DE102008062038A1 - Emergency power system for supplying electricity to e.g. air conditioning system in cabin of civilian aircraft, has evaporation system evaporating fuel cell-product water, and heat exchanger whose supply air is cooled down by water - Google Patents

Abstract

The system has a heat exchanger (4), and a fuel cell unit (2) producing electricity and cooled by a cooling circuit, where the system is arranged in a pressing area of an aircraft. An evaporation system evaporates fuel cell-product water, and supply air and/or exhaust air of the heat exchanger is cooled down by the water. The evaporation system includes a nozzle for injecting fuel cell product water into a cooling air flow and/or a porous evaporation body, which is arranged in the cooling air flow. An independent claim is also included for a method for operating an emergency power system for an aircraft with a fuel cell unit.

Description

The The present invention relates to a note power system for an aircraft with a fuel cell unit for generating electrical energy, wherein the fuel cell unit via a cooling circuit, the heat exchanger includes, cooled and wherein the note energy system advantageously in the printed Area of the aircraft is arranged.

Such Note energy systems, which in an emergency electrical energy through a Fuel cell unit available can make are an alternative to those provided in most civil aircraft Note power systems over Rammed air turbines work. In note energy systems with a fuel cell unit is a fuel, such. As hydrogen, with oxygen in the Fuel cell unit oxidizes, whereby electrical energy is generated. This produces in addition to the electrical energy waste heat and Water. As fuel cells z. B. Proton Exchange Membrane (PEM) fuel cells are used, which have relatively low working temperatures.

The during operation of the fuel cell unit resulting waste heat must be withdrawn from the system to ensure the proper functioning of the fuel cell unit to guarantee. This is a cooling circuit provided in which a coolant circulates, that the waste heat the fuel cell unit receives and emits through the heat exchanger again.

Around to simplify the installation of the Notenergie system, it is advantageous when all components of the note energy system are arranged close together are, and advantageously in the printed area of the aircraft. This is also the heat exchanger arranged in this printed area of the aircraft. During an emergency However, it tries to maintain pressure in the hull by removing all closable openings getting closed. In addition, no ventilation takes place, as the Aircraft air conditioning in an emergency usually not in operation is. The heat exchanger must therefore the waste heat of the system to the air within the closed hull.

The Temperature of air in the closed hull envelope will therefore increase steadily. This increased Air temperature affects Size and mass of the Heat exchanger. In addition, results from the maximum reasonable temperature for the passengers one Upper limit for the increase the air temperature.

task It is therefore an object of the present invention to provide improved cooling of a Notenergiesystems for an airplane available to deliver.

According to the invention this Problem solved by a Notenergiesystem according to claim 1. The inventive note energy system for an airplane has a fuel cell unit for generating electrical Energy on which over a cooling circuit, the one heat exchanger includes, cooled becomes. Advantageously, the note energy system is printed Area of the aircraft arranged. According to the invention is a plant for evaporation provided by fuel cell product water through which the supply air and / or the exhaust air of the heat exchanger chilled becomes. During operation of the fuel cell arises as a reaction product Water, which now according to the invention for cooling the supply air and / or the Exhaust air of the heat exchanger the fuel cell unit is used. Through this additional cooling will the effectiveness of heat exchanger elevated and the warming the for cooling to disposal reduced air in the fuselage. Alternatively to the fuel cell product water or additively to this, stored water can be used in a storage container. As far as the following of the use of fuel cell product water the speech is always within the scope of the invention, additional or Alternatively, this stored water can be used.

Especially it is advantageous if the fuel cell product water for cooling the supply air of the heat exchanger is used. This results in a lower heat exchanger inlet temperature achieved so that the heat exchanger in his size and his Weight can be made smaller.

by virtue of Their low operating temperature of about 70 ° C to 80 ° C produce PEM fuel cells while liquid Water. This can therefore be used directly to the supply air and / or the exhaust air of the heat exchanger cool. The evaporation enthalpy produced by the evaporation of the water takes care of it a temperature reduction of the air flow. For fuel cells with higher Operating temperature must on the other hand, the exhaust gases cooled down first be before water in liquid Form available stands. Therefor If necessary, a water separator is provided.

advantageously, has the plant according to the invention for the evaporation of fuel cell product water while a nozzle for injecting the Fuel cell product water in the cooling air flow and / or a porous Evaporation body on, which in the cooling air flow is arranged.

According to the invention, therefore, a nozzle can be provided, via which the fuel cell product water is atomized in the cooling air flow. Advantageously, the nozzle is in the supply air duct for Heat exchanger arranged. The water pressure in front of the nozzle can be the pure operating pressure of the fuel cell. Alternatively, a pump may be provided over which the water pressure is increased to achieve a finer atomization. Water atomization works the better, the higher the pressure in front of the nozzle, because finer droplets offer a large surface and therefore evaporate faster than large ones.

alternative the plant for evaporation can have a porous evaporation body, which in the cooling air flow is arranged. The porous one Evaporating body is advantageously made of a hydrophilic material. Of the porous Evaporating body is supplied with fuel cell product water and thus ensures evaporation, during the Airflow through or over the porous one Body flows. It deals therefore a contact humidifier. As a porous evaporation body can z. As a tile, in particular made of a hydrophilic material be. The advantage of such an evaporation plant is that that no high pressure is needed becomes.

there can be the porous one Evaporator body separated from the heat exchanger accomplished and in particular in the cooling air duct in front of the heat exchanger be arranged so that the heat exchanger supply air through or over the porous one Evaporating body flows. However, this variant has the disadvantage that the porous evaporation body an additional Component represents, and also to a pressure drop in the cooling air path to lead can.

When Further advantageous variant can therefore be provided that the heat exchangers even the porous one Evaporating body includes by the heat exchanger z. B. from a porous Material is or coated with a porous material. Again, this is the porous Material with the fuel cell product water wets and uses the Evaporation enthalpy directly on the surface of the heat exchanger. This is no additional device in the cooling air flow necessary.

In furthermore advantageously the plant according to the invention is designed for the evaporation of fuel cell product water, that after activation of the note energy system, the resulting fuel cell product water first collected and delayed for cooling the cooling air flow is used. The design of the heat exchanger for cooling the Fuel cell unit is characterized by the maximum temperature of the cooling air during the throughout system operation. At the beginning of the mission has the cooling air while still a relatively low temperature level, which, however increases during the course of the mission. To the size and thus the weight of the heat exchanger Therefore, the product water can be collected according to the invention be and z. B. only from a certain cooling air temperature or after Expiration of a certain time to be introduced into the cooling air flow. Likewise, it can be provided that the introduced amount of water with the time or with the cooling air temperature increases. This allows the maximum cooling air temperature, which the Design of the heat exchanger determined to be lowered significantly. By collecting the water At the beginning of operation, there is an additional one at the time of the highest cooling air temperature Amount of water available, the for cooling can be used.

The inventive plant for the evaporation of fuel cell product water has advantageously a collection container for collecting the resulting fuel cell product water as well an appropriate control over which the addition of the water to the cooling air flow is controlled. Alternatively, the collection container and the supply line be designed so that emerging fuel cell product water first collects and later into the cooling air flow is introduced.

In Furthermore advantageously, it is provided that the heat exchanger via a Exhaust duct connected to the air distribution system of the aircraft cabin is, so while the operation of the Notenergie system heated by the heat exchanger exhaust air over the Air distribution system can be distributed in the cabin. These allows a uniform distribution the waste heat the fuel cell system over the cabin. Through this even distribution can Short circuit currents the warm exhaust air are greatly reduced. This can cause the temperature the heat exchanger supply air via a long period are kept low, making this smaller can be dimensioned. In addition, overheating of individual areas of the aircraft avoided. It can by the use of the air distribution system the aircraft cabin resorted to an existing component which saves costs and weight.

The The invention is of particular advantage when the supply air for the heat exchanger from the printed area taken from the cabin. Especially can be provided a supply air duct, which with the cabin exhaust system communicates.

advantageously, is the exhaust duct of the heat exchanger communicates with the mixing chamber of the air distribution system of the cabin. This will result in a uniform distribution the warm air allows.

In a further advantageous manner, a fan provided via which the drain is transported from the heat exchanger to the air distribution system of the cabin. Advantageously, this fan belongs to the air conditioning and / or air distribution system. It can therefore be used to introduce the exhaust air from the heat exchanger to the air distribution system to an already existing component, z. B. the recirculation fan of the air conditioning air distribution system.

The The present invention further includes the use of a note energy system according to the invention in combination with an air conditioning and / or air distribution system for the Cabin of an airplane. Furthermore, the present invention includes the use of the note energy system according to the invention in an airplane.

The The present invention further includes an air conditioning and / or Air distribution system for the cabin of an aircraft, which via an exhaust duct with the heat exchangers a note energy system as described above is. This allows the warm air from the heat exchanger evenly in the Aircraft cabin be distributed.

The The present invention further includes an aircraft having a note energy system and / or an air conditioning and / or an air distribution system, as described above. For the Aircraft yield the same benefits as they did above were presented.

The The present invention further includes a method of operation an emergency energy system for an aircraft, wherein the note energy system, a fuel cell unit for generating electrical energy, which via a Cooling circuit the one heat exchanger includes, is cooled. The note energy system is advantageously in the printed Area of the aircraft arranged. According to the invention it is provided that the Supply air and / or the exhaust air of the heat exchanger by the evaporation of fuel cell product water is cooled. By the evaporation according to the invention of fuel cell product water can thus the cooling capacity of the heat exchanger elevated or the heat exchanger be dimensioned smaller.

In Advantageously, while the fuel cell product water by means of a nozzle into the cooling air flow injected and / or over a porous one Evaporating body into the cooling air flow brought in.

In continues to be advantageous manner after activation of the Notenergiesystems initially collecting the resulting fuel cell product water and only delayed for cooling the cooling air flow used.

In Advantageously, the method according to the invention is carried out as such this above regarding the operation of the note energy system according to the invention shown has been.

The The present invention will now be described with reference to exemplary embodiments and drawings shown in more detail. Show

1 : An embodiment of an aircraft according to the invention with an exemplary embodiment of an emergency energy system according to the invention,

2 A first embodiment of a supply air duct to the heat exchanger of a Notenergiesystems invention and

3 : A second embodiment of a supply air duct to the heat exchanger of a Notenergiesystems invention.

1 shows an embodiment of an aircraft according to the invention. This is a civil aircraft with an aircraft cabin 6 , in particular for the transport of persons. As part of the air conditioning system of the aircraft is an air distribution system 7 provided at which air from the mixing chamber 8th via air distribution lines 9 evenly distributed in the cabin. The cabin is part of the printed area of the aircraft.

The aircraft is equipped with an embodiment of a note energy system according to the invention, which in an emergency by means of a fuel cell unit 2 provides electrical energy. The fuel cell unit includes a fuel cell stack having a plurality of fuel cells in which a fuel such as. B. hydrogen is oxidized with oxygen to generate electrical energy. The fuel cells of the exemplary embodiment are proton exchange membrane fuel cells. In order to dissipate the waste heat produced during operation of the fuel cells, a cooling circuit is provided, via which the fuel cell unit 2 is cooled. The cooling circuit has coolant lines 3 on which the fuel cell unit 2 with a heat exchanger 4 connect. The coolant is in the fuel cell unit 2 heats and flows over the coolant line 3 to the heat exchanger 4 to be cooled down there and flows over other coolant lines 3 back to the fuel cell unit 2 ,

The note energy system according to the invention is arranged in the embodiment in the printed area of the aircraft. Since all closable openings in the aircraft hull are closed during an emergency in order to maintain the pressure in the hull, the heat exchanger must 4 therefore release the system's waste heat into the air within the closed hull.

Around the efficiency of the heat exchanger to increase and thus the heat exchanger in terms of his size and his Weight as possible to be able to dimension small, are according to the invention more Features provided, which also realized independently can be.

As in 1 shown is the heat exchanger 4 of the note energy system via an exhaust duct 5 with the air distribution system 7 the aircraft cabin 6 connected so that when operating the note energy system that of the heat exchanger 4 heated exhaust air can be distributed through the air distribution system in the cabin. The exhaust duct 5 leads into the mixing chamber 8th from the air distribution system, from where the heated air evenly over the entire passenger cabin 6 is distributed. As a result, short-circuit currents, which would lead to an increased temperature of the supply air to the heat exchanger, can be significantly reduced. There is a fan 15 provided, via which the air into the air distribution system 7 is fed. At the blower 15 it may be a dedicated blower for the Notenergiesystem, or preferably a fan, which belongs to the already existing air conditioning or air distribution system, eg. B. the recirculation fan of the air distribution system. Furthermore, a supply air duct 10 provided, via which exhaust air from the passenger cabin 6 to the heat exchanger 15 flows. The supply air duct 10 It does not have to be directly connected to the cabin, but it can also suck air from another part of the printed area inside the fuselage.

Furthermore, a plant for the evaporation of fuel cell product water is provided according to the invention, via which the supply air 14 to the heat exchanger 4 is cooled. Due to their low operating temperature, the PEM fuel cells produce liquid water during operation, which according to the invention is used to increase the efficiency of the heat exchanger. The evaporation enthalpy of the water ensures a reduction in the temperature of the air flow 14 to the heat exchanger and thus to increased efficiency.

In 2 and 3 two different embodiments of this system for the evaporation of fuel cell product water are shown. As in 2 shown can be a nozzle 11 in the supply air duct 10 of the heat exchanger 4 be arranged over which fuel cell product water is atomized in the heat exchanger supply air stream. For this purpose, water from the fuel cell via a supply line 12 to the nozzle 11 passed to be atomized there. The water pressure in front of the nozzle can be the pure operating pressure of the fuel cell unit 2 be increased or via a separate pump to achieve a finer atomization.

Alternatively, as in 3 shown, a porous evaporation body 13 be provided, which in the cooling air flow 14 to the heat exchanger 4 is arranged. In the porous body 13 it can be z. B. to act a tile of a hydrophilic material. The porous evaporation body is wetted with product water, which in turn via a conduit 12 Water is passed from the fuel cell to the porous evaporator body. The supply air 14 to the heat exchanger flows through or over the porous evaporation body 13 so that the water evaporates according to the principle of a contact humidifier. The cooling air thus flows first through the wetted with water porous body 13 before going through the heat exchanger 4 flows.

When Another variant can be a heat exchanger be provided, which itself consists of a porous material or with a porous one Material is coated. This porous material is as described above wets with product water from the fuel cells and thus uses the enthalpy of vaporization directly on the surface of the heat exchanger.

Furthermore, it can be provided that the water produced by the fuel cells during their operation is not introduced immediately into the cooling air flow. Namely, the design of the heat exchanger is determined by the maximum temperature of the cooling air during the entire system operation. At the beginning of the mission, however, the cooling air still has a relatively low temperature level, which then rises in the course of use. Therefore, it is provided according to the invention to collect the resulting product water during operation of the fuel cell and injected increasingly with increasing cooling air temperature or operating time or to introduce into the porous material. By collecting the water at the beginning of the use is thus at the time of the highest cooling air temperature, an additional amount of water available, which can be used for cooling. In this way, the maximum occurring cooling air temperature, which determines the design of the heat exchanger can be significantly reduced. Advantageously, a collecting container for collecting the fuel cell product water and a controller is provided, via which the addition of the fuel cell product water to the cooling air flow is controlled. The control can be based on the cooling air temperature, which is measured for this purpose with a temperature sensor, or z. B. based on the passage of time.

Claims (11)

Notation energy system for an aircraft with a fuel cell unit for generating electrical energy, wherein the fuel cell unit via a Cooling circuit the one heat exchanger includes, is cooled, and wherein the note power system advantageously in the printed Area of the aircraft is arranged, characterized by a Plant for the evaporation of fuel cell product water and / or of water that has been stored, over which the supply air and / or the exhaust air of the heat exchanger chilled becomes. Notation energy system according to claim 1, wherein the plant for atomizing fuel cell product water, a nozzle for injection of the fuel cell product water in the cooling air flow and / or a porous Evaporating body having, which in the cooling air flow is arranged. A note power system according to claim 1 or 2, wherein the Plant designed for the evaporation of fuel cell product water so is that after activation of the note energy system, the resulting fuel cell product water is first collected and only delayed for cooling the cooling air flow is used. Notation energy system according to one of the preceding claims, wherein the heat exchanger over a Exhaust duct connected to the air distribution system of the aircraft cabin so that when operating the note energy system that of the heat exchanger heated Exhaust air over the air distribution system can be distributed in the cabin. Notenergie system according to claim 4, wherein the exhaust duct connected to the mixing chamber of the air distribution system of the cabin is. Notenergiesystem according to claim 4 or 5, with a Blower, over which the exhaust air from the heat exchanger is transported to the air distribution system of the cabin, the fan advantageously belongs to the air conditioning and / or air distribution system. Air conditioning and / or air distribution system for the cabin an airplane, which over an exhaust duct with the heat exchanger a Notenergiesystems connected according to one of the preceding claims is. Airplane with a Notenergiesystem and / or a Air conditioning and / or Air distribution system according to one of the preceding claims. Method for operating a note energy system for an aircraft with a fuel cell unit for generating electrical energy, wherein the fuel cell unit via a cooling circuit, the heat exchanger includes, is cooled, and wherein the note power system advantageously in the printed Area of the aircraft is arranged, characterized in that the supply air and / or the exhaust air of the heat exchanger by the evaporation of Fuel cell product water is cooled. The method of claim 9, wherein the fuel cell product is water by means of a nozzle into the cooling air flow is injected and / or over a porous one Evaporating body into the cooling air flow is introduced. The method of claim 10 or 11, wherein after activation of the Notenergiesystems the resulting fuel cell product water first collected and delayed for cooling the cooling air flow is used.