Apparatus and method for volume and mass estimation of a multiphase fluid stored at cryogenic temperatures

• US 9,513,155 B2
• Filed: 03/26/2014
• Issued: 12/06/2016
• Est. Priority Date: 09/27/2011
• Status: Active Grant

• Current Assignee: HPDI Technology Limited Partnership
• Original Assignee: Westport Power Inc. (Westport Fuel Systems, Inc.)
• Inventors: Harper, Gregory C., Batenburg, Gregory A., Schranz, Paul S.
• Primary Examiner(s): McCall, Eric S
• Assistant Examiner(s): Keramet-Amircolai, Mohammed E
• Application Number:
  US14/226,650
• Publication Number:
  US 20140223992A1
• Time in Patent Office: 986 Days
• Field of Search: 73/233.1, 73/290.3, 73/240.1, 733/04.C, 733/11
• US Class Current: 1/1
• CPC Class Codes: F17C 13/021 having the height as the parameter
• CPC Class Codes: F17C 2201/0109 with exteriorly curved end-piece
• CPC Class Codes: F17C 2201/035 with substantially horizontal main axis
• CPC Class Codes: F17C 2201/056 Small (<1 m3)
• CPC Class Codes: F17C 2201/058 portable (<30 l)
• CPC Class Codes: F17C 2203/0629 Two walls
• CPC Class Codes: F17C 2205/0332 Safety valves or pressure relief valves
• CPC Class Codes: F17C 2221/011 Oxygen
• CPC Class Codes: F17C 2221/012 Hydrogen
• CPC Class Codes: F17C 2221/014 Nitrogen
• CPC Class Codes: F17C 2221/016 Noble gases (Ar, Kr, Xe)
• CPC Class Codes: F17C 2221/033 Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
• CPC Class Codes: F17C 2223/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2223/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2223/047 with a dip tube
• CPC Class Codes: F17C 2225/045 with a dip tube
• CPC Class Codes: F17C 2250/032 using computers
• CPC Class Codes: F17C 2250/0417 with electrical means
• CPC Class Codes: F17C 2250/0421 Mass or weight of the content of the vessel
• CPC Class Codes: F17C 2250/043 Pressure
• CPC Class Codes: F17C 2250/0473 : Time or time periods
• CPC Class Codes: F17C 2250/0495 : the indicated parameter is a converted measured parameter
• CPC Class Codes: F17C 2260/025 : Reducing transfer time
• CPC Class Codes: F17C 2260/026 : by calculation
• CPC Class Codes: F17C 2270/0168 : by vehicles
• CPC Class Codes: G01F 17/00 : Methods or apparatus for determining the capacity of containers or cavities, or the volume of solid bodies measuring linear dimensions to determine volume G01B
• CPC Class Codes: G01F 23/14 : by measurement of pressure
• CPC Class Codes: G01F 23/26 : by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
• CPC Class Codes: G01F 23/296 : Acoustic waves
• CPC Class Codes: G01F 23/30 : by floats
• CPC Class Codes: G01F 23/80 : Arrangements for signal processing
• CPC Class Codes: G01F 25/00 : Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
• CPC Class Codes: G01F 25/0084 : for measuring volume
• CPC Class Codes: G01N 9/24 : by observing the transmission of wave or particle radiation through the material
• CPC Class Codes: Y02E 60/32 : Hydrogen storage

Abstract

An apparatus and method estimate fluid mass in a cryogenic tank that holds a multiphase fluid comprising a liquid and a vapor. The apparatus comprises a level sensor, a pressure sensor and a computer. The level sensor provides a parameter representative of a level of the liquid. The pressure sensor provides a pressure signal representative of vapor pressure inside the cryogenic tank. The computer is operatively connected with the level sensor and the pressure sensor to receive the parameter and the pressure signal, and is programmed to determine the level from inputs comprising the parameter, to calculate a first volume of the liquid from inputs comprising the level, and to calculate a first mass of the liquid from inputs comprising the first volume and the pressure signal.

Claims

1. A method of estimating fluid mass in a cryogenic tank that holds a multiphase fluid comprising a liquid and a vapour, wherein the liquid has a density and the vapour has a pressure, the method comprising steps of:

employing a capacitance-type level sensor to provide a parameter representative of a level of the liquid in the cryogenic tank;

measuring the vapour pressure inside the cryogenic tank;

adjusting respective parameters representative of a capacitance of an empty level and a capacitance of a full level of the capacitance-type level sensor as a function of the vapour pressure;

measuring a parameter representative of the actual capacitance of the capacitance-type level sensor;

calculating the level of the liquid in the cryogenic tank as a function of the parameters representative of the capacitance of the empty level, the capacitance of the full level, and the actual capacitance of the capacitance-type level sensor;

calculating a first volume of the liquid as a function of the level of the liquid in the cryogenic tank; and

calculating a first mass of the liquid from inputs comprising the first volume and the density of the liquid.

2. The method of claim 1, wherein the fluid is a fuel for combustion in an internal combustion engine in a vehicle, the method further comprising a step of estimating a fuelling range for the vehicle from the first mass.

3. The method of claim 1, wherein the step of employing the capacitance-type level sensor comprises sub-steps of:

providing a pair of spaced apart conductors, the spaced apart conductors being disposed within the cryogenic tank and forming in part a capacitor; and

calibrating the capacitance-type level sensor at least once prior to first introduction of the cryogenic liquid in the cryogenic tank, wherein calibrating the capacitance-type level sensor comprises steps of;

applying a measuring signal to the capacitor;

measuring a parameter representative of a dry capacitance of the capacitor in a dry state, a first dielectric having a first dielectric constant being disposed between the spaced apart conductors in the dry state;

estimating the parameter representative of the capacitance of the empty level in the cryogenic tank, a second dielectric having a second dielectric constant being disposed between the spaced apart conductors at the empty level, the parameter representative of the capacitance of the empty level being estimated based on the parameter representative of the dry capacitance and a first ratio of dielectric constants comprising the first dielectric constant and the second dielectric constant; and

estimating the parameter representative of the capacitance of the full level in the cryogenic tank, a third dielectric having a third dielectric constant being disposed between the spaced apart conductors at the full level, the parameter representative of the capacitance of the full level being estimated based on the parameter representative of the dry capacitance and a second ratio of dielectric constants comprising the first dielectric constant and the third dielectric constant.

4. The method of claim 3, wherein the second dielectric is the vapour and the third dielectric is the liquid.

5. The method of claim 3, wherein the step of calibrating further comprises a sub-step of calculating the second dielectric constant and the third dielectric constant as a function of the vapour pressure.

6. The method of claim 1, wherein the step of calculating the level of the liquid in the cryogenic tank comprises a sub-step of interpolating the level of the liquid in the cryogenic tank between the empty level and the full level based on the actual capacitance of the capacitance-type level sensor.

7. The method of claim 1, wherein the step of calculating the first volume comprises a sub-step of employing a mathematical relationship between the level of the liquid in the cryogenic tank and the first volume.

8. The method of claim 1, wherein the step of calculating the first volume comprises a sub-step of employing an empirical relationship between the level of the liquid in the cryogenic tank and the first volume.

9. The method of claim 1, wherein the step of calculating the first mass comprises

estimating the density of the liquid from inputs comprising the vapour pressure.

10. The method of claim 9, wherein the step of estimating the density comprises a sub-step of employing a mathematical relationship between the vapour pressure and the density.

11. The method of claim 9, wherein the step of estimating the density comprises a sub-step of employing an empirical relationship between the vapour pressure and the density.

12. The method of claim 9, wherein the density is estimated from inputs comprising a speed of propagation of acoustic waves through the liquid.

13. The method of claim 9, wherein the step of estimating the density comprises sub-steps of:

(i) estimating a composition of the liquid; and

(ii) estimating the density based on the composition of the liquid.

14. The method of claim 1, wherein the step of calculating the first mass comprises a sub-step of estimating a composition of the liquid.

15. The method of claim 14, wherein the step of estimating the composition comprises a sub-step of employing a fluid composition sensor.

16. The method of claim 14, wherein the step of estimating the composition comprises a sub-step of estimating a methane composition.

17. The method of claim 1, further comprising a step of calculating a second mass of the vapour, a total fluid mass being the sum of the first mass and the second mass.

18. The method of claim 17, wherein the fluid is a fuel for combustion in an internal combustion engine of a vehicle, the method further comprising a step of estimating fuelling range for the vehicle from the total fluid mass.

19. The method of claim 17, wherein the step of calculating the second mass comprises sub-steps of:

(i) calculating a second volume occupied by the vapour;

(ii) estimating a density of the vapour; and

(iii) estimating the second mass based on the second volume and the density.

20. The method of claim 19, wherein the step of estimating the density comprises a sub-step of calculating the density as a function of the vapour pressure.

21. The method of claim 19, wherein the step of estimating the density comprises sub-steps of:

(i) estimating a composition of the vapour; and

(ii) estimating the density based on the composition of the vapour.

22. The method of claim 1, wherein the fluid is natural gas.

23. An apparatus for estimating fluid mass in a cryogenic tank that holds a multiphase fluid comprising a liquid and a vapour, the apparatus comprising:

a capacitance-type level sensor capable of providing a parameter representative of a capacitance of the capacitance-type level sensor;

a pressure sensor capable of providing a pressure signal representative of vapour pressure inside the cryogenic tank; and

a computer operatively connected with the capacitance-type level sensor and the pressure sensor to receive the parameter and the pressure signal, and being programmed to;

determine vapour pressure inside the tank as a function of the pressure signal;

adjust respective parameters representative of a capacitance of an empty level and a capacitance of a full level of the capacitance-type level sensor as a function of the vapour pressure;

calculate a level of the liquid in the cryogenic tank as a function of the parameters representative of the empty level capacitance, the full level capacitance and the capacitance of the capacitance-type level sensor;

calculate a first volume of the liquid as a function of the level of the liquid in the cryogenic tank; and

calculate a first mass of the liquid from inputs comprising the first volume and a density of the liquid.

24. The apparatus of claim 23, wherein the fluid is natural gas.

25. The apparatus of claim 23, wherein the fluid is a fuel for combustion in an internal combustion engine in a vehicle, the computer being further programmed to estimate a fuelling range for the vehicle from the first mass.

26. The apparatus of claim 23, wherein the capacitance-type level sensor comprises a pair of spaced apart conductors disposed within the cryogenic tank and a measurement apparatus operatively connected with the spaced apart conductors and being adapted to apply a measuring signal thereto and measure instantaneous values of parameters therefrom representative of corresponding instantaneous values of capacitance of the spaced apart conductors, the computer being in communication with the measurement apparatus and being further programmed to calibrate the capacitance-type level sensor at least once prior to first introduction of the cryogenic liquid in the cryogenic tank, the computer being programmed to:

command the measuring signal be applied to the spaced apart conductors;

receive a parameter from the measurement apparatus representative of a dry capacitance of the spaced apart conductors in a dry state, a first dielectric having a first dielectric constant being disposed between the spaced apart conductors in the dry state;

estimate the parameter representative of the capacitance of the empty level in the cryogenic tank, a second dielectric having a second dielectric constant being disposed between the spaced apart conductors at the empty level, the parameter representative of the capacitance of the empty level being estimated based on the parameter representative of the dry capacitance and a first ratio of dielectric constants comprising the first dielectric constant and the second dielectric constant; and

estimate the parameter representative of the capacitance of the full level in the cryogenic tank, a third dielectric having a third dielectric constant being disposed between the spaced apart conductors at the full level, the parameter representative of the capacitance of the full level being estimated based on the parameter representative of the dry capacitance and a second ratio of dielectric constants comprising the first dielectric constant and the third dielectric constant.

27. The method of claim 26, wherein the second dielectric is the vapour and the third dielectric is the liquid.

28. The apparatus of claim 26, wherein the computer is further programmed to calculate the second dielectric constant and the third dielectric constant as a function of the vapour pressure.

29. The apparatus of claim 23, wherein the computer is further programmed to interpolate the level of the liquid in the cryogenic tank between the empty level and the full level based on the capacitance of the capacitance-type level sensor.

30. The apparatus of claim 23, wherein the computer is further programmed to employ a mathematical relationship between the level of the liquid in the cryogenic tank and the first volume.

31. The apparatus of claim 23, wherein the computer is further programmed to employ an empirical relationship between the level of the liquid in the cryogenic tank and the first volume.

32. The apparatus of claim 23, wherein the computer is further programmed to:

estimate the density of the liquid from inputs comprising the vapour pressure.

33. The apparatus of claim 32, wherein the computer is further programmed to employ a mathematical relationship between the vapour pressure and the density.

34. The apparatus of claim 32, wherein the computer is further programmed to employ an empirical relationship between the vapour pressure and the density.

35. The apparatus of claim 32, wherein the apparatus further comprises an ultrasonic sensor for sensing a speed of propagation of acoustic waves in the liquid, the density of the cryogenic liquid being estimated from inputs comprising the speed of propagation of the acoustic waves.

36. The apparatus of claim 23, wherein the apparatus further comprises a fluid composition sensor providing a fluid composition signal;

the computer being responsive to the fluid composition signal to estimate at least a portion of a composition of the liquid.

37. The apparatus of claim 36, wherein the fluid composition sensor is a methane composition sensor.

38. The apparatus of claim 36, wherein the computer is further programmed to estimate the density based on the at least a portion of the composition of the liquid.

39. The apparatus of claim 23, wherein the computer is further programmed to calculate a second mass of the vapour, a total fluid mass being the sum of the first mass and the second mass.

40. The apparatus of claim 39, wherein the fluid is a fuel for combustion in an internal combustion engine of a vehicle, the computer being further programmed to estimate a fuelling range for the vehicle from the total fluid mass.

41. The apparatus of claim 39, wherein the computer is further programmed to:

calculate a second volume occupied by the vapour;

estimate a density of the vapour; and

estimate the second mass based on the second volume and the density.

42. The apparatus of claim 41, wherein the computer is further programmed calculate the density as a function of the vapour pressure.

43. The apparatus of claim 41, wherein the apparatus further comprises a fluid composition sensor providing a fluid composition signal;

the computer being responsive to the fluid composition signal to estimate at least a portion of a composition of the vapour, the computer being further programmed to estimate the density based on the at least a portion of the composition of the vapour.