired indirect type cyclothermic tunnel oven and its associated systems, as proposed in accordance with an embodiment of the present disclosure.
[0047] FIG. 2 is an exemplary representation of a spiral finned type radiating tube in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0048] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0049] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0050] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0051] The term ‘flue gas’ as used herein refers to hot gases coming out of a chimney, venting a burner or a combustion chamber.
[0052] The term ‘heat exchanger’ as used herein refers to a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall to prevent mixing or they may be in direct contact.
[0053] The term ‘radiation’ as used herein refers to a process where heat emanates from an object that cannot hold any more thermal energy. It does not require anything in which to move (for example, air or another object), like convection and conduction require, but rather can happen even in a vacuum.
[0054] The term ‘convection’ as used herein refers to a process where heat transfer occurs by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying heat energy with it.
[0055] The term ‘spiral’ as used herein refers to a curve which emanates from a central point, getting progressively farther away as it revolves around the point.
[0056] The present disclosure generally relates to the field of ovens, particularly to fuel fired indirect type cyclothermic tunnel oven.
[0057] In an aspect, fuel fired indirect type cyclothermic tunnel oven (also interchangeably referred to as “oven” hereinafter) of the present disclosure can be configured to have a plurality of zones of different lengths, each zone having a common width as per requirement. Such zones can also be called as baking zones hereinafter. In an aspect, total length and width of the oven can be configured to be in accordance with its production capacity. In another aspect, the oven can be so configured that the baking time can vary with the type of product being baked from say 3 minutes to 20 minutes.
[0058] In an aspect, the oven can be configured to have very flexible control of temperature in various baking zones in the oven in order to have uniformity of baking to products of any size and shape. Each baking zone can include the product being baked on conveying racks, which can travel from one end of the baking zone to the other. In another aspect the conveying rack can be so configured that the convection air can come into desired contact with the product being baked. In an embodiment the zone can be configured to have bundles of radiating tubes at its top and bottom. In an aspect, the zone can have attached a combustion chamber that can burn a fuel via burners, wherein the zone and the combustion chamber can be so configured together that the flue gas generated in the combustion chamber can enter only the radiating tube bundles not be dispersed anywhere else in the zone. This can take care of food safety considerations and can also ensure that final baked product is as required and fit for human consumption.
[0059] In an aspect, the zone can be configured with two types of heat exchangers, wherein one such type of heat exchanger can be a forced flue gas system (also called radiating type heat exchanger herein) having a combustion chamber, one or more burners, radiating tube bundles, heat recovery zone, radiation heat exchanger circulating fan, header and associated control systems, valves and piping, among other components, all of which are well within the scope of the present disclosure. This radiating type heat exchanger can be so configured that the fuel being combusted and/or the flue gas does not come in contact with the product being baked.
[0060] In an aspect, the combustion chamber can be configured to consume a fuel that can include heavy fuel oil, diesel oil, natural gas, petroleum gas etc. The burners of the combustion chamber can be so configured in accordance with the fuel being burnt. In an aspect, the fuel used in the combustion chamber can be liquid (heavy fuel oil, diesel oil etc.) or gas (natural gas, petroleum gas etc.). In an aspect the burners of the combustion chamber can be configured so as to achieve the closest possible stoichiometric values. In an aspect, combustion of fuel can occur within the combustion chamber generating hot flue gas.
[0061] In an aspect, the hot flue gas can be isolated from contact with the product being baked and can be bifurcated in a controlled fashion into the radiating tube bundles. In such a fashion, the radiating tube bundles at the top and the bottom of the zone can be heated.
[0062] In another aspect, such hot radiating tube bundles and can transfer such heat to the zone by radiation, thereby heating the product being baked. In an aspect, the flue gas from which heat has been extracted while heating the radiation tubes can be discharged from the radiation tube bundles into a special receiver s a header. This flue gas can be called used up flue gas.
[0063] In an aspect, the used up flue gas can be collected in header and can then be re-circulated back into the combustion chamber using the circulating fan, where it can be heated again and then can again be used for heating the top and bottom radiating tube by the same process as explained above.
[0064] In another aspect, any excess used up flue gas can be exhausted. In an aspect, the excess used up flue gas can be exhausted through a heat recovery zone which can recover any excess heat from this excess used up flue gas. In another aspect, this heat recovered can be added to the baking zone by suitable arrangement of heat exchangers thereby making the whole system still more efficient.
[0065] In an aspect, on an average, heat from the radiation type heat exchanger can contribute about 60% of that required for the baking process. In an aspect, forced internal air circulation system or the convection type heat exchanger can be incorporated, wherein in an aspect, the heat exchanger of the type forced internal air circulation system (also called convection type heat exchanger herein), can be so configured that convectional hot air currents can be created within the zone. Such convectional hot air currents can be called convection air, which convection air can always be in contact with the product being baked.
[0066] In an aspect, convection type heat exchanger can include lower and upper ducts, moisture removal system, convection heat exchanger circulating fan, and associated control systems, valves and piping.
[0067] In an aspect, the convection air can be sucked into the convection type heat exchanger via the lower duct due to the airflow pressure created by the convection heat exchanger circulation fan. This convection air can be forced through the bottom radiating tube bundle, which can be made hot by operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle the convection air can become hot and by convection can transfer this heat to the product being baked and can also carry some moisture away from the zone .
[0068] In an aspect, the moisture laden convection air can further be made to pass through the top radiating tube bundle and can be further sucked into the upper duct due to the airflow pressure created by the convection heat exchanger circulation fan. The moisture from this moisture laden convection air can be discharged to atmosphere through flaps. In another aspect, the moisture from this moisture laden convection air can be removed by a moisture removal system.
[0069] In an aspect, the convection air after removal of such moisture can then be fed back into the lower duct due to airflow pressure created by the convection heat exchanger circulation fan and then recirculated over the bottom radiant tube bundle and can be reheated. This reheated convection air can then again be recirculated over the product being baked and the top radiant tube bundle. In this fashion, the convection type heat exchanger can circulate hot convection air over the product being baked, can heat the product being baked via convection currents and can remove moisture from the zone.
[0070] In another aspect, during this process of circulation, this convection air can also create turbulence within the zone to displace stagnant hot convection air layers and further help in removal of moisture from the zone.
[0071] In an aspect, on an average, heat from the convection type heat exchanger can contribute about 40% of that required for the baking process.
[0072] While the above exemplary embodiment can be understood with a reference to a cyclothermic oven with both a radiation type heat exchanger as well as a convection type heat exchanger; it can be readily understood by those well versed in the art that one or both systems or a combination of those or a combination of any plurality of those can be employed in any oven required for baking food.
[0073] In an aspect, the radiating tube bundles of the present disclosure can include spiral finned type radiating tubes (also called as the device herein), wherein the spiral finned type radiating tube can include a tube along the length of which can be coiled a spiral fin. In this fashion, the radiating tube can have a plurality of spiral fins coiled along its length.
[0074] In an aspect, the spiral finned type radiating tube can have a larger surface area than those of the non-spiral finned type, the additional surface area being provided by the two sides of the spiral fin. Due such increase in the surface area, the spiral finned type radiating tube can radiate more heat and so, the heat transfer by radiation in the radiating type heat exchanger can be increased. Accordingly the radiating tube can have a larger surface area to radiate the heat so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0075] In another aspect, the larger surface area of the spiral finned type radiating tube due to the plurality of spiral fins can also contact more of the convection air being circulated per unit time in the convection type heat exchanger and can cause the convection air to remain in contact with the spiral finned type radiating tube for a longer time. Due such increase in the surface area of the spiral finned type radiating tube and the more time the convection air remains in contact with the spiral fins, the heat transfer by convection in the convection type heat exchanger can be increased. Accordingly the radiating tube bundles can have a larger surface area to increase heat transfer by convection so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0076] Spiral finned type radiating tubes as described herein above can facilitate optimized heat exchange and can improve the efficiency of the system.
[0077] In an embodiment, the spiral finned type radiating tubes of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes of the present disclosure can be made of a combination of metals.
[0078] The device of the present disclosure can be used for manufacturing biscuits, bread, cookies, buns and a lot of other bakery products in the indirect type fuel fired oven. The consistent and efficient temperature control on account of the optimized heat exchange can provide a gentle texture development and distinctive characteristics on the surface of the product being baked.
[0079] The device of the present disclosure can be used in food processing ovens such as tunnel ovens, rack ovens and other types of ovens where tubes are used for heat transfer in indirect cyclotherm ovens.
[0080] Although the present disclosure is directed to baking in fuel fired indirect type cyclothermic tunnel oven, it can be understood that the device described can be used for various other heat exchange applications including heating, drying and curing a variety of products for various industries by implementing the device suitably.
[0081] The device as disclosed herein above can enhance heat exchange and thereby the efficiency of any heat exchange system.
[0082] The device as described herein above can be retrofitted in existing indirect fuel fired cyclothermic tunnel ovens. The device can also be retrofitted in existing heat exchangers where suitable, and particularly for ovens for baking food.
[0083] FIG. 1 illustrates a schematic view of an exemplary zone 102 of a fuel fired indirect type cyclothermic tunnel oven and its associated systems as proposed in accordance with an embodiment of the present disclosure.
[0084] In an aspect, the fuel fired indirect type cyclothermic tunnel oven ( also called oven from here on ) can be configured to have a plurality of zones 102 of different lengths, each zone having a common width as per requirement. Such zone 102 can also be called as a baking zone.
[0085] In an aspect, the total length and width of the oven can be configured to be in accordance with its production capacity.
[0086] In an aspect, the oven can be so configured that the baking time can vary with the type of product being baked from say 3 minutes to say 20 minutes, for instance.
[0087] In an aspect, the oven can be configured to have very flexible control of temperature in the various zones 102 in the oven in order to have uniformity of baking to products of any size and shape.
[0088] In another aspect each zone 102 can include the product being baked 112.
[0089] In an aspect, the product being baked 112 can be kept on conveying rack 136 which can travel from one of the zone 102 to the other by any suitable means. In another aspect, the conveying rack 136 can be so configured that the convection air 124 can come into excellent contact with the product being baked 112.
[0090] In an embodiment, the zone 102 can be configured to have bundles of radiating tubes 104-1 and 104-2 at its top and bottom respectively.
[0091] In an aspect, the zone 102 can have attached a combustion chamber 106. The combustion chamber 106 can burn fuel via burners 108. The zone 102 and the combustion chamber 106 can be so configured together that the flue gas generated in the combustion chamber can enter only the radiating tube bundles 104-1 and 104-2 and not be dispersed anywhere else in the zone 102.
[0092] In an aspect, the zone 102 can be configured with two types of heat exchangers.
[0093] In an aspect, one such type of heat exchanger can be a forced flue gas system (also called radiating type heat exchanger herein) having a combustion chamber 106, burners 108, radiating tubes (detailed in FIG. 2 as 200), which can be configured into radiating tube bundles 104-1 and 104-2, heat recovery zone 114, radiation heat exchanger circulating fan 116, header 120, and associated control systems, valves and piping etc. This radiating type heat exchanger can be so configured so that the fuel being combusted and/or the flue gas does not come in contact with the product being baked.
[0094] In an aspect, the combustion chamber 106 can be configured to consume a fuel that can include heavy fuel oil, diesel oil, natural gas, petroleum gas etc. The burners 108 of the combustion chamber 106 can be so configured in accordance with the fuel being burnt.
[0095] In an aspect, fuel used in the combustion chamber 106 can be liquid (heavy fuel oil, diesel oil etc.) or gas (natural gas, petroleum gas etc.). In an aspect, burners 108 of the combustion chamber 106 can be configured so as to achieve the closest possible stoichiometric values
[0096] In an aspect, combustion of fuel can occur within the combustion chamber 106, the product of such combustion being hot flue gas 110.
[0097] In an aspect, hot flue gas 110 can be isolated from contact with the product being baked 112. In another aspect, hot flue gas 110 can be bifurcated in a controlled fashion into the radiating tube bundles 104-1 and 104-2 at the top and bottom of the zone 102. In such a fashion, the radiating tube bundles 104-1 and 104-2 at the top and the bottom of the zone 102 can be heated.
[0098] In another aspect, such radiating tube bundles 104-1 and 104-2 so made hot can transfer such heat to the zone 102 by radiation, thereby heating the product being baked 112.
[0099] In an aspect, flue gas from which heat has been extracted while heating the radiation tubes can be discharged from the radiation tube bundles 104-1 and 104-2 into a special receiver illustrated as header 120. This flue gas can be called used up flue gas 118.
[00100] In an aspect, the used up flue gas 118 can be collected in header 120. From the header 120, this used up flue gas 118 can be recirculated back into the combustion chamber 106 using the radiation heat exchanger fan 116, and can be heated up by the burners 108 in the combustion chamber 106 to be again used for heating the top and bottom radiating tube bundles 104-1 and 104-2 by the same process as explained above.
[00101] In another aspect, any excess used up flue gas 122 can be exhausted. In an aspect, excess used up flue gas 122 can be exhausted through a heat recovery zone 114, wherein the heat recovery zone 114 can be a separate zone to recover further heat from the excess used up flue gas 122.
[00102] In another aspect, heat recovered from the excess used up flue gas 122 can be added to zone 102 by suitable arrangement of heat exchangers, thereby reducing the heat demanded from the radiation type heat exchanger and so, reducing the fuel consumption in the combustion chamber 106.
[00103] In the exemplary embodiment, in order to operate radiating type heat exchanger, fuel can be burnt in the combustion chamber 106 through burners 108 and the radiation heat exchanger fan 116 can be started. Hot flue gas 110 can be produced in combustion chamber 106 due to burning of fuel there. Due to airflow pressure created by the radiation heat exchanger fan 116, the hot flue gas 110 can be forced equally into the radiating tube bundles 104-1 and 104-2. The hot flue gas 110 can transfer its heat to the radiating tube bundles 104-1 and 104-2. In turn the radiating tube bundles 104-1 and 104-2 can transfer heat by radiation to the product being baked 112. The used up flue gas 118 can be extracted from the radiating tube bundles and can be collected in header 120. From the header 120 this used up flue gas 118 can be recirculated back into the combustion chamber 106 using the radiation heat exchanger fan 116, can be heated up by the burners 108 in the combustion chamber 106 and can be again used for heating the top and bottom radiating tube bundles 104-1 and 104-2 by the same process as explained above.
[00104] Excess used up flue gas 122, if any, can be transferred to the heat recovery zone while the remaining used up flue gas 118 can be recirculated back into the combustion chamber 106 by the radiation heat exchanger circulating fan 116. Thus, the radiation heat exchanger circulating fan 116 can keep the flue gas circulating in the whole radiation type heat exchanger and the product being baked 112 can be heated by radiation from the hot radiating tube bundles 104-1 and 104-2.
[00105] In an aspect, on an average, heat from the radiation type heat exchanger can contribute about 60% of that required for the baking process.
[00106] In another aspect, the forced internal air circulation system or the convection type heat exchanger can be incorporated, wherein this convection type heat exchanger can be so configured that convectional hot air currents can be created within the zone. Such convectional hot air currents can be called convection air 124.
[00107] In an aspect, the convection type heat exchanger can be so configured that convection air 124 being circulated in the convection type heat exchanger can always be in contact with the product being baked 112.
[00108] In an aspect, the convection type heat exchanger can include a lower duct 126, an upper duct 128, a moisture removal system 130, a convection heat exchanger circulating fan 132, and associated control systems, valves and piping.
[00109] In an aspect, convection air 124 that can be always in contact with the product being baked 112 can be sucked into the convection type heat exchanger via the lower duct 126 due to the airflow pressure created by the convection heat exchanger circulation fan 132. In another aspect, this convection air 124 can be forced through the bottom radiating tube bundle 104-2. The bottom radiating tube bundle 104-2 can be made hot by the operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle 104-2 the convection air 124 can become hot and by convection can transfer this heat to the product being baked 112 and can also carry some moisture away from the zone 102.
[00110] In an aspect, the moisture laden convection air 134 can further be made to pass through the top radiating tube bundle 104-1 and can be further sucked into the upper duct 128 due to the airflow pressure created by the convection heat exchanger circulation fan 132.
[00111] In an aspect, moisture from this moisture laden convection air 134 can be discharged to atmosphere through flaps. In another aspect, moisture from this moisture laden convection air 134 can be removed by a moisture removal system 130.
[00112] In an aspect, convection air 124 after removal of such moisture can be fed back into the lower duct due to the airflow pressure created by the convection heat exchanger circulation fan 132 and then recirculated over the bottom radiant tube bundle 104-2 and can be reheated. This reheated convection air 124 can then again be recirculated over the product being baked 112 and the top radiant tube bundle 104-1. In this fashion, the convection type heat exchanger can circulate hot convection air 124 over the product being baked 112, can heat the product being baked 112 via convection currents, and can remove moisture from the zone 102.
[00113] In another aspect, during this process of circulation, convection air 124 can also create turbulence within the zone 102 to displace stagnant hot convection air 124 layers and further help in removal of moisture from the zone 102.
[00114] In an aspect, on an average the heat from the convection type heat exchanger can contribute about 40 % of that required for the baking process.
[00115] In the exemplary embodiment, in order to operate the convection type heat exchanger, the convection heat exchanger circulation fan 132 can be started. Due to airflow pressure created by the convection heat exchanger circulation fan 132, convection air 124 that can be always in contact with the product being baked 112 can be sucked into the convection type heat exchanger via the lower duct 126, and can be further forced through the bottom radiating tube bundle 104-2. The bottom radiating tube bundle 104-2 can be made hot by the operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle 104-2, the convection air 124 can become hot and by convection carry the heat to the product being baked 112 and can also carry some moisture away from the zone. The moisture laden convection air 134 can further be made to pass through the top radiating tube bundle 104-1 and can be further sucked into the upper duct 128 due to the airflow pressure created by the convection heat exchanger circulation fan 132. The moisture from this moisture laden convection air 134 can be discharged to atmosphere through flaps. In another aspect, moisture from this moisture laden convection air 134 can be removed from the moisture laden air convection by a moisture removal system 130. The convection air 124 after removal of such moisture can then be fed back into the lower duct 126 due to the airflow pressure created by the convection heat exchanger circulation fan 132 and then recirculated over the bottom radiant tube bundles 104-2 and can be reheated. This reheated convection air 124 can then be recirculated over the product being baked 112 and the top radiant tube bundle 104-1. In this fashion, convection type heat exchanger can circulate hot convection air 124 over the product being baked 112, can heat the product being baked 112 via convection currents, and can remove moisture from the zone 102. During this process of circulation, convection air 124 can also create turbulence within the zone 102 to displace stagnant hot convection air 124 layers and further help in removal of moisture from the zone 102
[00116] While the above exemplary embodiment can be understood with a reference to a cyclothermic oven with both a radiation type heat exchanger as well as a convection type heat exchanger; it can be readily understood by those well versed in the art that one or both systems or a combination of those or a combination of any plurality of those can be employed in any oven required for baking food.
[00117] FIG. 2 is an exemplary representation of a device that can be called a spiral finned type radiating tube in accordance with an embodiment of the present disclosure.
[00118] In an aspect the radiating tube bundles (illustrated as 104-1 and 104-2 in FIG. 1) can include spiral finned type radiating tubes of which one can be illustrated as 200.
[00119] In an aspect, the spiral finned type radiating tube 200 can include a tube 222 along the length of which can be coiled a spiral fin 224. In this fashion, the radiating tube 200 can have a plurality of spiral fins 224 coiled along its length.
[00120] In an aspect, the spiral finned type radiating tube 200 can have a larger surface area than those of the non-spiral finned type, the additional surface area being provided by the two sides of the spiral fin 224. Due such increase in the surface area, the spiral finned type radiating tube 200 can radiate more heat and therefore heat transfer by radiation in the radiating type heat exchanger can be increased. Accordingly, radiating tube bundles (shown as 104-1 and 104-2 in FIG. 1) can have a larger surface area to radiate the heat so as to decrease fuel consumption, which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[00121] In another aspect, larger surface area of the spiral finned type radiating tube 200 due to plurality of spiral fins 224 can also contact more of the convection air being circulated per unit time in the convection type heat exchanger, and can cause convection air to remain in contact with the spiral finned type radiating tube 200 for a longer time.
[00122] In an aspect, due such increase in the surface area of the spiral finned type radiating tube 200, and more time the convection air remains in contact with the spiral fins, heat transfer by convection in the convection type heat exchanger can be increased. Accordingly, radiating tube bundles (shown as 104-1 and 104-2 in FIG. 1) can have a larger surface area to increase heat transfer by convection so as to decrease fuel consumption, which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[00123] For exemplary radiating tubes known in the art comprising ERW pipes having an outside diameter of 101.6 mm and a wall thickness of 1.6 mm, in accordance with the present disclosure, the spiral finned type radiating tube 200 having the same sized pipe can be provided with fins having 22.2 mm pitch with 0.9 to 1 mm thick fins of length 10 mm thereby having an increased surface area of 4840 square centimetre which can be used as heat transfer surface within the baking zone of the oven.

Following can be the exemplary comparative parameters per meter length.
Sr.No. PARAMETERS SPIRAL FINNED TYPE RADIATING TUBES 200 CONVENTIONAL TUBES
1 Outer Diameter 121.6 mm with fin 101.6 mm
2 Wall Thickness 1.6 mm 1.6 mm
3 Wt. per meter 4070 gms 3569 gms
4 Specific heat 0.46 0.46
5 Heat required to heat pipe up to 650 C from ambient temp of 30 deg. C 1161 KJ 1017 KJ
6 Outer surface area for heat exchange 4840 sq. cm 3192 sq. cm
7 emissivity 1.51 1

[00124] From the above table, it can deduced that by increasing weight by 1.14 times, heat required to heat up the spiral finned type radiating tube 200 to a constant temperature of 650 deg. C can also be increased 1.14 times. But the total heat transfer area can be increased by 1.5 times (by way of radiation and convection). Hence, fuel consumed in ovens provided with spiral finned type radiating tubes 200 can be less than that in conventional ovens. Accordingly, there can be lesser pollution by the fuel burnt.
[00125] Spiral finned type radiating tubes 200 as described herein above can facilitate optimized heat exchange and can improve the efficiency of the system.
[00126] In an embodiment, spiral finned type radiating tubes 200 of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes 200 of the present disclosure can be made of a combination of metals. For eg. while the tube 222 can be made of copper, the spiral fins 224 can be made of aluminium.
[00127] Device of the present disclosure can be used for manufacturing biscuits, bread, cookies, buns and a lot of other bakery products in the indirect type fuel fired oven. The consistent and efficient temperature control on account of the optimized heat exchange can provide a gentle texture development and distinctive characteristics on the surface of the product being baked.
[00128] The device of the present disclosure can be used in food processing ovens such as tunnel ovens, rack ovens and other types of ovens where tubes are used for heat transfer in indirect cyclotherm ovens.
[00129] Although the above description of the present disclosure is directed to baking in fuel fired indirect type cyclothermic tunnel oven, it can be understood that the device described can be used for various other heat exchange applications including heating, drying and curing a variety of products for various industries by implementing the device suitably.
[00130] The device as disclosed herein above can enhance heat exchange and thereby the efficiency of any heat exchange system.
[00131] The device as described herein above can be retrofitted in existing indirect fuel fired cyclothermic tunnel ovens. The device can also be retrofitted in existing heat exchangers where suitable, and particularly for ovens for baking food.
[00132] In an embodiment, the spiral finned type radiating tubes 200 of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes 200 of the present disclosure can be made of a combination of metals. For eg. while the tube can be made of copper, the spiral fins can be made of aluminium.
[00133] In another embodiment of the disclosure, the component or the parts of the present disclosure can be coated, painted or coloured with a suitable chemical to retain or improve its properties, or to improve the aesthetics or appearance.
[00134] In an embodiment of the disclosure, the components of the present disclosure can be connected or arranged by using any suitable method and may include without limitation use of one or more of welding, adhesives, riveting, fastening devices such as but not limited to screw, nut, bolt, hook, clamp, clip, buckle, nail, pin, ring.
[00135] In an embodiment of the disclosure, one or more of a process or step carried out by the system may involve use of a electronic device or a data processing device or a sensor or a microcontrollers or a PLC (Programmable logic controller) or a PID (proportional–integral–derivative) controller, or a combination thereof, which may further involve one or more predefined algorithms or programs or logic.
[00136] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
[00137] It will be further understood that the terms "comprises" or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, or components, but do not preclude or rule out the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.
[00138] The use of the expression “at least” or “at least one” suggests the use of one or more elements, as the use may be in one of the embodiments to achieve one or more of the desired objects or results.
[00139] The process steps, method steps, algorithms or the like may be described in a sequential order, such processes, methods and algorithms may be configured to work in alternate orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. The steps of processes described herein may be performed in any order practical. Further, some steps may be performed simultaneously, in parallel, or concurrently.
[00140] The aim of this specification is to describe the invention without limiting the invention to any one embodiment or specific collection of features. Person skilled in the relevant art may realize the variations from the specific embodiments that will nonetheless fall within the scope of the invention.
[00141] It may be appreciated that various other modifications and changes may be made to the embodiment described without departing from the spirit and scope of the invention.

ADVANTAGES OF INVENTION
[00142] The present disclosure provides for a device in the form of spiral finned type radiating tube which improves the efficient of heat exchange in ovens used for baking different kinds of foods.
[00143] Due to such increase in efficiency, the amount of fuel used for the same transfer of heat to the product being baked can be reduced and hence, ovens with such a device can be much more economical in operation.
[00144] Due to lowered fuel consumption, the device can reduce air pollution caused by fuel in ovens used for baking different kinds of foods.
[00145] The device can easily be retrofitted to optimize heat exchange in ovens used for baking different kinds of foods by taking out the heat exchangers presently installed and replacing them with those using the device of the present disclosure.
TECHNICAL FIELD
[0001] The present disclosure relates to the field of ovens, particularly to fuel fired indirect type cyclothermic tunnel ovens.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Ovens have been used for heating, baking and roasting food since prehistoric times. The earliest ovens were found in Central Europe, and dated to 29,000 BC. In Ukraine from 20,000 BC they used pits with hot coals covered in ashes. The food was wrapped in leaves and set on top, then covered with earth. In camps found in Mezhirich, each mammoth bone house had a hearth used for heating and cooking. Ovens are also used for making bricks, for example as in a kiln. Some of the designs used for ovens have withstood the test of time and are used even now, for example the traditional Indian “tandoor”.
[0004] Commercial ovens for baking food have important considerations of automation and speed of manufacture, over and above safety of operating personnel and fitness for human consumption for the food being baked. Several mechanisms and controls are used to achieve these purposes. Typically such ovens are fueled by natural gas; diesel oil etc. and so require means wherein such fuels as well as the flue gas generated when such fuels burn does not come in contact with the food being baked.
[0005] Cyclothermic ovens are very flexible ovens and a wide variety of foods can be baked therein in commercial volumes. Hence they find wide applicability in the baking industry. These ovens are suitable for baking different products ranging from biscuits and cookies to bread and pastries. A cyclothermic oven uses combustion to heat air, which is then passed around the walls of the cooking chamber in heat exchangers that include radiation tube bundles therein. Heat transfer in these ovens is mainly by radiation due to the temperature difference between the walls and the products being baked. The combustible products produce heat while they burn and are never in contact with the product being baked. This is required to take care of food safety considerations and also to ensure that final baked product is as required and fit for human consumption.
[0006] Fuel fired indirect type cyclothermic tunnel ovens have heat exchangers comprising radiation tubes in which the hot flue gas is used to bake the food, heat transfer to the food taking place mainly by radiation. The fuel or the flue gas never comes into contact with the food being baked. The oven has a tunnel on which, via conveyer belts, the food traverses from one zone to the other zone of the oven. Each zone is configured for a certain temperature and humidity environment in line with the requirement of the product being made. Some such ovens may also have another heat exchange system in which heat transfer may also be made by convection.
[0007] Most ovens used for baking food include heat exchangers, which in turn include bundles of tubes through which a hot fluid passes which can in turn be used to heat the product being baked either by radiation or by convection. The heat exchangers are the heart of the oven and any increase in their heat exchange efficiency increases that of the oven itself with associated benefits such as lowered fuel consumption, more economical operation and lowered air pollution.
[0008] Present heat exchangers used in ovens are inefficient, which in turn leads to uneconomical operation. In case such ovens employ natural gas or diesel, consumption of such fuels increases in turn also increasing the air pollution.
[0009] There is therefore a need in the art for a device that can increase the efficiency of heat exchange in baking ovens with its concomitant benefits such as lowered fuel consumption and less air pollution.
[0010] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0011] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0012] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

OBJECTS OF THE INVENTION
[0013] It is an object of the present disclosure to provide a device for optimized heat exchange in ovens used for baking different kinds of foods.
[0014] It is an object of the present disclosure to provide a device that facilitates decreased fuel consumption in ovens used for baking different kinds of foods.
[0015] An additional object of the present disclosure is to provide a device that reduces air pollution caused by fuel in ovens used for baking different kinds of foods.
[0016] Yet another object of the present disclosure is to provide a device that can be retrofitted for optimizing heat exchange in ovens used for baking different kinds of foods.
[0017] Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figure, which is not intended to limit the scope of the present disclosure.

SUMMARY OF THE INVENTION
[0018] The present disclosure generally relates to the field of ovens, particularly to fuel fired indirect type cyclothermic tunnel oven.
[0019] In an aspect, fuel fired indirect type cyclothermic tunnel oven (also interchangeably referred to as “oven” hereinafter) of the present disclosure can be configured to have a plurality of zones of different lengths, each zone having a common width as per requirement. Such zones can also be called as baking zones hereinafter. In an aspect, total length and width of the oven can be configured to be in accordance with its production capacity. In another aspect, the oven can be so configured that the baking time can vary with the type of product being baked from say 3 minutes to 20 minutes.
[0020] In an aspect, the oven can be configured to have very flexible control of temperature in various baking zones in the oven in order to have uniformity of baking to products of any size and shape. Each baking zone can include the product being baked on conveying racks, which can travel from one end of the baking zone to the other. In another aspect the conveying rack can be so configured that the convection air can come into desired contact with the product being baked. In an embodiment the zone can be configured to have bundles of radiating tubes at its top and bottom. In an aspect, the zone can have attached a combustion chamber that can burn a fuel via burners, wherein the zone and the combustion chamber can be so configured together that the flue gas generated in the combustion chamber can enter only the radiating tube bundles not be dispersed anywhere else in the zone. This can take care of food safety considerations and can also ensure that final baked product is as required and fit for human consumption.
[0021] In an aspect, the zone can be configured with two types of heat exchangers, wherein one such type of heat exchanger can be a forced flue gas system (also called radiating type heat exchanger herein) having a combustion chamber, one or more burners, radiating tube bundles, heat recovery zone, radiation heat exchanger circulating fan, header and associated control systems, valves and piping, among other components, all of which are well within the scope of the present disclosure. This radiating type heat exchanger can be so configured that the fuel being combusted and/or the flue gas does not come in contact with the product being baked.
[0022] In an aspect, the combustion chamber can be configured to consume a fuel that can include heavy fuel oil, diesel oil, natural gas, petroleum gas etc. The burners of the combustion chamber can be so configured in accordance with the fuel being burnt. In an aspect, the fuel used in the combustion chamber can be liquid (heavy fuel oil, diesel oil etc.) or gas (natural gas, petroleum gas etc.). In an aspect the burners of the combustion chamber can be configured so as to achieve the closest possible stoichiometric values. In an aspect, combustion of fuel can occur within the combustion chamber generating hot flue gas.
[0023] In an aspect, the hot flue gas can be isolated from contact with the product being baked and can be bifurcated in a controlled fashion into the radiating tube bundles. In such a fashion, the radiating tube bundles at the top and the bottom of the zone can be heated.
[0024] In another aspect, such hot radiating tube bundles and can transfer such heat to the zone by radiation, thereby heating the product being baked. In an aspect, the flue gas from which heat has been extracted while heating the radiation tubes can be discharged from the radiation tube bundles into a special receiver s a header. This flue gas can be called used up flue gas.
[0025] In an aspect, the used up flue gas can be collected in header and can then be re-circulated back into the combustion chamber using the circulating fan, where it can be heated again and then can again be used for heating the top and bottom radiating tube by the same process as explained above.
[0026] In another aspect, any excess used up flue gas can be exhausted. In an aspect, the excess used up flue gas can be exhausted through a heat recovery zone which can recover any excess heat from this excess used up flue gas. In another aspect, this heat recovered can be added to the baking zone by suitable arrangement of heat exchangers thereby making the whole system still more efficient.
[0027] In an aspect, on an average, heat from the radiation type heat exchanger can contribute about 60% of that required for the baking process. In an aspect, forced internal air circulation system or the convection type heat exchanger can be incorporated, wherein in an aspect, the heat exchanger of the type forced internal air circulation system (also called convection type heat exchanger herein), can be so configured that convectional hot air currents can be created within the zone. Such convectional hot air currents can be called convection air, which convection air can always be in contact with the product being baked.
[0028] In an aspect, convection type heat exchanger can include lower and upper ducts, moisture removal system, convection heat exchanger circulating fan, and associated control systems, valves and piping.
[0029] In an aspect, the convection air can be sucked into the convection type heat exchanger via the lower duct due to the airflow pressure created by the convection heat exchanger circulation fan. This convection air can be forced through the bottom radiating tube bundle, which can be made hot by operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle the convection air can become hot and by convection can transfer this heat to the product being baked and can also carry some moisture away from the zone .
[0030] In an aspect, the moisture laden convection air can further be made to pass through the top radiating tube bundle and can be further sucked into the upper duct due to the airflow pressure created by the convection heat exchanger circulation fan. The moisture from this moisture laden convection air can be discharged to atmosphere through flaps. In another aspect, the moisture from this moisture laden convection air can be removed by a moisture removal system.
[0031] In an aspect, the convection air after removal of such moisture can then be fed back into the lower duct due to airflow pressure created by the convection heat exchanger circulation fan and then recirculated over the bottom radiant tube bundle and can be reheated. This reheated convection air can then again be recirculated over the product being baked and the top radiant tube bundle. In this fashion, the convection type heat exchanger can circulate hot convection air over the product being baked, can heat the product being baked via convection currents and can remove moisture from the zone.
[0032] In another aspect, during this process of circulation, this convection air can also create turbulence within the zone to displace stagnant hot convection air layers and further help in removal of moisture from the zone.
[0033] In an aspect, on an average, heat from the convection type heat exchanger can contribute about 40% of that required for the baking process.
[0034] While the above exemplary embodiment can be understood with a reference to a cyclothermic oven with both a radiation type heat exchanger as well as a convection type heat exchanger; it can be readily understood by those well versed in the art that one or both systems or a combination of those or a combination of any plurality of those can be employed in any oven required for baking food.
[0035] In an aspect, the radiating tube bundles of the present disclosure can include spiral finned type radiating tubes (also called as the device herein), wherein the spiral finned type radiating tube can include a tube along the length of which can be coiled a spiral fin. In this fashion, the radiating tube can have a plurality of spiral fins coiled along its length.
[0036] In an aspect, the spiral finned type radiating tube can have a larger surface area than those of the non-spiral finned type, the additional surface area being provided by the two sides of the spiral fin. Due such increase in the surface area, the spiral finned type radiating tube can radiate more heat and so, the heat transfer by radiation in the radiating type heat exchanger can be increased. Accordingly the radiating tube can have a larger surface area to radiate the heat so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0037] In another aspect, the larger surface area of the spiral finned type radiating tube due to the plurality of spiral fins can also contact more of the convection air being circulated per unit time in the convection type heat exchanger and can cause the convection air to remain in contact with the spiral finned type radiating tube for a longer time. Due such increase in the surface area of the spiral finned type radiating tube and the more time the convection air remains in contact with the spiral fins, the heat transfer by convection in the convection type heat exchanger can be increased. Accordingly the radiating tube bundles can have a larger surface area to increase heat transfer by convection so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0038] Spiral finned type radiating tubes as described herein above can facilitate optimized heat exchange and can improve the efficiency of the system.
[0039] In an embodiment, the spiral finned type radiating tubes of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes of the present disclosure can be made of a combination of metals.
[0040] The device of the present disclosure can be used for manufacturing biscuits, bread, cookies, buns and a lot of other bakery products in the indirect type fuel fired oven. The consistent and efficient temperature control on account of the optimized heat exchange can provide a gentle texture development and distinctive characteristics on the surface of the product being baked.
[0041] The device of the present disclosure can be used in food processing ovens such as tunnel ovens, rack ovens and other types of ovens where tubes are used for heat transfer in indirect cyclotherm ovens.
[0042] Although the present disclosure is directed to baking in fuel fired indirect type cyclothermic tunnel oven, it can be understood that the device described can be used for various other heat exchange applications including heating, drying and curing a variety of products for various industries by implementing the device suitably.
[0043] The device as disclosed herein above can enhance heat exchange and thereby the efficiency of any heat exchange system.
[0044] The device as described herein above can be retrofitted in existing indirect fuel fired cyclothermic tunnel ovens. The device can also be retrofitted in existing heat exchangers where suitable, and particularly for ovens for baking food.
[0045] Other features of embodiments of the present disclosure will be apparent from accompanying drawings and from detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is an exemplary representation of the schematic of a zone of the fuel fired indirect type cyclothermic tunnel oven and its associated systems, as proposed in accordance with an embodiment of the present disclosure.
[0047] FIG. 2 is an exemplary representation of a spiral finned type radiating tube in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0048] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0049] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0050] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0051] The term ‘flue gas’ as used herein refers to hot gases coming out of a chimney, venting a burner or a combustion chamber.
[0052] The term ‘heat exchanger’ as used herein refers to a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall to prevent mixing or they may be in direct contact.
[0053] The term ‘radiation’ as used herein refers to a process where heat emanates from an object that cannot hold any more thermal energy. It does not require anything in which to move (for example, air or another object), like convection and conduction require, but rather can happen even in a vacuum.
[0054] The term ‘convection’ as used herein refers to a process where heat transfer occurs by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying heat energy with it.
[0055] The term ‘spiral’ as used herein refers to a curve which emanates from a central point, getting progressively farther away as it revolves around the point.
[0056] The present disclosure generally relates to the field of ovens, particularly to fuel fired indirect type cyclothermic tunnel oven.
[0057] In an aspect, fuel fired indirect type cyclothermic tunnel oven (also interchangeably referred to as “oven” hereinafter) of the present disclosure can be configured to have a plurality of zones of different lengths, each zone having a common width as per requirement. Such zones can also be called as baking zones hereinafter. In an aspect, total length and width of the oven can be configured to be in accordance with its production capacity. In another aspect, the oven can be so configured that the baking time can vary with the type of product being baked from say 3 minutes to 20 minutes.
[0058] In an aspect, the oven can be configured to have very flexible control of temperature in various baking zones in the oven in order to have uniformity of baking to products of any size and shape. Each baking zone can include the product being baked on conveying racks, which can travel from one end of the baking zone to the other. In another aspect the conveying rack can be so configured that the convection air can come into desired contact with the product being baked. In an embodiment the zone can be configured to have bundles of radiating tubes at its top and bottom. In an aspect, the zone can have attached a combustion chamber that can burn a fuel via burners, wherein the zone and the combustion chamber can be so configured together that the flue gas generated in the combustion chamber can enter only the radiating tube bundles not be dispersed anywhere else in the zone. This can take care of food safety considerations and can also ensure that final baked product is as required and fit for human consumption.
[0059] In an aspect, the zone can be configured with two types of heat exchangers, wherein one such type of heat exchanger can be a forced flue gas system (also called radiating type heat exchanger herein) having a combustion chamber, one or more burners, radiating tube bundles, heat recovery zone, radiation heat exchanger circulating fan, header and associated control systems, valves and piping, among other components, all of which are well within the scope of the present disclosure. This radiating type heat exchanger can be so configured that the fuel being combusted and/or the flue gas does not come in contact with the product being baked.
[0060] In an aspect, the combustion chamber can be configured to consume a fuel that can include heavy fuel oil, diesel oil, natural gas, petroleum gas etc. The burners of the combustion chamber can be so configured in accordance with the fuel being burnt. In an aspect, the fuel used in the combustion chamber can be liquid (heavy fuel oil, diesel oil etc.) or gas (natural gas, petroleum gas etc.). In an aspect the burners of the combustion chamber can be configured so as to achieve the closest possible stoichiometric values. In an aspect, combustion of fuel can occur within the combustion chamber generating hot flue gas.
[0061] In an aspect, the hot flue gas can be isolated from contact with the product being baked and can be bifurcated in a controlled fashion into the radiating tube bundles. In such a fashion, the radiating tube bundles at the top and the bottom of the zone can be heated.
[0062] In another aspect, such hot radiating tube bundles and can transfer such heat to the zone by radiation, thereby heating the product being baked. In an aspect, the flue gas from which heat has been extracted while heating the radiation tubes can be discharged from the radiation tube bundles into a special receiver s a header. This flue gas can be called used up flue gas.
[0063] In an aspect, the used up flue gas can be collected in header and can then be re-circulated back into the combustion chamber using the circulating fan, where it can be heated again and then can again be used for heating the top and bottom radiating tube by the same process as explained above.
[0064] In another aspect, any excess used up flue gas can be exhausted. In an aspect, the excess used up flue gas can be exhausted through a heat recovery zone which can recover any excess heat from this excess used up flue gas. In another aspect, this heat recovered can be added to the baking zone by suitable arrangement of heat exchangers thereby making the whole system still more efficient.
[0065] In an aspect, on an average, heat from the radiation type heat exchanger can contribute about 60% of that required for the baking process. In an aspect, forced internal air circulation system or the convection type heat exchanger can be incorporated, wherein in an aspect, the heat exchanger of the type forced internal air circulation system (also called convection type heat exchanger herein), can be so configured that convectional hot air currents can be created within the zone. Such convectional hot air currents can be called convection air, which convection air can always be in contact with the product being baked.
[0066] In an aspect, convection type heat exchanger can include lower and upper ducts, moisture removal system, convection heat exchanger circulating fan, and associated control systems, valves and piping.
[0067] In an aspect, the convection air can be sucked into the convection type heat exchanger via the lower duct due to the airflow pressure created by the convection heat exchanger circulation fan. This convection air can be forced through the bottom radiating tube bundle, which can be made hot by operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle the convection air can become hot and by convection can transfer this heat to the product being baked and can also carry some moisture away from the zone .
[0068] In an aspect, the moisture laden convection air can further be made to pass through the top radiating tube bundle and can be further sucked into the upper duct due to the airflow pressure created by the convection heat exchanger circulation fan. The moisture from this moisture laden convection air can be discharged to atmosphere through flaps. In another aspect, the moisture from this moisture laden convection air can be removed by a moisture removal system.
[0069] In an aspect, the convection air after removal of such moisture can then be fed back into the lower duct due to airflow pressure created by the convection heat exchanger circulation fan and then recirculated over the bottom radiant tube bundle and can be reheated. This reheated convection air can then again be recirculated over the product being baked and the top radiant tube bundle. In this fashion, the convection type heat exchanger can circulate hot convection air over the product being baked, can heat the product being baked via convection currents and can remove moisture from the zone.
[0070] In another aspect, during this process of circulation, this convection air can also create turbulence within the zone to displace stagnant hot convection air layers and further help in removal of moisture from the zone.
[0071] In an aspect, on an average, heat from the convection type heat exchanger can contribute about 40% of that required for the baking process.
[0072] While the above exemplary embodiment can be understood with a reference to a cyclothermic oven with both a radiation type heat exchanger as well as a convection type heat exchanger; it can be readily understood by those well versed in the art that one or both systems or a combination of those or a combination of any plurality of those can be employed in any oven required for baking food.
[0073] In an aspect, the radiating tube bundles of the present disclosure can include spiral finned type radiating tubes (also called as the device herein), wherein the spiral finned type radiating tube can include a tube along the length of which can be coiled a spiral fin. In this fashion, the radiating tube can have a plurality of spiral fins coiled along its length.
[0074] In an aspect, the spiral finned type radiating tube can have a larger surface area than those of the non-spiral finned type, the additional surface area being provided by the two sides of the spiral fin. Due such increase in the surface area, the spiral finned type radiating tube can radiate more heat and so, the heat transfer by radiation in the radiating type heat exchanger can be increased. Accordingly the radiating tube can have a larger surface area to radiate the heat so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0075] In another aspect, the larger surface area of the spiral finned type radiating tube due to the plurality of spiral fins can also contact more of the convection air being circulated per unit time in the convection type heat exchanger and can cause the convection air to remain in contact with the spiral finned type radiating tube for a longer time. Due such increase in the surface area of the spiral finned type radiating tube and the more time the convection air remains in contact with the spiral fins, the heat transfer by convection in the convection type heat exchanger can be increased. Accordingly the radiating tube bundles can have a larger surface area to increase heat transfer by convection so as to decrease fuel consumption which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[0076] Spiral finned type radiating tubes as described herein above can facilitate optimized heat exchange and can improve the efficiency of the system.
[0077] In an embodiment, the spiral finned type radiating tubes of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes of the present disclosure can be made of a combination of metals.
[0078] The device of the present disclosure can be used for manufacturing biscuits, bread, cookies, buns and a lot of other bakery products in the indirect type fuel fired oven. The consistent and efficient temperature control on account of the optimized heat exchange can provide a gentle texture development and distinctive characteristics on the surface of the product being baked.
[0079] The device of the present disclosure can be used in food processing ovens such as tunnel ovens, rack ovens and other types of ovens where tubes are used for heat transfer in indirect cyclotherm ovens.
[0080] Although the present disclosure is directed to baking in fuel fired indirect type cyclothermic tunnel oven, it can be understood that the device described can be used for various other heat exchange applications including heating, drying and curing a variety of products for various industries by implementing the device suitably.
[0081] The device as disclosed herein above can enhance heat exchange and thereby the efficiency of any heat exchange system.
[0082] The device as described herein above can be retrofitted in existing indirect fuel fired cyclothermic tunnel ovens. The device can also be retrofitted in existing heat exchangers where suitable, and particularly for ovens for baking food.
[0083] FIG. 1 illustrates a schematic view of an exemplary zone 102 of a fuel fired indirect type cyclothermic tunnel oven and its associated systems as proposed in accordance with an embodiment of the present disclosure.
[0084] In an aspect, the fuel fired indirect type cyclothermic tunnel oven ( also called oven from here on ) can be configured to have a plurality of zones 102 of different lengths, each zone having a common width as per requirement. Such zone 102 can also be called as a baking zone.
[0085] In an aspect, the total length and width of the oven can be configured to be in accordance with its production capacity.
[0086] In an aspect, the oven can be so configured that the baking time can vary with the type of product being baked from say 3 minutes to say 20 minutes, for instance.
[0087] In an aspect, the oven can be configured to have very flexible control of temperature in the various zones 102 in the oven in order to have uniformity of baking to products of any size and shape.
[0088] In another aspect each zone 102 can include the product being baked 112.
[0089] In an aspect, the product being baked 112 can be kept on conveying rack 136 which can travel from one of the zone 102 to the other by any suitable means. In another aspect, the conveying rack 136 can be so configured that the convection air 124 can come into excellent contact with the product being baked 112.
[0090] In an embodiment, the zone 102 can be configured to have bundles of radiating tubes 104-1 and 104-2 at its top and bottom respectively.
[0091] In an aspect, the zone 102 can have attached a combustion chamber 106. The combustion chamber 106 can burn fuel via burners 108. The zone 102 and the combustion chamber 106 can be so configured together that the flue gas generated in the combustion chamber can enter only the radiating tube bundles 104-1 and 104-2 and not be dispersed anywhere else in the zone 102.
[0092] In an aspect, the zone 102 can be configured with two types of heat exchangers.
[0093] In an aspect, one such type of heat exchanger can be a forced flue gas system (also called radiating type heat exchanger herein) having a combustion chamber 106, burners 108, radiating tubes (detailed in FIG. 2 as 200), which can be configured into radiating tube bundles 104-1 and 104-2, heat recovery zone 114, radiation heat exchanger circulating fan 116, header 120, and associated control systems, valves and piping etc. This radiating type heat exchanger can be so configured so that the fuel being combusted and/or the flue gas does not come in contact with the product being baked.
[0094] In an aspect, the combustion chamber 106 can be configured to consume a fuel that can include heavy fuel oil, diesel oil, natural gas, petroleum gas etc. The burners 108 of the combustion chamber 106 can be so configured in accordance with the fuel being burnt.
[0095] In an aspect, fuel used in the combustion chamber 106 can be liquid (heavy fuel oil, diesel oil etc.) or gas (natural gas, petroleum gas etc.). In an aspect, burners 108 of the combustion chamber 106 can be configured so as to achieve the closest possible stoichiometric values
[0096] In an aspect, combustion of fuel can occur within the combustion chamber 106, the product of such combustion being hot flue gas 110.
[0097] In an aspect, hot flue gas 110 can be isolated from contact with the product being baked 112. In another aspect, hot flue gas 110 can be bifurcated in a controlled fashion into the radiating tube bundles 104-1 and 104-2 at the top and bottom of the zone 102. In such a fashion, the radiating tube bundles 104-1 and 104-2 at the top and the bottom of the zone 102 can be heated.
[0098] In another aspect, such radiating tube bundles 104-1 and 104-2 so made hot can transfer such heat to the zone 102 by radiation, thereby heating the product being baked 112.
[0099] In an aspect, flue gas from which heat has been extracted while heating the radiation tubes can be discharged from the radiation tube bundles 104-1 and 104-2 into a special receiver illustrated as header 120. This flue gas can be called used up flue gas 118.
[00100] In an aspect, the used up flue gas 118 can be collected in header 120. From the header 120, this used up flue gas 118 can be recirculated back into the combustion chamber 106 using the radiation heat exchanger fan 116, and can be heated up by the burners 108 in the combustion chamber 106 to be again used for heating the top and bottom radiating tube bundles 104-1 and 104-2 by the same process as explained above.
[00101] In another aspect, any excess used up flue gas 122 can be exhausted. In an aspect, excess used up flue gas 122 can be exhausted through a heat recovery zone 114, wherein the heat recovery zone 114 can be a separate zone to recover further heat from the excess used up flue gas 122.
[00102] In another aspect, heat recovered from the excess used up flue gas 122 can be added to zone 102 by suitable arrangement of heat exchangers, thereby reducing the heat demanded from the radiation type heat exchanger and so, reducing the fuel consumption in the combustion chamber 106.
[00103] In the exemplary embodiment, in order to operate radiating type heat exchanger, fuel can be burnt in the combustion chamber 106 through burners 108 and the radiation heat exchanger fan 116 can be started. Hot flue gas 110 can be produced in combustion chamber 106 due to burning of fuel there. Due to airflow pressure created by the radiation heat exchanger fan 116, the hot flue gas 110 can be forced equally into the radiating tube bundles 104-1 and 104-2. The hot flue gas 110 can transfer its heat to the radiating tube bundles 104-1 and 104-2. In turn the radiating tube bundles 104-1 and 104-2 can transfer heat by radiation to the product being baked 112. The used up flue gas 118 can be extracted from the radiating tube bundles and can be collected in header 120. From the header 120 this used up flue gas 118 can be recirculated back into the combustion chamber 106 using the radiation heat exchanger fan 116, can be heated up by the burners 108 in the combustion chamber 106 and can be again used for heating the top and bottom radiating tube bundles 104-1 and 104-2 by the same process as explained above.
[00104] Excess used up flue gas 122, if any, can be transferred to the heat recovery zone while the remaining used up flue gas 118 can be recirculated back into the combustion chamber 106 by the radiation heat exchanger circulating fan 116. Thus, the radiation heat exchanger circulating fan 116 can keep the flue gas circulating in the whole radiation type heat exchanger and the product being baked 112 can be heated by radiation from the hot radiating tube bundles 104-1 and 104-2.
[00105] In an aspect, on an average, heat from the radiation type heat exchanger can contribute about 60% of that required for the baking process.
[00106] In another aspect, the forced internal air circulation system or the convection type heat exchanger can be incorporated, wherein this convection type heat exchanger can be so configured that convectional hot air currents can be created within the zone. Such convectional hot air currents can be called convection air 124.
[00107] In an aspect, the convection type heat exchanger can be so configured that convection air 124 being circulated in the convection type heat exchanger can always be in contact with the product being baked 112.
[00108] In an aspect, the convection type heat exchanger can include a lower duct 126, an upper duct 128, a moisture removal system 130, a convection heat exchanger circulating fan 132, and associated control systems, valves and piping.
[00109] In an aspect, convection air 124 that can be always in contact with the product being baked 112 can be sucked into the convection type heat exchanger via the lower duct 126 due to the airflow pressure created by the convection heat exchanger circulation fan 132. In another aspect, this convection air 124 can be forced through the bottom radiating tube bundle 104-2. The bottom radiating tube bundle 104-2 can be made hot by the operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle 104-2 the convection air 124 can become hot and by convection can transfer this heat to the product being baked 112 and can also carry some moisture away from the zone 102.
[00110] In an aspect, the moisture laden convection air 134 can further be made to pass through the top radiating tube bundle 104-1 and can be further sucked into the upper duct 128 due to the airflow pressure created by the convection heat exchanger circulation fan 132.
[00111] In an aspect, moisture from this moisture laden convection air 134 can be discharged to atmosphere through flaps. In another aspect, moisture from this moisture laden convection air 134 can be removed by a moisture removal system 130.
[00112] In an aspect, convection air 124 after removal of such moisture can be fed back into the lower duct due to the airflow pressure created by the convection heat exchanger circulation fan 132 and then recirculated over the bottom radiant tube bundle 104-2 and can be reheated. This reheated convection air 124 can then again be recirculated over the product being baked 112 and the top radiant tube bundle 104-1. In this fashion, the convection type heat exchanger can circulate hot convection air 124 over the product being baked 112, can heat the product being baked 112 via convection currents, and can remove moisture from the zone 102.
[00113] In another aspect, during this process of circulation, convection air 124 can also create turbulence within the zone 102 to displace stagnant hot convection air 124 layers and further help in removal of moisture from the zone 102.
[00114] In an aspect, on an average the heat from the convection type heat exchanger can contribute about 40 % of that required for the baking process.
[00115] In the exemplary embodiment, in order to operate the convection type heat exchanger, the convection heat exchanger circulation fan 132 can be started. Due to airflow pressure created by the convection heat exchanger circulation fan 132, convection air 124 that can be always in contact with the product being baked 112 can be sucked into the convection type heat exchanger via the lower duct 126, and can be further forced through the bottom radiating tube bundle 104-2. The bottom radiating tube bundle 104-2 can be made hot by the operation of the radiating type heat exchanger. Hence, while being forced over the hot bottom radiating tube bundle 104-2, the convection air 124 can become hot and by convection carry the heat to the product being baked 112 and can also carry some moisture away from the zone. The moisture laden convection air 134 can further be made to pass through the top radiating tube bundle 104-1 and can be further sucked into the upper duct 128 due to the airflow pressure created by the convection heat exchanger circulation fan 132. The moisture from this moisture laden convection air 134 can be discharged to atmosphere through flaps. In another aspect, moisture from this moisture laden convection air 134 can be removed from the moisture laden air convection by a moisture removal system 130. The convection air 124 after removal of such moisture can then be fed back into the lower duct 126 due to the airflow pressure created by the convection heat exchanger circulation fan 132 and then recirculated over the bottom radiant tube bundles 104-2 and can be reheated. This reheated convection air 124 can then be recirculated over the product being baked 112 and the top radiant tube bundle 104-1. In this fashion, convection type heat exchanger can circulate hot convection air 124 over the product being baked 112, can heat the product being baked 112 via convection currents, and can remove moisture from the zone 102. During this process of circulation, convection air 124 can also create turbulence within the zone 102 to displace stagnant hot convection air 124 layers and further help in removal of moisture from the zone 102
[00116] While the above exemplary embodiment can be understood with a reference to a cyclothermic oven with both a radiation type heat exchanger as well as a convection type heat exchanger; it can be readily understood by those well versed in the art that one or both systems or a combination of those or a combination of any plurality of those can be employed in any oven required for baking food.
[00117] FIG. 2 is an exemplary representation of a device that can be called a spiral finned type radiating tube in accordance with an embodiment of the present disclosure.
[00118] In an aspect the radiating tube bundles (illustrated as 104-1 and 104-2 in FIG. 1) can include spiral finned type radiating tubes of which one can be illustrated as 200.
[00119] In an aspect, the spiral finned type radiating tube 200 can include a tube 222 along the length of which can be coiled a spiral fin 224. In this fashion, the radiating tube 200 can have a plurality of spiral fins 224 coiled along its length.
[00120] In an aspect, the spiral finned type radiating tube 200 can have a larger surface area than those of the non-spiral finned type, the additional surface area being provided by the two sides of the spiral fin 224. Due such increase in the surface area, the spiral finned type radiating tube 200 can radiate more heat and therefore heat transfer by radiation in the radiating type heat exchanger can be increased. Accordingly, radiating tube bundles (shown as 104-1 and 104-2 in FIG. 1) can have a larger surface area to radiate the heat so as to decrease fuel consumption, which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[00121] In another aspect, larger surface area of the spiral finned type radiating tube 200 due to plurality of spiral fins 224 can also contact more of the convection air being circulated per unit time in the convection type heat exchanger, and can cause convection air to remain in contact with the spiral finned type radiating tube 200 for a longer time.
[00122] In an aspect, due such increase in the surface area of the spiral finned type radiating tube 200, and more time the convection air remains in contact with the spiral fins, heat transfer by convection in the convection type heat exchanger can be increased. Accordingly, radiating tube bundles (shown as 104-1 and 104-2 in FIG. 1) can have a larger surface area to increase heat transfer by convection so as to decrease fuel consumption, which can result in more economical operation of the oven. Fuel consumption being lower, flue gas emitted into the atmosphere can be lesser which can reduce air pollution.
[00123] For exemplary radiating tubes known in the art comprising ERW pipes having an outside diameter of 101.6 mm and a wall thickness of 1.6 mm, in accordance with the present disclosure, the spiral finned type radiating tube 200 having the same sized pipe can be provided with fins having 22.2 mm pitch with 0.9 to 1 mm thick fins of length 10 mm thereby having an increased surface area of 4840 square centimetre which can be used as heat transfer surface within the baking zone of the oven.

Following can be the exemplary comparative parameters per meter length.
Sr.No. PARAMETERS SPIRAL FINNED TYPE RADIATING TUBES 200 CONVENTIONAL TUBES
1 Outer Diameter 121.6 mm with fin 101.6 mm
2 Wall Thickness 1.6 mm 1.6 mm
3 Wt. per meter 4070 gms 3569 gms
4 Specific heat 0.46 0.46
5 Heat required to heat pipe up to 650 C from ambient temp of 30 deg. C 1161 KJ 1017 KJ
6 Outer surface area for heat exchange 4840 sq. cm 3192 sq. cm
7 emissivity 1.51 1

[00124] From the above table, it can deduced that by increasing weight by 1.14 times, heat required to heat up the spiral finned type radiating tube 200 to a constant temperature of 650 deg. C can also be increased 1.14 times. But the total heat transfer area can be increased by 1.5 times (by way of radiation and convection). Hence, fuel consumed in ovens provided with spiral finned type radiating tubes 200 can be less than that in conventional ovens. Accordingly, there can be lesser pollution by the fuel burnt.
[00125] Spiral finned type radiating tubes 200 as described herein above can facilitate optimized heat exchange and can improve the efficiency of the system.
[00126] In an embodiment, spiral finned type radiating tubes 200 of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes 200 of the present disclosure can be made of a combination of metals. For eg. while the tube 222 can be made of copper, the spiral fins 224 can be made of aluminium.
[00127] Device of the present disclosure can be used for manufacturing biscuits, bread, cookies, buns and a lot of other bakery products in the indirect type fuel fired oven. The consistent and efficient temperature control on account of the optimized heat exchange can provide a gentle texture development and distinctive characteristics on the surface of the product being baked.
[00128] The device of the present disclosure can be used in food processing ovens such as tunnel ovens, rack ovens and other types of ovens where tubes are used for heat transfer in indirect cyclotherm ovens.
[00129] Although the above description of the present disclosure is directed to baking in fuel fired indirect type cyclothermic tunnel oven, it can be understood that the device described can be used for various other heat exchange applications including heating, drying and curing a variety of products for various industries by implementing the device suitably.
[00130] The device as disclosed herein above can enhance heat exchange and thereby the efficiency of any heat exchange system.
[00131] The device as described herein above can be retrofitted in existing indirect fuel fired cyclothermic tunnel ovens. The device can also be retrofitted in existing heat exchangers where suitable, and particularly for ovens for baking food.
[00132] In an embodiment, the spiral finned type radiating tubes 200 of the present disclosure can be made of any suitable heat conducting metal. In another embodiment, the spiral finned type radiating tubes 200 of the present disclosure can be made of a combination of metals. For eg. while the tube can be made of copper, the spiral fins can be made of aluminium.
[00133] In another embodiment of the disclosure, the component or the parts of the present disclosure can be coated, painted or coloured with a suitable chemical to retain or improve its properties, or to improve the aesthetics or appearance.
[00134] In an embodiment of the disclosure, the components of the present disclosure can be connected or arranged by using any suitable method and may include without limitation use of one or more of welding, adhesives, riveting, fastening devices such as but not limited to screw, nut, bolt, hook, clamp, clip, buckle, nail, pin, ring.
[00135] In an embodiment of the disclosure, one or more of a process or step carried out by the system may involve use of a electronic device or a data processing device or a sensor or a microcontrollers or a PLC (Programmable logic controller) or a PID (proportional–integral–derivative) controller, or a combination thereof, which may further involve one or more predefined algorithms or programs or logic.
[00136] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
[00137] It will be further understood that the terms "comprises" or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, or components, but do not preclude or rule out the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.
[00138] The use of the expression “at least” or “at least one” suggests the use of one or more elements, as the use may be in one of the embodiments to achieve one or more of the desired objects or results.
[00139] The process steps, method steps, algorithms or the like may be described in a sequential order, such processes, methods and algorithms may be configured to work in alternate orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. The steps of processes described herein may be performed in any order practical. Further, some steps may be performed simultaneously, in parallel, or concurrently.
[00140] The aim of this specification is to describe the invention without limiting the invention to any one embodiment or specific collection of features. Person skilled in the relevant art may realize the variations from the specific embodiments that will nonetheless fall within the scope of the invention.
[00141] It may be appreciated that various other modifications and changes may be made to the embodiment described without departing from the spirit and scope of the invention.

ADVANTAGES OF INVENTION
[00142] The present disclosure provides for a device in the form of spiral finned type radiating tube which improves the efficient of heat exchange in ovens used for baking different kinds of foods.
[00143] Due to such increase in efficiency, the amount of fuel used for the same transfer of heat to the product being baked can be reduced and hence, ovens with such a device can be much more economical in operation.
[00144] Due to lowered fuel consumption, the device can reduce air pollution caused by fuel in ovens used for baking different kinds of foods.
[00145] The device can easily be retrofitted to optimize heat exchange in ovens used for baking different kinds of foods by taking out the heat exchangers presently installed and replacing them with those using the device of the present disclosure.

CLAIMS:
1. A radiating tube of a heat exchanger, wherein the radiating tube comprises a tube with a plurality of spiral fins coiled around the length of said tube to increase overall surface area of the radiating tube.

2. The radiating tube of claim 1, wherein the plurality of spiral fins contact with more convection air being circulated per unit time.

3. The radiating tube of claim 1, wherein the heat exchanger is a convection type heat exchanger.

4. The radiating tube of claim 1, wherein the heat exchanger is a radiating type heat exchanger.

5. The radiating tube of claim 1, wherein the radiating tube is made of one or a combination of heat conducting materials.

6. The radiating tube of claim 1, wherein a plurality of the radiating tubes together form a radiating tube bundle.