Fuel tank inerting system
An aircraft fuel tank inerting system includes an inlet, an oxygen absorption unit, and a vent to discharge oxygen from the system. The inlet may be configured to be in fluid communication with a ullage of a fuel tank. In embodiments, the oxygen absorption unit is in communication with the inlet and includes a chamber, a temperature reversible oxygen absorption medium within said chamber, and a temperature controller for selectively heating or cooling the medium. The reversible oxygen absorption medium may be a medium which absorbs oxygen by chemisorption.
1. An aircraft fuel tank inerting system, comprising:
an inlet, configured to be in fluid communication with a ullage of a fuel tank;
an oxygen absorption unit, in communication with said inlet to extract oxygen from the ullage, and comprising:
a chamber,
a temperature reversible oxygen absorption medium within said chamber, and
a temperature controller for selectively heating in a desorption mode and cooling the medium in an adsorption mode;
a vent for discharging oxygen from the inerting system, wherein the reversible oxygen absorption medium is a medium which absorbs oxygen by chemisorption.
2. The aircraft fuel tank inerting system as claimed in claim 1 , wherein the reversible oxygen absorption medium comprises Cobalt or a Cobalt derived material.
3. The aircraft fuel tank inerting system as claimed in claim 1 , wherein the inerting system further comprises a control system the control system including control valves on the inlet and vent.
4. The aircraft fuel tank inerting system as claimed in claim 3 , wherein the control system further controls the temperature controller.
5. The aircraft fuel tank inerting system as claimed in claim 1 , wherein the temperature controller comprises a heater.
6. The aircraft fuel tank inerting system as claimed in claim 1 , wherein the temperature controller comprises a heat exchanger associated with the chamber.
7. The aircraft fuel tank inerting system as claimed in claim 6 , wherein the temperature controller is arranged to selectively supply the heat exchanger with hot or cold air.
8. The aircraft fuel tank inerting system as claimed in claim 1 , wherein the system comprises a plurality of oxygen absorption units.
9. The aircraft fuel tank inerting system as claimed claim 8 , wherein the plurality of oxygen absorption units are arranged in parallel and the system further comprises a valve arrangement to enable switching of the oxygen absorption unit that is in communication with the ullage.
10. The aircraft fuel tank inerting system as claimed in claim 1 , wherein the inerting system is arranged to cycle the, or each, oxygen absorption unit between:
a first, oxygen absorbing, configuration, in which:
the oxygen absorption unit is in fluid communication with the fuel tank ullage,
the temperature controller is cooling the medium; and
a second, oxygen desorption, configuration, in which:
the oxygen absorption unit is isolated from the fuel tank ullage; and
the temperature controller is heating the medium.
11. The aircraft fuel tank inerting system as claimed in claim 10 , wherein the inerting system comprises a plurality of oxygen absorption units and the oxygen absorption units are configured or controlled such that at least one unit is in the first, oxygen absorption, configuration when another unit is in the second, oxygen desorption, configuration, such that continuous oxygen absorption is available.
12. The aircraft fuel tank inerting system as claimed in claim 1 , wherein the vent for discharging oxygen from the inerting system comprises an ejector.
13. The aircraft fuel tank inerting system as claimed in claim 12 , wherein the vent is provided with motive flow from a source of pressurised air.
14. An aircraft comprising at least one fuel tank and an inerting system as claimed in claim 1 .
15. The aircraft fuel tank inerting system as claimed in claim 7 , wherein the heat exchanger is a jacket partially surrounding a portion of the chamber, the jacket being arranged to circulate the hot air or cold air.
16. The aircraft fuel tank inerting system as claimed in claim 15 , wherein at least one of:
the hot air is provided from bleed air; and
the cold air is provided from cabin waste air or a ram air source.
17. The aircraft fuel tank inerting system as claimed in claim 3 , wherein:
in the absorption mode, at least one control valve on the inlet is open and a control valve on the vent is closed to draw the oxygen from the ullage into the chamber of the oxygen adsorption unit; and
in the desorption mode, the at least one control valve on the inlet is closed and the control valve on the vent is open.