Integrated cargo fire suppression and inerting system

An integrated fire suppression system receives inert gas from onboard gas generators and water effluent from onboard water generators. The inert gas and water effluent are mixed in a gas-water mixer to generate an inert aerosol. The inert aerosol is provided to a fire suppressant distribution network and sprayed into areas of the aircraft requiring fire suppression to provide cooling and to prevent reignition.

BACKGROUND

This disclosure relates generally to fire suppression systems. More particularly, this disclosure relates to onboard fire suppression systems for aircraft.

Fire suppression systems onboard aircraft include both high-rate discharge and metered/low-rate discharge systems. The high-rate discharge systems provide initial fire suppression knock down, while the metered/low-rate discharge systems prevent reignition by maintaining at least the required minimum halon concentration in the cargo bay. Both the high-rate discharge Fire Extinguisher and metered/low-rate discharge Fire Extinguisher are line replaceable units that are dedicated to fire suppression. The fire suppressants utilized by both the high-rate discharge and metered/low-rate discharge systems can include environmentally hazardous materials, such as Halon-1301. In addition, other systems onboard the aircraft generate waste effluents, both gaseous and liquid, that are vented overboard or disposed of in another manner.

SUMMARY

According to one aspect of the disclosure, a fire suppression system includes a water supply system configured to collect conditioned water effluent from at least one onboard water source; a gas generation system configured to provide a supply of inert gas to an inert flow line; a gas-water mixer disposed downstream of the water supply system and the gas generation system, the gas-water mixer configured to receive the conditioned water effluent and the supply of inert gas and to generate an inert aerosol; and a fire suppressant distribution network disposed downstream of the gas-water mixer, the fire suppressant distribution network configured to provide the inert aerosol to areas of an aircraft.

According to another aspect of the disclosure, a method of providing fire suppression capabilities for an aircraft includes collecting conditioned water from at least one onboard water generating system of the aircraft; directing the conditioned water to an inert gas-water mixer; directing an inert gas to the inert gas-water mixer via an inert flow line, thereby generating an inert aerosol; and feeding the inert aerosol to a fire suppressant distribution network and directing the inert aerosol to an affected area of the aircraft for fire suppression.

DETAILED DESCRIPTION

Fire suppression system10is disposed onboard aircraft12and is configured to provide fire suppression and atmosphere inerting to cargo holds14, among other locations on aircraft12. Cargo holds14are configured to store cargo during aircraft operation. For example, cargo hold14acan be a forward cargo hold, cargo hold14bcan be a bulk cargo hold, and cargo hold14ccan be an aft cargo hold. Controller16communicates with components of fire suppression system10via communication network17. Controller16controls the provision of fire suppressing agents from each of HRD module20, M/LRD module22, and integrated suppression system24. In addition, controller16controls the opening and closing of shut-off valves32, mixing valve30, and metering valve46, as shown by the connection between controller16and distribution line26. Spray nozzles36a-36care disposed in cargo holds14a-14c, respectively. Distribution line26extends through aircraft12and is connected to spray nozzles36in each cargo hold14by supply lines28a-28c. Supply line28aextends to spray nozzles36a, supply line28bextends to spray nozzles36b, and supply line28cextends to spray nozzles36c. Check valves34a-34care disposed on supply lines28a-28c, respectively, to prevent air from flowing out of the associated cargo hold14and into fire suppression system10. Shut-off valves32a-32care each respectively disposed upstream of check valves34a-34con supply lines28a-28c. Shut-off valves32are configured to prevent fire suppressant from flowing to any non-burning/healthy cargo hold14. As such, the maximum amount of fire suppressant can be provided to the compromised cargo hold14.

HRD supply line40extends from HRD vessels38to mixing valve30. HRD supply line40provide a flowpath for a fire suppressing agent to flow from HRD vessels38to distribution line26. HRD module20is configured to provide a supply of fire suppressing agent, such as Novec-1230, HFC-125, 2-BTP, HFC-236fa, HFC-227ea, and Halon-1301, among others, to cargo holds14to provide initial fire suppression. HRD module20discharges the supply of fire suppressant in response to a fire being detected. HRD module20is configured to start providing the full supply of fire suppressing agent from HRD module20to the affected cargo hold14in about 1-2 seconds. Typically, the entire HRD supply is fully dispensed. While HRD supply line40is described as connected to mixing valve30, it is understood that HRD supply line40can extend directly to distribution line26to provide the fire suppressing agent directly to distribution line26.

M/LRD supply line44extends between M/LRD supply vessels42and mixing valve30. M/LRD supply line44provides a flowpath for fire suppressant to flow from M/LRD supply vessels42to distribution line26. Metering valve46is disposed on M/LRD supply line44and is configured to meter the flow of fire suppressing agent out of M/LRD supply line44. M/LRD module22is configured to provide fire suppressing agent to cargo holds14to maintain the minimum required fire suppressant concentration after the initial HRD event has ended, to inert atmosphere after the fire is suppressed, and to prevent any secondary fire reignition.

Inert gas supply50is disposed upstream of distribution line26. Inert gas supply50is connected to gas-water mixer52via inert flow line64. Inert flow line64extends from N2/inert storage58and to gas-water mixer52. N2/inert storage58stores pressurized, gaseous nitrogen, and other inert gasses, such as argon (Ar), helium (He), and neon (Ne), among others, for use in fire suppression.

Inert gas supply50further collects excess and waste gasses from NGS62. ASM68generates nitrogen-enriched air (“NEA”) for use in fuel tank inerting. The NEA is ported to the fuel tanks onboard aircraft12to maintain an inert environment in the fuel tanks. The NEA and other inert gasses generated in excess of that required for fuel tank inerting are directed through ASM port line70to inert flow line64. In some examples, the excess NEA and other inert gasses are ported to N2/inert storage58via inert supply line63for later use.

APU60can generate exhaust gasses and/or water effluent for use in fire suppression. APU exhaust supply line66extends from the exhaust of combustion-based APU60ato the cargo compartments14a-14c. The exhaust of combustion-based APU60agenerates carbon dioxide (CO2) and other exhaust gasses useful for fire suppression. Filter69is disposed in exhaust line66to treat the exhaust from combustion-based APU60ato remove contaminants. In this case, the filtered exhaust can be ported directly to the cargo compartments14a-14cfor fire suppression. No exhaust treatment is required for fuel cell-based APU60b. The exhaust from fuel cell-based APU60b(i.e., liquid water) can be ported directly to water supply line56via supply line61and/or sent to an onboard storage tank (not shown) as needed.

Inert flow line64receives inert gasses from N2/inert storage58and NGS62. Inert flow line64extends to gas-water mixer52and is configured to provide the inert gasses to gas-water mixer52. Inert flow check valve72is disposed on inert flow line64and is configured to prevent backflow out of gas-water mixer52. Pump74is disposed on inert flow line64upstream of check valve34and is configured to drive the inert gasses downstream through check valve34to gas-water mixer52. Pump74generates sufficient pressure to drive the inert aerosol downstream from gas-water mixer52and generate a water mist at spray nozzles36.

Water supply48is disposed upstream of distribution line26. Water supply48is connected to gas-water mixer52via water supply line56. The water is entrained in the inert gasses in gas-water mixer to generate the inert aerosol for fire suppression. Onboard water generators54a-54nare systems onboard aircraft12that generate waste water as a byproduct of normal operation. In one example, onboard water generator54ais a cabin air conditioning and temperature control system (“CACTCS”). The CACTCS removes water from the air during inlet ram air conditioning. Water supply line56receives water from the drain of the CACTCS, and the water can be stored for later use for fire suppression. Onboard water generator54bcan be an environmental control system (“ECS”), which removes moisture from the pressurized and mixed cabin air. Water supply line56receives water from the drain of the ECS, and the water can be stored for fire suppression. Both the CACTCS and ECS continuously dehumidify air prior to the air entering the cabin. As such, both the CACTCS and ECS are continuously generating a supply of water that is useful for fire suppression. Other onboard water generators54can include the lavatory54cand galley54dcompartments. The water can be condensed from the moist air in the lavatories and galleys and can be stored for later use in fire suppression. In some examples, grey water is diverted from the lavatory and galley compartments and stored for later use in fire suppression. The water effluent from onboard water generators54can be stored in any desired manner. For example, a storage tank (not shown) can be disposed upstream of gas-water mixer52and can be configured to provide the stored water to gas-water mixer52in response to a command from controller16. In another example, the water effluent can be stored in the bilge of aircraft12. The water effluent can then be pumped out of the bilge and to gas-water mixer52as needed.

Integrated suppression system24utilizes waste effluent from onboard systems to provide additional fire suppression capabilities onboard aircraft12. Inert gasses from inert gas supply50are combined with water from water supply48to generate an inert aerosol in gas-water mixer52. Controller16controls the flow of fire suppressing agents from HRD module20, M/LRD module22and integrated suppression system24. Controller16communicates with shut-off valves32to shift shut-off valves32to the desired open or closed position in response to a fire being detected in one of cargo holds14. Controller16communicates with inert gas supply50to control the flow of inert gasses to gas-water mixer52. Controller16also communicates with water supply48to control the flow of water to gas-water mixer52. Mixing valve30is configured to modulate the ratio of fire suppressant provided from HRD module20, integrated suppression system24, and M/LRD module22. In some examples, mixing valve30is a three-way proportioning valve. Controller16controls the position of mixing valve30to control the ratio of the fire suppressants from each source.

As an example, the detection of a fire in cargo hold14ais described in detail. When a fire event is detected, controller16initiates fire suppression. Controller16commands shut-off valves32band32cto the closed position and shut-off valve32ato the open position. With shut-off valves32band32cin the closed position, fire suppressant is prevented from flowing to either cargo hold14bor cargo hold14c. With shut-off valve32ain the open position, the fire suppressant is able to flow to cargo hold14athrough supply line28a.

Initially, controller16modulates mixing valve30to provide flow from HRD module20. Controller16activates HRD module20. Fire suppressing agent flows out of HRD vessels38, through HRD supply line40and into distribution line26. Distribution line26provides the fire suppressing agents to supply line28a, and supply line28aprovides the fire suppressing agents to spray nozzles36a. The fire suppressing agents are sprayed into cargo hold14athrough spray nozzles36ato suppress the fire and generate an inert atmosphere. HRD module20provides a fire suppressing agent to cargo hold14ato dilute the air in cargo hold14aand to extinguish the fire. HRD vessels38are typically pressure vessels that start dispensing their supply of fire suppressing agent within 1-2 seconds of activation. Typically, the entire HRD supply is fully dispensed.

To prevent reignition of the fire, controller16modulates mixing valve30to provide flow from integrated suppression system24to provide LRD fire suppression to cargo hold14a. In some examples, controller16modulates mixing valve to provide fire suppression from both integrated suppression system24and M/LRD module22. While fire suppression system10is described as including both integrated suppression system24and M/LRD module22, it is understood that the integrated suppression system24provides sufficient LRD capabilities. M/LRD module22is configured to provide additional metered/LRD capabilities where necessary.

Pump74drives inert gas from at least one of NGS62and N2/inert storage58downstream to gas-water mixer52. While pump74is described as driving the inert gas to gas-water mixer52, it is understood that N2/inert storage58can be pressurized to provide the stored nitrogen to gas-water mixer52and downstream into distribution line26. Water supply line56provides collected water to gas-water mixer52. At gas-water mixer52, the collected water is entrained in the inert gas to generate the inert aerosol. The inert aerosol is driven downstream through mixing valve30and into distribution line26. The inert aerosol flows through distribution line26to supply line28a. The inert aerosol is dispensed into cargo hold14athrough spray nozzles36a. The inert aerosol provides a spray of small, highly penetrating fluid particles that provide both cooling and inerting in cargo hold14a, thereby preventing reignition of the fire.

As discussed above, onboard water generators54, such as the CACTCS and ECS, continuously generate water effluent as a byproduct of dehumidification. As such, a fresh supply of water can continuously be provided to gas-water mixer52to generate additional inert aerosol. In addition, NGS62can continuously provide additional N2and other inert gases, to gas-water mixer52to generate additional inert aerosol. As such, additional inert aerosol can be continuously generated during flight to provide additional fire suppressing capabilities.

Integrated suppression system24provides significant advantages. Integrated suppression system24utilizes waste effluents, both liquid and gaseous, from various on-board systems to generate the inert aerosol utilized for fire suppression. As such, the waste effluents are repurposed, reducing the waste generated by aircraft12. In addition, utilizing the waste effluents reduces the need for additional on-board systems that are dedicated solely to fire suppression, thereby saving weight and space on aircraft12. For example, with integrated suppression system24on aircraft12, some M/LRD supply vessels42can be eliminated from aircraft12. In some examples, M/LRD module22can be eliminated from aircraft12, such that integrated suppression system24provides full metered/LRD capabilities, providing a cost and weight savings. Inert gasses that are typically vented overboard by ASM68, such as Ar, He, and Ne, among others, are instead captured and utilized to generate the inert aerosol. NEA in excess of that required for fuel tank inerting is also provided to integrated suppression system24to generate the inert aerosol. Utilizing inert gasses and waste water generated by onboard systems to generate a fire suppressing inert aerosol also reduces the use of environmentally harmful greenhouse gasses that are typically used in fire suppression, such as Halon-1301.

FIG. 2is a flow chart depicting method100of fire suppression for an aircraft, such as aircraft12(FIG. 1). In step102, conditioned water is collected from at least one onboard water generating system, such as the CACTCS, ECS, lavatory, and galley, among others. In some examples, the conditioned water is collected in a water supply line, such as water supply line56(FIG. 1) until needed. In other examples, the conditioned water is stored in a storage tank dedicated to the fire suppression system. In yet another example, the conditioned water is stored in the bilge and is pumped out of the bilge when needed. In step104, the conditioned water is flowed to a gas-water mixer, such as gas-water mixer52(FIG. 1).

In step106, an inert gas is flowing to the gas-water mixer via an inert gas line, such as inert flow line64(FIG. 1), and the inert gas and water are mixed in the gas-water mixer to generate an inert aerosol. For example, N2and other inert gasses can be provided to the gas-water mixer from onboard N2/inert storage, such as N2/inert storage58(FIG. 1). In other examples, N2and other inert gasses in excess of that required for fuel tank inerting can be ported to the inert flow line from the onboard ASM, such as ASM68(FIG. 1).

In step108, the inert aerosol is fed to a fire suppressing distribution network, such as distribution line26(FIG. 1), supply lines28(FIG. 1), and spray nozzles36(FIG. 1), and sprayed into an area of the aircraft requiring fire suppression. For example, a controller, such as controller16(FIG. 1) can activate a pump, such as pump74(FIG. 1), and adjust relevant valves, such as metering valve46(FIG. 1) and shut-off valves32(FIG. 1), to drive the inert aerosol downstream though the distribution network from the gas-water mixer and to the affected area of the aircraft, such as cargo holds14(FIG. 1). The controller controls the valves to direct the inert gas-water inert aerosol to the desired area of the aircraft, and the inert gas-water inert aerosol is sprayed out of the spray nozzles.

Discussion of Possible Embodiments

A fire suppression system includes a water supply system, a gas generation system, a gas-water mixer disposed downstream of the water supply system and the gas generation system, and a fire suppressant distribution network disposed downstream of the gas-water mixer. The water supply system is configured to collect conditioned water effluent from at least one onboard water source. The gas generation system is configured to provide a supply of inert gas to an inert flow line. The gas-water mixer is configured to receive the conditioned water effluent and the supply of inert gas and to generate an inert aerosol. The fire suppressant distribution network is configured to provide the inert aerosol to areas of an aircraft.

The at least one onboard water source comprises at least one of a cabin air conditioning and temperature control system and an environmental control system.

The onboard water source further comprises at least one of an aircraft lavatory and an aircraft galley.

At least a portion of the conditioned water includes grey water.

The gas generation system comprises at least one storage tank connected to the inert flow line.

The gas generation system further comprises an air separation module configured to generate nitrogen-enriched air and to provide a first portion of the nitrogen-enriched air to a fuel tank for fuel tank inerting and a second portion of the nitrogen-enriched air to the inert flow line for generating the inert aerosol.

A combustion-based auxiliary power unit configured to provide APU exhaust gases to the cargo compartment.

A filter disposed on an exhaust supply line extending between the combustion-based auxiliary power unit and the cargo compartment, the filter configured to remove contaminants from the APU exhaust gases.

A fuel cell-based auxiliary power unit configured to provide APU water effluent to the gas-water mixer.

A high-rate discharge module connected to the fire suppressant distribution network.

A metered/low-rate discharge fire suppressant module connected to the fire suppressant distribution network.

A mixing valve disposed at an intersection of the inert flow line and the fire suppressant distribution network, the mixing valve configured to control a fire suppressant ratio between the high-rate discharge module and the inert gas-water mixture within the fire suppressant distribution network.

A method of providing fire suppression capabilities for an aircraft includes collecting conditioned water from at least one onboard water generating system of the aircraft; directing the conditioned water to an inert gas-water mixer; directing an inert gas to the inert gas-water mixer via an inert flow line, thereby generating an inert aerosol; and feeding the inert aerosol to a fire suppressant distribution network and directing the inert aerosol to an affected area of the aircraft for fire suppression.

Generating nitrogen-enriched air for fuel tank inerting with an air separation module; and directing a portion of the nitrogen-enriched air from the air separation module to the inert flow line.

Capturing an APU exhaust from a combustion-based auxiliary power unit and directing the exhaust to the affected area of the aircraft.

Filtering the APU exhaust prior to directing the APU exhaust to the affected area of the aircraft.

Capturing an APU water effluent from a fuel cell-based auxiliary power unit and directing the APU water effluent to the inert gas-water mixer.

The step of collecting conditioned water from at least one onboard water generating system of the aircraft includes removing water from air during air conditioning; and providing the removed water to the gas-water mixer to generate the inert aerosol.

The onboard water generating system comprises at least one of a cabin air conditioning and temperature control unit and an environmental control system.

The step of collecting conditioned water from at least one onboard water generating system of the aircraft includes collecting grey water from at least one of an aircraft lavatory and an aircraft galley; and providing the collected grey water to the gas-water mixer to generate the inert aerosol.