Patent Application
20080098894
This invention generally relates to heat exchangers and mass separators. More particularly, this invention relates to a heat exchanger and fuel stabilization device within a fuel delivery system.
Conventional energy conversion devices utilize fuel to absorb heat generated by other systems. The heat from other systems is directed through a heat exchanger to reject heat into the fuel. The thermal capacity of the fuel is determined in large part by the resistance to the formation of autooxidative reactions. Autooxidative reactions generate insoluble materials know as “coke” or “coking” in hydrocarbon fuels containing dissolved oxygen at elevated temperatures, for example above 325° F.
It is known that removing dissolved oxygen from fuel increases the temperature at which the autooxidative reactions occur, thereby increasing the thermal capacity of the fuel. Devices for removing dissolved oxygen from fuel rely on relative proximity between a stream of fuel and a surface through which dissolved oxygen is drawn.
Disadvantageously, a fuel stream flowing through a passage in a deoxygenation device includes a center portion where fuel is not sufficiently close to an oxygen permeable surface for the desired removal of dissolved oxygen. Reducing the size of the passage can reduce the amount of fuel that is distant from the oxygen permeable surface. However such small passages can result in an undesirable pressure drop through the deoxygenation device. Further, mixing members within the fuel passages are known to induce secondary motion that causes more of the fuel stream to contact the oxygen permeable surfaces. However, such mixing members can also incur undesirable pressure loses as well as increasing overall costs.
Accordingly, it is desirable to design and develop a fuel stabilization unit that provides for the removal of dissolved oxygen, while maintaining desired fuel pressures.
An example fuel delivery system includes a fuel conditioning unit that includes a fuel stabilization unit that receives vibratory energy for mixing fuel within fuel passages that improves the removal of dissolved oxygen from an oxygen containing fuel.
Fuel includes dissolved oxygen that is removed to improve thermal capacity. Fuel leaving the fuel stabilization unit includes little dissolved oxygen and can therefore be heated to temperatures not possible with the dissolved oxygen without generating coke forming autooxidative reactions. A vibration generator transmits vibratory energy into the fuel stabilization unit to induce mixing of fuel. The mixing of fuel improves overall fuel deoxygenation by enhancing oxygen transfer through an oxygen permeable surface. Further, mixing of fuel improves thermal energy transfer.
Accordingly, the example fuel stabilization unit receives directed vibratory energy to improve fuel mixing and thereby fuel deoxygenation efficiency.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
Referring to
The heat exchanger 28 is mechanically attached or integrally formed with the fuel stabilization unit 26 to transmit vibratory energy 30 into fuel within the fuel stabilization unit 26. The heat exchanger 28 receives a flow of fluid medium 18, along with the flow of fuel 14. The flow of fluid medium 18 generates vibrations 30 that are transmitted into the fuel flow 14 during passage through the fuel stabilization unit 26. The vibratory energy creates large-scale vertical or secondary flow structures in the fuel to aid in circulating fuel adjacent oxygen permeable surfaces.
The heat exchanger 28 includes vibration generators 32 that create the vibratory energy 30 that is transmitted into the fuel flowing through the fuel stabilization unit 26. The example vibration generators 32 respond to the flow of the fluid medium 18 to create the desired vibration energy 30 that is transmitted into the fuel flow 14. The example vibration generators 32 include fins or baffles that respond to the flow of the fuel stream 14 or the fluid medium, or both to create the desired vibration energy. Further, the vibration generators 32 may include other passive structures that utilize the flow of a fluid to produce the desired vertical flow structures that are sustained by the vibratory energy. The amount of vibration energy 30 that is created and transmitted to the fuel stabilization unit 26 is determined to provide the desired large-scale secondary flow characteristics that encourage fuel mixing and deoxygenation of the fuel.
Referring to
The vibration generator 38 is an actuated device that creates the desired vibration energy through positive actuation. The vibration generator 38 can include, for example, an electric motor or other electrically powered device. Further, other known actuators such as hydraulic and pneumatic devices can be utilized as the vibration generator 38 to create the desired vibration energy utilized to create the desired mixing of the fuel.
Referring to
The energy conversion device 22 is illustrated schematically and can include, for example, a gas turbine engine, an internal combustion engine, or any other known engine. The vibration energy 50 is harnessed by a mechanical attachment between portions of the energy conversion device 22 or accompanying housing or covering that vibrates as a result of operation.
Referring to
The fuel stream 56 includes a center flow area 58 bounded by adjacent flow areas 60. The adjacent flow areas 60 are adjacent the oxygen permeable membrane 52 such that oxygen is efficiently removed. The fuel within the center flow area 58 is distant from the permeable membrane 52 and therefore contains more dissolved oxygen than fuel in the adjacent flow areas 60. Vibratory energy 64 is directed into the fuel 56 in a direction transverse to fuel flow to create mixing by means of vibration induced secondary flow motions, schematically shown by arrows 62, that circulates fuel from the center flow area 58 into the adjacent flow areas 60.
The mixing of fuel between the center flow area 58 and the adjacent flow areas 60 improves overall fuel deoxygenation as more of the fuel is placed in adjacent contact with the oxygen permeable membranes 52.
Further, although the fuel 56 is mixed due to the vibratory induced turbulence, the fuel flow path is not restricted, providing little pressure drop for fuel flowing through the fuel stabilization unit.
Referring to
The vibratory energy 64 is directed at an angle 72 relative to the flow of the fuel. The vibratory energy 64 can be introduced at any angle relative to the flow of fuel as is desired to produce the enhanced mixing of the fuel adjacent the fuel permeable membrane 52.
Accordingly, the example fuel stabilization unit receives directed vibratory energy to improve fuel mixing and thereby fuel deoxygenation efficiency without an accompanying drop in fuel pressure.
Although a several embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention and that other embodiments are feasible. For that reason, the following claims should be studied to determine the true scope and content of this invention.
