Viscometer for newtonian and non-newtonian fluids
AssigneeRosemount Inc.
InventorRoger Kenneth Pihlaja
Life of this patent
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Abstract
A viscometer comprises a plurality of capillary tubes connected in series with a mass flow meter. The capillary tubes are smooth, straight, and unimpeded, and each has a different known, constant diameter. Differential pressure transducers sense differential pressure across measurement lengths of each capillary tube, and the mass flow meter senses fluid mass flow rate and fluid density. A data processor connected to the mass flow meter and the differential pressure transducers computes viscosity parameters of fluid flowing through the viscometer using non-Newtonian fluid models, based on the known, constant diameters and measurement lengths of each capillary tube, the sensed differential pressures across each measurement length, the fluid mass flow rate, and the fluid density.
Claims23
A viscometer comprising:
- a first capillary tube having a first diameter D1 and a first tube length LTot1;
- a first differential pressure transducer operating across a first measurement length L1 of the first capillary tube to sense a first differential pressure ΔP1, the first measurement length L1 extending across a smooth, straight, and unimpeded portion of the first capillary tube configured to produce steady state laminar flow;
- a second capillary tube fluidly connected in series after the first capillary tube and having a second diameter D2≠D1 and a second tube length LTot2;
- a second differential pressure transmitter operating across a second measurement length L2 of the second capillary tube to sense a second differential pressure ΔP2, the second measurement length L2 extending across a smooth, straight, and unimpeded portion of the second capillary tube configured to produce steady state laminar flow;
- a mass flow meter fluidly connected in series after the second capillary tube, and capable of sensing fluid density ρ and fluid mass flow rate m;
- and
- a processor in data communication with the mass flow meter, and capable of computing viscosity parameters of fluid flowing through the first capillary tube, the second capillary tube, and the mass flow meter using non-Newtonian fluid models, based on D1, D2, L1, L2, ΔP1, ΔP2, ρ, and m.
The viscometer of claim 9, wherein the processor is configured to compute τ0, μA, and n by iterating alternately between solving for τ0 and μA using a Bingham plastic model, and solving for μA and n using a Ostwald-de Waele model.
A method for characterizing viscosity of a fluid, the method comprising:
- sensing a first differential pressure of the fluid across a first length of a smooth, straight, and unimpeded first capillary having a constant first diameter;
- sensing a second differential pressure of the fluid across a second length of a smooth, straight, and unimpeded second capillary fluidly connected in series with the first capillary, and having a constant second diameter;
- sensing fluid density and fluid mass flow rate at a mass flow meter fluidly connected in series with the second capillary;
- computing adjustable viscosity parameters of a non-Newtonian fluid model using the first and second capillary lengths, the first and second diameters, the sensed first and second differential pressures, the fluid density, and the fluid mass flow rate;
- and
- outputting the computed adjustable viscosity parameters in an output signal.
A viscometer comprising:
- first capillary tube coupled to a first differential pressure sensor configured to sense a first differential pressure across a steady state region of the first capillary tube;
- a second capillary tube fluidly connected in series with the first capillary tube, and coupled to a second differential pressure sensor configured to sense a second differential pressure across a steady state region of the second capillary tube;
- a sensor device fluidly connected in series with the first and second capillary tube, and capable of sensing fluid mass flow rate and fluid density;
- and
- a data processor which computes a plurality of viscosity parameters of fluid passing through the first capillary tube, the second capillary tube, and the sensor device based on the mass flow rate, the density, the differential pressure across each capillary tube, and the dimensions of each capillary tubes.
Dependencies are inferred from the claim text.