Method and system for fire prevention and/or fire fighting

Abstract

A method for fire prevention and/or fire fighting on board an aircraft comprises the steps detecting a fire event, leading an extinguishant to a fire source through a cooling-system piping system (12) which serves, in the normal operation of the aircraft, to supply a refrigerant to a cooling station (14a, 14b) and/or discharge a refrigerant from a cooling station (14a, 14b), and flooding the fire source with the extinguishant.

Claims

1. A method for fire prevention and/or fire fighting on board an aircraft, comprising: detecting a fire event, leading an extinguishant to a fire source through a cooling-system piping system, supplying a refrigerant to a cooling station and/or discharging the refrigerant from a cooling station via the cooling-system piping system before the extinguishant is led through the cooling-system piping system in the normal operation of the aircraft, draining the refrigerant from the cooling-system piping system into a storage tank before the extinguishant is led through the cooling-system piping system to the fire source, and wherein an amount of the refrigerant is used as the extinguishant.

2. The method according to claim 1, wherein the extinguishant is led through the cooling system piping system together with the refrigerant led through the cooling-system piping system in the normal operation of the aircraft, and the fire source is flooded with a mixture of extinguishant and refrigerant led through the cooling-system piping system in the normal operation of the aircraft.

3. The method according to claim 1, wherein the refrigerant led through the cooling-system piping system in the normal operation of the aircraft is used as propellant in order to convey the extinguishant through the cooling-system piping system to the fire source.

4. The method according to claim 1, wherein the refrigerant led through the cooling-system piping system in the normal operation of the aircraft is utilised as extinguishant in a fire event.

5. The method according to claim 1, wherein a two-phase refrigerant, in particular CO2, is employed as the refrigerant led through the cooling-system piping system in the normal operation of the aircraft.

6. The method according to claim 1, wherein the flooding of the fire source with extinguishant takes place at an interval or a plurality of intervals.

7. A system for fire prevention and/or fire fighting on board an aircraft, having: a detection device configured to detect a fire event, a cooling-system piping system which is configured to, in the normal operation of the aircraft, (a) supply a refrigerant to a cooling station and/or discharge a refrigerant from a cooling station, and (b) lead an extinguishant to a fire source in response to the detection device detecting the fire event, and a supply device configured to supply the cooling-piping system with the extinguishant, a drain device including a valve to drain the refrigerant, that is led through the cooling-system piping system in the normal operation of the aircraft, from the cooling-system piping system into a storage tank, and a controller including a computer readable medium having instructions for causing a computer to execute a method to control the valve of the drain device to drain the refrigerant from the cooling-system piping system before the extinguishant is led through the cooling-system piping system to the fire source wherein an amount of the refrigerant is used as the extinguishant.

8. The system according to claim 7, wherein the cooling-system piping system is configured to lead the extinguishant, together with the refrigerant led through the cooling-system piping system in the normal operation of the aircraft, to the fire source, and in that the device for flooding the fire source with the extinguishant is configured to flood the fire source with a mixture of extinguishant and refrigerant led through the cooling-system piping system in the normal operation of the aircraft.

9. The system according to claim 7, wherein the cooling-system piping system is configured to use the refrigerant led through the cooling-system piping system in the normal operation of the aircraft as propellant in order to convey the extinguishant through the cooling-system piping system to the fire source.

10. The system according to claim 7, wherein the system is configured to utilise the refrigerant led through the cooling-system piping system in the normal operation of the aircraft as extinguishant in a fire event.

11. The system according to claim 7, wherein a two-phase refrigerant, in particular CO2, is employed as the refrigerant led through the cooling-system piping system in the normal operation of the aircraft.

12. The system according to claim 7, wherein the device for flooding the fire source with the extinguishant is structured to flood the fire source with extinguishant at an interval or a plurality of intervals.

13. The system according to claim 7, further comprising a control system which is configured to control the operation of the system for fire prevention and/or fire fighting on board an aircraft in dependence on signals characteristic of the seriousness and the other nature of the fire event and/or in dependence on data on the nature of the fire.

14. The method according to claim 1, wherein the amount of the refrigerant used as extinguishant is led through the cooling-system piping in the normal operation of the aircraft.

15. The system according to claim 7, wherein the amount of the refrigerant used as extinguishant is led through the cooling-system piping in the normal operation of the aircraft.

16. A method for fire prevention and/or fire fighting on board an aircraft, comprising: detecting a fire event, leading an extinguishant to a fire source from a storage tank through a cooling-system piping system, which serves, in the normal operation of the aircraft, to supply a refrigerant to a cooling station and/or discharge the refrigerant from a cooling station, if an amount of extinguishant in the storage tank is insufficient, opening a shutoff valve assigned to a reservoir, such that the reservoir supplies extinguishant to the cooling system piping system, flooding the fire source with the extinguishant, wherein an amount of the refrigerant is used as the extinguishant.

Description

(1) Preferred embodiments of the invention will now be explained in more detail with reference to the appended schematic drawings, of which

(2) FIG. 1 shows a general diagram of a system for fire prevention and/or fire fighting on board an aircraft, and

(3) FIG. 2 shows a flow chart in which a method for fire prevention and/or fire fighting on board an aircraft is illustrated.

(4) FIG. 1 illustrates a system 10 for fire prevention and/or fire fighting on board an aircraft. The system 10 is designed as an integrated cooling system and fire prevention/fire fighting system. The system 10 comprises a cooling-system piping system 12, through which, in the normal operation of the aircraft, a refrigerant flows in order to supply cooling energy to two cooling stations 14a, 14b embodied as evaporators. The cooling stations 14a, 14b each comprise a heat exchanger 15a, 15b, through which the refrigerant, supplied to the cooling stations 14a, 14b, flows. On flowing through the heat exchangers 15a, 15b of the cooling stations 14a, 14b, the refrigerant releases cooling energy to corresponding cooling energy consumers, for example food stored in the region of the aircraft galleys. Alternatively to this, the cooling stations 14a, 14b may also serve to supply other cooling energy consumers on board the aircraft, for example electrical or electronic systems, with cooling energy. The supply of the refrigerant to the cooling stations 14a, 14b is controlled by control valves 16a, 16b which are each arranged upstream of the cooling stations 14a, 14b in the cooling-system piping system 12.

(5) The refrigerant led through the cooling-system piping system 12 is a two-phase refrigerant, in particular CO.sub.2. The refrigerant is supplied to the cooling stations 14a, 14b at least predominantly in the liquid state or as wet steam. On flowing through the heat exchangers 15a, 15b provided in the cooling stations 14a, 14b, the refrigerant evaporates, releasing its cooling energy to the cooling energy consumers supplied with cooling energy by the cooling stations 14a, 14b. In a region of the cooling-system piping system 12 arranged downstream of the cooling stations 14a, 14b, the refrigerant is therefore at least substantially in the gaseous state.

(6) Furthermore, a storage tank 18 is arranged in the cooling-system piping system 12. A receiving space of the storage tank 18 is designed such that it can hold a part or the total amount of the refrigerant circulating through the cooling-system piping system 12. A heat exchanger 20, through which a further refrigerant flows, is arranged in the storage tank 18. The refrigerant held in the receiving space of the storage tank 18 is cooled, condensed and optionally also supercooled by cooling energy supplied to the storage tank 18 by the further refrigerant. Moreover, the storage tank 18 can perform the function of a separator for separating refrigerant in the liquid state from refrigerant in the gaseous state. Corresponding sensors 22, 24, 26 serve to detect the temperature, pressure and refrigerant level in the storage tank 18. High pressures may arise in the storage tank 18, in particular at high ambient temperatures. The storage tank 18 is therefore designed for high pressures. A pressure relief valve 28 serves, if necessary, to reduce the pressure in the storage tank 18.

(7) A conveying device 30 embodied, for example, in the form of a pump is arranged in the cooling-system piping system 12 downstream of the storage tank 18. The conveying device 30 serves to convey refrigerant predominantly in the liquid state from the storage tank 18 and, in the normal operation of the system 10, supply it to the cooling stations 14a, 14b. Furthermore, the conveying device 30 can be used to return refrigerant withdrawn from the storage tank 18 to the storage tank 18 via a bypass line 32. The refrigerant flow through the bypass line 32 can be controlled by means of a bypass valve 34 arranged in the bypass line 32. If necessary, the conveying device 30 can also be operated such that it supplies a part of the refrigerant withdrawn from the storage tank 18 to the cooling stations 14a, 14b and returns a part of the refrigerant withdrawn from the storage tank 18 to the storage tank 18 again via the bypass line 32.

(8) FIG. 1 furthermore illustrates a plurality of aircraft regions 36a-d presenting potential fire risks. The aircraft region 36a is a closed space, whereas the aircraft regions 36b and 36c are formed by units presenting potential fire risks, such as, for example, electrical or electronic aircraft systems. The aircraft region 36d is a fuel tank. Finally, in the illustration according to FIG. 1, the cooling stations 14a, 14b configured as evaporators are also classed as aircraft regions presenting potential fire risks.

(9) A fire warning system 38a-f is assigned to each aircraft region 36a-d and each cooling stations 14a, 14b. The fire warning systems 38a-f each comprise corresponding sensors which acquire measured values allowing conclusions to be drawn about the presence of a fire risk or about a fire risk that already exists. The sensors can be, for example, smoke or temperature sensors. Furthermore, the fire warning system 38d assigned to the aircraft region 36d configured as a fuel tank is equipped with a sensor for detecting the fuel concentration in a gas phase in the fuel tank. The signals output by this sensor allow conclusions to be drawn about the presence of an ignitable or flammable gas mixture in the fuel tank. Finally, each fire warning system 38a-f is equipped with a signalling system which emits audible and/or visible signals in order to point out a fire risk or a fire that already exists to people situated in the vicinity of the aircraft regions 36a-d or the cooling stations 14a, 14b.

(10) The signals output by the sensors of the fire warning systems 38a-f are supplied to an electronic control system 40. The control system 40 processes the signals and reports the presence of a fire risk or a fire that already exists to a corresponding indicating device 42 situated in the cockpit of the aircraft.

(11) Each of the aircraft regions 36a-d is connected to the cooling-system piping system 12 via a connecting line 44a-d. The connecting lines 44a and 44b assigned to the aircraft regions 36a and 36b branch off from the cooling-system piping system 12 immediately downstream of the storage tank 18. By contrast, the branching-off points of the connecting lines 44a and 44b assigned to the aircraft regions 36c and 36d lie downstream of the conveying device 30. Finally, each cooling station 14a, 14b is assigned a connecting line 44e, 44f which each branches off from the cooling-system piping system 12 upstream of the control valve 16a, 16b for controlling the refrigerant supply into the cooling stations 14a, 14b. A flow limiter 46a-d is arranged in each connecting line 44a-d. Further flow limiters 46e-f assigned to the cooling stations 14a, 14b are situated in the cooling-system piping system 12 upstream of the branching-off of the connecting lines 44e, 44f from the cooling-system piping system 12.

(12) The connecting lines 44a-f serve to supply an extinguishant to the aircraft regions 36a-d and to the cooling stations 14a, 14b via corresponding flooding devices 47a-f, configured in the form of nozzles, in a fire event, i.e. in the event of a fire risk or a fire that already exists. The flooding of the aircraft regions 36a-d and of the cooling stations 14a, 14b with the extinguishant in a fire event is effected in the case of the aircraft regions 36a and 36c and in the case of the cooling station 14a by controlling shutoff valves 48a-c arranged in the connecting lines 44a and 44c, and 44e, respectively. By contrast, in the case of the aircraft regions 36b and 36d and in the case of the cooling station 14b, automatic triggering devices 50a-c are provided, which automatically flood the aircraft regions 36b and 36d and the cooling station 14b with the extinguishant when a fire event is detected by the fire warning systems 38b, 38d and 38f.

(13) The refrigerant stored in the storage tank 18 and serving, in normal operation, to cool the cooling stations 14a, 14b may serve as the extinguishant. Additional extinguishant, which may be either likewise the refrigerant serving, in normal operation, to cool the cooling stations 14a, 14b, but also another extinguishant, is stored in a reservoir 52. In similar fashion to the storage tank 18, the reservoir 52 is equipped with corresponding sensors 54, 56, 58 for detecting the temperature, pressure and extinguishant level in the reservoir 52. A shutoff valve 60 serves to control the extinguishant discharge from the reservoir 52. Finally, a pressure relief valve 62 is present, which serves, if necessary, to reduce the pressure in the reservoir 52.

(14) Finally, a shutoff valve 64 and a pressure relief valve 66 are provided in the cooling-system piping system 12 upstream of the storage tank 18. Furthermore, a drain line 68, in which a drain valve 70 is arranged, is connected to the cooling-system piping system 12.

(15) In the following, the operation of the system 10 illustrated in FIG. 1 is explained. In the normal operation of the system 10, i.e. when there is no fire event, the system 10 is operated as a cooling system. For this purpose, refrigerant which is at least predominantly in the liquid state is supplied from the storage tank 18 to the cooling stations 14a, 14b by means of the conveying device 30. On flowing through the heat exchangers 15a, 15b of the cooling stations 14a, 14b, the refrigerant releases cooling energy to corresponding cooling energy consumers and in the process is converted into the gaseous state. Refrigerant leaving the cooling stations 14a, 14b in the gaseous state is recirculated into the storage tank 18, where it is cooled or supercooled and thereby converted back into the liquid state again. The recirculation of the refrigerant from the cooling stations 14a, 14b into the storage tank 18 can be controlled with the aid of the shutoff valve 64. An undesired excess pressure in the cooling-system piping system 12 can be reduced via the pressure relief valve 66 as appropriate.

(16) If one of the fire warning systems 38b, 38d, 38f detects a fire event, the corresponding triggering device 50a, 50b, 50c automatically ensures an immediate flooding of the aircraft regions 36b, 36d and of the cooling station 14b. Furthermore, the control system 40 ensures that the pilots in the cockpit are informed about the fire event via the indicating device 42. The flow limiters 46b, 46d, 46f ensure a permanent, stable supply of the fire source with extinguishant and reduce the risk of the flooding devices 47b, 47d, 47f, configured in the form of nozzles, icing up. Furthermore, the design of the flooding devices 47b, 47d, 47f, configured in the form of nozzles, reduces the icing risk. The signalling system of the fire warning systems 38b, 38d, 38f emit audible and/or visible signals in order to point out the fire event to people situated in the vicinity of the fire source. Such a method procedure illustrated on the right in FIG. 2 means that the refrigerant circulating in the cooling-system piping system 12, in the normal operation of the system, performs a dual function and serves as extinguishant in a fire event.

(17) If the amount of refrigerant serving as extinguishant held in the storage tank 18 and the cooling-system piping system 12 is sufficient for the fire prevention and/or fire fighting in the aircraft regions 36b, 36d and the cooling station 14b, the shutoff valve 60 can remain closed, thereby preventing additional extinguishant from being led out of the reservoir 52 into the cooling-system piping system 12. By contrast, if additional extinguishant is required for the fire prevention and/or fire fighting in the aircraft regions 36b, 36d and the cooling station 14b, it is possible, optionally under the control of the control system 40, for the shutoff valve 60 downstream of the reservoir 52 to be opened and thereby the supply of extinguishant from the reservoir 52 into the cooling-system piping system 12 to be enabled. The extinguishant stored in the reservoir 52 can in this case correspond to the refrigerant circulating in the cooling-system piping system 12 in the normal operation of the system 10 or be another extinguishant.

(18) In the case of the aircraft region 36d configured in the form of a fuel tank, the extinguishant can serve for fire fighting, but also for inerting the fuel tank. The latter is possible in particular when using CO.sub.2 as refrigerant or extinguishant. By supplying CO.sub.2 into the fuel tank, the oxygen content of the gas phase in the fuel tank and consequently the ignitability or flammability of the gas mixture is reduced. Moreover, the expansion of the CO.sub.2, which is normally kept under elevated pressure in the cooling-system piping system 12, is associated with a temperature reduction of the CO.sub.2 as it is supplied into the fuel tank. As a result, the CO.sub.2 cools the tank and thus reduces the evaporation of fuel which occurs at high ambient temperatures and consequently the risk of formation of an ignitable gas mixture.

(19) By contrast, if one of the fire warning systems 38a, 38c, 38e detects a fire event, the flooding of the aircraft regions 36a, 36c and of the cooling station 14a is controlled by corresponding control of the shutoff valves 48a-c. The flooding of the aircraft regions 36a, 36c and of the cooling station 14a can be effected at an interval or a plurality of intervals. In this case, different method procedures are possible. The method procedure can be decided on individually in the cockpit. Alternatively to this, however, an automatic control of the method procedure by means of the control system 40 is also possible. For this purpose, the control system 40 evaluates the signals supplied to it by the sensors of the fire warning system 38a, 38c, 38e. Furthermore, the control system 40 takes account of data, stored in a data base, on the design of the aircraft regions 36a, 36c and of the cooling station 14a.

(20) In an alternative method procedure, illustrated on the left in FIG. 2, firstly the refrigerant present in the cooling-system piping system 12 can be drained from the cooling-system piping system 12. For this purpose, the drain valve 70 arranged in the drain line 68 is opened. Subsequently, the shutoff valve 60 assigned to the reservoir 52 is opened, thereby enabling the supply of extinguishant from the reservoir 52 into the cooling-system piping system 12. Finally, the shutoff valve 48a-c assigned to the fire source is opened. The flooding of the fire source then takes place as described above in connection with the flooding of the aircraft regions 36b, 36d and of the cooling station 14b. Such a method procedure is suitable particularly when an extinguishant is held in the reservoir 52 which differs from the refrigerant circulating in the cooling-system piping system 12 in the normal operation of the system and the refrigerant circulating in the cooling-system piping system 12 in the normal operation of the system is not suitable for fire prevention and/or fire fighting in the aircraft regions 36a, 36c and the cooling station 14a.

(21) In a further alternative method procedure, illustrated in the middle in FIG. 2, by contrast a draining of the refrigerant present in the cooling-system piping system 12 from the cooling-system piping system 12 is dispensed with. Instead, merely the shutoff valve 60 assigned to the reservoir 52 is opened and extinguishant is supplied from the reservoir 52 into the cooling-system piping system 12. Furthermore, the shutoff valve 48a-c assigned to the fire source is opened. A mixture of refrigerant and extinguishant then flows through the cooling-system piping system 12 and the fire source is flooded with this mixture of refrigerant and extinguishant. The flooding of the fire source takes place once again as described above in connection with the flooding of the aircraft regions 36b, 36d and the cooling station 14b. Such a method procedure is expedient particularly when a rapid flooding of the fire source is required and the refrigerant does not impair the fire-preventing or fire-fighting effect of the extinguishant.

(22) Finally, in a fire event in the aircraft regions 36a, 36c and the cooling station 14a, as in a fire event in the aircraft regions 36b, 36d and the cooling station 14b, the refrigerant circulating in the cooling-system piping system 12 in the normal operation of the system can also perform a dual function and serve as extinguishant in a fire event.

(23) In a further alternative method procedure (not illustrated in the figures), the refrigerant led through the cooling-system piping system 12 in the normal operation of the system 10 is used as propellant in order to convey the extinguishant from the reservoir 52 through the cooling-system piping system 12 to the fire source. For this purpose, for example refrigerant under an elevated pressure with respect to the atmospheric pressure can be led out of storage tank 18 into the reservoir 52.