System and method for measuring flow
View Patent ↗One embodiment of the present invention can comprise a primary flow measurement system, a secondary flow measurement system in fluid communication with the primary flow measurement system and a control coupled to the primary flow measurement system and the secondary flow measurement system. The controller can comprise a processor and a memory accessible by the processor. The processor can execute computer instructions stored on the memory to calculate a flow rate using the primary flow measurement system, in a first mode of operation, and calculate the flow rate using the secondary flow measurement system, in a second mode of operation. The computer instructions can be further executable to switch between the first mode of operation and the second mode of operation based on a predefined parameter.
1. A system of determining a flow rate of a fluid comprising:
a constant volume chamber;
a sonic nozzle in fluid communication with the constant volume chamber;
one or more valves configured to direct a flow of a fluid to the constant volume chamber and the sonic nozzle;
sensors configured to read one or more parameters of the fluid; and
a controller coupled to the sensors configured to receive measurements from the sensors, the controller comprising:
a processor;
a memory accessible by the processor, the memory storing a set of computer instructions comprising instructions executable by the processor to:
in a first mode of operation, calculate the flow rate as fluid accumulates in the constant volume chamber; and
in a second mode of operation, calculate the flow rate as the fluid flows through the sonic nozzle; and
switch between the first mode of operation and the second mode of operation after a delay to allow the constant volume chamber to equilibrate.
2. The system of claim 1 , wherein, in the first mode of operation, the flow rate is calculated based on the change in pressure over time of the fluid.
3. The system of claim 2 , wherein the flow rate is approximately calculated according to
ⅆ
m
ⅆ
t
=
ⅆ
P
ⅆ
t
V
RT
.
4. The system of claim 1 , wherein, in the second mode of operation, the flow rate is calculated based on a fluid pressure.
5. The system of claim 4 , wherein, in the second mode of operation, the flow rate is approximately calculated according to
massflowrate
=
PA
γ
RT
RT
.
6. The system of claim 1 , wherein, in the second mode of operation, the flow rate is calculated based on a fluid density.
7. The system of claim 6 , wherein, in the second mode of operation, the flow rate is approximately calculated according to
massflowrate
=
ρ
A
γ
RT
.
8. The system of claim 1 ,
wherein said one or more valves are further configured to regulate the flow through the system; and
wherein the computer instructions further comprise instructions executable to control said one or more valves to regulate the flow.
9. The system of claim 8 , wherein said one or more valves comprise:
a first valve downstream of the constant volume chamber; and
a second valve downstream of the sonic nozzle.
10. The system of claim 1 , wherein the flow rate comprises a mass flow rate.
11. The system of claim 1 , wherein the flow rate comprises a volumetric flow rate.
12. The system of claim 1 , wherein the computer instructions are executable to switch between the first mode of operation and the second mode of operation based on a predefined parameter.
13. The system of claim 1 , wherein the sonic nozzle is a variable orifice sonic nozzle.
14. A method of determining a flow rate of a fluid comprising:
for a first mode of operation, calculating the flow rate as fluid accumulates in a constant volume chamber for a first range of flow rates; and
for a second mode of operation, calculating the flow rate as the fluid flows through a sonic nozzle;
delaying to allow the constant volume chamber to equilibrate; and
switching between the first mode of operation and the second mode of operation.
15. The method of claim 14 , wherein, in the first mode of operation, the flow rate is calculated based on the change in pressure over time of the fluid.
16. The method of claim 15 , wherein, in the first mode of operation, the flow rate is approximately calculated according to
ⅆ
m
ⅆ
t
=
ⅆ
P
ⅆ
t
V
RT
.
17. The method of claim 14 , wherein, in the second mode of operation, the flow rate is calculated based on a fluid pressure.
18. The method of claim 17 , wherein, in the second mode of operation, the flow rate is approximately calculated according to
massflowrate
=
PA
γ
RT
RT
.
19. The method of claim 14 , wherein, in the second mode of operation, the flow rate is calculated based on a fluid density.
20. The method of claim 19 , wherein, in the second mode of operation, the flow rate is approximately calculated according to
massflowrate
=
ρ
A
γ
RT
.
21. The method of claim 14 , further comprising:
controlling one or more valves to regulate the flow to the constant volume chamber and sonic nozzle.
22. The method of claim 14 , wherein the flow rate comprises a mass flow rate.
23. The method of claim 14 , wherein the flow rate comprises a volumetric flow rate.
24. A system of determining a flow rate of a fluid comprising:
a constant volume chamber;
a sonic nozzle in fluid communication with the constant volume chamber;
one or more valves configured to direct a flow of a fluid to the constant volume chamber and the sonic nozzle;
sensors configured to read one or more parameters of the fluid; and
a controller coupled to the sensors configured to receive measurements from the sensors, the controller comprising:
a processor;
a memory accessible by the processor, the memory storing a set of computer instructions comprising instructions executable by the processor to:
in a first mode of operation, calculate the flow rate as fluid accumulates in the constant volume chamber; and
in a second mode of operation, calculate the flow rate as the fluid flows through the sonic nozzle;
switch between the first mode of operation and the second mode of operation;
calculate the flow rate according to the first mode of operation in an overlap range of flow rates; and
calculate a cross sectional area of the sonic nozzle based on the flow rate calculated according to the first mode of operation.
25. The system of claim 24 , wherein the cross sectional area of the sonic nozzle is approximately calculated according to
A
=
massflowrate
*
RT
P
γ
RT
.
26. The system of claim 24 , wherein the cross sectional area of the sonic nozzle is approximately calculated according to
massflowrate
=
ρ
A
γ
RT
.
27. A system of determining a flow rate of a fluid comprising:
a constant volume chamber;
a sonic nozzle in fluid communication with the constant volume chamber;
one or more valves configured to direct a flow of a fluid to the constant volume chamber and the sonic nozzle;
sensors configured to read one or more parameters of the fluid; and
a controller coupled to the sensors configured to receive measurements from the sensors, the controller comprising:
a processor;
a memory accessible by the processor, the memory storing a set of computer instructions comprising instructions executable by the processor to:
in a first mode of operation, calculate the flow rate as fluid accumulates in the constant volume chamber; and
in a second mode of operation, calculate the flow rate as the fluid flows through the sonic nozzle;
switch between the first mode of operation and the second mode of operation;
calculate the flow rate according to the first mode of operation in an overlap range; and
calculate a heat capacity ratio of the fluid based on the flow rate calculated according to the first mode of operation.
28. The system of claim 27 , wherein the heat capacity ratio is approximately calculated according to
γ
=
(
RT
*
massflowrate
PA
)
2
RT
.
29. The system of claim 27 , wherein the heat capacity ratio is approximately calculated according to
γ
=
(
massflowrate
ρ
A
)
2
RT
.
30. A method of determining a flow rate of a fluid comprising:
for a first mode of operation, calculating the flow rate as fluid accumulates in a constant volume chamber for a first range of flow rates; and
for a second mode of operation, calculating the flow rate as the fluid flows through a sonic nozzle;
switching between the first mode of operation and the second mode of operation;
calculating the flow rate according to the first mode of operation in an overlap range of flow rates; and
calculating a cross sectional area of the sonic nozzle based on the flow rate calculated according to the first mode of operation.
31. The method of claim 30 , wherein the sonic nozzle is a variable orifice sonic nozzle.
32. The method of claim 30 , wherein the cross sectional area of the sonic nozzle is approximately calculated according to
A
=
massflowrate
*
RT
P
γ
RT
.
33. A method of determining a flow rate of a fluid comprising:
for a first mode of operation, calculating the flow rate as fluid accumulates in a constant volume chamber for a first range of flow rates; and
for a second mode of operation, calculating the flow rate as the fluid flows through a sonic nozzle;
switching between the first mode of operation and the second mode of operation
calculating the flow rate according to the first mode of operation in an overlap range; and
calculating a heat capacity ratio of the fluid based on a the flow rate calculated according to the first mode of operation.
34. The method of claim 33 , wherein the heat capacity ratio is approximately calculated according to
γ
=
(
RT
*
massflowrate
PA
)
2
RT
.
35. The method of claim 33 , wherein the heat capacity ratio is
approximately calculated according to
γ
=
(
massflowrate
ρ
A
)
2
RT
.