Differential pressure liquid flow controller

Abstract

Measurement accuracy and control precision can be affected by many factors, including contaminants in the liquid and irregularities in the flow path.SOLUTION: The fluid system includes a capillary tube, first and second temperature sensors, first and second pressure sensors, and a processor coupled to the sensors. The processor is configured to execute instructions to determine an output using the sensor data and using fluid parameter data received via an interface coupled to the processor. The processor is coupled to a controller in fluid communication with the capillary tube.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Priority claims This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 233,029 (Docket No. 4270.024PRV), filed August 13, 2021, which is incorporated by reference in its entirety.

[0002] This document relates generally, but not exclusively, to liquid flow controllers with improved performance. [Background technology]

[0003] Accurately measuring and controlling the flow rate of liquids or gases is important in many industrial, commercial, and medical applications. For example, semiconductor manufacturing requires fluid handling equipment where precision is critical to the fabrication and performance of the device. A flow controller can provide a flow path through which the liquid flow rate can be measured or controlled.

[0004] Measurement accuracy and control precision can be affected by many factors, including contaminants in the liquid and irregularities in the flow path. Summary of the Invention [Means for solving the problem]

[0005] The present subject matter includes a flow controller configured for accurate flow measurement and control. One example compensates for variations in fluid viscosity and density. Relationships can be established between variables such as temperature, pressure, fluid-specific parameters, and fluid flow rate. Measurement sensors can be configured to sense a first set of physical parameters and enable accurate measurement of a second set of physical parameters.

[0006] The inventors have recognized, among other things, that the problem to be solved may include receiving data corresponding to a fluid system and measuring or controlling a fluid flow rate using a flow controller. According to one example, a device can be configured to receive a temperature of a fluid in a capillary, a differential pressure across the capillary, flow rate information from a flow sensor, and fluid parameter data, and based on this data, the device can determine a flow control setting. The flow control setting, when implemented, varies the fluid flow rate and provides a negative feedback signal that enables the device to repeat data collection and again adjust the control to vary the fluid flow rate.

[0007] According to one example, the device can be configured to receive temperature of the fluid in the capillary, differential pressure across the capillary, and fluid parameter data, based on which the device can determine a fluid flow rate through the capillary, which can be expressed as a mass flow rate or a volume flow rate.

[0008] According to one example, the device can be configured to receive data related to the temperature of the fluid in the capillary, the differential pressure across the capillary, and a measured fluid flow rate. The measured fluid flow rate can be a volumetric flow rate or a mass flow rate. Taking into account the received data, the device can calculate a fluid parameter. The fluid parameter can be correlated with a component of the fluid or a selected physical parameter. The fluid parameter can be related to fluid density, fluid viscosity, or other physical parameters.

[0009] According to one example, the device can be configured to receive data related to a temperature of the fluid in the capillary, a pressure of the fluid in the capillary, and a measured fluid flow rate. The measured fluid flow rate can be a volumetric flow rate or a mass flow rate. In addition, the device can receive data related to physical parameters of the fluid in the capillary. Taking the received data into account, the device can calculate a differential pressure of the fluid in the capillary. The differential pressure can be related to fluid pressure measurements in the capillary at a first axial position in the capillary and a second axial position in the capillary.

[0010] Each of these non-limiting examples can stand on its own or can be combined with one or more of the other examples in various permutations or combinations.

[0011] This Summary is intended to provide an overview of the subject matter of this patent application. It is not intended to provide an exclusive or exhaustive description of the invention. The Detailed Description is intended to provide further information regarding this patent application.

[0012] In the drawings, which are not necessarily drawn to scale, like numerals may describe like components in different views. Like numerals with different letter prefixes may represent different instances of like components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram according to an example of the present subject matter; [Figure 2] 1 is a flowchart of a method according to an example of the present subject matter. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1 is a schematic diagram of a system 100 according to one example of the present subject matter. System 100 may be configured in a single package, sometimes referred to as a device.

[0015] The system 100 includes a capillary tube 116 having a lumen through which a fluid can flow. In the illustrated example, pressure sensors 110A and 110B, sometimes referred to as a first pressure sensor and a second pressure sensor, are attached to the capillary tube 116. The direction of fluid flow can be from left to right or from right to left through the capillary tube 116, in various examples.

[0016] In the illustrated example, temperature sensors 120A and 120B, sometimes referred to as first and second temperature sensors, are attached to the capillary tube 116. In the illustration, the temperature sensors are coupled to fittings attached to the ends (first and second ends) of the capillary tube 116. In other examples, a single temperature sensor (rather than dual) is provided and is located at either end or a location between the ends. The temperature sensors can have sensing surfaces configured to measure the temperature of the capillary wall or the fluid within the capillary tube.

[0017] Output signals from pressure sensors 110A and 110B and temperature sensors 120A and 120B are coupled to processor 114. Processor 114 may include an analog or digital computer having instructions or configurations adapted to implement the methods described herein. Processor 114 is coupled to interface 112. Interface 112 may include a user interface and may have a keyboard, a cursor control device (such as a mouse, trackball, or touchpad), a display, a printer, a microphone or speaker, or other components that enable human interaction with processor 114 or system 100. In one example, interface 112 includes a network interface configured to couple to a remote device via a wired or wireless connection.

[0018] In the illustrated example, the processor 114 is coupled to a flow sensor 122. The flow sensor 122 can be upstream or downstream of the capillary tube 116. In various examples, the flow sensor 122 includes a mass flow sensor or a volumetric flow sensor. The sensor can provide an output signal accessible to the processor 114, the signal being a function of the fluid flow rate through the system 100.

[0019] In the illustrated example, the processor 114 is coupled to a controller 124. The controller 124 can be upstream or downstream of the capillary tube 116 and can be proximal or distal to the capillary tube 116. In various examples, the controller 124 includes a valve with adjustable settings, or a pump, or other hydraulic component. In the case of a pump with a motor drive, the controller 124 can include signal lines that allow the processor 114 to set the motor speed and, therefore, the flow rate through the capillary tube 116. In the illustration, the controller 124 is depicted in series with the capillary tube 116, but other configurations are contemplated. For example, the controller 124 can include a bypass or shunt fluid path that allows the flow through the capillary tube 116 to be adjusted. The signal lines between the processor 114 and the controller 124 can include setting lines by which the controller 124 can be controlled and read lines by which the processor 114 can receive signals corresponding to the setting of the controller 124.

[0020] 2 shows a flowchart of a method 200 according to one example of the present subject matter. At 210, the method 200 includes receiving data. The data may include information about temperature from a temperature sensor or pressure from a pressure sensor. In addition, the received data may include fluid flow rate information from a flow sensor or device configuration information from a control device associated with the capillary tube of the system. In some examples, receiving the data may include receiving manually entered information regarding physical parameters of a fluid used in the system. The data may be received from a user interface or from an interface coupled to a data or communication network.

[0021] At 220, method 200 includes performing a calculation. The calculation may include executing an algorithm according to stored instructions or programming. The calculation may include determining a temperature, determining a pressure, or a pressure differential. In other examples, the calculation may include determining a flow rate or generating an output signal corresponding to the flow rate, pressure differential, temperature, or a physical parameter of the fluid.

[0022] At 230, method 200 includes providing an output. Providing an output can include generating a human-perceivable signal, such as displaying a value or parameter. In various examples, generating an output includes generating a signal configured to operate a control device in the fluid pathway. The signal can, for example, control fluid flow rate or fluid pressure or another parameter.

[0023] In Poiseuille flow, a liquid moves under the force of a pressure gradient. The gradient can be represented by a differential pressure. The differential pressure is the difference in pressure seen at the inlet and outlet of a pipe or capillary. The differential pressure is a function of fluid viscosity, volumetric flow rate, and parameters that define the pipe. Fluid viscosity is a function of temperature, whereby increasing the temperature decreases the viscosity.

[0024] The Poiseuille equation is satisfied when the fluid flow is laminar rather than turbulent. Laminar flow is associated with fluid flow below a critical Reynolds number (Re).

[0025] As the flow rate increases, the Reynolds number increases until it reaches a critical value above which laminar flow changes to transitional flow and then turbulent flow. Because the Reynolds number is inversely proportional to viscosity, which decreases with increasing temperature, such a change is expected to occur at lower flow rates when the liquid temperature is higher. Experimental testing can determine the threshold flow rate and associated critical Reynolds number at various temperatures.

[0026] Fluid flow can be represented graphically in a depiction of a Q-ΔP curve, where fluid flow and differential pressure are plotted.

[0027] Theoretical flow rate and measured flow rate can differ, and the instrumentation can be calibrated to provide an accurate measurement. In some cases, flow rate errors can be related to viscosity and the difference between theory and measurement. Because viscosity is a function of temperature, an accurate temperature measurement provides an accurate measurement of flow rate.

[0028] Temperature can be measured directly or indirectly. When measuring temperature directly, the sensing surface of the temperature sensor is in contact with the liquid being measured. When measuring temperature indirectly, the sensing surface of the temperature sensor is attached to measure the wall temperature of the liquid flow tube.

[0029] Indirect measurements can avoid complications that arise from direct contact with the liquid being tested. For example, concerns about contaminants may make direct measurements undesirable or impossible.

[0030] An example of the present subject matter includes directly measuring the liquid temperature during development. One example is configured to measure the temperature of the liquid tube and improve the method to obtain better flow calculations.

[0031] One example of the present subject matter is directed to achieving a better understanding of the relationship between flow measurements and temperature. For example, accurate temperature measurements can extend the operating range of a liquid flow controller.

[0032] The liquid temperature can be measured directly at the inlet, outlet, or both the inlet and outlet of the liquid flow controller (LFC). In addition, the LFC temperature can be measured before and after the capillary tube.

[0033] An example considers the temperature effect of viscosity on Q deltP DP LFC: Q-deltP refers to mass flow differential pressure.

[0034] One example involves a setup for the liquid temperature measured directly across a flow resistor; body temperature was also measured.

[0035] An example includes configuration for liquid temperature to directly assess actual temperature versus body temperature effects on testing.

[0036] In various examples of the present subject matter, the temperature is related to measurements at a single temperature sensor site or multiple temperature sensor sites. The temperature sensors can be attached to the capillary wall and provide a signal related to the fluid temperature. The sensor sites can be at axial locations along the length of the capillary, and in various examples, the sensor sites are at or between the ends. In some examples, the temperature sensors have sensing surfaces that are in physical contact with the fluid within the capillary.

[0037] The following equation is useful in characterizing the fluid in the capillary:

[0038]

number

[0039] μ act. =f(T)=Ae B / T

[0040] This describes the relationship between temperature (B) and viscosity μ as a function of the constants A and B.

[0041] Conversion of theoretical flow rate from calibration. Q m =ρQ v

[0042] It describes the relationship between mass flow rate (mass per unit time) and volume flow rate (volume per unit time), and ρ represents density (mass per unit volume).

[0043]

number

[0044] This equation shows that mass flow rate is a function of the differential pressure (across the capillary), the product of the ratio of actual density to standard density, and the product of the ratio of standard viscosity to actual viscosity.

[0045] It should be noted that there are relationships between certain of the various parameters. For example, viscosity is a fluid parameter that is affected by temperature. In addition, differential pressure and temperature are related.

[0046] The onset of transitional and turbulent flow can be seen at various temperatures. In some cases, the critical Re is 2500.

[0047] Features such as wall contour or edge irregularities at the capillary inlet can affect the critical Reynolds number. Irregularities can cause turbulence in the inlet flow, thereby lowering the critical Reynolds number. Irregularities can be addressed by removing sharp edges and providing an appropriate contour radius at the capillary inlet. In one example, a filter can be placed upstream of the capillary inlet to capture particles and debris. However, the filter can be placed far enough away so as not to cause disturbances by itself.

[0048] The accuracy of the flow calculation over the operating range of the LFC is examined using a temperature compensation method that utilizes the following calculation to adjust for density and viscosity: In the equation below, the variables A, B, and C are determined by the physical dimensions of the system, here related to a capillary tube. viscosity:

[0049]

number

[0050] density:

[0051]

number

[0052] If the tube is configured in a helical fashion, deformation of the capillary inner diameter may be observed.

[0053] In one example, computational fluid dynamics (CFD) modeling can be applied to the flow path at selected locations, for example, CFD modeling is performed downstream of the second pressure sensor to check for turbulence in the flow.

[0054] A ferrule seal can be provided by a commercially available ferrule (such as that provided by VICI-Valco).

[0055] An example of the disclosed subject matter can be configured for use with a variety of liquids, including TEOS (tetraethyl orthosilicate or tetraethoxysilane), water, isopropyl alcohol, methanol, solvents, petroleum products, polymers, and biological fluids.

[0056] In one example, the temperature can be controlled based on an output signal provided by a processor, for example, the temperature of the capillary, the temperature at the inlet end of the capillary, or the temperature at the outlet end of the capillary.

[0057] Analysis of QvΔP can reveal differences if the downstream liquid stream is coupled to a vacuum rather than being exhausted to atmosphere.

[0058] In one configuration, the capillary tube is insulated.

[0059] In one configuration, a syringe (plastic or non-plastic) is used to determine the response time.

[0060] The vacuum pump can be configured to draw air and remove air bubbles, which may affect response time.

[0061] In one example, an air bubble is introduced into the system and the effect on the response time is measured, for example, if an air bubble is present in the capillary, a change can be monitored.

[0062] The flow rate is a function of the temperature. Q=f(ΔP) (μ std / μ act ) Q1=f(ΔP)·(μ std / μ act ) Q2=f(ΔP)·(μ std / (μ act +Δ)) Q1 / Q2=(μ act +Δ) / μ act =1+Δ / μact μ act = 1 and Δ = 0.01, Q1 / Q2 = 1 ± 0.01 μ act = 0.8 and Δ = 0.01, Q1 / Q2 = 1 ± 0.02

[0063] In one example of the present subject matter, a device is configured to operate a component fluidly coupled in series with a capillary. The component can be positioned in the fluid passage upstream or downstream of the capillary. In addition, the component can be coupled in a path parallel to the capillary.

[0064] The component, sometimes referred to as a controller, can be a component that allows for managing the flow of fluid through the capillary tube. The component can be a fluid pump for pressurizing the fluid. The pump can be a vane pump, a diaphragm pump, a piston pump, or other type of mechanical pump. In one example, the pump is driven by a motor, where the motor speed determines the pump flow rate or pump pressure, and the motor speed is determined by a signal from the processor. In various examples, the controller includes a pump with a variable pressure setting or a bypass channel, and a signal delivered to the controller allows for variation in pump performance. In one example, the controller includes a valve. The valve can be controlled by a signal from the processor. In one example, the controller includes a variable orifice, and the signal from the processor can be configured to adjust or select the size of the orifice.

[0065] In one example, the control unit includes a thermal device, and thus an output signal from the processor can be configured to increase or decrease the thermal energy delivered to the device.

[0066] In this example, a first temperature sensor and a second temperature sensor are each coupled to a respective end of the capillary tube, and a first pressure sensor and a second pressure sensor are also coupled to a respective end of the capillary tube.

[0067] The interface may include a user-operable data input device. Examples of the interface may include a cursor control device (such as a mouse, trackball, or touchpad), a keyboard, a touchscreen, or a microphone. In addition, various instances of the interface may include a printer and a display screen. In one example, the interface includes a network interface configured to communicate data and instructions via a wired or wireless connection with a communications or data network.

[0068] In one example, the interface allows for input of fluid parameters, which can include physical parameters including fluid viscosity, fluid density, and fluid composition (including contaminants, particles, and other components).

[0069] In one example, a flow sensor is coupled to the capillary tube. The flow sensor can include a mass flow sensor, such as a Coriolis sensor. In various examples, the flow sensor can include a mechanical-based sensor (such as a turbine flow meter), a pressure-based sensor (such as a Pitot tube), a variable area flow meter, an optical flow meter, an open channel flow meter, a thermal mass flow meter, a vortex flow meter, a sonar flow meter, an electromagnetic flow meter, an ultrasonic flow meter, and an optical flow meter. The flow sensor can provide a signal to the processor.

[0070] In one example, a processor executes an algorithm to receive sensor data (temperature, pressure, flow rate) and data characterizing fluid parameters. Based on the received data, the processor provides an output signal to a controller. The output signal can be adjusted to achieve a specific flow rate or establish a specific temperature, pressure, or pressure differential associated with the capillary tube.

[0071] In one example, a processor receives sensor data (temperature and pressure) and executes an algorithm to receive data characterizing fluid parameters. Control elements can be omitted or can be operated at fixed settings. Based on the received data, the processor provides an output signal to determine a flow rate. The output signal can be adjusted to provide a precise flow rate based on received data regarding the temperature and pressure differential associated with the capillary tube. The flow rate can be indicated by a visual display.

[0072] In one example, the processor executes an algorithm to receive sensor data (temperature, pressure, flow rate). Based on the received data, if configured with a fixed or non-adjustable control element associated with the capillary tube, the processor provides an output signal corresponding to a selected fluid parameter. The output signal can be adjusted to provide data indicative of fluid viscosity, fluid density, particle count, or another parameter. In one example, the output signal can be used for fluid identification or fluid matching.

[0073] In one example, a processor receives temperature sensor data, pressure sensor data, and flow rate and executes an algorithm to receive data characterizing a fluid parameter. The pressure sensor data can be associated with a sensor at a first end of the capillary tube, a sensor at a second end of the capillary tube, or some other pressure data. Based on the received data, the processor, if configured with a fixed or non-adjustable control element associated with the capillary tube, provides an output signal corresponding to a differential pressure. The output signal can be correlated to the differential pressure relative to one sensed pressure data received by the processor.

[0074] In one example, a processor executes an algorithm to receive temperature sensor data, differential pressure sensor data, and flow rate and receive data characterizing a fluid parameter. The temperature sensor data can be associated with a sensor at a first end of the capillary tube, a sensor at a second end of the capillary tube, or some other temperature data. Based on the received data, the processor provides an output signal corresponding to the temperature, if configured with a fixed or non-adjustable control element associated with the capillary tube.

[0075] One objective includes measuring liquid temperature and liquid flow rate. This may be true for high and low flow rates. Various techniques can be used to measure liquid temperature. Also, consider some of the costs associated with directly measuring liquid temperature. A relationship may be found between flow rate measurement and temperature. Accurate temperature measurement can extend the operating range of the flow rate measurement. One interesting aspect relates to the flow driving the temperature profile.

[0076] One aspect of the present subject matter relates to measuring or controlling differential pressure to control flow. Fluid flow is affected by many factors, including various physical parameters of the fluid (such as viscosity, particle content, and density) and fluid temperature. In one example of the present application, a control component is configured to manage the fluid flow. The control component may include a pump, a valve, a reservoir, or other device that affects the fluid flow. In one example, an algorithm is executed by a processor to provide control of the fluid, or to control a device in fluid communication with the capillary, or to provide a measurement of a calculated value.

[0077] In one example, the present subject matter includes a device that is calibrated at a first temperature and then operated at another temperature. One example of the present subject matter provides a correlation that allows calibration curves to be generated under standard and non-standard conditions.

[0078] Various precautions The above description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are also referred to herein as "examples." Such examples may include elements in addition to those shown or described. However, the inventors also contemplate examples in which only those elements shown or described are provided. Furthermore, the inventors also contemplate examples using any combination or permutation of those shown or described elements (or one or more aspects thereof) with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0079] In the event of a conflict in usage between this document and any document incorporated by reference, the usage in this document shall prevail.

[0080] As used herein, the terms "a" or "an" are used, as is common in patent documents, to include one or more, regardless of any other instance or usage of "at least one" or "one or more." The term "or" is used herein to refer to a non-exclusive or, such as "A or B" including "A but not B," "B but not A," and "A and B," unless otherwise indicated. The terms "comprising" and "in which" are used herein as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the appended claims, the terms "comprising" and "comprising" are open-ended, i.e., systems, devices, articles, compositions, formulations, or processes that include elements in addition to those listed after such terms in a claim are still considered to be within the scope of that claim. Furthermore, in the appended claims, terms such as "first," "second," and "third" are used merely as labels and are not intended to impose numerical requirements on their objects.

[0081] Geometric terms such as "parallel," "perpendicular," "circular," or "square" are not intended to require absolute mathematical precision unless the context dictates otherwise. Instead, such geometric terms allow for variations due to manufacturing or equivalent functions. For example, if an element is described as "circular" or "nearly circular," components that are not exactly circular (e.g., slightly rectangular or polygonal) are still encompassed by this description.

[0082] The example methods described herein can be at least partially machine- or computer-implemented. Some examples include a computer-readable or machine-readable medium encoded with instructions operable to configure an electronic device to perform the methods described in the examples above. Implementations of such methods can include code, such as microcode, assembly language code, high-level language code, etc. Such code can include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, in one example, the code can be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memory (RAM), read-only memory (ROM), etc.

[0083] The above description is intended to be illustrative, not limiting. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be utilized by those of ordinary skill in the art who review the above description. The Abstract is provided to enable the reader to quickly ascertain the nature of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be construed as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in fewer than all features of a particular disclosed embodiment. Accordingly, the appended claims are hereby contemplated, with each claim standing on its own as a separate embodiment, incorporated into the Detailed Description as an example or embodiment, and such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled. [Explanation of symbols]

[0084] 100 systems 110A Pressure Sensor 110B Pressure Sensor 112 Interface 114 processors 116 Capillary 120A Temperature Sensor 120B Temperature Sensor 122 Flow sensor 124 Control Unit

Claims

1. 1. A fluid system comprising: a capillary tube having a diameter substantially smaller than a length of the capillary tube, the capillary tube further having a first end and a second end; at least one temperature sensor, at least one temperature sensor coupled to measure the temperature of at least one object selected from objects including a wall of the capillary tube to indirectly measure the temperature of a fluid flowing within the capillary tube, and coupled in proximity to the fluid to directly measure the temperature of the fluid flowing within the capillary tube; at least one pressure sensor for measuring a differential pressure of the fluid flowing within the capillary; a processor coupled to the at least one temperature sensor and the at least one pressure sensor, the processor comprising: a temperature based on the at least one temperature sensor; the pressure difference; and at least one fluid parameter; a processor configured to execute instructions to determine an output using the at least one fluid parameter, wherein the at least one fluid parameter is received using an interface coupled to the processor; and A fluid system comprising:

2. The fluid system of claim 1 , further comprising a control unit in fluid communication with the capillary tube and coupled to the processor, the control unit including at least one device selected from devices including a valve, a pump, and an orifice.

3. The fluid system of claim 1 , wherein the interface includes a user-operable data input device.

4. The fluid system of claim 1 , wherein the interface comprises a connection to a network.

5. The fluid system of claim 1 , further comprising a flow sensor coupled to the processor and fluidly coupled to the capillary tube.

6. The fluid system of claim 5 , wherein the flow sensor comprises a mass flow sensor.

7. 1. A fluid system comprising: a capillary tube having a first end and a second end; at least one temperature sensor coupled to the capillary tube; a first pressure sensor disposed at the first end of the capillary tube; a second pressure sensor disposed at the second end of the capillary tube; a processor coupled to the at least one temperature sensor, the first pressure sensor, and the second pressure sensor, the processor comprising: a temperature based on the at least one temperature sensor; a first pressure based on the first pressure sensor; a second pressure based on the second pressure sensor; and at least one fluid parameter; a processor configured to execute instructions to determine an output using the capillary tube, the output corresponding to a measure of flow rate in the capillary tube; A fluid system comprising:

8. The fluid system of claim 7 , wherein the processor is coupled to a display configured to provide a visual representation of the output.

9. The fluid system of claim 7 , further comprising an interface having a user-operable data input device.

10. The fluid system of claim 9 , wherein the interface comprises a connection to a network.

11. 1. A fluid system comprising: a capillary tube having a first end and a second end; at least one temperature sensor, at least one temperature sensor coupled to measure the temperature of at least one object selected from objects including a wall of the capillary tube to indirectly measure the temperature of a fluid flowing within the capillary tube, and coupled in proximity to the fluid to directly measure the temperature of the fluid flowing within the capillary tube; at least one pressure sensor for measuring a differential pressure of the fluid flowing within the capillary; a processor coupled to the at least one temperature sensor and the at least one pressure sensor, the processor comprising: a temperature based on the at least one temperature sensor; the pressure difference; and a flow rate based on a flow sensor coupled to the capillary; a processor configured to execute instructions to determine an output using a capillary tube, the output being based on at least one parameter of the fluid in the capillary tube; A fluid system comprising:

12. The fluid system of claim 11 , wherein the flow sensor comprises a mass flow sensor.

13. The fluid system of claim 11 , wherein the processor is coupled to a display configured to provide a visual representation of the output.

14. 1. A fluid system comprising: a capillary tube having a first end and a second end; at least one temperature sensor, at least one temperature sensor coupled to measure the temperature of at least one object selected from objects including a wall of the capillary tube to indirectly measure the temperature of a fluid flowing within the capillary tube, and coupled in proximity to the fluid to directly measure the temperature of the fluid flowing within the capillary tube; at least one pressure sensor for measuring a differential pressure of the fluid flowing within the capillary; a processor coupled to the at least one temperature sensor and the at least one pressure sensor, the processor comprising: a first temperature based on the at least one temperature sensor; and a first pressure based on the at least one pressure sensor; and at least one fluid parameter; a flow rate received from a flow sensor in fluid communication with the capillary tube; a processor configured to execute instructions to determine an output using the differential pressure associated with the first pressure; A fluid system comprising:

15. The fluid system of claim 14 , further comprising an interface having a user-operable data input device.

16. The fluid system of claim 15 , wherein the interface comprises a connection to a network.

17. The fluid system of claim 14 , wherein the flow sensor comprises a mass flow sensor.

18. The fluid system of claim 14 , wherein the flow sensor comprises a volumetric flow sensor.

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