Heating system for use in galleys in transport means and a method of on-board heating of food in transport means, particularly in aircraft

The invention relates to a heating system for use in galleys of transportation and a method for heating of food on board means of transport, particularly aircraft.

On board aircraft, as well as other mobile devices devices for heating food are operated. The meals are thereby delivered usually by the so-called Gastronomieuntemehmen Catering in ready cooked condition and must be heated without damaging the product and time-optimized just before serving to the passengers. Due to an insufficient and not optimized for product quality supply of thermal energy in the product, often suffer especially the sensory quality (taste, texture) and the product appearance.

Moreover, the simultaneous operation of multiple heaters cause (for example, ovens and equipment for water heating) load peaks in the galley operating normally undesirably increased costs, as increased expenses for energy supply by generators, energy cells and for possibly only briefly occurring power demand of the load peaks other power sources yields. This increased expense can be found among others in negative side effects on aircraft again as system and operating costs as well as weight and physical volume required by the dimensioning of the power source in the event of the maximum power demand (peak load).

Previous processes for the introduction of additional heat energy without increasing the electrical output provide sensible, latent or thermochemical heat storage systems for additional heating.

In <patcit id="pcit0001" dnum="WO9963277A"><text>WO 99/63277</text></patcit> will be described with additional assembly on the basis of storage and retrieval system of latent heat, which can be used to compensate for peak loads a cooking appliance.

In <patcit id="pcit0002" dnum="DE3639545C1"><text>DE 3639545 C1</text></patcit> described systems, a process principle for heat storage and transformation and refrigeration by means of two in a closed circuit at different temperatures working in combination metal / metal-hydrogen. Many metals react in technically relevant temperature and pressure ranges with hydrogen under high heat of reaction to metal. By varying the applied hydrogen pressure, the heat temperature can be varied. The high-temperature storage can be provided as a heat energy buffer in the event of increased heat energy needs and release heat energy to a saucepan.

In <patcit id="pcit0003" dnum="US6392201A"><text>US-A-6,392,201</text></patcit> describes a catering cart having a latent heat storage.

Object of the present invention is therefore to ensure the heating of galleys in transport with heaters, avoid load peaks in the galley operation and thereby lead to a discharge of the electrical system in the transport. Furthermore, the heating system should be optimized so that sufficient for the product heating heat output is provided to protect the product of the food to be heated at the same time limiting the absolute temperature.

This object is achieved by the measures specified in claim 1 or. 6

In particular, is achieved with the proposed heating system and the process optimization of the energy supply for devices in galleys. At least part of the heating operation or the entire heating is ensured by a suitable heat storage material, so that the readily available thermal energy of the heat accumulator can be used in periods of increased power demand within the electrical system, thereby leading to a reduction of the electrical system. The memory on the basis of latent or thermochemical heat storage is here implemented not as an additional unit but as a fully integrated part of the heater.

The hydrogen is removed in the case of use of a heat storage based on metal hydride from a decentralized hydrogen storage, hydrogen line system or a central hydrogen production (eg reforming).

During the hydrogen desorption phase, which is stored in thermal energy, the hydrogen can be delivered to one of the previously referred to as a source memory which includes a Tieftemperaturhydrid, or a conduit system or to a fuel cell. Outside the period of use of the heater, additional electric power is generated by combining the disclosed herein heaters with a fuel cell. This can be provided either for other consumers available or can be used for the electric heating of the heat accumulator during the hydrogen desorption phase, provided that no other source of heat is simultaneously available.

The advantage of this method is to attach the heating of the devices in the furnace chamber is optimized so that sufficient for the product heating heat output is at the same time limiting the absolute temperature realized by suitable heat storage material selection for product protection without the heat distribution (eg a fan ) must prevent scorching. The electric heating is integrated into the tank / reactors. It is thus guaranteed a high energy input without overheating the product. The energy input can be obtained by thermal radiation, by utilizing the heat conduction (possibly assisted by thermally conductive product packaging - for example, aluminum trays) or by a heat transfer fluid to be heated up feed.

Another advantage of the integrated design of the heating system disclosed herein results from a weight-saving construction of the reactors, which are characterized by the following factors: eg<ul><li>thin walls,</li><li>Compacting the metal hydride material</li><li>Use of direct heat transfers (metal - wall - tray - food, with no additional heat transfer medium must be used).</li></ul>

Further developments and advantageous embodiments of the invention are given in claims 2 to. 5 Further embodiments of the inventive method are described in the dependent claims 7 to 12th

Further details and advantages will become apparent from the following description of an embodiment of the invention.

In the drawing, exemplary embodiments are shown according to the invention, which is described with reference to Figures 1 and 2 in more detail. In the figures, identical components are provided with the same reference numerals

Figures 1 and 2 each show a schematic representation of an embodiment of a heating system for use in galleys of transport with a process for the heating of foodstuffs can be performed.

To relieve the electrical system, such as on board an aircraft, the total load share a suitable heat storage material can be ensured on the basis of latent or thermochemical heat storage for heat supply in the furnace chamber, which is fully integrated into components of the respective heater. The heating is integrated into the heating or furnace chamber such that sufficient of the product heating heat output is at the same time limiting the absolute temperature realized by suitable heat storage material selection for product protection without the heat distribution (for example a fan) must prevent scorching.

The memory on the basis of latent or thermochemical heat storage is here implemented not as an additional unit, but as a fully integrated part of the heater.

There are applied the following definitions:<dl id="dl0001" compact="compact"><dt>Latent heat storage</dt><dd>Creation of available energy is depleted by phase change of the storage medium (eg solid / liquid)</dd><dt>Sensible heat storage</dt><dd>Creation of available energy is depleted by temperature change of the storage medium</dd><dt>Thermochemical heat storage</dt><dd>Creation of available energy is depleted by a chemical reaction of the storage medium</dd><dt>heat storage</dt><dd>Unit for the intermediate storage of thermal energy</dd><dt>Hydrogen storage</dt><dd>Unit for the intermediate storage of hydrogen</dd><dt>high-temperature hydride</dt><dd>Metal hydride having a hydrogen desorption pressure of 1 bar at temperatures above 200 ° C. </dd><dt>Tieftemperaturhydrid</dt><dd>Metal at temperatures which has a hydrogen desorption pressure of 1 below 100 ° C bar.</dd></dl>

In the heating system for use in on-board kitchens of means of transport illustrated in Figure 1, a heater 1 for heating of food products is shown in which a heat accumulator 3 is used with high temperature metal hydride as a heating medium. The heater 1, for example formed as furnace for heating food in aircraft, has a boiler room 2A, in the example, catering containers 2 are arranged with the food to be heated. The boiler room 2A can be formed in a further, not shown embodiment, in a manner that these specifically for the heating of liquids, such as water in continuous or storage (boiler) is used methods and in coffee machines, water heaters, general water heaters and similar apparatus shall apply.

The high temperature metal hydride is a thermo-chemical heat accumulator 5, which is used by a chemical reaction of the storage medium to create an energy reserve available. As metal is, for example, a magnesium alloy used.

In low-load periods, hydrogen is desorbed by supplying thermal energy by means of electric heating elements. 5 This hydrogen can be fed via a hydrogen conduit system 4, and a valve 10 is either a hydrogen storage unit 11 or be provided as a fuel for disposal via a valve 9 to a fuel cell 12th The released energy of the fuel cell can be used to heat the storage elements 3 again. Alternatively, there is provided power via a DC power source (G) or via the electrical system of the means of transport. A suitable control system with a control unit 15 ensures the operation regarding the area of ​​the load minimum. The required electrical power. If the hydrogen completely desorbed, is located in the heating elements prior to pure metal. If now the contents of the catering container 2 to a desired consumption temperature to be heated, so hydrogen from the hydrogen storage 11 at a pressure which is above the absorption pressure of the metal used (anhydride) s is located at the desired temperature, is supplied. The level of this pressure varies with the absorption temperature and is substance specific. A suitable weight-optimized piping system, which is realized with thin walls, appropriate material selection and short distances, as Wasserstoffverteilsystem 6 guarantees a uniform reaction and thus heat release in the heating elements. If the catering container 2 consist of highly thermally conductive materials, they act as additional thermally conductive structures. In this case, a direct contact between the heating elements 5 containing heat storage 3 and catering containers 2 is desirable.

The electric heating to provide heat during the Wärmeeinspeicherung, and as an optional addition of the votes from the thermal storage heat output during the hydrogen absorption can be integrated in such a way in the components of the heater 1, the radiant heat of the electric heating is 5 so evened out that it is not for Zerrstörung the product / foodstuff results.

In a use of the heat accumulator 3 based on metal hydride with the described combination of the heater 1 with the fuel cell 12, during the hydrogen desorption phase of the heat storage of the emitted hydrogen is used to produce additional electrical energy, the electrical energy generated either for other consumers in the onboard power grid for available on or is but used for the electric heating of the heat accumulator during Wärmeeinspeicherung itself.

In the process variant shown in Figure 2, a latent heat storage material 13 is integrated into the heating elements 5 containing heat storage 3 instead of the metal hydride. This is heated in low-load times over the electrical heating elements 3 (or other heat source) to the desired temperature. Control of the power supply via a control unit 15. In order to keep the energy loss in the downtime low, a special insulation is to provide 14 of the entire heating chamber 2A. To heat the food, the catering Behältem 2 are inserted into the heating system and the thermal storage is to heat the food evenly heat. By selecting a suitable heat storage material can be carried out a gentle product heat their food.

In both variants, the heating in the heating or furnace chamber 1 to increase the heat distribution by an additional circulation of a heat transfer medium (eg, air, water) can be added.

The entire system design is carried out in compliance with the special safety requirements of the respective transport largely weight and space optimized.

LIST OF REFERENCE NUMBERS

<dl id="dl0002" compact="compact"><dt>1</dt><dd>Heating system for heating of foodstuffs</dd><dt>2</dt><dd>Catering container</dd><dt>2A</dt><dd>boiler room</dd><dt>3</dt><dd>heat storage</dd><dt>4</dt><dd>Hydrogen line system</dd><dt>5</dt><dd>electrical heating elements</dd><dt>6</dt><dd>Wasserstoffverteilsystem in memory</dd><dt>7</dt><dd>water drainage</dd><dt>8th</dt><dd>air supply</dd><dt>9</dt><dd>Valve to the fuel cell</dd><dt>10</dt><dd>Valve for hydrogen storage unit</dd><dt>11</dt><dd>Hydrogen storage unit</dd><dt>12</dt><dd>fuel cell</dd><dt>13</dt><dd>Latent heat storage material</dd><dt>14</dt><dd>isolation</dd><dt>15</dt><dd>control unit</dd><dt>G</dt><dd>DC power source</dd></dl>