Abstract: A method of estimating a quantity of a liquid fuel in a fuel tank of an aircraft is disclosed. A surface of the fuel is illuminated with light so that the light is reflected or scattered by the surface of the fuel onto an array of sensors. The light travels to and from the surface of the fuel via a measurement path containing a transmission medium. A measured time of flight is made at each sensor for the light which travels via the measurement path to that sensor. At least one of the sensors is illuminated with light via a reference path containing a transmission medium with substantially the same refractive index as the transmission medium in the measurement path, the reference path having a known reference distance which does not vary in accordance with the quantity of the fuel.

Abstract: An aircraft fuel system, comprising: a fuel tank; a fuel line; and an engine; wherein the fuel line includes a first conduit configured to carry fuel from the tank towards the engine, and a second conduit configured to carry fuel from the engine towards the tank, wherein one of the first conduit or the second conduit is disposed annularly around the other of the first conduit or the second conduit. Also, a method of operating the system. The system may be used to suppress ice formation in the first conduit and/or provide leakage detection.

Abstract: A cyclonic separator with an inlet, a fuel outlet, an inner wall comprising a water-permeable material, an outer wall, a cavity between the inner wall and the outer wall, and a water outlet. The cyclonic separator is adapted to discharge water from the water outlet via the cavity and relatively less dense liquid fuel from the fuel outlet. The water-permeable material enables water in the cyclonic separator to flow through the water-permeable material into the cavity, but substantially prevents liquid fuel in the cyclonic separator from doing so.

Abstract: A method of conditioning oxygen depleted air (ODA) exhausted from a fuel cell comprising the steps of; taking fuel from an aircraft fuel tank collector cell, delivering said fuel to a rear mounted engine via a primary heat exchanger, taking exhaust ODA from a fuel cell, passing the ODA through the primary heat exchanger in the opposite direction to the fuel, such that the fuel acts as a heat sink for the ODA, to cool the ODA, passing the ODA through a dryer, to dry the ODA and using the cooled, dried ODA to inert fuel in the aircraft fuel tank.

Abstract: A method for dehydrating liquid fuel is disclosed. The method includes injecting a supply of dry gas into a liquid fuel via an outlet submerged in the liquid fuel. Also, a system for dehydrating liquid fuel is disclosed having a container for storing a liquid fuel, a line for delivering a supply of dry gas, and an outlet disposed near the bottom of the container and connected to the gas line for injecting dry gas into the liquid fuel.

Abstract: A tank assembly with a tank for storing liquid hydrocarbon, the tank having a floor for supporting a weight of the liquid hydrocarbon. A filter is fitted to the floor of the tank. The filter is arranged to allow liquid water in the tank to drain out of the tank through the filter but substantially prevent the liquid hydrocarbon in the tank from doing so. The filter has a permeation member, such as a membrane, which is formed from a material such as graphene oxide which allows liquid water in the tank to drain out of the tank by permeating through the permeation member but substantially prevent the liquid hydrocarbon in the tank from doing so.

Abstract: A sensor for measuring a level of a liquid such as fuel and/or water in a tank such as a fuel tank. The sensor includes a stack of capacitors, each capacitor with one or more graphene measurement electrodes and one or more graphene reference electrodes. A measurement system is arranged to measure a capacitance of each capacitor between its measurement electrode(s) and its reference electrode(s) and thereby infer the liquid level. The graphene measurement and reference electrodes are formed in a single layer of graphene oxide by reductive etching.

Abstract: The invention relates to liquid hydrocarbons containing cyclic ortho esters as dehydrating dehydrating icing inhibitors and to methods of using the compounds. The liquid hydrocarbons include fuels such aviation fuels, lubricants, hydraulic fluids and hydrocarbon solvents.

Abstract: A dehumidifier comprises: a first channel for transporting air at a first pressure; a second channel for transporting air at a second pressure lower than the first pressure; and a graphene oxide barrier separating the first channel and the second channel. The relatively lower pressure of air in the second channel causes water vapor to be drawn out of the air in the first channel.

Abstract: An aircraft fuel tank system comprising an aircraft fuel tank and a time domain reflectometry (TDR) fuel gauge for measuring a filling level of fuel in the aircraft fuel tank. The TDR fuel gauge comprises an electromagnetic signal generator and a cable, the cable comprising a first cable part and a second cable part which are coupled in series to the signal generator. The first cable part extends downwardly within the fuel tank and the second cable part extends upwardly within the fuel tank. The first and second cable parts are arranged such that for at least one filling level the first cable part extends down into the fuel from an ullage space at a first location and the second cable part extends up out of the fuel into an ullage space at a second location which is spaced apart from the first location.

Abstract: A method of estimating a quantity of a liquid fuel in a fuel tank of an aircraft is disclosed. A surface of the fuel is illuminated with light so that the light is reflected or scattered by the surface of the fuel onto an array of sensors. The light travels to and from the surface of the fuel via a measurement path containing a transmission medium. A measured time of flight is made at each sensor for the light which travels via the measurement path to that sensor. At least one of the sensors is illuminated with light via a reference path containing a transmission medium with substantially the same refractive index as the transmission medium in the measurement path, the reference path having a known reference distance which does not vary in accordance with the quantity of the fuel.

Abstract: A cyclonic separator with an inlet, a fuel outlet, an inner wall comprising a water-permeable material, an outer wall, a cavity between the inner wall and the outer wall, and a water outlet. The cyclonic separator is adapted to discharge water from the water outlet via the cavity and relatively less dense liquid fuel from the fuel outlet. The water-permeable material enables water in the cyclonic separator to flow through the water-permeable material into the cavity, but substantially prevents liquid fuel in the cyclonic separator from doing so.

Abstract: A fuel tank system comprising a fuel tank; a device with a fuel inlet for receiving a fuel/water mix, and a water outlet in fluid communication with the fuel tank; and a filter formed from a water-permeable material, such as graphene oxide, which enables water from the fuel/water mix to flow through the water-permeable material and the water outlet into the fuel tank, but substantially prevents liquid fuel in the fuel/water mix from doing so. The device may be a valve, pressure sensing line, or any other device in a fuel tank suffering the problem of water accumulation.

Abstract: A method for predicting a quantity of a contaminant in a fuel tank at the end of a time period, the method comprising the steps of: determining a quantity of the contaminant in the fuel tank at the start of the time period; determining at least one operating condition of the fuel tank during the time period; using information relating to the at least one operating condition of the fuel tank to generate a predicted quantity of the contaminant accumulated in the fuel tank during the time period; and calculating, based upon the quantity of the contaminant at the start of the time period and the predicted quantity of the contaminant accumulated during the time period, a predicted quantity of the contaminant at the end of a time period.

Abstract: An aircraft fuel system, comprising: a fuel tank; a fuel line; and an engine; wherein the fuel line includes a first conduit configured to carry fuel from the tank towards the engine, and a second conduit configured to carry fuel from the engine towards the tank, wherein one of the first conduit or the second conduit is disposed annularly around the other of the first conduit or the second conduit. Also, a method of operating the system. The system may be used to suppress ice formation in the first conduit and/or provide leakage detection.

Abstract: A method for dehydrating liquid fuel, the method comprising injecting a supply of dry gas into a liquid fuel via an outlet submerged in the liquid fuel. Also, a system for dehydrating liquid fuel, the system comprising a container for storing a liquid fuel, a line for delivering a supply of dry gas, and an outlet disposed near the bottom of the container and connected to the gas line for injecting dry gas into the liquid fuel.

Abstract: A tank assembly with a tank for storing liquid hydrocarbon, the tank having a floor for supporting a weight of the liquid hydrocarbon. A filter is fitted to the floor of the tank. The filter is arranged to allow liquid water in the tank to drain out of the tank through the filter but substantially prevent the liquid hydrocarbon in the tank from doing so. The filter has a permeation member, such as a membrane, which is formed from a material such as graphene oxide which allows liquid water in the tank to drain out of the tank by permeating through the permeation member but substantially prevent the liquid hydrocarbon in the tank from doing so.

Abstract: The invention relates to liquid hydrocarbons containing cyclic ortho esters as dehydrating dehydrating icing inhibitors and to methods of using the compounds. The liquid hydrocarbons include fuels such aviation fuels, lubricants, hydraulic fluids and hydrocarbon solvents.

Abstract: A probe for determining a characteristic of the contents in a fuel tank. The probe includes at least one analysis element. The or each analysis element has an input for inputting light to a sampling region to be analysed and an output for outputting light that has passed through the sampling region from the input. A system including a probe and a spectrometer is also provided.

Abstract: An aircraft fuel tank ventilation system, comprising a refrigerative dehumidifying device having a refrigerating element in contact with air flowing between a vent open to the atmosphere and a fuel tank. Also, a method of dehumidifying air introduced into an aircraft fuel tank via the ventilation system, the method comprising directing atmospheric air from the vent into contact with the refrigerating element, and cooling the refrigerating element so as to remove water vapor from the air flowing from the vent towards the fuel tank by condensation.