Multi-gas flow device
View Patent ↗A system and method of characterizing or controlling a flow of a fluid is provided that involves a sensor conduit and a bypass. A plurality of fluids may be utilized in the flow control device based on characteristic information of the device generated during calibration thereof. The characteristic information, in turn is based on a dimensionless parameters, such as adjusted dynamic pressure and adjusted Reynolds number.
1. A flow sensor comprising:
a bypass with a plurality of bypass tubes;
a sensor conduit in fluid communication with the bypass;
a sensor assembly operatively coupled to the sensor conduit to generate a measured signal representative of a flow rate of a fluid through the sensor conduit; and
a processor operatively configured to receive the measured signal and to generate a flow rate representation based at least partially on the measured signal and a characteristic function of the flow sensor, the characteristic function at least partially defined by a dynamic pressure of fluid flowing through the bypass and further based on a bypass bias function, wherein the bypass bias function is based on a ratio of dynamic pressure of a fluid flowing through the bypass relative to a measured dynamic pressure of a calibration gas flowing through the bypass.
2. The flow sensor of claim 1 , wherein the characteristic function is further defined by a Reynolds number of the fluid flowing through the bypass.
3. The flow sensor of claim 2 , wherein the characteristic function is further defined by a ratio of the dynamic pressure to the pressure drop across the bypass.
4. The flow sensor of claim 3 , wherein the characteristic function is further defined by a product of the Reynolds number and an aspect ratio of the bypass.
5. The flow sensor of claim 1 , wherein the bypass bias function is further based on a ratio of a pressure drop of the fluid flowing through the flow sensor to a measured pressure drop of the calibration gas flowing through the flow sensor.
6. The flow sensor of claim 5 , wherein the bypass bias function is at least partially defined by a polynomial function F B =(a 0 +a 1 X+a 2 X 2 +a 3 X 3 ), wherein a 0 , a 1 , a 2 , and a 3 are bypass bias function coefficients defined during flow of the calibration gas through the flow sensor and X is a product of the Reynolds number of the fluid flowing through the bypass and a ratio of the inside diameter to the length of the bypass tubes.
7. The flow sensor of claim 6 , further comprising a storage device operatively coupled to the circuit and comprising a plurality of bypass bias coefficients.
8. A flow sensor comprising:
a bypass with a plurality of bypass tubes;
a sensor conduit in fluid communication with the bypass;
a sensor assembly operatively coupled to the sensor conduit to generate a measured signal representative of a flow rate of a fluid through the sensor conduit; and
a processor operatively configured to receive the measured signal and to generate a flow rate representation based at least partially on the measured signal and a characteristic function of the flow sensor, the characteristic function at least partially defined by a dynamic pressure of fluid flowing through the bypass and at least partially based on the dimensionless number:
Re
(
D
L
)
=
ρ
U
D
μ
(
D
L
)
where Re is a Reynolds number of the fluid flowing through the bypass, ρ is the density of the fluid, μ is the viscosity of the fluid, U is the mean velocity of the fluid flowing through the bypass, D is the inside diameter of the bypass tubes, and L is the bypass tube length.
9. The flow sensor of claim 8 , wherein the characteristic function defines calibration curve defined by the relationship:
Q
Δ
P
=
G
(
Re
D
L
)
where
Q
=
1
2
(
ρ
U
2
)
and ΔP is the pressure drop across the flow sensor.
10. The flow sensor of claim 9 , wherein the calibration curve is defined by the relationship:
(
Q
Δ
P
)
f
=
(
Q
Δ
P
)
c
·
F
B
where the bypass bias function is F B =(a 0 +a 1 X+a 2 X 2 +a 3 X 3 ), and a 0 , a 1 , a 2 , and a 3 are bypass bias function coefficients defined using a calibration gas and the subscripts f and c respectively denote values corresponding to the fluid and the calibration gas.