Fuel freezing point monitoring device

#The present invention generally relates monitoring the freezing temperature of fuel onboard a vehicle. More specifically, the present invention relates to monitoring the freezing point of jet fuel onboard an aircraft.

#In recent years, Russia officially opened Russian airspace to commercial airlines and flight routes over the North Pole are available for use. An era of commercial transpolar flight has begun, offering an unprecedented efficient and economic link between cities of North America, Asia and Europe. The polar routes are extremely attractive to the airlines and their customers for many reasons, the paramount of which being faster non-stop services between such major centers as New York and Hong Kong, cutting up to six hours off regular travel time. For the first time, airlines can offer faster, possibly cheaper, flights between the world's most important business centers. Not only is non-stop service highly attractive for the travel-weary customer, there are also numerous benefits for the airlines. In addition to significant fuel savings and reduced amount of operation time and labor cost, there is the further benefit of a smoother flight due to a lack of headwinds along these routes during the winter months.

#With any significant change in flight operations, a thorough review of the technical challenges involved and their possible impact on aircraft safety is critical. With polar flights, there are two particular issues related to the freezing point of the jet fuel on the aircraft. Should the jet fuel in the wing tanks reach its freezing point, there is a possibility of the following: (1) The flow of fuel to the engine becomes blocked, causing the engine to stutter and, possibly, loss of the aircraft; or (2) the fuel solidifies and becomes trapped within tanks, curtailing the amount of useful fuel available to the engine. Certainly, the scenario of fuel freezing has always been an important consideration, even for regular flights. However, with polar flight, this issue is heightened as the aircraft is often flying in outside ambient temperatures that can commonly reach minus seventy degrees Celsius (−70° C.) or colder. Flying over the North Pole's large permafrost and the drastic reduction in sunlight during the winter months means an increase in the possibility of fuel in the wing tanks reaching its freezing point. All outbound aircraft in the US are dispatched with Jet A fuel, with a specification freezing point of −40° C. With no means of testing the fuel as it is being uploaded to each aircraft, the pilot must fly assuming that the freezing point of the fuel in the aircraft is −40° C. as specified.

#FIG. 1 is a schematic of the basic concept according to the present invention;

#FIG. 2 is a cross-sectional view of a test chamber according to the present invention;

#FIG. 3 is a perspective view of the test chamber of FIG. 2 according to the present invention;

#The present invention is a fuel freezing point monitoring device. The fuel freezing point monitoring device can be mounted in an aircraft to monitor the freezing point of onboard fuel. The fuel freezing point monitoring device is capable of monitoring the phase transition or fluidity of the aircraft fuel to determine the freezing point of the fuel. When an external motive force, such as pump or gravity drain, is not available, the fuel freezing point monitoring device can also include a means to assist in delivering a fuel sample from an aircraft fuel source to the fuel freezing point monitoring device. The fuel freezing point monitoring device eliminates the freezing point assumption of onboard fuel by actually measuring the freezing point of the fuel. The pilot will have knowledge of the approximate freezing point of the composite onboard fuel and will no longer need to assume a conservative fuel freezing point value. Together with the en-route fuel temperature information provided by existing aircraft sensors, the pilot will have the information to ensure a safe flight and to operate the aircraft efficiently.

#As is a requirement for most onboard equipment of an aircraft, the fuel freezing point monitoring device should be small, lightweight and avoid the use of dangerous liquids or gases. It is desirable to mount the fuel freezing point monitoring device next to or close to an aircraft fuel tank. Where there is concern over the freezing point of fuel in separate fuel tanks, it may be beneficial to have a manifold to allow fuel from active tanks to enter one fuel freezing point monitoring device, or incorporate the fuel freezing point monitoring device into a hand-held device that can be conveniently attached and detached to suitable nodes for the purpose of fuel analysis. In doing so, the complexity and costs involved in equipping each fuel tank with a dedicated fuel freezing point monitoring device can be avoided. The following embodiments consider all the above-mentioned concerns with equipment to be used onboard an aircraft.

#FIG. 1 shows the basic concept employed in all setups of the fuel freezing point monitoring device to be further disclosed. A jet fuel sample 1 from an aircraft fuel tank is delivered into an internal channel of a light-leak-proof and thermally conductive test chamber 3. The configuration of the test chamber 3 is the main difference in all the setups to be further disclosed. A pump 2 is shown as an example of a means of transferring the fuel sample 1 to the fuel freezing point monitoring device. A sufficient amount of fuel sample 1 is needed to completely fill the test chamber 3 and purge the test chamber 3 of any residual fuel sample remaining from a previous test. Excess fuel from the test chamber 3 is returned through a drain tube 4 to either a fuel tank or a sump. Once the test chamber 3 is completely filled with the new fuel sample 1, the flow into the test chamber 3 is halted. The fuel freezing point monitoring device includes a light emitter 13 as a light source and a light detection unit 15 for monitoring light levels. The light emitter 13 and light detection unit 15 are light devices that interact in combination with the test chamber 3 to provide a beam of light through the fuel sample 1. The test chamber 3 is in thermal contact with a surface that is chilled by a cooler 16, so that the fuel sample 1 can be cooled. A temperature sensor 17 is embedded in the test chamber 3 in close proximity to the fuel sample 1. A data acquisition and control unit 18 is used to control the cooling and warming rates of the fuel sample 1; to collect information from the temperature sensor 17 and from the light detection unit 15; and to analyze the collected data. A microprocessor equipped with the necessary software and hardware is utilized as part of the data acquisition and control unit 18.