Patent Application
20180318730
The subject matter disclosed herein generally relates to the field of vacuum systems for a fuel degassing unit for an internal combustion, and more particularly to an apparatus and method for generating a vacuum utilized in removing dissolved gases from a fuel stream.
A fuel degassing unit reduces the amount of gasses dissolved within fuel for an internal combustion engine. In one example, by removing gases like oxygen, it increases the maximum allowable temperature of the fuel and allows the fuel to be used as a heat sink. One method of removing dissolved oxygen from fuels is by using a semipermeable membrane de-oxygenator. In a membrane de-oxygenator, fuel is pumped over an oxygen permeable membrane. As the fuel passes over the membrane, a partial oxygen pressure differential across the membrane promotes the transport of oxygen out of the fuel through the membrane. A vacuum is one means of generating the required partial oxygen pressure differential described above for fuel degassing. Typically, deeper vacuum is created using multiple stages of vacuum pump heads and of vacuum pumps.
Fuel degassing will be of increasing importance on next generation aircraft engines, marine engines, stationary power engines, vehicle engines, and diesel engines as heat loads increase due to additional electronic equipment. An apparatus and method for increasing the efficiency and reliability of vacuum sources in a fuel degassing unit providing is greatly desired.
According to one embodiment, a fuel system is provided. The fuel system comprising: an engine that in operation consumes fuel; a fuel tank that in operation supplies fuel to the engine; a fuel degassing unit fluidly connecting the engine to the fuel tank, the fuel degassing unit in operation separates selected species from the fuel; and a vacuum generation device operably connected to the fuel degassing unit, the vacuum generation device in operation generates a vacuum to remove the selected species from the fuel degassing unit; wherein the vacuum generation device comprises at least one operating fluid-free vacuum pump that operates without an operating fluid.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the vacuum generation device includes at least two operating fluid-free vacuum pumps oriented in parallel.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the vacuum generation device includes at least two operating fluid-free vacuum pumps oriented in series.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the vacuum generation device includes at least one ejector.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the ejector and the operating fluid free vacuum pump are oriented in series.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the ejector and the operating fluid free vacuum pump are oriented in parallel.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include at least one operating fluid vacuum pump that operates with an operating fluid, wherein at least one operating fluid-free vacuum pump fluidly connects the operating fluid vacuum pump and the fuel degassing unit.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include a brake booster fluidly interjected between the operating fluid vacuum pump and the operating fluid-free pump.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include a brake booster fluidly interjected between the operating fluid-free pumps in series.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include a brake booster fluidly interjected between the ejector and the operating fluid-free pumps.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the selected species include at least one of oxygen, nitrogen, carbon dioxide, water vapor, and hydrocarbon vapor.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the vacuum generation device is enclosed within a thermally managed container.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the vacuum generation device and the fuel degassing unit are enclosed within a thermally managed container.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the operating fluid free-vacuum pump is at least one of a diaphragm vacuum pump, a rocking piston vacuum pump, a scroll vacuum pump, a roots vacuum pump, a parallel screw vacuum pump, a claw type vacuum pump, and a rotary vane vacuum pump.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include a semipermeable membrane within the fuel degassing unit, the semipermeable membrane in operation filters selected species out of the fuel.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where fuel absorbs heat from the vacuum generation device.
In addition to one or more of the features described above, or as an alternative, further embodiments of the fuel system may include where the at least one operating fluid-free vacuum pump is driven by an electric motor.
According to another embodiment, a method of assembling a fuel system is provided. The method comprising: providing an engine that in operation consumes fuel; providing a fuel tank that in operation supplies fuel to the engine; fluidly connecting a fuel degassing unit to each of the engine and the fuel tank, the fuel degassing unit fluidly connects the engine to the fuel tank, wherein the fuel degassing unit in operation separates selected species from the fuel; and operably connecting a vacuum generation device to the fuel degassing unit, the vacuum generation device in operation generates a vacuum to remove the selected species from the fuel degassing unit; wherein the vacuum generation device comprises at least one operating fluid-free vacuum pump that operates without an operating fluid.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include where the operating fluid free-vacuum pump is at least one of a diaphragm vacuum pump, a rocking piston vacuum pump, a scroll vacuum pump, a roots vacuum pump, a parallel screw vacuum pump, a claw type vacuum pump, and a rotary vane vacuum pump.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include inserting a semipermeable membrane into the fuel degassing unit, the semipermeable membrane in operation filters selected species out of the fuel.
Technical effects of embodiments of the present disclosure include a fuel system utilizing an operating fluid-free vacuum pump to remove selected dissolved gaseous species from fuel.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
Various embodiments of the present disclosure are related to the removal of selected dissolved gaseous species (e.g. oxygen, carbon dioxide, water vapor . . . etc.) from fuel. The selected dissolved gaseous species may be referred to as selected species for short. In one example, fuel serves as a heat sink on some aircraft and cars by absorbing heat from engine accessories. At high temperature, however, the fuel reacts with dissolved oxygen to form solid carbonaceous deposits (“varnish” or “lacquering”) in the fuel passages. The deposits can foul surfaces for heat exchange and clog fuel system components. When fuel is heated above approximately 250° F., the increased rate of these auto-oxidation reactions shortens typical fuel system maintenance intervals. Further, water in fuel may also be problematic because water degrades the heating value of fuel. Water can also freeze in the fuel system and block fuel flow. Water can also allow microorganisms to grow in fuel that can occlude flow of fuel and whose metabolic byproducts contribute to corrosion of fuel system components. Additionally, carbon dioxide in fuel may also be problematic. Carbon dioxide in fuel can cause vapor lock under certain conditions. Vapor lock is the undesired presence of gases and vapors in the fuel system that can adversely affect delivery of fuel to the engine. Many viable fuel degassing technologies require a vacuum source in order to remove dissolved oxygen and other selected species. The vacuum source removes the dissolved selected species by transporting the selected species through a semipermeable membrane.
Rotary vane vacuum pumps may be used, but tend to be heavy and require regular maintenance (oil changes) due to operating fluids such as oil. Also, over extended operating periods, oil from the rotary vane vacuum pump has been found to diffuse upstream and eventually reach the backside of the semipermeable membrane, resulting in gradual performance decline of the semipermeable membrane. In addition, some operating fluids such as oils are hygroscopic, which requires more frequent oil changes and thus increases operating costs. Further, in one aircraft example, a hydrocarbon fuel can contain up to 200 mg of dissolved water per kg of fuel. Thus, with the about 2,500 kg/hr typical fuel consumption of a single-aisle aircraft, up to 0.5 kg/hr of water vapor may be processed by the vacuum pump. Unless properly addressed, water can condense and flood the pump cavity and thereby severely degrade vacuum pump performance. Embodiments disclosed herein seek to address the operating fluid (e.g. oil) mitigation and water build up matters associated with current technology being used in fuel degassing systems.
The vacuum generation device 100 is operably connected to the fuel degassing unit 18. The vacuum generation device 100 in operation generates to remove the selected species from the degassing unit 18. In an embodiment, the vacuum generation device 100 in operation generates a vacuum across the semipermeable membrane 40 to enable filtration of the selected species 13a, thus pulling the selected species 13a through the semipermeable membrane 40. In an embodiment, vacuum generation device 100 comprises at least one operating fluid-free vacuum pump 120 that operates without an operating fluid. In various embodiments, the operating fluid-free vacuum pump 120 may be at least one of a diaphragm vacuum pump, a rocking piston vacuum pump, a scroll vacuum pump, a roots vacuum pump, a parallel screw vacuum pump, a claw type vacuum pump, and a rotary vane vacuum pump. The fluid-free vacuum pump 120 can be driven by various power sources. In an embodiment, an electric motor drives the fluid-free vacuum pump 120. In another embodiment, mechanical power from an engine transmitted via a shaft, belt or gear(s) drives the fluid-free vacuum pump 120. Similarly, a hydraulic motor or a pneumatic motor can provide power to the fluid-free vacuum pump 120. Advantageously, by utilizing an operating fluid-free vacuum pump 120 instead of an operating fluid vacuum pump 130 next to the semipermeable membrane 40 the risk is reduced of the semipermeable membrane 40 being unintentionally coated in an operating fluid such as oil, which degrades the performance of the semipermeable membrane 40. The operating fluid vacuum pump 130 contains an operating fluid that may be used as a lubricant or sealant, such as, for example oil.
In an embodiment, the vacuum generation device 100 may be enclosed within a thermally managed container 180a, as seen in
Further, as seen in
In an alternative embodiment seen in
It is understood that the illustrated orientations of the operating fluid-free vacuum pumps 120, operating fluid vacuum pumps 130, and ejectors 140 in
Referring now to
While the above description has described the flow process of
As described above, embodiments can be in the form of processor-implemented processes and devices for practicing those processes, such as a processor. Embodiments can also be in the form of computer program code containing instructions embodied in tangible media, such as network cloud storage, SD cards, flash drives, floppy diskettes, CD ROMs, hard drives, or any other computer-readable storage medium, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes a device for practicing the embodiments. Embodiments can also be in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into an executed by a computer, the computer becomes an device for practicing the embodiments. When implemented on a general-purpose microprocessor, the computer program code segments configure the microprocessor to create specific logic circuits.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.
