Patent Publication Number: US-8991197-B2

Title: Thermodynamic pump for cryogenic fueled devices

Description:
REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a divisional application of Ser. No. 11/750,246, filed on May 17, 2007, the disclosure of which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     There is an interest in using cryogenic fluids such as liquid hydrogen, nitrous oxide, methane, or other fluids as fuel for internal combustion engines, ground vehicles, aircraft, and other devices. In order for cryogenic fluids to be used as fuel for these applications, the cryogenic fluid may need to be supplied to the engine at specific conditions. These conditions may require cryogenic fluid to be gasified, heated from its cryogenic temperatures to room temperature, and pressurized from low storage pressures to much higher operation pressures. To accomplish this state change, a mechanical pump is sometimes used to increase the pressure, accompanied by a heat exchanger to increase the temperature. However, due to the extreme cold and poor lubricity of cryogenic fluid, many mechanical pumps, which utilize rotating components, may not work well. In addition, many mechanical pumps may suffer from low efficiencies, poor reliability, and complexity. Beyond the complexity of the pump, a separate system, such as a heat exchanger, may need to be utilized to increase the temperature of the cryogenic fluid. Further, in some existing apparatus, both the pump and the heat exchanger may create a fire hazard by producing liquid air which may be flammable. Still other existing devices may use cryogenic fluid warmed in a large tank, or what is called a batch method. This may require excessive weight and size. 
     An apparatus, and/or method for conditioning cryogenic fluid for use in a device, is needed to decrease one or more problems associated with one or more of the existing apparatus and/or methods. 
     SUMMARY 
     In one aspect of the disclosure, a method is provided for converting cryogenic fluid for use in a device. In one step, cryogenic fluid is heated to gas using heat transferred from the device to a vessel. In another step, temperature and pressure of the gas within the vessel is controlled. In still another step, the gas within the vessel is transferred to the device. 
     In another aspect of the disclosure, an apparatus is provided for fueling a device using cryogenic fluid. The apparatus comprises the following: a cryogenic fluid supply container; a vessel connected to the supply container with an entrance valve to regulate flow of cryogenic fluid from the supply container to the vessel; a heat transfer system capable of transferring heat from a device to the vessel to heat gas in the vessel; and an accumulator connected to the vessel with an exit valve to regulate flow of gas from the vessel to the accumulator. The accumulator is capable of being connected to a device. 
     In a further aspect of the disclosure, gas fueling a device is provided. The gas was formed by heating cryogenic fluid in a vessel using heat transferred from the device. The temperature and pressure within the vessel was controlled during formation of the gas. The gas from the vessel was transferred to the device. 
     These and other features, aspects and advantages of the disclosure will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a front view of one embodiment of an apparatus for fueling a device using hydrogen; 
         FIG. 2  is a graph showing the pressure and the temperature inside one embodiment of a vessel when an entrance valve is opened as a function of time; 
         FIG. 3  is a graph showing the operating range of density versus temperature for various pressures within one embodiment of a vessel; and 
         FIG. 4  is a flowchart showing one embodiment of a method for converting a cryogenic fluid such as hydrogen in a liquid state for use in a device. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is of the best currently contemplated modes of carrying out the disclosure. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the disclosure, since the scope of the disclosure is best defined by the appended claims. 
       FIG. 1  shows a front view of one embodiment of an apparatus  10  which supplies hydrogen fuel  14  to device  12 . The device  12  being fueled may comprise an aircraft, a vehicle, an internal combustion engine, and/or another type of hydrogen fueled device. The apparatus  10  may comprise a thermodynamic pump. The apparatus  10  may include a liquid hydrogen supply container  16 , an entrance valve  18 , a vessel  20 , a first temperature sensor  22 , a first pressure sensor  24 , an exit valve  26 , a heat transfer system  28 , an accumulator  30 , a second temperature sensor  32 , and a second pressure sensor  34 . 
     The liquid hydrogen supply container  16  may contain hydrogen  14  in a liquid state, and may be connected through one or more pipes  36  to the entrance valve  18  which may be connected to the vessel  20 . The vessel  20  may comprise a pipe or other type of vessel in which a liquid or gas may be contained. In one embodiment, the vessel  20  may comprise a 3 foot long pipe having a 2 to 5 inch diameter. In other embodiments, varying sized vessels  20  may be used depending on the hydrogen demand of the device  12 . For instance, in one embodiment, two or more vessels  20  may be used in parallel and manifolded together, and the accumulator  30  may be replaced by a manifold downstream of exit valve  26 . 
     The entrance valve  18  may be adapted to open to allow hydrogen  14  in a liquid state to be transferred from the supply container  16  into vessel  20 . The latent heat of vessel  20  may cause the hydrogen  14  supplied from the supply container  16  to vaporize and mix with residual warm hydrogen gas in vessel  20 . Continued contact of the hydrogen in vessel  20  with the hydrogen at valve  18  may reduce the temperature of the gaseous hydrogen in vessel  20  to near liquid hydrogen temperatures. Once the desired temperature of the hydrogen in vessel  20  is reached, valve  18  may be closed to lock near liquid hydrogen temperature gaseous hydrogen in vessel  20  to be heated using a heat transfer system  28 . 
     The heat transfer system  28  may comprise one or more continuous closed loop pipes which are connected between the vessel  20  and a connected device  12 . The heat transfer system  28  may allow heat from the connected device  12 , in the form of heated device coolant or in another form, to be transferred to the vessel  20  in order to heat the hydrogen  14  within the vessel  20  to a warm higher pressure gas. The first temperature sensor  22  and the first pressure sensor  24  may be connected to the vessel  20  in order to monitor the temperature and pressure of the hydrogen  14  within the vessel  20  in both liquid and gaseous states. The vessel  20  may be connected to the exit valve  26 . The exit valve  26  may be adapted to close to lock hydrogen  14  in a near liquid hydrogen temperature gas state within the vessel  20  so that it can be heated to a high pressure warm state, to open to allow hydrogen  14  in a gaseous state to be transferred to the accumulator  30 , and to close to prevent more hydrogen  14  in a gaseous state to enter the accumulator  30 . The exit valve  26  may be connected to the accumulator  30  through one or more pipes  38 . The second temperature sensor  32  and the second pressure sensor  34  may be connected to the accumulator  30  in order to monitor the temperature and pressure of the hydrogen  14  in a gaseous state within the accumulator  30 . The accumulator  30  may be adapted to store the hydrogen  14  in a gaseous state within the accumulator  30  until the device  12  requires hydrogen fueling. The accumulator  30  may be connected through one or more pipes  40  to the device  12  to allow hydrogen  14  in a gaseous state to be transferred to the device  12  in order to fuel the device  12 . 
     In one embodiment, when the apparatus  10  of  FIG. 1  is in operation, the entrance valve  18  may be opened to allow hydrogen  14  in a liquid state to be transferred from the liquid hydrogen supply container  16  to the vessel  20  while the exit valve  26  is closed. After enough hydrogen  14  in a liquid state is transferred into the vessel  20 , the entrance valve  18  may be closed. The heat transfer system  28  may then transfer heat from the connected device  12  to the vessel  20 , in order to heat the hydrogen  14  within the vessel  20  from a liquid to a gaseous state. At any time, if the first temperature sensor  22  and/or the first pressure sensor  24  detect a temperature and/or pressure within the vessel  20  above a first set-amount, indicating that the temperature and/or pressure within the vessel  20  is too high, the entrance valve  18  may be opened to allow more hydrogen  14  in a liquid state to be transferred into the vessel  20  to lower the temperature and/or pressure within the vessel  20 . In such manner, catastrophic failure due to over-pressurization within the vessel  20  may be avoided without having to vent hydrogen  14  in a gaseous state. The entrance valve  18  may then be closed. 
     Similarly, if the first temperature sensor  22  and/or the first pressure sensor  24  detect a temperature and/or pressure within the vessel  20  above a first set-amount, indicating that the temperature and/or pressure within the vessel  20  is too high, the exit valve  26  may be opened to allow hydrogen  14  in a gaseous state to be transferred from the vessel  20  to the accumulator  30  in order to lower the temperature and/or pressure within the vessel  20 . Likewise, when the first temperature sensor  22  and/or the first pressure sensor  24  detect a temperature and/or pressure within the vessel  20  which indicates that the hydrogen  14  within the vessel is in a suitable gaseous state, the exit valve  26  may be opened to allow the hydrogen  14  in a gaseous state to be transferred to the accumulator  30 . 
     When enough hydrogen  14  in a gaseous state has been accumulated in the accumulator  30 , the exit valve  26  may be closed. When the second temperature sensor  32  and/or the second pressure sensor  34  detect a temperature and/or pressure within the accumulator  30  indicating that the hydrogen  14  within the accumulator  30  is in a suitable gaseous state to fuel the connected device  12 , the accumulator  30  may transfer hydrogen  14  in a gaseous state to the connected device  12 . If the second temperature sensor  32  and/or the second pressure sensor  34  detect that the temperature and/or pressure within the accumulator  30  is below a second set-amount, the exit valve  26  may be opened to allow more hydrogen  14 , which has been heated within the vessel  20  to a gaseous state, to be transferred into the accumulator  30  to increase the temperature and/or pressure of the hydrogen  14  within the accumulator  30 . 
     When the vessel  20  needs to be recharged, the entrance valve  18  may be opened to allow hydrogen  14  in a liquid state to be transferred to the vessel  20  from the supply container  16 . The pressure within the vessel  20  may initially drop which will may allow some of the hydrogen  14  in a liquid form to flow inside the vessel  20 . The hydrogen  14  in a liquid form may vaporize as it enters the vessel  20  but at a much lower temperature than the temperature within the vessel  20 .  FIG. 2  is a graph showing the pressure P and the temperature T inside one embodiment of the vessel  20  when the entrance valve  18  is opened as a function of time. The net result may be an increase in density (and increase in mass) inside the vessel  20  showing a net positive mass flow through the vessel  20 . The exit valve  26  may then be closed to allow the hydrogen  14  within the vessel  20  to be heated to a gaseous state, during which the pressure inside the vessel  20  may rise substantially. In one embodiment where the vessel  20  is 3 feet long and 5 inches in diameter, due to the small size of the vessel  20 , the pressure may exceed 1000 psia.  FIG. 3  is a graph showing the operating range of density versus temperature for various pressures within one embodiment of a vessel  20 . 
     The apparatus  10  of  FIG. 1  may not utilize any vents for lowering temperature and/or pressure of the hydrogen  14  within the vessel  20 . This may help to avoid wasting hydrogen  14  as a result of venting. Instead, over pressure and/or temperature protection may be provided by the ability of the apparatus  10  to depressurize and/or lower the temperature of the hydrogen  14  within the vessel  20  utilizing the hydrogen  14  within the upstream liquid supply container  16 . Moreover, the apparatus  10  may avoid the use of high speed rotational parts. Rather, pressure and/or temperature within the vessel  20  may be achieved utilizing excess heat from the device  12  itself. Rather than utilizing a large number of movable parts, the only movable parts the apparatus  10  may use may be the entrance and exit valves  18  and  26 , which may help reliability and durability. The non-flowing gasification process of the apparatus  10  may result in a stable supply of hydrogen  14  for the device  12 , as opposed to a typical heat exchanger where the hydrogen may flow through the heat exchanger potentially creating an unsteady supply by causing ice to form in the heating fluid side of the heat exchanger. The closed-loop nature of the apparatus  10  may mitigate the risk of liquid air formation within the apparatus  10 . The apparatus  10  may be able to handle a relatively wide range of flow rates and pressures to accommodate for the hydrogen requirements of the device  12 . 
       FIG. 4  is a flowchart showing one embodiment of a method  242  for converting hydrogen  14  in a liquid state for use in a device  12 . The device  12  may comprise an internal combustion engine, an aircraft, a vehicle, or other type of device. In one step  244 , hydrogen  14  in a liquid state in a vessel  20  may be heated to a gaseous state using heat transferred from the device  12 . In one embodiment, a size of the vessel  20  may be determined based on the requirements of the device  12 . In another step  246 , temperature and pressure of the hydrogen  14  within the vessel  20  may be controlled. In one embodiment, a first temperature sensor  22  and a first pressure sensor  24  may be used to control the temperature and pressure of the hydrogen  14  within the vessel  20 . In another embodiment, hydrogen  14  in a liquid state may be transferred from a supply container  16  to the vessel  20  when at least one of the temperature and pressure of the hydrogen  14  within the vessel  20  is over a first set-amount. The method  242  may not utilize any vents to lower at least of the temperature and pressure of the hydrogen  14  within the vessel  20 . In another embodiment, hydrogen  14  in the vessel  20  may be heated using heat transferred from the device  12  when at least one of the temperature and pressure of the hydrogen  14  within the vessel  20  is under a third set-amount. In still another step  248 , hydrogen  14  in a gaseous state within the vessel  20  may be transferred to the device  12 . In one embodiment, hydrogen  14  in a gaseous state within the vessel  20  may be first transferred to an accumulator  30 , and then transferred to the device  12 . 
     In another embodiment, additional steps of the method  242  may comprise providing a supply container  16 , and transferring hydrogen  14  in a liquid state from the supply container to the vessel  20 . Still other steps may comprise providing an entrance valve  18  to the vessel  20 , providing an exit valve  26  to the vessel  20 , and heating the hydrogen  14  in a liquid state within the vessel  20  to a gaseous state while both of the entrance and exit valves  18  and  26  are closed. The entrance valve  18  may be connected to a liquid hydrogen supply container  16 , and the exit valve  26  may be connected to an accumulator  30  which may be connected to the device  12 . In yet another embodiment, an additional step of the method  242  may comprise controlling the temperature and pressure of hydrogen  14  in a gaseous state within the accumulator  30 . A second temperature sensor  32  and a second pressure sensor  34  may be used to control the temperature and pressure of hydrogen  14  in a gaseous state within the accumulator  30 . When at least of the temperature and pressure of the hydrogen  14  in a gaseous state within the accumulator  30  is under a second set-amount, additional hydrogen  14  in a gaseous state may be transferred from the vessel  20  to the accumulator  30 . 
     In an additional embodiment, hydrogen  14  fueling a device  12 , while in a gaseous state, may be provided. The hydrogen  14  in the gaseous state may have been formed by heating hydrogen  14  in a liquid state in a vessel  20  to a gaseous state using heat transferred from the device  12 . The temperature and pressure within the vessel  20  may have been controlled during formation of the hydrogen  14  into the gaseous state. The hydrogen  14  in the gaseous state may have been transferred to the device  12 . The device  12  being fueled may be at least one of an internal combustion engine, an aircraft, a vehicle and another type of fueled device. 
     Although the above embodiments are directed towards using hydrogen  14  to fuel the device  12 , all of the embodiments of the disclosure are equally applicable to using another type of cryogenic fluid rather than hydrogen, such as nitrous oxide, methane, or other type of very low temperature or substantially low temperature fluid to fuel the device  12 . 
     One or more embodiments of the disclosure may reduce and/or eliminate one or more problems of one or more of the existing apparatus and/or methods. For instance, one or more embodiments of the apparatus and/or method of the disclosure may reduce the need for high speed rotational parts, reduce the need for moving parts other than valves, reduce hydrogen waste due to venting, provide a more stable supply of hydrogen, help in mitigating the risk of liquid air formation, more easily handle a wide range of flow rates and pressures depending on the hydrogen requirements, increase durability, increase reliability, take up less space, take up less weight, be less costly, decrease hydrogen loss, be more stable, accommodate a wide range of devices, mitigate liquid air formation, be more efficient, be easier to implement, and/or may reduce one or more other types of problems with one or more of the existing apparatus and/or methods. 
     It should be understood, of course, that the foregoing relates to exemplary embodiments of the disclosure and that modifications may be made without departing from the spirit and scope of the disclosure as set forth in the following claims.