WO2020005273A1 - Systèmes de transport par tube utilisant un mélange gazeux constitué d'air et d'hélium - Google Patents

Systèmes de transport par tube utilisant un mélange gazeux constitué d'air et d'hélium Download PDF

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Publication number
WO2020005273A1
WO2020005273A1 PCT/US2018/040256 US2018040256W WO2020005273A1 WO 2020005273 A1 WO2020005273 A1 WO 2020005273A1 US 2018040256 W US2018040256 W US 2018040256W WO 2020005273 A1 WO2020005273 A1 WO 2020005273A1
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WIPO (PCT)
Prior art keywords
tube
helium
air
power
capsule
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PCT/US2018/040256
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English (en)
Inventor
Alexandre Neophytou
Michael Sarin
Alexandre Zisa
Spencer BALDWIN
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Hyperloop Transportation Technologies, Inc.
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Publication date
Application filed by Hyperloop Transportation Technologies, Inc. filed Critical Hyperloop Transportation Technologies, Inc.
Priority to EP18924654.9A priority Critical patent/EP3814164A4/fr
Priority to PCT/US2018/040256 priority patent/WO2020005273A1/fr
Priority to CN201880097012.7A priority patent/CN112638693A/zh
Publication of WO2020005273A1 publication Critical patent/WO2020005273A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L13/00—Electric propulsion for monorail vehicles, suspension vehicles or rack railways; Magnetic suspension or levitation for vehicles
    • B60L13/03—Electric propulsion by linear motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L13/00—Electric propulsion for monorail vehicles, suspension vehicles or rack railways; Magnetic suspension or levitation for vehicles
    • B60L13/10—Combination of electric propulsion and magnetic suspension or levitation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61B—RAILWAY SYSTEMS; EQUIPMENT THEREFOR NOT OTHERWISE PROVIDED FOR
    • B61B13/00—Other railway systems
    • B61B13/08—Sliding or levitation systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61B—RAILWAY SYSTEMS; EQUIPMENT THEREFOR NOT OTHERWISE PROVIDED FOR
    • B61B13/00—Other railway systems
    • B61B13/10—Tunnel systems
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
    • E01B25/00—Tracks for special kinds of railways
    • E01B25/30—Tracks for magnetic suspension or levitation vehicles

Definitions

  • the present invention relates generally to the field of tube transportation. More specifically, the present invention is related to tube transportation systems using a gaseous mixture of air and helium.
  • the Hyperloop is a system where a capsule is levitated in a tube at low-pressure (and in turn low air density). Levitation reduces, substantially, ground friction. Low air density reduces, substantially, air drag.
  • the white paper proposed an air-ski supported capsule riding inside of an evacuated tube, 100 Pascal (Pa) absolute, and propelled by linear induction motors.
  • An air compressor was placed at the nose of the capsule to provide air to the ski pads and to improve the speed capability of the capsule.
  • the inclusion of a large compressor improved the capsule speed but required a large battery array to power it during the Hyperloop journey. It additionally took valuable space from the passenger compartment and added significant complexity.
  • the compressor serves as an important component for improving the speed of the capsule, where such improvement is not due to the thrust provided to push the capsule down the tube but is due to the reduction in the effective frontal area of the capsule.
  • the compressor provided a second path to direct air from in front of the capsule to the rear of capsule, adding to the annular region between the capsule and tube.
  • the ratio of this annulus to total tube area, known as the bypass ratio, is a key predictor of choking.
  • FIG. 1 depicts a schematic of a vehicle (also referred to as pod or capsule) within a tube (Source: see paper to Chin et al. titled“Open-Source Conceptual Sizing Models for the Hyperloop Passenger Pod”, dated 5-9 January 2015).
  • Drag is mainly the contribution of two components: pressure drag and friction drag.
  • Pressure drag is the pressure exerted as the vehicle moves forward and pushes the air.
  • Friction drag is the viscous force exerted by the air that flows around the vehicle surface. Drag is given by the equation below:
  • Ptube Pressure in the tube, absolute
  • V pod Velocity of the pod squared
  • C D is the drag coefficient that includes pressure drag and drag due to friction effects.
  • the drag is proportional to density. Consequently, reducing density has a substantial effect on drag and in turn on propulsion power. This can be obtained with a low- pressure tube.
  • the drag is proportional to the square of the velocity. Thus, drag rises fast with increasing velocity.
  • An undesired flow phenomenon occurs when the vehicle reaches high subsonic speed.
  • the air that flows around the vehicle in the bypass gap in FIG. 1 gets choked. This results in a large increase of pressure in front of the vehicle. In turn, drag increases and the required propulsion power becomes greater.
  • a description of the physical phenomenon of choked flow is now provided where the key physics relates to the speed of sound. As the vehicle moves forward, it pushes the air in front which increases upstream pressure.
  • FIG. 4 depicts a graph of drag versus vehicle speed which identifies the critical vehicle speed that demarcates the pressure equilibrium scenario depicted in FIG. 2 and the choked flow scenario depicted in FIG. 3.
  • a maximum vehicle speed can be defined at which choking flow occurs. This maximum speed has been studied in the previously noted paper to Chin et al. (2015).
  • FIG. 5 extracted from the Chin et al. (2015) article, depicts a graph of the bypass area ratio (Bypass/Tube) versus the bypass air flow Mach number.
  • FIG. 5 demonstrates that, for a reasonable vehicle size (bypass area less than 50% of tube area), the maximum vehicle speed is about Mach 0.25. This corresponds to 300 km/h. This is clearly unacceptable for such a novel transportation system. There are several ways to get around this issue.
  • FIGS. 6(A)-(B) The drawback of the approach depicted in FIGS. 6(A)-(B) is that the installation of a compressor introduces significant cost, complexity in the design of the vehicle, and safety issues. Regarding safety, Uncontained Engine Failure (UERF) where the blade of the compressor can break and damage the vehicle itself, the tube, and other vehicles, and induce high constraints in the development of such a transport system.
  • UERF Uncontained Engine Failure
  • German patent publication, DE 2054063 Al discloses a high-speed passenger and container mass transit system using helium.
  • German patent publication, much like the current tube-based transportation systems fails to utilize a mixture of air and helium, where the composition of each gas in the mixture is dynamically determined to optimize drag.
  • German patent publication, much like the current tube-based transportation systems fails to utilize a mixture of air and helium, where the composition of each gas is dynamically determined depending on the desired velocity of the capsule.
  • the present invention provides a tubular transportation system for transporting one or more passengers or one or more cargos via a capsule along a predetermined route, the tubular transportation system comprising: a plurality of substantially evacuated tubes arranged along the predetermined route, each tube in the plurality of substantially evacuated tubes maintained at a pressure that is below atmospheric pressure; means for maintaining within each tube in the plurality of substantially evacuated tubes, a gaseous composition comprising a mixture of a first percentage, x, of helium and a second percentage, ( 100-x ), of air, and wherein the first percentage, x, of helium is picked based on a predetermined power value and a leak rate associated with each tube.
  • the present invention provides a tubular transportation system for transporting one or more passengers or one or more cargos via a capsule along a predetermined route
  • the tubular transportation system comprising: a plurality of substantially evacuated tubes arranged along the predetermined route, each tube in the plurality of substantially evacuated tubes maintained at a pressure that is below atmospheric pressure; means for maintaining within each tube in the plurality of substantially evacuated tubes, a gaseous composition comprising a mixture of a first percentage, x, of helium and a second percentage, ( 100-x ), of air; and wherein the first percentage, x, of helium is picked based on a predetermined power value and a leak rate associated with each tube, wherein the predetermined power value is a function of a first power to pump each tube to the substantially evacuated state and a second power to overcome aerodynamic drag.
  • the present invention provides a tubular transportation system for transporting one or more passengers or one or more cargos via a capsule along a predetermined route, the tubular transportation system comprising: a plurality of substantially evacuated tubes arranged along the predetermined route, each tube in the plurality of substantially evacuated tubes maintained at a pressure that is below atmospheric pressure; means for maintaining within each tube in the plurality of substantially evacuated tubes, a gaseous composition comprising a mixture of a first percentage, x, of helium and a second percentage, ( 100-x ), of air, and wherein the first percentage, x, of helium is picked based on a predetermined power value, a desired speed of the capsule, and a leak rate associated with each tube.
  • FIG. 1 depicts a schematic of a vehicle (also referred to as pod or capsule) within a tube- based transportation system.
  • FIG. 2 depicts the equilibrium mechanism where when pressure waves reach the front of the vehicle, the right amount of air flow escapes to the back of the vehicle.
  • FIG. 3 depicts the choking phenomenon that results when the pressure waves from the back of the vehicle do not reach the front of the vehicle.
  • FIG. 4 depicts a graph of drag versus vehicle speed which identifies the critical vehicle speed that demarcates the pressure equilibrium scenario depicted in FIG. 2 and the choked flow scenario depicted in FIG. 3.
  • FIG. 5 depicts a graph of the bypass area ratio (Bypass/Tube) versus the bypass air flow Mach number.
  • FIG. 6(A) depicts a scenario where an axial compressor is used at the front of the capsule in a tube-based transportation system.
  • FIG. 6(B) depicts the drag as a function of the vehicle speed in the scenario of FIG. 6(A).
  • FIG. 7 depicts Table 2 showing the distinguishing features of lightest weight gases, of which helium and hydrogen have the lowest densities.
  • FIG. 8 depicts Table 3 noting a list of the speed of sound entries for various gases.
  • FIG. 9 depicts Table 4 showing the mean free path for different molecules.
  • FIG. 10 depicts a view of the 2D mesh used in the present simulations.
  • FIG. 11 depicts Table 5 which compares air density to helium at 100 Pa.
  • FIG. 12 depicts a graph showing the drag coefficient from 2D simulation for air and helium.
  • FIG. 13 investigates the effect of density by plotting the actual drag for a 3D capsule against the capsule velocity.
  • FIG. 14 depicts a graph illustrating power reduction based on using light-weighted gas.
  • FIG. 15 depicts the results of CFD studies comparing maximum velocities at the K-limit attainable due to variations in the helium-air mixtures.
  • FIG. 16 depicts identifying a capsule speed given a power requirement for a specific combination of air and helium.
  • FIG. 17 illustrates a comparison of drag versus velocity, at the Kantrowitz limit, graphs for four basic tube pressures from 1-1000 Pa along with percentages of helium in air.
  • FIG. 18 illustrates a power versus velocity graph where the power requirements are reviewed for various pressures and various air-helium mixtures to identify optimal operational ranges.
  • FIG. 19 illustrates a drag versus velocity graph, just as FIG. 17, but for a lower bypass ratio of 0.208.
  • FIG. 20 illustrates a power versus velocity graph, just as FIG. 18, but for the lower bypass ratio of 0.208.
  • FIG. 21 illustrates a comparison of two non-limiting bypass ratio examples used in this disclosure, along with a sample calculation of how the bypass ratio is calculated in each instance.
  • FIG. 22 illustrates helium in the low bypass system (0.208) does allow speeds compared to the high bypass (0.489) region for certain gaseous mixtures of helium and air.
  • FIG. 23 illustrates a table depicting volume loading at 50 slm/km by percentage of helium.
  • FIG. 24 illustrates a table depicting volume loading at 5 slm/km by percentage of helium.
  • FIG. 25 depicts a graph of pump power (in kW) versus the percentage of helium for various pressures.
  • FIGS. 26A-C shows a summary of power requirements (kW) to balance aerodynamic drag at a pressures of 1000 Pa, 100 Pa and 10 Pa, respectively, for various capsule speeds versus percentages of helium and Air.
  • FIG. 27 depicts a graph of total power (in kW) (combining pumping power and aerodynamic power) versus the percentage of helium for various velocities at 100 Pa.
  • FIGS. 28A-C depicts such a non-limiting example, where the same analysis as FIGS. 25- 27 is performed for a leak of 5 slm/km.
  • FIG. 29 illustrates see how these graphs depicted in FIGS. 25-27 may be combined to provide optimum operating points for power (cost) and helium-air ratios.
  • FIG. 30 shows a graph of the diffusion coefficients for various gas in air.
  • FIG. 31 depicts a first implementation that includes a set of helium tanks uniformly fitted along the tube length, where helium is injected with controlled valves that open or close to maintain the desired level of helium.
  • FIG. 32 depicts a second implementation that includes helium tanks embedded in the vehicles.
  • FIG. 33 depicts an approach that combines the approaches of FIGS. 31 and 32. DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • the present invention overcomes the pitfalls associated with the prior art by using a mixture of air and helium (in various ratios to be described later) to modify the fluid properties such as speed of sound, which enables reaching high vehicle speed at acceptable propulsion power.
  • Advantages of using a mixture of air and helium include obtaining different fluid properties, such as, reduced density, higher speed of sound and higher free molecular path. These different fluid properties can substantially reduce the drag on the vehicle and the propulsion power needed.
  • the present invention discloses mixing different gases that are lighter than air, where these gases have smaller molecular diameter.
  • gases There are numerous gasses which meet the requirement of a gas molecule smaller than air.
  • the subject of this patent application is the use of helium, which has attractive properties that can be exploited in tube-based transportation systems. While, the air in the tube could be replaced completely by helium, this could be hard to achieve.
  • the present invention discloses using a mixture of air and helium in various ratios (which is discussed in detail later in this patent application), which still has interesting properties, while also providing an implementation at a lower cost (when compared to previously described prior art systems and when compared to equivalent systems that use just helium).
  • Table 1 demonstrates that the amount of helium to be injected in a 10 km tube is low, whether considering pure helium or a mixture of helium and air. At 100 Pa, the entire 10 km tube could be filled with pure helium at current cost of less than $300 (-$14.00/kg He). However, it is not possible to maintain a 100% helium content in a large welded tube due to leakage of air from outside the tube. It is the intent of this art to define optimum percentages of helium and air which reduce drag in the tube. Some of the advantages of the present invention are listed below. Gases that are lighter than air have a lower density, a higher speed of sound, and higher free mean path. This offers at least three advantages, simultaneously.
  • the first advantage is the possibility of significantly reducing the density of the gas. Since drag is proportional to the density, a reduction of the density of the gas directly impacts the drag. Table 2 below shows the density at atmospheric pressure for usual gases, extracted from the website (Source: Engineering Toolbox website).
  • Table 2 depicts the distinguishing features of lightest weight gases, of which helium and hydrogen have the lowest densities.
  • Helium has a density seven times lower than air at atmospheric pressure. This ratio is the same in a tube pressure of 100 Pa, which means that drag can be expected to be reduced by a factor of about seven. This is a major advantage that goes to the root of high speed transportation: reducing drag by reducing density.
  • R gas is the gas constant (8.3145 J/kg/K)
  • W gas is the gas molecular mass (kg/mol)
  • T is the temperature of the fluid. From EQN 2, the speed of sound can be increased by changing the molecular mass. In particular, a lightweight gas has a high speed of sound.
  • Table 3 is a list of the speed of sound entries for various gases (Source: Engineering Toolbox Website): From Table 3, it is seen that the lightest weight gases stand out in terms of their speed of sound entry.
  • Helium and hydrogen have the highest speed of sound.
  • Helium has a speed of sound three times higher than air while hydrogen has a speed of sound four times higher than air.
  • it is preferred to use Helium in the tube since flammability issues would have to be addressed with hydrogen, which would require some design changes).
  • Rmix is the specific gas constant of the mixture, ;1 ⁇ 2 « is the specific heat ratio of the mixture, and Tis the Temperature.
  • speed of sound is 664 m/s, which is twice the speed of sound in pure air.
  • the maximum speed of Mach 0.25 which was 300 km/h in air, now, based on the teachings of the present invention, becomes 600 km/h in the above noted mixture of air and helium. This gain is obtained without any other change in tube or capsule design.
  • the Kantrowitz limit occurs when gas flowing around the capsule becomes choked, i.e., at a speed of Mach 1. Mach 1 for air is 331 m/s at standard temperatures. Smaller molecular gases have higher speed of sound which allow them to flow much faster before choking. The capsule will not be subject to choking flows until the preferred, and much higher Mach speed is reached.
  • the Knudsen number compares to the mean free path, l, of the molecules and the vehicle characteristic size L (length or diameter). Hence, molecular flow region can be attained by increasing the mean free path.
  • k is the Botzmann constant
  • P is the pressure
  • d is the molecular diameter
  • Kn number can be derived not from just lowering the pressure, but rather from changing the diameter of the gas molecule, dm, in the denominator of the expanded free mean path (EQN. 5).
  • FIG. 11 depicts Table 5 which lists the density by mass figures for both air and helium at 100 Pa.
  • the reduction in density of over seven times (0.00116/0.00016) reduces drag in a similar ratio (i.e., seven times). This advantage holds true at differing pressures in the continuum range. (Note: Due to round off errors the bypass ratio is sometimes shown as 0.488 or 0.489)
  • Drag as previously noted in EQN. 1, is related to the drag coefficient by
  • the 2D simulations provide the Drag Coefficient at different pod velocities.
  • the estimated 3D drag is then obtained by multiplying the drag coefficient 1/2 P tube V pod S pod where p tUbe is the tube operating density, V pod is the pod velocity, and S pod is the frontal surface area of the pod.
  • FIG. 12 depicts a graph showing the drag coefficient from 2D simulation for air and helium.
  • the drag coefficient increases substantially when the velocity goes above the Kantrowitz limit. It is noted that the Kantrowitz limit for helium is reached at a speed about three times higher than that of air, which is in line with what was expected. It is also noted that below the Kantrowitz limit, the drag coefficients of helium and for air are similar (about 3.5 at 375 km/h). This is because the drag coefficient formula is drag divided by density.
  • FIG. 13 investigates the effect of density by plotting the actual drag for a 3D capsule against the capsule velocity. The graph below illustrates the behavior of the estimated Drag of the actual 3D pod for helium and air. The 3D drag is estimated using 2D Drag Coefficients and multiplying The graph in FIG. 13 confirms two important claims of the present invention:
  • the Kantrowitz limit Velocity for helium is about three times higher than that of air. Above the Kantrowitz limit, the drag starts rising substantially with velocity due to choking. Results shown in FIG. 13 confirm that helium can go to a velocity three times higher than that of air before reaching the Kantrowitz limit. Hence, helium can go to a velocity three times higher for a reasonable demand of power. Helium, therefore, can allow a capsule speed of nearly 1,000 km/h before the necessity of overcoming the Kantrowitz limit.
  • FIG. 14 depicts a graph illustrating power reduction based on using light-weighted gas, where the graph compares requirements to overcome aerodynamic drag with air versus helium (at 100 Pa).
  • the same power to offset aerodynamic drag can achieve speeds of over 900 kph in a helium-based system but can only achieve 425 kph in an air-based tube. Twice the speed is achieved for the same cost in aerodynamic power.
  • replacing air or part of air in the tube by light-weight gases provides at least the following advantages: lower density (and, hence, lower drag, implying lower propulsion power), higher speed of sound (and, hence, higher vehicle speed before occurrence of the choking phenomenon), and higher mean free path (and, hence, lower pump power to achieve molecular flow as molecular flow may avoid choke phenomenon and thus decrease propulsion power).
  • FIG. 15 depicts the results of CFD studies comparing maximum velocities at the K-limit attainable due to variations in the helium-air mixtures. Drag is a useful indicator to chart against velocity as there is no economic advantage to achieving higher speeds if the drag increases correspondingly.
  • the dashed vertical lines show the speed at the K limits, first, on the left, for pure air and lastly for pure helium.
  • the second vertical line, on the right, is for a 100% by volume helium filled tube and shows a maximum speed of exceeding 1,200 km/hr with an only nominal increase in drag. Comparing that to the air maximum speed line it is noted that the achievable speed has increased nearly three times from 425 km/hr to over 1,225 km/hr.
  • the operational cost is a function of power. Choosing an optimal speed with reference to cost can be qualitatively seen from the power versus gas mixture graph shown in FIG. 16. For example, given a power potential of approximately 27 kW, a target velocity of 800 km/hr may be achieved using a gaseous mixture of 5% air + 95% helium.
  • FIG. 17 illustrates a comparison of drag versus velocity, at the Kantrowitz limit, graphs for four basic tube pressures from 1-1000 Pa along with percentages of helium in air.
  • Drag is one of the key consumers of power that must be overcome by the propulsion system, the others being acceleration and gravity.
  • FIG. 18 illustrates a power versus velocity graph where the power requirements are reviewed for various pressures and various air-helium mixtures to identify optimal operational ranges. Aerodynamic power consumption graphs with varying helium percentages at pressures of 1, 10, 100 and 1000 Pascals are shown.
  • the present invention identifies that helium percentages in air ranging from 75%-99% are practical and effective for increasing capsule speeds from a base of 400 kph in pure air to as high as 1,150 kph in a mix of 99% He and 1 % air. Lower percentages of helium also provide improvements as shown, but due to the relative low cost of helium, do not provide optimum or most cost effective operating points. Helium percentages in the 75%-99% range are practical to control with current state-of-the-art mass flow controllers, sensors and control systems.
  • the present invention also shows optimum tube pressures which are economical to achieve, ranging from 10-100 Pa. Pressures below 10 Pa, such as 1-10 Pa, show promise in reducing drag, but move into the range of laminar flow and transition to a lower maximum speed at K limit. It is apparent, however, that even at these very low-pressure ranges below 1-10 Pa, helium shows an increase in attainable speeds and thus this operational environment will gain improvement from the addition of helium from the speed perspective. But, it is similarly interesting that the change in power requirements is very little compared to a pure air system. Thus, the range of power at 1 Pa with and without helium is only 0.5 to 2.5 kW.
  • a light-weighted gas system does not derive much incremental advantage at these pressure ranges (l-lOPa) in the drag/power regimes.
  • top speeds do enjoy a large incremental increase of 400 kph to 1,150 kph and thus it is expected that operations below 10 Pa will also include large percentages of helium similar to the ranges at 10 to 100 Pa.
  • FIG. 19 illustrates a drag versus velocity graph, just as FIG. 17, but for a lower bypass ratio of 0.208.
  • FIG. 19 depicts a low bypass system of 0.208 (4 m tube diameter and 10 m 2 pod area) and its aerodynamic drag improvements due to use of light- weighted gas mixtures.
  • the advantages of larger bypass ratio can be clearly seen in any of the above pressure graphs as the attainable speeds are more than double with the .489 bypass vs .208.
  • Top speed will be a major advantage on long routes and thus larger bypass ratios preferred, but on short routes the speed advantage is diminished, and smaller ratios may be acceptable.
  • smaller bypass ratios may be relevant for low-speed cargo operations during off hours and enables the use of larger cargo capsules in the same tube.
  • top speeds are reduced with the smaller bypass ratio, the advantages over pure air systems are still attained.
  • FIG. 20 illustrates a power versus velocity graph, just as FIG. 18, but for the lower bypass ratio of 0.208.
  • the power requirements may be reviewed for various pressures and various Air-helium mixtures to identify optimal operational ranges. Due the higher drag of the low ratio systems at same speeds, more power is required to attain the same speed. However, with the 0.208 bypass system, maximum speeds are still significantly increased over 100% air systems.
  • FIG. 21 illustrates a comparison of two non-limiting bypass ratio examples used in this disclosure, along with a sample calculation of how the bypass ratio is calculated in each instance. It should be noted that while this disclosure uses two bypass ratios, i.e., 0.489 bypass ratio for a capsule to transport humans and 0.208 bypass ratio for a cargo capsule, these ratios should in no way be used to limit the scope of the present invention, as the teaching of the present invention can be applied to other bypass ratios.
  • Adding helium helps significantly for the small bypass system scenario (versus a pure air system), where such an addition can be leveraged for larger capsules, such as cargo types.
  • Such addition of helium allows nearly three times the speed (when to compared to a pure air system), with only marginal increases in drag.
  • a significant speed penalty is paid for by the smaller bypass system as the maximum speed is limited to about half of that of the larger bypass system.
  • Using much lower pressures e.g., down to even 1 Pa) does not overcome the overwhelming advantages of large bypass systems.
  • each orifice follows standard gas laws and chokes at pressures drops above approximately 0.53 DR and will be limited to flow at sonic speeds.
  • the choking of each orifice maintains constant flow up to a tube pressure approximately 53,700 Pa.
  • Tube pressures in the region of 1-1000 Pa essentially creates equal air leaks.
  • each of these orifices will contribute small amount of Air into the vacuum vessel which must continuously be pumped if base pressure is to be maintained.
  • FIG. 23 illustrates a table depicting volume loading at 50 slm/km by percentage of helium.
  • leak rate 24 illustrates a table depicting volume loading at 5 slm/km by percentage of helium.
  • Such leak rates are merely provided as examples and should not be used to limit the scope of the invention. A discussion is now presented regarding how this leak rate must be accounted for in calculating preferred helium ratios as well as ideal operating pressure.
  • This leak rate is directly related to methods and materials of construction of the tube, where with knowledge of such methods and materials, one can populate Table in FIGS. 23 or 24 with more accurate numbers.
  • the leak rate may be calculated using standard vacuum system practices and should be measured for each part of the route. Such estimated data associated with different portions of the route is critical in estimating base tube pressures and percentages of helium that can be reasonably achieved within each portion of the route.
  • FIG. 25 depicts a graph of pump power (in kW) versus the percentage of helium for various pressures. As can be seen from FIG.
  • vacuum pumps are very sensitive to volumetric flow rates with power (kW), increasing in a geometric fashion at He-Air percentages beyond approximately 90%. These pumping power curves show the diminishing returns of trying to maintain high percentages of helium with respect to pumping power (kW). This deleterious effect is most pronounced at low tube pressures which is counter to the desire to operate at low pressure to reduce drag.
  • FIG. 25 shows the negative effects of high helium percentages versus necessary pump power to maintain those percentages. More is not better. The present invention leverages this effect to achieve optimum performance within a tube-based transportation system. In one embodiment, the most economical operating percentages can be deduced when coupling this result with the power required to overcome aerodynamic drag.
  • FIGS. 26A-C shows a summary of power requirements (kW) to balance aerodynamic drag at a pressures of 1000 Pa, 100 Pa and 10 Pa, respectively, for various capsule speeds versus percentages of helium and Air.
  • the highest speeds can only be attained with the highest percentages of helium.
  • capsule/propulsion power as shown in FIG. 25, those helium rich environments come at the cost of much added pump power.
  • the present invention uses a non-limiting example of 50 slm/km air leakage, but the specific air leakage number should not be used to limit the scope of the present invention. However, it should be noted that the teachings of the present invention may be applied to another leak rate, e.g. 5 slm/km, without departing from the scope of the invention.
  • FIGS. 28A-C depicts such a non-limiting example, where the same analysis as FIGS. 25- 27 is performed for a leak of 5 slm/km.
  • FIG. 28A depicts a graph of pump power (in kW) versus the percentage of helium for various pressures for an air leak of 5 slm/km.
  • FIG 28B depicts a graph of the capsule power (in kW) at 100 Pa. Since capsule power is not dependent on leak rate this is the same as graph 26B previously shown.
  • FIG. 28C depicts a graph of total power (in kW) (combining pumping power and aerodynamic power) versus the percentage of helium for various velocities at 100 Pa for an air leak of 5 slm/km.
  • the graphs in FIG. 27 depicts fairly flat power requirements at 600, 700 and 800 km/h up to 90% He mixtures. Looking closely at the graph in FIG. 27 (and using the data behind the graph to identify more precisely), it is seen that 75%-85% helium in the tube appears acceptable. An operator would not want to operate at 75% He and 800 km/h, however, as there would be very little safety margin before reaching the K-limit and ensuing shock in the bypass area.
  • FIG. 29 illustrates see how these graphs depicted in FIGS. 25-27 may be combined to provide optimum operating points for power (cost) and helium-Air ratios.
  • FIG. 29 shows an optimum helium operating point at 600 kph based solely on power requirements— least cost per km for tube pressures of 100 Pa for this set of speeds. This could be considered the most economic (or eco mode) at that pressure and set of speeds.
  • the same optimization can be done at 700 kph requiring 80% of helium and 20 percentage of Air, with nearly 50% more power expended, but resulting in shorter transit times by 17% (based on increasing the speed from 600 km/h to 700 km/h).
  • Some operators may choose the‘optimum’ power to attain maximum speeds.
  • the methods as per the present invention identify what percentages of helium are required to achieve such maximum speeds.
  • operation at minimum power which provides the longest capsule battery life and allows longer routes where trackside power is not available.
  • an‘affordable’ power that allows some higher speed operations but still allows increase in the route length.
  • Route calculations rely on the length, curvature and elevation changes within the route and the source of propulsion power. Differing motives of operation will dictate what percentage of helium is ideal based on the route and whether operating at‘optimum’,‘minimum’ or‘affordable’ conditions.
  • the process of adding helium to the tube is certainly a very cost effective and simple method of improving tube-based transportation system performance.
  • Using helium to optimize improves both capital and operational economics.
  • identifying and operating in these optimum spots, and even varying the percentage of helium based on changing operations (passenger vs cargo) can be automated and implemented during daily operations.
  • the percentage of helium is a major determinant of maximum speed and least power along with bypass ratio, air leakage, and tube pressure.
  • the distribution and percentages of the light-weight gas within the length of the tube is an important consideration to maintain these advantages.
  • the ability to maintain that percentage of helium and homogeneity within the tube is important to achieving these advantages.
  • we also see that much higher percentages of the light-weight gas are sometimes desired or required.
  • Different portions of a route may be speed constrained due to curves, stations, elevations changes, etc., while other portions of the route will allow maximum speeds.
  • a homogeneous mixture must be attainable, but there several conditions under which the most helium rich mixture economically attainable is preferred, such as high-speed sections of the route. Methods of achieving both homogeneous and enriched He atmospheres are described below.
  • the tube that guides and encloses the vehicles 3.
  • the pump that maintains low pressure in the tube and compensates for Air leaks (from atmosphere to the tube)
  • the present invention proposes additional components to create and to maintain a homogeneous mixture of gases and additionally how to improve some tube areas resulting in increased local percentages of light-weight gases.
  • a source of gas (other than air)
  • One or many gas tanks in each vehicle or in some vehicles located at known critical geometry locations on the capsule which are most prone to shock or disturbances from high speed flow surrounding the capsule. These specifically are near the nose such that light-weighted gas concentration can be increased as the flow begins its movement over the capsule body, along the capsule body at points where flows are near the critical K-limit, near the tail to reduce shock waves and instability created therein, and finally at the tail to increase the gas concentration in preparation for any following capsule.
  • a system to inj ect light-weighted gases that is comprised of a valve, regulator, mass flow controller, electronic controls and injector nozzles located in any of several locations within the hyperloop system. This system is under control of the operations control center which is continuously monitoring gas concentrations within the tube and supplying commands to the injection system on proper amounts to inject in order to maintain optimum gas ratios.
  • a system to recycle gas A system integrated into the pumping system, which separates light-weighted gases from the air/gas mix, so that they are not exhausted to atmosphere but are recycled back into the tube.
  • This is comprised of an air separation unit or membrane style gas separation unit which takes the vacuum pump exhaust from the tube and separates out the light-weighted gases for recycling into the gas inj ection system or to a storage system for future use when the preferred gas ratio is out of balance.
  • a system to monitor gas pressure and gas concentrations including gas sensors, a data feedback and logging function plus a data control system.
  • the output from these transducers is sent to the OCC unit which uses software algorithms to compare measured vs ideal concentrations and responds with control outputs to the gas injection system.
  • the gas control system further has optimization routines to provide closed loop control of required gas concentrations and homogeneity based on sensor output.
  • OCC Operations Control Center
  • the methods used to place the preferred gases into the tube is an area to optimize. Multiple methods are envisioned for filling the tube with these gases. Individual and/or combined methods such as injection through the tube wall, injection from the capsule, from valves placed onto the tube or tube attachments, from the capsule, or potentially from the vacuum pumping system all are viable methods.
  • Injecting the small diameter gas through various critical points in the capsule has some potential significant advantages to enrichen the helium content in localized areas around the capsule to reduce shock waves, turbulence, and possible capsule instability due to these factors. It can also be surmised that capsules in the tube behind a lead injecting capsule may benefit significantly by these same factors. Such a method of optimized capsule shell injection is another advantage of the present invention.
  • Novel methods of capturing the vacuum pump exhaust and separating out the smaller diameter gases through typical air separation units or other types of separation could be used to recycle the gas back into the tube and are also envisioned as part of the present invention. Additionally, there are certain methods to introduce the gas into the tube that are preferred, such as to evacuate the tube and refill it partially with the preferred gas. Several repetitions of this pump and backfill can be done until the percentage of preferred gas or gas mixture is at the proper level. Such methods are also envisioned as part of the present invention.
  • Mixture homogeneity is another challenge. Homogeneity can be ensured by the uniformly spaced reservoirs of gas, or gas tanks. Homogeneity can also be ensured by the motion of the vehicle, possibly creating vortices and/or turbulence in their wake that mix the gases.
  • FIG. 30 depicts a graph of the diffusion coefficients for various gas in air (source: Engineering Toolbox website).
  • FIG. 30 shows that light-weight gases, such as helium and hydrogen, have much higher diffusion coefficients in air than other gases.
  • helium has a diffusion coefficient almost four times higher than methane or water vapor with hydrogen being slightly superior. This makes helium and hydrogen the best candidates to obtain and maintain a homogeneous mixture within the tubes.
  • FIG. 31 depicts a first implementation that includes a set of helium tanks uniformly fitted along the tube length, where helium is injected with controlled valves that open or close to maintain the desired level of helium.
  • the pumping system is linked to a separator system that removes air and re-injects helium in the tank.
  • FIG. 32 depicts a second implementation that includes helium tanks embedded in the vehicles. The tanks open helium release via command control. The helium can be released in the wake of the vehicle, taking advantage of the vortices for good mixing.
  • the helium tank can be filled when vehicles are docked. Helium is collected by the separation system integrated in the Pumping System.
  • FIG. 33 depicts an approach that combines the approaches of FIGS. 31 and 32.
  • the embodiment depicted in FIG. 31 involves injection of the gases or mixtures directly into the tube via ports connected to mass flow controllers and valves, supplied by gas lines or compressed gas bottles, to precisely control the amounts of each gas introduced.
  • the amount will be dependent on analysis of the gases within the tube and controlled by the Operations Control Center (OCC).
  • OOC Operations Control Center
  • the spacing of these injection points needs to be engineered. It may be that injecting He into the tube just in front of the moving capsule will aid the capsule aerodynamics. Injecting He, such that its percentage is very high as the capsule approaches the injection point could aid in reducing shock waves and in reducing drag.
  • OCC Operations Control Center
  • FIG. 33 combines the teachings of the embodiments depicted in FIG. 30 and FIG. 31.
  • the feature of maintaining within each tube (in a plurality of substantially evacuated tubes) particular percentages of helium and air can be implemented in software process where a processor (or controller) executes instructions to control mechanisms, such as valves, to release specific percentages of helium or release specific percentages of helium and air.
  • a processor or controller
  • the feature of picking a percentage helium based on a predetermined power value and a leak rate associated with each tube can be implemented in software process where a processor (or controller) executes instructions stored in storage to identify such a percentage of helium.
  • the feature of picking a percentage helium based on a predetermined power value that is a function of both pump power and power to overcome drag and a leak rate associated with each tube can be implemented in software process where a processor (or controller) executes instructions stored in storage to identify such a percentage of helium.
  • the feature of picking a percentage helium based on a predetermined power value, a desired speed of the capsule, and a leak rate associated with each tube can be implemented in software process where a processor (or controller) executes instructions stored in storage to identify such a percentage of helium.
  • the above-described features and applications can be implemented as software processes that are specified as a set of instructions recorded on a computer readable storage medium (also referred to as computer readable medium).
  • a computer readable storage medium also referred to as computer readable medium.
  • processing unit(s) e.g., one or more processors, cores of processors, or other processing units
  • Embodiments within the scope of the present disclosure may also include tangible and/or non-transitory computer-readable storage media for carrying or having computer-executable instructions or data structures stored thereon.
  • Such non-transitory computer-readable storage media can be any available media that can be accessed by a general purpose or special purpose computer, including the functional design of any special purpose processor.
  • non-transitory computer-readable media can include flash memory, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions, data structures, or processor chip design.
  • the computer readable media does not include carrier waves and electronic signals passing wirelessly or over wired connections.
  • Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions.
  • Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments.
  • program modules include routines, programs, components, data structures, objects, and the functions inherent in the design of special-purpose processors, etc. that perform particular tasks or implement particular abstract data types.
  • Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps.
  • processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.
  • a processor will receive instructions and data from a read-only memory or a random access memory or both.
  • the essential elements of a computer are a processor for performing or executing instructions and one or more memory devices for storing instructions and data.
  • a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks.
  • mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks.
  • a computer need not have such devices.
  • a computer can be embedded in another device, e.g., a controller, a programmable logic controller, just to name a few.
  • the term“software” is meant to include firmware residing in read- only memory or applications stored in magnetic storage or flash storage, for example, a solid-state drive, which can be read into memory for processing by a processor.
  • multiple software technologies can be implemented as sub-parts of a larger program while remaining distinct software technologies.
  • multiple software technologies can also be implemented as separate programs.
  • any combination of separate programs that together implement a software technology described here is within the scope of the subject technology.
  • the software programs, when installed to operate on one or more electronic systems define one or more specific machine implementations that execute and perform the operations of the software programs.
  • a computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment.
  • a computer program may, but need not, correspond to a file in a file system.
  • a program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).
  • a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
  • Such computer-readable media include RAM, ROM, read-only compact discs (CD-ROM), recordable compact discs (CD-R), rewritable compact discs (CD-RW), read-only digital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a variety of recordable/rewritable DVDs (e g., DVD-RAM, DVD-RW, DVD+RW, etc.), flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic or solid state hard drives, read-only and recordable Blu-Ray ® discs, ultra density optical discs, any other optical or magnetic media, and floppy disks.
  • RAM random access memory
  • ROM read-only compact discs
  • CD-R recordable compact discs
  • CD-RW rewritable compact discs
  • read-only digital versatile discs e.g., DVD-ROM, dual-layer DVD-ROM
  • flash memory e.g., SD cards, mini-
  • the computer-readable media can store a computer program that is executable by at least one processing unit and includes sets of instructions for performing various operations.
  • Examples of computer programs or computer code include machine code, for example is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter. While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some implementations are performed by one or more integrated circuits, for example application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). In some implementations, such integrated circuits execute instructions that are stored on the circuit itself.
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Power Engineering (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

L'invention concerne un système de transport tubulaire permettant de transporter un ou plusieurs passagers ou une ou plusieurs cargaisons par l'intermédiaire d'une capsule le long d'un itinéraire prédéterminé. Le système de transport tubulaire comprend : (1) une pluralité de tubes quasiment sous vide disposés le long de l'itinéraire prédéterminé, chaque tube étant maintenu à une pression qui est inférieure à la pression atmosphérique ; et (2) un moyen permettant de maintenir à l'intérieur de chaque tube de la pluralité de tubes quasiment sous vide, une composition gazeuse comprenant un mélange d'un premier pourcentage, x, d'hélium et d'un second pourcentage, (100-x), d'air, et le premier pourcentage, x, d'hélium étant choisi sur la base d'une valeur de puissance prédéterminée et d'un taux de fuite associé au tube.
PCT/US2018/040256 2018-06-29 2018-06-29 Systèmes de transport par tube utilisant un mélange gazeux constitué d'air et d'hélium WO2020005273A1 (fr)

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EP18924654.9A EP3814164A4 (fr) 2018-06-29 2018-06-29 Systèmes de transport par tube utilisant un mélange gazeux constitué d'air et d'hélium
PCT/US2018/040256 WO2020005273A1 (fr) 2018-06-29 2018-06-29 Systèmes de transport par tube utilisant un mélange gazeux constitué d'air et d'hélium
CN201880097012.7A CN112638693A (zh) 2018-06-29 2018-06-29 使用空气和氦气的气体混合物的管道运输系统

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WO2020005278A1 (fr) * 2018-06-29 2020-01-02 Hyperloop Transportation Technologies, Inc. Procédé d'utilisation d'air et d'hélium dans des systèmes de transport par tube à basse pression

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