WO2013190367A2

WO2013190367A2 - Heat exchange means for cooking devices and methods for retrofitting cooking devices

Info

Publication number: WO2013190367A2
Application number: PCT/IB2013/001302
Authority: WO
Inventors: Ludwig Weber; Herbert Fischhaber
Original assignee: Convotherm Elektrogeräte GmbH
Priority date: 2012-06-21
Filing date: 2013-06-20
Publication date: 2013-12-27
Also published as: WO2013190367A3

Abstract

Disclosed are heat exchange or heat transfer devices, systems and combinations thereof, for cooking devices and methods of retrofitting cooking devices with heat exchange or heat transfer devices. The heat exchange devices confer energy savings and efficiency to the operation of the cooking devices. More particularly, disclosed are heat exchange or heat transfer devices, systems and combinations that include contacting intake pipes containing cooler fluid or air with outlet pipes and/or heated areas of cooking devices, such as electrical areas, to effect heat exchange between the fluid or air and thus preheat the fluids in the intake pipes and to cool the outlet pipes and the heated areas. Also disclosed are methods of retrofitting cooking devices with the heat exchange means.

Description

Heat Exchange Means for Cooking Devices and Methods for Retrofitting

Cooking Devices

BACKGROUND

1. Field of the Disclosure

[0001] The present disclosure relates to cooking devices and methods for retro-fitting cooking devices. More particularly, the present disclosure relates to heat transfer means, such as heat exchange systems and combinations, for cooking devices and methods of retrofitting cooking devices with such heat exchange means. The heat exchange means confer energy savings and efficiency to the operation of the cooking devices.

2. Background of the Disclosure

[0002] According to the state of the art, a cooking device, in particular a commercial combisteamer has several pipes for, e.g., air supply and/or fluid supply, as well as for discharge of exhaust or waste air and/or fluid. Typically, the pipes are arranged separate from each other in different areas of the cooking device according to their origin, use and/or their preferred discharge position.

[0003] One such example of this kind of system is shown in DE 3909283. In the disclosed system, a pipe that has cold water running through it is coiled around a discharge pipe of a cooking device having hot air from the cooking chamber flowing through it. The coiled pipe having cold water running through it is disposed within a sleeve made of second pipe surrounding both the coiled pipe having cold water running through it and the discharge pipe. The sleeve does not carry any air or fluid to or from the cooking device. The coiled pipe carrying cold water is not in direct contact with the contents of the discharge pipe, nor disposed within any of the elements or components of the cooking device itself. DE 3909283 states that the heat exchanger of this configuration causes the heat from condensed water and steam carried away from the cooking chamber to be carried away by the water flowing through the coil. The cold water in the coli may be supplied to the cooking chamber of the cooking device.

SUMMARY

[0004] It is an object of the present disclosure to improve the known cooking devices by integrating the separate supply and discharge pipes into heat exchange systems.

[0005] It is also an object of the present disclosure to increase the efficiency of the cooking devices through the use of such heat exchange systems.

[0006] It is a further object of the present disclosure to decrease the energy consumption of the cooking devices through the use of such heat exchange systems.

[0007] It is a still further object of the present disclosure to provide methods for retrofitting cooking devices with such heat exchange systems.

[0008] These and other objects are met through the present disclosure wherein novel combinations and integrations of the heretofore separate supply and discharge pipes are joined into heat exchange systems. The combinations and integrations afford increased efficiency in the cooking devices due to the use of warmer air or fluids to preheat cooler air or fluids and/or for the cooler air of fluids to cool heated areas of the cooking device. Thus, less energy and time is required to heat the cooler air and/or fluids to their operational temperatures. In the embodiments where cooler air and/or fluids are used to remove heat from areas/components of the cooking device, this may serve to prolong the life and efficiency of those heated areas/components or of components of those heated areas/components. [0009] As used herein, the "cooking device" refers to any device that is used to heat/cook food and/or ingredients during a cooking process, e.g., any oven, microwave or steamer. Especially preferred in the present disclosure is a cooking device applicable for commercial use. "Combisteamer" means a cooking device used for cooking with hot air, steam or superheated steam.

[00010] As used herein, the term "flow pipe" refers to any tube or pipe that carries a medium, in particular a fluid or gaseous medium, e.g., air, water or steam. In particular embodiments, the flow pipe can be a suction pipe, an intake pipe, an exhaust pipe, an injection pipe, a connecting pipe, a bypass pipe, a drain pipe, a waste pipe, a water pipe (in particular a hot water pipe or a cold water pipe), a gas pipe, a pipe for filling a water reservoir such as in a steam generator, an air outlet or intake for an electric space or a combustible air supply.

[00011] As used herein, the term "heat transfer boosting means"

encompasses any means, apparatus or combination of apparatuses, or measure or combinations of measures which effects or increases heat transfer or heat exchange from, e.g., a flow pipe, to the environment as well as from the environment to the flow pipe. The term "heat transfer boosting means" also encompasses any means, apparatus or combination of apparatuses, or measure or combinations of measures, which effects or increases heat transfer or exchange from one flow pipe to another. By providing the heat transfer or exchange means, given a temperature difference between the medium in the flow pipe(s) and/or the environment and flow pipe(s), the temperature of the two can be changed more efficiently by transfer of heat, i.e. either increased or decreased, and the temperature of the environment and/or the flow pipe(s) and/or surroundings as well can be either decreased or increased

correspondingly.

[000 2] In one embodiment, the heat transfer boosting means is comprised of an increased surface area of, for example, the flow pipe by, e.g., cross- sectional changes or length (conformational) changes, as compared to a cross- section of the flow pipe upstream and/or downstream of the heat transfer boosting means. These cross-sectional changes include, e.g., a change in cross-sectional shape as such, e.g., from round to square, a change in wall thickness, convexities, the addition of fins (in particular metal fins), a punching or crimping of the pipe or similar measure with the same effect. In an alternative embodiment, when fins are used to provide the cross-sectional increase in surface area, the fins can be directed inwards or outwards, can be parallel discs, can be radial structures, with any of the forgoing integrally formed with the pipe or added to the pipe. In another preferred embodiment, the heat transfer boosting means is a kink or curvature in the flow pipe. Moreover, the pipe may be internally spiraled, thus causing the pipe to increase the surface area of the medium in contact with the inner surface of the pipe and thus increase the volume of the medium available for heat transfer. By having one or more kinks and/or curves, the surface area of the flow pipe(s) is increased compared to a part of the flow pipe(s) upstream or downstream of the heat transfer boosting means. In a particularly preferred embodiment, the pipe(s) can have a spiral or serpentine form.

[00013] In another embodiment, the flow pipe is a suction pipe for air supply. Typically in combisteamers, dry cold air ("cold" as compared to the environment in and near the combisteamer) is sucked into the cooking device. On average, the temperature in the cooking device is higher than the

temperature of the air sucked in. By providing a suction pipe with heat transfer boosting means, the temperature of the air in the suction pipe is increased. This allows a preheating of the cold air so that the warm or hot air which is needed for the processes performed by the cooking device can be reached more quickly and effectively.

[00014] In still another embodiment, the flow pipe is a cold water pipe and in particular a cold water pipe for filling a steam generator in a combisteamer. On average, the temperature in the cooking device is higher than the temperature of the cold water in the cold water pipe. By providing the cold water pipe with heat transfer boosting means, the temperature of the water in the cold water pipe is increased. This provides a preheating of the cold water in the cold water pipe which again decreases heating efforts later if water is needed, in particular, for steam generation. At the same time, this preheating can lead to a significant cooling effect of the environment surrounding the cold water pipe, as heat is absorbed by the cold water in the pipe.

[00015] In order to enhance the effect of preheating, the temperature of the cold medium in the flow pipe can be increased by directing the flow pipe through a "heated" space, i.e., a space containing or enclosing electrical equipment or devices. As used herein, "heated space" means any space in which the temperature of the environment is elevated due to the operation of, and/or components in, the space. The term heated space can include areas which are intentionally heated, but heated space preferably excludes such intentionally heated areas. In a combisteamer for example, there are often areas in which electrical components for control of the combisteamer are placed. For purposes of protection of those areas from the environment of the combisteamer, such "electric spaces" are generally enclosed. These electric spaces can be, for example, a compartment of the cooking device where electrical components are located. An electric space can be a separate area, especially a box within the cooking device. Also, an electric space may usually be provided with air-cooling to additionally reduce the heat build-up often found in such areas. Typically, an electric space contains a variety of electrical components such as relays or water valves and similar types of devices that lead to an increased temperature in the electric space of up to approximately 80°C.

[00016] At a typical ambient temperature of between 30°C to 100°C, the temperature of the air in the flow pipe, and thus the pipe itself, is approximately the same as the ambient temperature. With the typical cold water temperature of between 5°C to 20°C, the typical temperature of the cold water flow pipe is approximately the same as the temperature of the cold water. In both cases, the temperature difference between the temperature in a heated space, such as an electric space and the temperature of the medium in the pipe and the pipe itself is significant. This is the basis for one embodiment of the present disclosure where heat transfer between the cold air/water and electric space leads to a considerable heat transfer from the electric space to the flow pipe and a temperature increase of the medium in the flow pipe. At the same time, this has a cooling effect on the electric space which allows for a reduction or possibly an elimination of other cooling means and/or measures for the electric space. In other embodiments, the heat transfer or exchange between the electric space and a cooler medium is provided between a flow pipe being a suction pipe and/or a flow pipe being a cold water pipe.

[00017] Thus, it is advantageous if the heat transfer or exchange means is arranged in the electric space. This increases the heat/cold transfer between the flow pipe and its environment, in this case the electric space.

[00018] In another embodiment, a temperature increase is provided by heat exchange of a suction pipe with an exhaust pipe. By this, waste heat form the exhaust pipe can be used to raise the temperature of the medium in the suction pipe. This leads to a particularly energy efficient pre-heating process. The heat transfer or exchange between the suction pipe and the exhaust pipe can be a parallel flow, a counter-current flow or a cross-flow heat transfer or exchange. The heat exchanger can be a phase-change heat exchanger. In an alternative embodiment, the heat exchanger may also be formed between any flow pipe that serves as an inlet of air, liquid or both with any exhaust pipe that serves as an outlet for air, liquid or both.

[00019] In yet another embodiment, a suction pipe for a supply of cold air can be provided in an exhaust pipe carrying either liquid or air. The temperature of the medium in the exhaust pipe is typically higher than the temperature of the medium in the suction pipe. Therefore, through heat transfer or exchange, a temperature increase of the medium in the suction pipe is possible. At the same time, the temperature of the medium in the exhaust pipe is lowered. The greater the length of time that the contact between the supply and exhaust pipes takes place, the greater the amount of heat transfer or exchange that will take place. If the cooking device is a combisteamer, the medium in the exhaust pipe is typically hot air or steam, or a combination of them, with a temperature of about 100°C, sometimes higher. In this particular configuration, it is not only possible to heat the air in the suction pipe, but at the same time the humidity and temperature in the exhaust pipe is decreased thereby reducing humidity and temperature emission to the environment surrounding the cooking device.

[00020] In particular, the exhaust air may condense by being in contact with the lower temperature of the supplied air. The enthalpy of condensation thereby increases the level of efficiency of the heat transfer.

[00021] As can be seen from the above, different configurations of heat transfer or exchange means, measures and/or apparatuses can be combined in parallel or in series. For example, a cold air supply pipe can first be placed in position for heat exchange or transfer with, in or through an electrical space and thereafter can be placed in heat exchange or transfer position with, in or through an exhaust pipe. This kind of sequential placement serves the purpose of using the heat exchange of all media to the greatest extent possible.

[00022] Another aspect of the present disclosure relates to methods for retrofitting a cooking device wherein an apparatus is connected to a flow pipe and wherein the apparatus changes the temperature of the medium in the flow pipe. Retrofitting refers to the addition of the new technology and/or new features of the present disclosure to an existing or old system, in this case a conventional cooking device. The retrofitting allows for an increase or decrease in the temperature of the medium in the flow pipe. This can either be used for pre-heating a colder medium going into the cooking device or for cooling warmer medium leaving or in the cooking device.

[00023] The present disclosure will be described in more detail hereinafter with reference to specific exemplary embodiments and reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[00024] Further details, features and advantages of the present disclosure will result from the following description of embodiments using the drawings in which:

[00025] Figure 1 shows a schematic representation of a combisteamer with a counter-current heat exchanger of the present disclosure;

[00026] Figure 2 shows a schematic representation of an alternative embodiment of a combisteamer with a heat transfer boosting means of the present disclosure;

[00027] Figure 3 shows a schematic representation of a cross-section through a flow pipe with heat transfer boosting means of the present disclosure using external fins;

[00028] Figure 4 shows a schematic representation of a cross-section through a flow pipe with heat transfer boosting means of the present disclosure produced by punching or crimping the exterior of the pipe without reducing the flow of fluid through the pipe;

[00029] Figure 5 shows a schematic representation of a combisteamer with a heat exchanger of the present disclosure formed by the cold water pipe for filing the steam generator passing through a heat-generating area of the combisteamer; and

[00030] Figure 6 shows a schematic representation of a combisteamer with a heat exchanger of the present disclosure formed by the cold water pipe for filling the steam generator passing through a heat-generating area of a combisteamer with solid state relay(s) attached to it.

DETAILED DESCRIPTION OF THE DISCLOSURE

[00031] The present disclosure will now be described in detail with respect to the embodiments shown in the Figures, in which like numerals represent like elements.

[00032] Figure 1 shows a generalized design of a combisteamer 1 having an embodiment of the heat transfer or exchange means of the present disclosure depicted therein, in Figure 1, combisteamer 1 has a housing 2 containing a cooking chamber 3 and a heating chamber 4. Heating chamber 4 is divided by a suction panel 5 from cooking chamber 3 and suction panel 5 serves to separate cooking chamber 3 from heating chamber 4 and protect a fan wheel 6 and a heating element/coil 7 from being inadvertently touched or damaged.

[00033] Through a suction panel opening 8 in suction panel 5, air is sucked in from cooking chamber 3 to heating chamber 4 in the direction of arrows "A" and distributed to fan wheel 6 and heated by heating element/coil 7 and returned to cooking chamber 3 in the direction of arrows "B". During steaming, water is distributed within heating chamber 4 (water inlet not shown). For

dehumidification during cooking, a flap 9 is opened and fresh air is sucked into heating chamber 4 of cooking chamber 3 via an intake pipe 10 in the direction of arrows "C". The humid hot air in cooking chamber 3 is pushed out through a drain 11 by the incoming cool air from intake pipe 10 and then into an appliance condenser 12 and thereafter into the environment through an air outlet pipe 13. In the embodiment shown in Figure 1 , air outlet pipe 13 is led through the interior of intake pipe 10 thereby forming a heat exchanger 14. These positions of course could be reversed, with intake pipe 10 being lead through air outlet pipe 13. In either configuration, cold air flowing through the intake pipe 10 is heated while the humid hot air flowing through air outlet pipe 13 is cooled. As the humid hot air is cooled, it condenses, which leads to a very effective heat transfer. In this manner, the energy needed for heating the cold air entering via intake pipe 10 by heating element/coil 7 is decreased while at the same time the temperature of the exhaust exiting via air outlet pipe 13 is decreased, thereby producing less humidity and heat emission to the environment surrounding combisteamer 1. An inlet 15 is often employed for filling appliance condenser 12 for various purposes, such as during the cleaning cycle of combisteamer 1.

[00034] Figure 2 again shows a generalized combisteamer 1 having another embodiment of the heat transfer or exchange means of the present disclosure depicted therein. Combisteamer 1 in Figure 2 is largely parallel in structure and function to combisteamer 1 in Figure 1. Combisteamer 1 has housing 2 containing cooking chamber 3 and heating chamber 4 divided by suction panel 5 that separates cooking chamber 3 from heating chamber 4 and thereby protects fan wheel 6 and heating element/coil 7 from being damaged or touched. Combisteamer 1 of Figure 2 also has inlet 15 akin to inlet 15 in Figure 1. Also in Figure 2, through central gap 8 in suction panel 5, air is sucked in from cooking chamber 3 to the heating chamber 4 in the direction of arrows "A" and distributed and to fan wheel 6 and heated by heating element/coil 7 and returned to cooking chamber 3 in the direction of arrows "B". During steaming, water is distributed within cooking chamber 3. Fordehumidification during cooking, flap 9 is opened and fresh air is sucked into the chamber via an intake pipe 20 in the direction of arrows "C". Intake pipe 20 has a heat transfer boosting means 21 in form of various bends 22 forming a serpentine-like structure, thereby increasing the surface area and volume of intake pipe 20 and configuring heat exchanger 21. Heat exchanger 21 can be placed in or through an electric space or other heated space (not shown in Figure 2) of combisteamer 1. Fresh cold air is sucked into cooking chamber 3 via intake pipe 20 through heat exchanger 21 and through, e.g., the electric space. The cold air flowing through intake pipe 20 is heated while, e.g., the electric space is cooled. In this manner, the energy needed for heating the cold air by the heating element/coil 7 is decreased while the temperature in, e.g., the electric space is decreased as well. This has the mutual beneficial effect of reducing the need for other cooling measures, such as passive or active ventilation for cooling the electric space and/or for heating the cold air. As the preheated air entering through intake pipe 20 is pushed into cooking chamber 3, humid hot air in cooking chamber 3 is pushed out through drain 11 to an appliance condenser 12 and into the environment surrounding combisteamer 1 via an air outlet pipe 23, in a manner similar to that described with respect to Figure 1. As can be envisioned, intake pipe 20 does not need to be configured to allow cold air to enter heating chamber 3 directly after passing through the electric space, but could be diverted into the air outlet pipe 23 to effect further heating of the cold air in intake pipe 20 and cooling of the humid hot air in air outlet pipe 23.

[00035] An additional alternative embodiment of the present disclosure is depicted in Figures 3 and 4 showing embodiments where heat exchange boosting means lead to increased heat transfer and this can be achieved by cross-sectional changes of air intake pipes 10 and 20 of Figures 1 and 2.

[00036] In Figure 3, one possible heat exchange boosting means 30 is shown. In Figure 3, heat exchange boosting means 30 is comprised of a plurality of fins 32 that are integrally formed in conjunction with a round pipe 33 and extend outwardly from round pipe 33. An additional alternative embodiment of heat exchange boosting means of the present disclosure is depicted in Figure 4. In Figure 4, the heat exchange boosting means 40 is comprised of crimping a pipe 41 to form a plurality of convexities 42 and a plurality of concavities 43. [00037] Figure 5 has combisteamer 1 including housing 2. Housing 2 contains cooking chamber 3 and heating chamber 4 divided by suction panel 5 that separates cooking chamber 3 from the heating chamber 4 and thereby protects fan wheel 6 and a heating element/coil 7 from being touched or damaged. Again here, through central gap 8 in suction panel 5, air is sucked in from cooking chamber 3 into heating chamber 4 in the directions of arrows "A" and heated by heating element/coil 7 and distributed by fan wheel 6 in the direction of arrows "B". During steaming, steam is produced by a steam generator 50 and led into heating chamber 4 via an intermediate pipe 51. In steam generator 50, water 52 is heated by a heating element 53 thereby generating steam. Water 52 enters steam generator 50 via a cold water pipe 54. In this embodiment of the present disclosure, cold water 52 is preheated in a heat exchanger 55 in which cold water pipe 54 is led in a spiral 56. Heat exchanger 55 is located in the electric space 57, the interior of which is not shown. In this manner, cold water 52 used for generating steam in steam generator 50 is preheated, and by preheating cold water 52, the energy cost for heating cold water 52 is reduced. At the same time, there is a cooling effect in the environment of electric space 57. To assure that any condensation produced when cold water 52 heated in electric space 57 does not contact or harm components in electric space 57, the condensation is collected and discharged by means not shown.

[00038] In Figure 6, combisteamer 1 corresponds in its general aspects to combisteamer 1 in Figure 5. Also here, steam is produced by steam generator 50 in which water reservoir 52 is heated by heating element 53 thereby producing steam that is fed through intermediate pipe 51 into heated chamber 4 and thereafter into cooking chamber 3. Before filling water reservoir 52 with cold water 52 from water pipe 54, the water is preheated with a heat exchanger 60 in water pipe 54 again formed of spiral 56 in water pipe 54. Again, heat exchanger 60 is placed in an electric space 61, the interior of which again is not shown, and contributes to cooling the electric space 61 and heating cold water 52. Additionally, there are solid state relays 62 placed on electric space 61 and solid state relays 62 also experience cooling. Again, as described in relation to Figure 5, any condensation along water pipe 54 is collected and discharged.

[00039] In the above detailed description, specific embodiments of this disclosure have been described in connection with its preferred embodiments. However, to the extent that the above description is specific to a particular embodiment or a particular use of this disclosure, this is intended to be illustrative only and merely provides a concise description of the exemplary embodiments. Accordingly, the present disclosure is not limited to the specific embodiments described above but, rather, the present disclosure includes all alternatives, modifications, and equivalents falling within the true scope of the appended claims. Various modifications and variations of this disclosure will be obvious to a worker skilled in the art and it is to be understood that such modifications and variations are to be included within the purview of this application and the spirit and scope of the claims.

[00040] All of the patents, publications and other documents referred to herein are incorporated herein in their entirety as if fully set forth verbatim herein.

Claims

WHAT IS CLAIMED IS:

1. A cooking device comprising at least one fluid intake pipe and at least one fluid outlet pipe, wherein the at least one fluid intake supply pipe supplies fluid to the cooking device and the at least one fluid outlet pipe exhausts fluid from the cooking device, wherein the fluid in the at least one intake pipe is at a lower temperature than the fluid in the at least one fluid outlet pipe, wherein the at least one fluid intake supply pipe is in contact with the at least one fluid outlet pipe sufficient to effect transfer of heat between the at least one fluid outlet pipe and the at least one fluid intake pipe, and wherein the contact is comprised of the at least one fluid intake pipe passing through at least a portion of the at least one fluid outlet pipe or the at least one fluid outlet pipe passing through at least a portion of the at least one fluid inlet pipe.

2. A cooking device comprising at least one fluid intake pipe and at least one heated space, wherein the at least one fluid intake pipe supplies fluid to the cooking device, wherein the fluid in the at least one intake pipe is at a lower temperature than the at least one heated space, and wherein the at least one fluid intake pipe passes through at least a portion of the at least one heated space sufficient to effect transfer of heat between the at least one fluid inlet pipe and the at least one heated space.

3. A cooking device comprising at least one fluid intake pipe, wherein the at least one fluid intake pipe supplies fluid to the cooking device, wherein the at least one fluid intake pipe comprises heat transfer means.

4. A cooking device according to claim 3, wherein the heat transfer means comprises cross-sectional changes to the at least one fluid intake pipe to providing increased surface area to the at least one fluid intake pipe.

5. A cooking device according to claim 3, wherein the heat transfer means comprises serpentine structure in the at least one fluid intake pipe.

6. A cooking device according to claim 1 , wherein the medium in the at least one fluid intake pipe is air.

7. A cooking device according to claim 1 , wherein the medium in the at least one fluid intake pipe is water.

8. A cooking device according to claim 2, wherein the heated space comprises an electric space.