Flowmeter fluid composition and temperature correction

Claim 2

A method according to Claim 1 characterised in that the gauge correction factor is determined according to a relationship selected from: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 or 1/C G = {(A O + k e )/(A O + k co )} n1 {B O + c pe )/(B O + c pco )} n2 {T e /T c } n3 or and the volumetric correction factor (C V ) is determined according to a relationship selected from: C V = (k e /k co ) n4 (c pe /c pco ) n5 (T e /T c ) n6 or 1/C V = {(C O + k e )/(C O + k co )} n 4{D O + c pe )/(D O + c pco )} n 5 {T e /T c } n 6 or Where: n₁ through n₆, A i , B i , m i , C i , D i , q i , and r i = constants determined by the calibration process, and k co , c pco and Tc = thermal conductivity, specific heat and temperature of the calibration gas.

Claim 3

A method according to Claim 1 or 2 characterised in that the gauge correction factor is determined according to the relationship: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 and the volumetric correction factor C V is determined according to the relationship: C V = (k e /k co ) n4 (c pe /c pco ) n5 (T e /T c ) n6 and n₁ through n₆, respectively, are approximately equal to: -   0.015331 -   0.060124 0.387617 -   0.85033 0.9845898 0.027236

Claim 5

A method according to Claim 4 characterised in that the gauge correction factor is determined according to a relationship selected from: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 or 1/C G = {(A O + k e )/(A O + k oc )} n 1{B O + c pe )/(B O + c pco )} n 2{T e /T c } n 3 or and the mass correction factor (C M ) is determined according to a relationship selected from: C M = (k e /k co ) n ⁴(c pe /c pco ) n5 (T e /T c ) n6 or 1/C M = (C O + k e )/(C O + k co ) }n 4{(D O + c pe )/(D O + c pco )} n 5 {T e /T c } n 6 or Where: n₁through n₆, A i , B i , m i , c i , D i , q i , and r i = constants determined by the calibration process, and K co , c pco and T c = thermal conductivity, specific heat and temperature of the calibration gas.

Claim 7

A method according to Claim 6 characterised in that the gauge correction factor is determined according to a relationship selected from: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 or 1/C G = {(A O + k e )/(A O + k co )} n 1{B O + c pe )/(B O + c pco )} n 2{T e /T c } n 3 or and the energy correction factor (C E ) is determined according to a relationship selected from: C E = (k e /k co ) n4 (c pe /c pco ) n5 (T e /T c ) n6 or 1/C E = {(C O + k e )/(C O + k co )} n 4 {(D O + c pe )/(D O + c pco )} n 5 {T e /T c } n 6 or Where: n₁through n₆, A i , B i , m i , c i , D i , q i , and r i = constants determined by the calibration process, and K co , c pco and T c = thermal conductivity, specific heat and temperature of the calibration gas.

Claim 11

Apparatus for compensating the flow measurement of a gaseous fluid of interest for changes in the composition, pressure and temperature of that fluid in a flowmeter having a first dynamic microbridge exposed to the flow and producing a flow-related output signal, the apparatus characterised by operating according to the method of any of the preceding claims.

Claim 12

Apparatus for compensating the flow measurement of a gaseous fluid of interest for changes in the composition, pressure and temperature of that fluid in a flowmeter having a first dynamic microbridge exposed to the flow and producing a flow-related output signal, the apparatus characterised by: (A) means to obtain an uncorrected dynamic microbridge sensor output (G) for the fluid of interest; (B) means to obtain the specific heat (c pe ) thermal conductivity (k e ) and temperature (T e ) of the fluid of interest; (C) means to apply a gauge correction factor (C G ) to G to obtain a corrected sensor output (G c ), said C G being determined according to a known relationship among values of specific heat (C pe ) thermal conductivity (k e ) and temperature (T e ) of the fluid of interest normalised with respect to a reference gas; (D) means to obtain an uncorrected volumetric flow value (V) for the fluid of interest in relation to the corrected sensor output, G c ; (E) means to apply a volumetric correction factor (C V ) to the flow value (V) to obtain the corrected volumetric flow value (V C ), C V being determined according to a known relationship, among values of specific heat (C pe ), thermal conductivity (k e ) and temperature (T e ) of the fluid of interest normalised with respect to the reference gas.

Claim 13

Apparatus according to Claim 12 characterised by means to determine the gauge correction factor according to a relationship selected from: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 or 1/C G = {(A O + k e )/(A O + k co )} n1 {(B O + c pe )/(B O + c pco )} n 2 {T e /T c } n 3 or and the volumetric correction factor (C V ) is determined according to a relationship selected from: C V = (k e /k co ) n4 (c pe /c pco ) n5 (T e /T c ) n6 or 1/C V = {(C O + k e )/(C O + k co )} n 4 {(D O + c pe )/(D O + c pco )} n 5 {T e /T c } n 6 or Where: n₁through n₆, A i , B i , m i , c i , D i , q i , and r i = constants determined by the calibration process, and K co , c pco and T c = thermal conductivity, specific heat and temperature of the calibration gas.

Claim 14

Apparatus according to Claim 12 or 13 characterised by means to determine the gauge correction factor according to the relationship: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 and the volumetric correction factor C V is determined according to the relationship: C V = (k e /k co ) n4 (c pe /c pco ) n5 (T e /T c ) n6 and n₁ through n₆, respectively, are approximately equal to: -   0.015331 -   0.060124 0.387617 -   0.85033 0.9845898 0.027236

Claim 15

Apparatus for compensating the mass flow measurement of a gaseous fluid of interest for changes in the composition, pressure and temperature of that fluid in a flowmeter having a first dynamic microbridge exposed to the flow and producing a flow-related output signal, the apparatus characterised by: (A) means to obtain an uncorrected dynamic microbridge sensor output (G) for the fluid of interest; (B) means to obtain the specific heat (c pe ) thermal conductivity (k e ) and temperature (T e ) of the fluid of interest; (C) means to apply a gauge correction factor (C G ) to G to obtain a corrected sensor output (G C ), said C G being determined according to a known relationship among values of specific heat (c pe ) thermal conductivity (k e ) and temperature (T e ) of the fluid of interest normalized with respect to a reference gas; (D) means to obtain an uncorrected mass flow value (M) for the fluid of interest in relation to the corrected gauge output (G C ); (E) means to apply a mass correction factor (C M ) to the mass flow value to obtain the corrected mass flow value (M C ), C M being determined according to a known relationship, among values of specific heat (c pe ), thermal conductivity (k e ) and temperature (T e ) of the fluid of interest normalized with respect to the reference gas.

Claim 16

Apparatus according to Claim 15 characterised by means to determine the gauge correction factor according to a relationship selected from: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 or 1/C G = {(A O + k e )/(A O + k oc )} n 1 {(B O + c pe )/(B O + c pco )} n 2 {T e /T c } n 3 or and the mass correction factor (C M ) is determined according to a relationship selected from: C M = (k e /k co ) n4 (c pe /c pco ) n5 (T e /T c ) n6 or 1/C M = {(C O + k e )/(C O + k co )} n 4 {(D O + c pe )/(D O + c pco )} n 5 {T e /T c } n 6 or Where: n₁through n₆, A i , B i , m i , c i , D i , q i , and r i = constants determined by the calibration process, and K co , c pco and T c = thermal conductivity, specific heat and temperature of the calibration gas.

Claim 17

Apparatus for compensating the energy flow measurement of a gaseous fluid of interest for changes in the composition, pressure and temperature of that fluid in a flowmeter having a first dynamic microbridge exposed to the flow and producing a flow-relating output signal, the apparatus characterised by: (A) means to obtaining an uncorrected dynamic microbridge sensor output (G) for the fluid of interest; (B) means to obtain the specific heat (c pe ) thermal conductivity (k e ) and temperature (T e ) of the fluid of interest; (C) means to apply a gauge correction factor (C G ) to G to obtain a corrected sensor output (G C ), said C G being determined according to a known relationship among values of specific heat (c pe ) thermal conductivity (k e ) and temperature (T e ) of the fluid of interest normalized with respect to a reference gas; (D) means to obtain an uncorrected energy flow value (E) for the fluid of interest in relation to the corrected gauge output (G C ) ; (E) means to apply an energy correction factor (C E ) to the flow value to obtain the corrected energy flow value, (E C ), C E being determined according to a known relationship, among values of specific heat (c pe ), thermal conductivity (k e ) and temperature (T e ) of the fluid of interest normalized with respect to the reference gas.

Claim 18

Apparatus according to Claim 17 characterised by means to determine the gauge correction factor according to a relationship selected from: C G = (k e /k co ) n1 (c pe /c pco ) n2 (T e /T c ) n3 or 1/C G = {(A O + k e )/(A O + k co )} n 1 {(B O + c pe )/(B O + c pco )} n 2 {T e /T c } n 3 or and the energy correction factor (C E ) is determined according to a relationship selected from: C E = (k e /k co ) n4 (c pe /c pco ) n5 (T e /T c ) n6 or 1/C E = {(C O + k e )/(C O + k co )} n 4 {(D O + c pe )/(D O + c pco )} n 5 {T e /T c } n 6 or {T e /T c } n 6 Where: n₁through n₆, A i , B i , m i , c i , D i , q i , and r i = constants determined by the calibration process, and K co , c pco and T c = thermal conductivity, specific heat and temperature of the calibration gas.

Claim 19

Apparatus according to any of Claims 12 to 18 characterised by a second microbridge, in relatively static communication with said fluid of interest, to determine c pe , k e and T e .

Claim 20

Apparatus according to any of Claims 12 to 19 characterised in that the means to apply C G in step (C) comprises means to determine C G according to a known relationship among variables selected from the group consisting of specific heat (c pe ), the differential of specific heat with respect to temperature (dc pe /dT), thermal conductivity (k e ), the differential of thermal conductivity with respect to temperature (dk e /dT), density, viscosity, speed of sound, optical absorption or diffusibility.