# US 8,783,303 B2 · Method and system for tank refilling

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- Number: US 8,783,303 B2
- Document ID: US8783303B2
- Status: Granted
- Kind: B2
- Application number: 12/982,966
- Filed: 2010-12-31
- Published: 2011-10-27
- Granted: 2014-07-22
- Earliest claimed: 2010-04-21
- Applicants: Ryan Harty; Steve Mathison
- Inventors: Ryan Harty; Steve Mathison
- Web page: https://patentgrep.com/patent/US8783303B2

## CPC

- F17C 13/023: {having the mass as the parameter}
- F17C 5/007: {for individual gas tanks or containers, e.g. in vehicles (filling with liquid fuel not under pressure, B60S5/02, B67D7/00)}
- F17C 5/06: for filling with compressed gases
- F17C 13/025: {having the pressure as the parameter}
- F17C 13/026: {having the temperature as the parameter}
- F17C 2201/0109: with exteriorly curved end-piece
- F17C 2201/054: medium (>1 m3)
- F17C 2203/0604: Liners
- F17C 2203/0619: with two layers
- F17C 2203/0624: with four or more layers
- F17C 2221/012: Hydrogen
- F17C 2221/033: Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
- F17C 2223/0123: gaseous, e.g. CNG, GNC
- F17C 2223/0153: Liquefied gas, e.g. LPG, GPL
- F17C 2223/0161: cryogenic, e.g. LNG, GNL, PLNG
- F17C 2223/036: Very high pressure (>80 bar)
- F17C 2225/0123: gaseous, e.g. CNG, GNC
- F17C 2225/036: Very high pressure, i.e. above 80 bars
- F17C 2250/043: Pressure
- F17C 2250/0439: Temperature
- F17C 2250/0443: Flow or movement of content
- F17C 2250/0491: Parameters measured at or inside the vessel
- F17C 2250/0495: the indicated parameter is a converted measured parameter
- F17C 2250/0631: Temperature
- F17C 2250/0694: with calculations
- F17C 2260/022: Avoiding overfilling
- F17C 2260/023: Avoiding overheating
- F17C 2260/025: Reducing transfer time
- F17C 2260/026: by calculation
- F17C 2265/065: for refuelling vehicle fuel tanks
- F17C 2270/0139: Fuel stations
- F17C 2270/0168: by vehicles
- F17C 2270/0176: Buses
- Y02E 60/32: Hydrogen storage
- F17C: VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES (storing fluids in natural or artificial cavities or chambers in the earth B65G5/00; construction or assembling of bulk storage containers employing civil-engineering techniques E04H7/00; variable-capacity gas-holders F17B; liquefaction or refrigeration machines, plants, or systems F25)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Disclosed is a simple, analytical method that can be utilized by hydrogen filling stations for directly and accurately calculating the end-of-fill temperature in a hydrogen tank that, in turn, allows for improvements in the fill quantity while tending to reduce refueling time. The calculations involve calculation of a composite heat capacity value, MC, from a set of thermodynamic parameters drawn from both the tank system receiving the gas and the station supplying the gas. These thermodynamic parameters are utilized in a series of simple analytical equations to define a multi-step process by which target fill times, final temperatures and final pressures can be determined. The parameters can be communicated to the station directly from the vehicle or retrieved from a database accessible by the station. Because the method is based on direct measurements of actual thermodynamic conditions and quantified thermodynamic behavior, significantly improved tank filling results can be achieved.

## Claims

### Claim 1

A method of filling a compressed gas tank, the method comprising:
calculating a hot soak initial temperature THSinit for an initial mass of gas within the tank;
determining a projected fill time using THSinit that is predicted to produce a gas final temperature Tfinal no greater than a target temperature T;
calculating a cold soak initial temperature TCSinit for an initial mass of gas within the tank;
calculating for the tank a composite heat capacity value MC corresponding to heat transferred to the tank, a tank assembly and the initial mass of gas within the tank gas, while filling the tank;
determining a target pressure Ptarget using TCSinit that is predicted to produce a target state of charge within the tank; and
delivering gas to the tank at a pressure ramp rate that will achieve Ptarget at the projected fill time.

### Claim 2 (depends on 1)

The method of filling a compressed gas tank according to claim 1, wherein:
the calculating the MC comprises:
calculating a composite heat capacity value MC according to at least one of the equations
MC
⁡
(
U
,
t
)
=
C
+
Aln
(
U
adiabatic
U
initial
)
+
g
⁡
(
1
-
ⅇ
-
k
⁢
⁢
Δ
⁢
⁢
t
)
j
and
MC
⁡
(
U
,
t
)
=
C
+
A
⁡
(
U
adiabatic
U
initial
)
+
g
⁡
(
1
-
ⅇ
-
k
⁢
⁢
Δ
⁢
⁢
t
)
j
wherein C, A, g, k and j are constants specific to the tank, Uinitial represents the initial internal energy of the initial volume of gas and Uadiabatic represents the adiabatic internal energy of a final mass of gas after filling the tank.

### Claim 3 (depends on 1)

The method of filling a compressed gas tank according to claim 1, wherein:
the determining the fill time further comprises
calculating an initial mass minit;
calculating an additional mass madd necessary to achieve the state of charge of 100% within the tank;
calculating the initial internal energy Uinitial;
estimating the average enthalpy haverage to be delivered to the tank with the additional mass; and
calculating an adiabatic internal energy Uadiabatic and an adiabatic temperature Tadiabatic,
wherein the calculating the MC comprises calculating a composite heat capacity value MC according to at least one of the equations
MC
⁡
(
U
,
t
)
=
C
+
Aln
(
U
adiabatic
U
initial
)
+
g
⁡
(
1
-
ⅇ
-
k
⁢
⁢
Δ
⁢
⁢
t
)
j
and
MC
⁡
(
U
,
t
)
=
C
+
A
⁡
(
U
adiabatic
U
initial
)
+
g
⁡
(
1
-
ⅇ
-
k
⁢
⁢
Δ
⁢
⁢
t
)
j
wherein C, A, g, k and j are constants specific to the tank.

### Claim 4 (depends on 3)

The method of filling a compressed gas tank according to claim 3, further comprising:
determining the values C, A, g, k and j for the tank.

### Claim 5 (depends on 1)

The method of filling a compressed gas tank according to claim 1, wherein:
the determining the target pressure Ptarget further comprises
calculating a cold initial mass minitC;
calculating an additional mass madd necessary to achieve the state of charge of 100% within the tank;
calculating the initial internal energy Uinitial;
estimating the average enthalpy haverage to be delivered to the tank with the additional mass; and
calculating an adiabatic internal energy Uadiabatic and an adiabatic temperature Tadiabatic,
wherein the calculating the MC comprises calculating a composite heat capacity value MC according to at least one of the equations
MC
⁡
(
U
,
t
)
=
C
+
Aln
(
U
adiabatic
U
initial
)
+
g
⁡
(
1
-
ⅇ
-
k
⁢
⁢
Δ
⁢
⁢
t
)
j
and
MC
⁡
(
U
,
t
)
=
C
+
A
⁡
(
U
adiabatic
U
initial
)
+
g
⁡
(
1
-
ⅇ
-
k
⁢
⁢
Δ
⁢
⁢
t
)
j
wherein C, A, g, k and j are constants specific to the tank.

### Claim 6 (depends on 4)

The method of filling a compressed gas tank according to claim 4, wherein:
the determining the values C, A, g, k and j for the tank further comprises
performing a plurality of test fills of the tank to a state of charge of 100% at a target fill time, wherein the test fills encompass a plurality of initial fill pressures and a plurality of pre-cooling temperatures;
calculating an end-of-fill MC for each test fill according to the equation
MC
=
m
2
⁡
(
u
adiabatic
-
u
final
)
(
T
final
-
T
initial
)
plotting MC against Uadiabatic/Uinitial and performing a best fit to determine the constant, C, and coefficient, A of the resulting curve;
plotting ΔMC against Δt (time—target fill time) and performing a best fit model to the resulting curve to determine the coefficients g, k and j for the equation:
ΔMC=g(1−e−k□t)j.

### Claim 7 (depends on 6)

The method of filling a compressed gas tank according to claim 6, wherein:
a first initial pressure represents a state of charge of less than 10% within the tank; and
a first pre-cooling temperature is an ambient temperature.

### Claim 8 (depends on 7)

The method of filling a compressed gas tank according to claim 7, wherein:
a second initial pressure represents a state of charge of about 50% within the tank; and
a second pre-cooling temperature is less than 0° C.

### Claim 9 (depends on 7)

The method of filling a compressed gas tank according to claim 7, wherein:
a first initial pressure is 2 MPa and a second initial pressure represents a state of charge of at least about 50% within the tank; and
a first pre-cooling temperature is an ambient temperature and a second pre-cooling temperature is −20° C.

### Claim 10 (depends on 1)

The method of filling a compressed gas tank according to claim 1, wherein the target state of charge is 100%.

### Claim 11

A method of refueling a hydrogen tank on a hydrogen powered vehicle, the method comprising:
calculating a hot soak initial temperature THSinit for an initial mass of gas within the tank;
determining a projected fill time using THSinit that is predicted to produce a final hydrogen temperature Tfinal no greater than a target temperature T;
calculating a cold soak initial temperature TCSinit for an initial mass of gas within the tank;
calculating for the tank a composite heat capacity value MC corresponding to heat transferred to the tank, a tank assembly and the initial mass of gas within the tank gas, while filling the tank;
determining a target pressure Ptarget using TCSinit that is predicted to produce a target state of charge; and
delivering gas to the tank at a pressure ramp rate that will achieve Ptarget at the projected fill time.